JP4723453B2 - Engine and motorcycle - Google Patents

Description

  The present invention relates to an engine and a motorcycle equipped with the engine.

  For example, an engine such as a parallel 4-cylinder (in-line 4) for motorcycles has conventionally adopted a “center cam train structure”. As shown in the plan view of FIG. 1A, the center cam train structure is formed by a chain line portion 4 arranged at the center of four cylinders 1 (shown by broken-line circles in FIG. 1A). 3 drives two camshafts 2 on the intake side and the exhaust side, respectively.

  By the way, a cylinder head block (hereinafter simply referred to as a “head block”) 5A is provided with each cylinder in order to resist the stress during combustion of each cylinder 1 when fastened to a cylinder block (not shown) below the cylinder head block. It is necessary to place bolts 6 on both sides of 1 and fix them firmly.

  However, in the center cam train structure as described above, the chain line portion 4 is arranged at the center, and the sprocket 4a of the chain line portion 4, particularly the sprocket 4a is obstructive, and the bolt 6 is placed at the position of the sprocket 4a. Could not be placed. Therefore, it is necessary to dispose the bolts 6 on both sides of the sprocket 4a. The number of bolts 6 is inevitably increased by two, and as shown in FIG. 1 (a), both sides of the sprocket 4a. In some cases, the width of the entire head block 5A (indicated by “4A + B” in FIG. 1A) is increased by the distance B between the bolts 6.

  In order to solve this problem, a so-called “side cam train structure” as shown in FIG. In the side cam train structure, the chain line portion 4 is arranged at the end of the head block 5B, and there is an advantage that the head block 5B can be made substantially smaller by B 'with respect to the center cam train structure. B 'is generally about 20 to 30 mm.

  Reducing the width of the head block is advantageous, for example, for a motorcycle having a frame structure such as a double cradle type having a pair of tank rail frames as a main frame.

  The pair of tank rail frames is a thick frame having a rectangular cross section extending rearward and downward from the head pipe and spaced apart from each other, and the fuel tank is disposed along the frame. The head block is a pair of tank rails. Usually located between the frames. For this reason, an increase in the distance between the pair of tank rail frames increases the rigidity of the motorcycle frame as a whole (especially longitudinal rigidity and torsional rigidity), but causes the entire frame to lose its stickiness and turn. Performance and operability may be reduced.

  By the way, the upper surface of the cylinder head block incorporating the valve mechanism is covered with a cylinder head cover (hereinafter simply referred to as “head cover”) together with the valve mechanism such as a camshaft exposed on the upper surface.

  As with the engine as a whole, the weight reduction of the head cover has always been a problem, but in the case of a motorcycle, since it is positioned above the vehicle body, the weight reduction is particularly important for the purpose of lowering the center of gravity.

  The camshaft formed on the shaft is rotatably arranged so that the lower half is embedded in the upper surface of the head block, and from above, the upper half is rotatably supported by the head cover. It may be.

  It is difficult to form the lower surface of the head cover having such a configuration so that the cam on the cam shaft is firmly supported against the stress at the time of combustion of each cylinder disposed below the cam cover, and inevitably has a weight. Cause an increase.

  In addition, since the valve timing cannot be adjusted without covering the head cover, adjustment of the valve timing may be forced while opening and closing the head cover many times.

Furthermore, when adjusting the normal tappet clearance, the head cover needs to be opened and closed.
JP-A-60-243307

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a lightweight engine that can easily adjust valve timing and tappet clearance, and a motorcycle equipped with the engine.

Engine according to the present invention includes a camshaft cap rotatably supporting the both end portions of the camshaft that is placed on the upper surface of the sheet cylinder head block from above, placed over the upper portion of the cylinder head block, covering the camshaft It includes a support portion that will be formed on the lower surface of the cylinder head cover, wherein the support portion is located between said cam shaft cap, a portion of the remaining camshaft from above that are not supported by the camshaft cap It is provided with the support part supported so that rotation is possible.

According to the present invention, since both ends of the camshaft are supported by the camshaft cap, the valve timing can be adjusted without the cylinder head cover. Further, since it is not necessary to form a support portion for supporting the camshaft from above on the cylinder head cover at the camshaft cap placement position, the configuration of the cylinder head cover is simplified and the weight can be reduced. Furthermore, it is not necessary to open and close the head cover when adjusting the normal tappet clearance.

In the above invention, the support portion is preferably provided between any pair of adjacent cam surfaces. In the above invention, the cylinder head block is preferably configured to cover the camshaft and a drive system power transmission mechanism that drives the camshaft. Furthermore, in the above invention, a through hole is formed in the cylinder head cover, a screw hole is formed in the support portion, and a bolt inserted into the through hole is screwed into the screw hole of the support portion. The cylinder head cover is preferably fixed on the cylinder head block.

  As described above, according to the present invention, it is possible to provide a lightweight engine that can easily adjust valve timing and tappet clearance and a motorcycle equipped with the engine.

  Hereinafter, an engine according to the present invention and a motorcycle equipped with the engine will be specifically described with reference to the accompanying drawings.

  The cylinder head block (hereinafter simply referred to as “head block”) 50 of the engine according to the embodiment of the present invention shown in the plan view of FIG. 2 shows an example applied to a parallel 4-cylinder DOHC type engine. It can be applied to any other multi-cylinder DOHC engine.

  In the drawings of the present embodiment, “F” indicates a direction corresponding to the front of the motorcycle 100 according to the present embodiment (for example, see FIG. 3).

  The head block 50 has two (a pair) camshafts 20 arranged along the arrangement direction of the cylinders 10. The two camshafts 20 are each provided with a cam 30 for each cylinder 10. In general, one camshaft 20 has an intake valve (not shown) and the other camshaft 20 has an exhaust valve (not shown). It is configured to be driven by a corresponding cam 30. However, in the present embodiment, the two camshafts 20 may correspond to the intake side or the exhaust side except when applied to a motorcycle of a specific form to be described later.

  One camshaft 20 is extended more than the other camshaft 20, and a drive system 40 is provided at the end thereof. The drive system 40 can be any power transmission mechanism that can drive the camshaft 20, and is, for example, a chain / sprocket mechanism, a belt / pulley mechanism, a gear mechanism, or the like.

  The drive system 40 is generally connected to a crankshaft (not shown), and drives the camshaft 20 at a rotational speed that is half the number of rotations of the crankshaft.

  Gears 45 that mesh with each other are provided at the center position of the two camshafts 20 (that is, the center position that sandwiches the two cylinders 10 on both sides). These gears 45 constitute a power transmission mechanism that transmits power from one camshaft 20 to the other camshaft 20. The power transmission mechanism may be, for example, a chain / sprocket mechanism, a belt / pulley mechanism, or the like other than the gear mechanism illustrated here.

  With such a power transmission mechanism accommodated in the head block 50, the bolt 60 can be disposed in the space below the power transmission mechanism. That is, the width dimension of the head block 50 is suppressed to the same level as the “side cam train structure” as described above (indicated by “4A” in FIG. 2).

  Further, unlike the “side cam train structure”, the drive system 40 according to the present embodiment directly drives only one camshaft 20, and therefore, the side cam corresponding to the other camshaft is “side cam”. The entire engine can be made smaller than the “train structure”.

  Such downsizing of the head block 50 can also reduce the cylinder head cover (hereinafter simply referred to as “head cover”) disposed on the head block 50 and contribute to lowering the center of gravity and reducing the weight of the engine. .

  FIG. 3 shows an example in which the head block 50 according to the present embodiment is applied to a motorcycle 100 having a tank rail frame as a main frame, for example, a double cradle type frame structure.

  In this double cradle type frame structure, a pair of thick tank rail frames 110 generally having a rectangular cross section extend away from the head pipe 120 rearward and downward, along which a fuel tank (not shown), etc. Is placed. In the example of FIG. 3, the head block 50 is disposed with the space 900 facing the front side (that is, the drive-side camshaft 20 is disposed rearward).

  The pair of tank rail frames 110 are narrow in the vicinity of their front ends connected to the head pipe 120, but the head block 50 is disposed with its space 900 facing the front side, so It is possible to contribute to reducing the distance between the tank rail frames 110.

  This reduction in the mutual separation distance reduces the possibility that the handlebar 130 that operates the front wheel 140 will interfere with the tank rail frame 110, optimizes the driver's knee grip, and improves the rigidity balance of the entire frame ( In particular, longitudinal rigidity and torsional rigidity can be reduced), and performance such as turning performance and operability as a motorcycle can be improved.

  FIG. 4 is a partial sectional right side view of the motorcycle 100 and shows an example in which the drive system 40b is arranged on the rear side in the same manner as described above. In this example, an example of gear drive is used as the drive system 40b. Show. The driven gear (connected to the camshaft 20) of the drive system 40b is located between the pair of tank rail frames 110, but the portion corresponding to the space 900 on the front side supports the engine 90 on the tank rail frame 110. There is also an advantage of not interfering with the hanger frame 112A. As described above, the advantage is particularly great in the motorcycle 100 of the type in which the cylinder of the engine 90 as shown in FIG. 4 is tilted forward.

  On the other hand, when the drive system 40b is arranged on the front side, the driven gear of the drive system 40b is now in a position where it interferes with the hanger frame 112A. Therefore, in such a case, the hanger frame 112B is disposed on the rear side of the cylinder block as indicated by a broken line in FIG.

  In this way, the head block 50 can be positioned between the pair of tank rail frames 110 while suppressing the separation distance between the pair of tank rail frames 110, so that the fuel tank, ECU ( The position of the electronic control unit) and air box is not increased, and the center of gravity of the motorcycle can be kept low. In addition, since the height of the fuel tank can be suppressed, it is easy for the driver to take a posture of lying down on his / her upper body or face, which contributes to improvement in running performance.

  FIG. 5 is a perspective view showing a detailed internal structure of the head block 50. On the upper surface of the head block 50, two camshafts 20 are parallel to each other via a support portion 59 (FIG. 2) integrally formed on the upper surface of the head block 50, and the lower half of the camshaft 20 is rotated about its axis. It is supported rotatably. As shown in FIG. 2, the support portion 59 is disposed at a position corresponding to each cylinder and between the pair of cam surfaces of the cam 30.

  As will be described later, the head cover 80 (see FIGS. 6 and 11) also has a camshaft at a position facing the support portion 59 of the head block 50 (except for a position supported by a camshaft cap 72 described later). A support portion 89 is provided to support 20 so as to be rotatably held about the axis from above.

  Each camshaft 20 has eight cams 30 at equal intervals in the axial direction, and each cam 30 has a cam surface (not shown) for operating a valve (here, one cylinder) Shows an example of four valves with two intake valves and two exhaust valves).

  Gears 45 are arranged at the center positions of the camshaft 20 and mesh with each other. Accordingly, one camshaft 20 (in the example of FIG. 5, the intake side) is driven by the drive system 40, and power is transmitted to the other camshaft 20 (in the example of FIG. 5, the exhaust side), The cam 30 can be operated. Reference numeral 52 indicates an exhaust port.

  Each camshaft 20 is fixed to the upper surface of the head block 50 by a camshaft cap 72 so that both ends can be rotated from above. In the present embodiment, each camshaft cap 72 is disposed so as to press the camshaft 20 at a position between the two cam surfaces of the cam 30 located at the end of the camshaft 20.

  In the example of FIG. 5, the camshaft caps 72 are arranged separately for each camshaft 20, but as shown by a broken line in FIG. 5, two camshafts 20 with one long camshaft cap. It is also possible to configure so as to hold down.

  In the present embodiment, each gear 45 is provided with a valve timing adjustment mechanism. This valve timing adjusting mechanism is a known mechanism that adjusts the rotational phase of the gear 45 with respect to the camshaft 20 by adjusting the position of the bolt 45b in the long hole 45a formed in the circumferential direction of the gear 45. is there.

  With the camshaft cap 72, the camshaft 20 can be fixed to the head block 50 before the head cover 80 (see FIG. 6) is put on the head block 50, and the valve timing adjustment formed on the gear 45 is also possible. The mechanism allows adjustment of the valve timing in this state.

  Furthermore, before the head cover 80 (see FIG. 6) is put on the head block 50, the clearance between the cam surface and the tappet (that is, the tappet clearance) can be adjusted.

  As shown in FIGS. 6 and 11, the head cover 80 has a back surface (lower surface) when the remaining portion of the camshaft 20 not pressed by the camshaft cap 72 (see FIG. 5) is put on the head block 50. It is formed so that it can be pressed down with.

  In other words, as described above, the head cover 80 can rotate only about the portion of the camshaft 20 that is not supported by the camshaft cap 72 in the position facing the support portion 59 of the head block 50 from above. A plurality of support portions 89 (see FIG. 11) are provided to support so as to be held. In FIG. 11, an example of a chain / sprocket mechanism is shown as the drive system 40.

  The head cover 80 covers the upper surface of the head block 50 and is configured to cover the internal camshaft 20, the gear 45, the drive system 40, the camshaft cap 72, and the like. A large number of through holes 84a are formed in the head cover 80, and bolts 84 (see the assembly drawing of FIG. 7) inserted through the through holes 84a are respectively formed at corresponding positions on the upper surface of the head block 50. The head block 50 is fixed by being screwed to 70.

  As shown in FIG. 5, in the present embodiment, the screw hole 70 is disposed at a position between the pair of cam surfaces of the cam 30 on the upper surface of the head block 50, and further, in the width direction end of the head block 50. It is also arranged in the part. However, since the camshaft cap 72 presses the camshaft 20 with the support portion 89 inside the head cover 80 (see FIG. 6), the through hole 84a (and the head cover) disposed at the end in the width direction of the head block 50. Similarly, the number of 80 through holes 84a) can be reduced or eliminated.

  Further, the lubrication oil supply system to the camshaft 20, the cam surface, and the valve (not shown) is lubricated on the intake side surface of the head block 50 as shown in FIGS. It is supplied from a cylinder block (not shown) below the oil path 78 (refer to the arrow in the figure for the supply direction).

  Lubricating oil paths 78 are formed at both ends in the width direction of the head block 50, and the lubricating oil supplied upward from a cylinder block (not shown) is supplied to the head cover by these two lubricating oil paths 78. Supplied from both sides in the width direction within 80.

  Lubricating oil supplied into the head cover 80 flows in a direction orthogonal to the camshaft 20 by a lubricating oil path 82 formed in the head cover 80, and then branched into two passages, respectively. The head cover 80 is configured to flow toward the center in the width direction along the direction 20.

  The branched lubricating oil path 82 flows downward from the head cover 80 at the position of each camshaft cap 72, and is introduced into the camshaft cap 72 from an introduction port 74 formed on the upper surface of each camshaft cap 72. The introduction port 74 passes through the camshaft cap 72 in the vertical direction, and can supply lubricating oil to the supporting portion of the camshaft 20 below, the cam 30, a valve (not shown), and the like.

  FIG. 9 is a perspective view showing a configuration of a head block 50B provided with a valve timing adjusting mechanism according to another embodiment. In the head block 50B, a valve timing adjusting mechanism is provided only in the gear 45 on the exhaust valve side. The valve timing adjustment mechanism is not provided in the gear 45B on the intake valve side. Instead, the valve timing adjustment mechanism is provided in the drive system 40B including the gear mechanism.

  As shown in FIG. 10, the valve timing adjustment mechanism provided in the drive system 40B has the same structure as the valve timing adjustment mechanism provided in the gear 45 on the intake valve side, and is provided on the camshaft 20 on the exhaust valve side. This is a known mechanism that adjusts the rotational phase of the gear 402 with respect to the camshaft 20 by adjusting the position of the bolt 408 in a long hole 406 formed in the circumferential direction of the formed gear 402.

  Although a manual valve timing adjustment mechanism is shown as an example here, it is needless to say that any appropriate known automatic valve timing adjustment mechanism can be arranged in the same manner.

  In another embodiment shown in FIG. 9 and FIG. 10, the same reference numerals are given to the same parts as those of the previous embodiment, and the description thereof is omitted.

  Although the present disclosure includes specific embodiments, since various modifications are possible, the specific embodiments cannot be considered in a limited sense. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various elements, features, functions and / or properties disclosed herein. The claims particularly point out certain combinations and subcombinations regarded as new and non-obvious. Other combinations and sub-combinations of features, functions, elements, and / or properties may be claimed through amendments of the current claim or through the presentation of new claims in this or related applications. Such claims, whether broader, narrower, equivalent or different from the scope of the original claims, are considered to be included within the subject matter of this disclosure.

  As described above, the present invention can be applied to applications such as motorcycles that are required to provide a light-weight engine that can easily adjust valve timing and tappet clearance.

(A) is a plan view of a head block having a conventional “center cam train structure”, and (b) is a schematic plan view of a head block having a conventional “side cam train structure”. FIG. 2 is a schematic plan view of a head block having a structure according to an embodiment of the present invention. FIG. 3 is a schematic partial plan view of a motorcycle showing an arrangement example of a head block of an engine having the structure shown in FIG. 2 (gear drive of a rear camshaft). Fig. 3 is a partial right side view of a motorcycle showing an arrangement example of a head block of an engine having the structure shown in Fig. 2 (gear drive of a rear camshaft). FIG. 3 is a perspective view showing an internal structure of the head block shown in FIG. 2. FIG. 6 is a perspective view showing a head cover for the head block shown in FIG. 5. FIG. 6 is a perspective view showing a state in which the head cover shown in FIG. 6 is attached on the head block shown in FIG. 5. FIG. 8 is a side view of FIG. 7 from the intake port side. It is a perspective view which shows the internal structure of the head block which has the structure concerning the 2nd Embodiment of this invention. FIG. 10 is a side view of the head block shown in FIG. 9 from the chain line portion side. It is II sectional drawing of FIG.

Explanation of symbols

10 cylinders
20 Camshaft
30 cams
50, 50B Cylinder head block
72 Camshaft cap
80 Cylinder head cover
100 motorcycle

Claims (3)

Two camshafts cap rotatably supporting the both end portions of the camshaft from above is disposed on the upper surface of the sheet cylinder head block,
And a support portion that will be formed on the lower surface of the cylinder head cover covering the camshafts are covered above the cylinder head block,
The support portion is located between the two camshaft caps, and supports the portion of the remaining camshaft not supported by the camshaft cap so as to be rotatable from above .
An engine comprising: The engine according to claim 1 , wherein the support portion is provided between a pair of adjacent cam surfaces . The engine according to claim 1, wherein the cylinder head block is configured to cover the camshaft and a drive system power transmission mechanism that drives the camshaft .

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