WO2006137519A1

WO2006137519A1 - Engine

Info

Publication number: WO2006137519A1
Application number: PCT/JP2006/312608
Authority: WO
Inventors: Shohei Kono; Manabu Hashimoto; Souhei Honda
Original assignee: Honda Motor Co., Ltd.
Priority date: 2005-06-23
Filing date: 2006-06-23
Publication date: 2006-12-28
Also published as: EP1895135A1; BRPI0613155A2; DE602006011315D1; AU2006260106B2; AU2006260106A1; MY142921A; PE20070129A1; EP1895135A4; KR20080007377A; ES2337182T3; CA2606776A1; PA8682301A1; TW200704873A; KR100947005B1; CA2606776C; AR054794A1; EP1895135B1; TWI318660B

Abstract

An engine where a crankshaft (12) and a camshaft (36) are connected by a timing transmission device (37) composed of a drive rotation member (45), a driven rotation member (46), and an endless transmission member (47), a working window (55) for attaching and detaching the driven rotation member (46) to and from the cam shaft (36) is opened in an outer end surface (5c) of a cylinder head (5), and a lid body (57) for closing the working window (55) is joined to the outer end surface. The outer end surface (5c), to which the lid body (57) is joined, of the cylinder head (5) is the inclined surface (5c) inclined such that that outer peripheral section of the driven rotation member (46) which is on the opposite side of the drive rotation member (45) is exposed from the working window (55). The construction improves workability in installation of the endless transmission member on the driven rotation member, installation of the driven rotation member on the camshaft, etc., and in addition, the construction contributes to downsizing of the engine.

Description

Specification

Engine

Technical field

[0001] The present invention provides a drive rotary member fixed to the crankshaft and a slave fixed to the camshaft between the crankshaft supported by the crankcase and the valve camshaft supported by the cylinder head. The rotating and rotating members and the timing of the endless transmitting member force applied to both rotating members are connected via a transmission, and a working window is provided on one side of the cylinder head to attach and detach the driven rotating member to the camshaft. This relates to the improvement of the engine in which the lid that closes the working window is joined to the cylinder head.

Background art

[0002] As disclosed in Patent Document 1, an engine having a high power is already known.

Patent Document 1: Japanese Patent Laid-Open No. 10-54296

Disclosure of the invention

Problems to be solved by the invention

[0003] In a conventional engine with a force A, as disclosed in Patent Document 1, the cylinder head has an outer end surface where the working window is open so that the outer end surface of the cylinder head is axially outward of the driven rotating member. As a result, the driven rotating member is placed in the back of the work window. For this reason, the endless transmission member is attached to the driven rotating member and the driven rotating member is attached to the camshaft. The work is disturbed by the cylinder head around the driven rotating member, and the workability is poor. In addition, the entire lid that is joined to the outer end surface of the cylinder head inevitably causes the driven rotating member to move away in the axial direction, which hinders the compactness of the engine.

[0004] The present invention has been made in view of the situation of force A, and has good workability such as mounting of an endless transmission member to a driven rotating member and mounting of a driven rotating member to a camshaft. It is an object of the present invention to provide a notable engine.

[0005] Further, according to the present invention, when a camshaft is mounted on the engine body in advance in an engine having a force A, when the timing transmission device is assembled to the crankshaft and the camshaft, a predetermined phase relationship between the crankshaft and the force shaft The purpose is to be able to give The

Means for solving the problem

[0006] In order to achieve the above object, the present invention provides a drive rotating member that is fixed to a crankshaft between a crankshaft supported by a crankcase and a valve camshaft supported by a cylinder head. The driven rotary member fixed to the camshaft and an endless transmission member that is strung over both rotary members are connected via a timing transmission device, and is connected to the outer end surface of the cylinder head to the camshaft of the driven rotary member. In an engine with an open work window for attaching and detaching the lid and a lid that closes the work window, the outer end surface of the cylinder head to which the lid is joined is at least on the opposite side of the driven rotary member from the driven rotary member. A first feature is that a part of the outer periphery of the metal is formed on an inclined surface so that the working window force is exposed.

[0007] In addition to the first feature, the present invention is characterized in that the inclined surface is formed so that the driven window member is exposed to the working window force over a half circumference opposite to the drive rotating member. This is the second feature.

[0008] Further, according to the present invention, in addition to the first or second feature, the cylinder bore is connected to the crankcase, and a part of the timing transmission chamber on one side of which accommodates the timing transmission device is provided. The cylinder head is overlaid on the cylinder block with a gasket, and the cylinder head is fastened to the cylinder block with a plurality of main connecting bolts arranged around the cylinder bore. The third feature is that the cylinder head is fastened to the cylinder block by an auxiliary connecting bolt arranged in the cylinder.

Furthermore, in addition to the first or second feature, the present invention is characterized in that the side wall of the lid body is inclined so as to follow the inclined surface of the cylinder head. .

[0010] Further, in addition to the first feature, the present invention is configured so that the first mark displayed on the outer surface of the driven rotating member coincides with the first mark when the crankshaft is at a predetermined rotational position. A second mark displayed on the engine body, a bolt hole formed in the end wall of the hub of the driven rotary member, fitted to one end of the camshaft, a positioning groove extending radially from the bolt hole, a cam A positioning pin that protrudes from a center of one end surface of the shaft in a certain direction and engages with the positioning groove when the cam shaft is in a predetermined phase relationship with respect to the crank shaft at the predetermined rotation position; The cam shaft is also provided on one end surface of the cam shaft, and the cam shaft is at the predetermined rotational position. A screw hole that coincides with the bolt hole when in a predetermined phase relationship with respect to the rank shaft, and a mounting bolt that passes through the bolt hole and is screwed into the screw hole to fix the hub to the cam shaft. The fifth feature is to provide.

[0011] Further, in addition to the fifth feature, the present invention provides a straight line passing through the center of the crankshaft and the camshaft when the camshaft has a predetermined phase relationship with respect to the crankshaft at the predetermined rotational position. A sixth feature is that the first and second alignment marks, the positioning groove and the positioning pin are aligned.

Furthermore, in addition to the sixth feature, the present invention has a seventh feature in which the bolt hole and the screw hole are arranged at positions where the central forces of the hub and the camshaft are eccentric.

[0013] Furthermore, the present invention is characterized in that, in addition to the seventh feature, the screw hole and the positioning pin are arranged at positions where the central forces of the cam shaft are also eccentric in opposite directions.

[0014] The drive rotation member, the driven rotation member, and the endless transmission member respectively correspond to a drive pulley 45, a driven pulley 46, and a timing belt 47 in an embodiment of the present invention described later.

The invention's effect

[0015] According to the first feature of the present invention, a part of the driven pulley exposed outside the work window can be easily gripped with a tool or the like without being obstructed by the cylinder head. The pulley can be easily attached to the camshaft and removed easily. Therefore, it can contribute to the improvement of assemblability and maintainability.

[0016] Further, according to the second feature of the present invention, the operation of attaching and detaching the driven pulley to and from the camshaft can be performed more easily, so that the assembling property and the maintenance property can be further improved.

[0017] Further, according to the third feature of the present invention, the cylinder block and the cylinder head gasket are also secured around the timing transmission chamber by fastening the cylinder head to the cylinder block with the main connection bolt and the auxiliary connection bolt. The surface pressure can be increased sufficiently. In addition, due to the presence of the inclined surface above the auxiliary connecting bolt, a sufficient space for receiving the tool for operating the auxiliary connecting bolt is secured, so that the auxiliary connecting bolt can be easily tightened. At the same time, it can contribute to the compactness of the engine. [0018] Further, according to the fourth feature of the present invention, the head of the engine body has a shape in which the lateral width is narrowed toward the front end side, so that the engine can be compact.

[0019] According to the fifth aspect of the present invention, the crankshaft is fixed at a rotational position corresponding to a specific position of the piston, and the first mark on the driven rotating member is aligned with the second mark on the engine body. However, the driven rotating member is inserted into the endless transmission member already hung on the driving rotating member, the positioning pin of the cam shaft is received in the bolt hole of the driven rotating member, and this positioning pin is guided to the positioning groove of the driven rotating member. As a result, the first and second alignment marks, the bolt holes and the screw holes, and the positioning grooves and the positioning pins are arranged all at once on a straight line passing through the centers of the crankshaft and camshaft. be able to. Therefore, in this state, if the mounting bolt is passed through the bolt hole of the driven rotating member and screwed into the screw hole of the camshaft and tightened, the crankshaft and camshaft are mounted on the engine body in advance. In addition, the timing transmission device is attached to the camshaft in the predetermined phase relationship, and the installation is easy and accurate.

[0020] According to the sixth aspect of the present invention, the first and second alignment marks, and the state where the positioning groove and the positioning pin are aligned on a straight line passing through the centers of the crankshaft and the camshaft are visually observed. This makes it easy to confirm that the crankshaft and camshaft are in a predetermined phase relationship.

[0021] According to the seventh feature of the present invention, the rotation of the driven rotating member can be reliably transmitted to the camshaft via one eccentric mounting bolt, and the mounting bolt is prevented from loosening. be able to.

[0022] According to the eighth feature of the present invention, a sufficient amount of eccentricity can be given to each of the bolt hole and the positioning groove formed in the narrow end wall of the hub of the driven rotating member, and therefore the positioning groove. The positioning effect on the positioning pins and the torque capacity of the mounting bolts can be increased.

[0023] The above and other objects, features, and advantages of the present invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings.

Brief Description of Drawings

FIG. 1 is a longitudinal plan view of a general-purpose four-cycle engine according to the present invention. (First Example )

[FIG. 2] FIG. 2 is a sectional view taken along line 2-2 of FIG. (First example)

[FIG. 3] FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. (First example)

FIG. 4 is an enlarged view of the periphery of the crankshaft in FIG. (First example)

FIG. 5 is a view taken in the direction of arrow 5 in FIG. (First example)

[FIG. 6] FIG. 6 is a sectional view taken along line 6-6 of FIG. (First example)

[FIG. 7] FIG. 7 is a sectional view taken along line 7-7 of FIG. (First example)

FIG. 8 is a sectional view taken along line 8-8 in FIG. (First example)

FIG. 9 is a cross-sectional view taken along line 9 9 in FIG. (First example)

FIG. 10 is a view taken in the direction of arrow 10 in FIG. (First example)

[11] Fig. 11 is a diagram corresponding to Fig. 10 with the driven pulley removed. (First example)

[12] FIG. 12 is an explanatory view of the installation procedure of the driven pulley to the camshaft. (First example)

Explanation of symbols

エンジン ... engine

1 ... Engine body

3 ... Cylinder block

3a--Cylinder bore

4 ... "Gasket

5 ••• 'Cylinder head

5c-- ... Outer end face = Inclined face

6 ... Main connecting bolt

7 ... Auxiliary connecting bolt

12 ... Crankshaft

35..Valve system

36 ·· 'Camshaft

37 ... Timing transmission device 45 · · Drive rotating member (drive pulley)

46 .. • Driven rotating member (driven pulley)

46a-

• Endless transmission member (timing belt)

48 ·· • Timing transmission room

48a- · Lower chamber

48b -... Intermediate room

48c- ··· Upper chamber

55, Work window

• Lid

60 ... Bolt hole

61 • Positioning groove

62a -... 1st sign

62b -... Second sign

66 · · • Screw holes

67 ·· 'Positioning pin

68 • Mounting bolt

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Example 1

[0027] First, in Figs. 1 to 4, the engine body 1 of the general-purpose four-cycle engine E is integrally connected to the crankcase 2 having a mounting seat 2a at the lower portion and the crankcase 2 and is inclined upward. A cylinder block 3 having a cylinder bore 3a and a cylinder head 5 joined to the upper end surface of the cylinder block 3 via a gasket 4 are constituted as components, and the cylinder head 5 is joined to the cylinder block 3, that is, For fastening, four main connecting bolts 6, 6,... Arranged at four locations around the cylinder bore 3a and two auxiliary connecting bolts 7, 7 described later are used.

[0028] The crankcase 2 is open on one side, and the opening surface force is also reduced on the inner peripheral wall. Is formed in a plurality of stepped portions 8, 8,... Aligned in the circumferential direction facing the open side, and the bearing bracket 10 is formed by a plurality of bolts 11, 11,. It is fixed. The bearing bracket 10 and the other side wall of the crankcase 2 support the opposite ends of the crankshaft 12 in a horizontal position via bearings 13 and 13 '. Further, the force at both ends of the balancer shaft 14 arranged adjacent to and parallel to the crankshaft 12 is also supported by the bearing bracket 10 and the other side wall of the crankcase 2 via bearings 15 and 15.

[0029] As shown in FIGS. 4 and 5, a continuous reinforcing rib 16 is formed on the outer peripheral surface of the crankcase 2 so as to surround the plurality of stepped portions 8, 8, and so on. The end of the rib 16 is integrally connected to the outer wall of the cylinder block 3 integrated with the crankcase 2.

[0030] Therefore, the reinforcing rib 16 is connected to the inner plurality of step portions 8, 8 ... on the outer peripheral surface of the crankcase 2, so that the step portions 8, 8 ... The support rigidity of the supported bearing bracket 10 and thus the support rigidity of the crankshaft 12 by the bearing bracket 10 can be effectively enhanced. As a result, the crankcase 2 can be made thinner and lighter. it can. In particular, by connecting the end of the reinforcing rib 16 to the outer wall of the cylinder block 3, the reinforcing function of the reinforcing rib 16 is enhanced, and the support rigidity of the bearing bracket 10 can be further enhanced.

Further, a side cover 17 that closes an open surface on one side is joined to the crankcase 2 by a plurality of bolts 24, 24. One end of the crankshaft 12 protrudes outward as an output shaft through the side cover 17, and an oil seal 18 closely attached to the outer peripheral surface of the output shaft is attached to the side cover 17.

In FIG. 1 again, the other end portion of the crankshaft 12 penetrates the other side wall of the crankcase 2, and an oil seal 19 in close contact with the other end portion of the crankshaft 12 is provided on the outer side of the bearing 13 ^. Is attached to the other side wall of the crankcase 2 adjacent to. A flywheel 21 that also serves as a rotor of the generator 20 is fixed to the other end of the crankshaft 12, and a cooling fan 22 is attached to the outer surface of the flywheel 21. Further, a recoil type starter 23 supported by the crankcase 2 is placed at the other end of the crankshaft 12.

In FIG. 1 and FIG. 3, the crankshaft 12 is connected via a piston 25 force S connecting rod 26 fitted to the cylinder bore 3a. The cylinder head 5 has a fuel connected to the cylinder bore 3a. A combustion chamber 27 and an intake port 28i and an exhaust port 28e that open to the combustion chamber 27 are formed, and an intake valve valve that opens and closes the open ends of the intake and exhaust ports 28i and 28e to the combustion chamber 27, respectively. 29i and exhaust valve 29e are attached. The intake and exhaust valves 29i and 29e are equipped with valve springs 30i and 30e that urge them in the closing direction, respectively. The intake and exhaust valves 29i and 29e are driven to open and close by a valve gear 35 that cooperates with the valve springs 30i and 30e.

The valve gear 35 will be described with reference to FIGS. 3, 4, and 6 to 12.

First, in FIG. 3, FIG. 4, and FIG. 6, the valve operating device 35 includes a camshaft 36 that is supported by the cylinder head 5 in parallel with the crankshaft 12 and includes an intake cam 36i and an exhaust cam 36e, and the crankshaft 12 And the timing transmission 37 that connects the camshaft 36, the intake rocker arm 38i that links the intake cam 36i and the intake valve 29i, and the exhaust rocker arm 38e that links the exhaust cam 36e and the exhaust valve 29e. The

[0036] The cam shaft 36 includes a bag-shaped bearing hole 39 formed in one side wall 5a of the cylinder head 5 and a ball bearing 41 fitted in the bearing mounting hole 40 of the partition wall 5b in the middle of the cylinder head 5. Both ends are supported. Further, a common single stopper shaft 42 for swinging the intake and exhaust outlet arm 38i, 38e is provided in the first and second support holes 43 'formed in the one side wall 5a and the partition wall 5b, respectively. , 43 support both ends. The first support hole 43 ′ of the one side wall 5 a has a bag shape, and the second support hole 43 of the partition wall 5 b has a through hole shape. The outer end of the stopper shaft 42 is formed at the outer end of the second support hole 43. A fixing bolt 44 for abutting the tip thereof is screwed to the partition wall 5b. Therefore, the stopper shaft 42 is prevented from moving in the thrust direction by the bag-like first support hole 43 ^ and the fixing bolt 44.

[0037] The fixing bolt 44 is integrally provided with a relatively large-diameter flange seat 44a in contact with the outer end surface of the outer race 41a of the ball bearing 41 that supports the camshaft 36 on the head.

[0038] By the way, the inner race 41b of the ball bearing 41 is press-fitted into the camshaft 36. Therefore, the flange seat 44a of the fixing bolt 44 contacts the outer end of the water race 4 la as described above. Then, the cam shaft 36 is prevented from moving in the thrust direction by the bag-shaped bearing hole 39 and the flange seat 44a.

Therefore, the thrust bolts 42 and the camshaft 36 are both thrust by a single fixing bolt 44. It is possible to prevent the movement in the direction, and the number of parts of the valve operating device 35 can be reduced and the structure can be simplified, contributing to the compactness of the valve operating device 35, and to improving the assembly of the device 35.

[0040] The timing transmission device 37 includes a toothed drive pulley 45 fixed to the crankshaft 12 and a toothed drive pulley 45 fixed to the camshaft 36, the number of teeth of which is twice that of the drive pulley 45. 46 and an endless timing belt 47 wound around these driving and driven pulleys 45 and 46. Thus, the rotation of the crankshaft 12 is decelerated to 1 Z2 by the timing transmission device 37 and transmitted to the camshaft 36. As the camshaft 36 rotates, the intake and exhaust cams 36i, 36e force intake and exhaust outlet cover arms 38i, 38e are swung against the urging forces of the valve springs 30i, 30e, respectively. Each 29e can be opened and closed.

[0041] This timing transmission 37 includes a lower chamber 48a defined between the bearing bracket 10 and the side cover 17, an intermediate chamber 48b formed in the cylinder block 3 on one side of the cylinder bore 3a, and a cylinder head 5 It is accommodated in a timing transmission chamber 48 formed by sequentially connecting an upper chamber 48c formed on one side. That is, the driving pulley 45 is disposed in the lower chamber 48a, the driven pulley 46 is disposed in the upper chamber 48c, and the timing belt 47 is disposed so as to pass through the intermediate chamber 48b. Thus, by effectively using the space between the bearing bracket 10 and the side cover 17 for the installation of the timing transmission device 37, the engine E can be made compact.

[0042] On the other hand, the cylinder head 5 is formed with a valve chamber 49 having an open upper surface between the one side wall 5a and the partition wall 5b, and the intake and exhaust cams 36i of the cam shaft 36 are formed in the valve chamber 49. 36e, intake and exhaust outlet arm 38i, 38e, etc. are accommodated. The open upper surface of the valve operating chamber 49 is closed by a head cover 52 joined to the cylinder head 5 with bolts 53.

[0043] The upper chamber 48c and the valve operating chamber 49 of the timing transmission chamber 48 are connected to an oil passage hole 75 provided in the partition wall 5b.

8 (see FIGS. 8 and 11) and a plurality of oil grooves 76 (see FIGS. 6 and 11) provided in the inner peripheral surface of the bearing mounting hole 40 are communicated with each other.

6 to 9, the outer end surface 5c of the cylinder head 5 is provided with a working window 55 that opens the upper chamber 48c so that the outer surface of the driven pulley 46 faces, and the driven pulley is passed through the working window 55. 46 is inserted into the timing belt 47, and the driven pulley 46 is removed from the camshaft 36. Installation work is performed. A lid body 57 for closing the work window 55 is joined to the outer end surface 5c by a plurality of bolts 58 via a seal member 56.

As clearly shown in FIG. 6, the outer end surface 5c of the cylinder head 5 to which the lid 57 is joined has at least a part of the outer periphery of the driven pulley 46 on the side opposite to the drive pulley 45. The inclined surface 5c is preferably inclined so as to be exposed from the working window 55 over a half circumference opposite to the driving pulley 45 of the driven pulley 46.

[0046] Here, a structure for mounting the driven pulley 46 to the camshaft 36 will be described.

[0047] As shown in FIG. 6, the driven pulley 46 includes a bottomed cylindrical hub 46a, a web 46b extending in a radial direction from the hub 46a, and a toothed rim formed on the outer periphery of the web 46b. The hub 46a is fitted to the outer periphery of the outer end of the camshaft 36 protruding toward the upper chamber 48c. The end wall of the hub 46a is provided with a bolt hole 60 that occupies a position where the central force is also eccentric, and a positioning groove 61 that extends from one side of the bolt hole 60 to the opposite side to the eccentric direction. A first mark 62a is engraved on the outer surface of the rim 46c, and a second mark 62b corresponding to the first mark 62a is engraved on the outer end surface 5c of the cylinder head 5. The web 46b is provided with a plurality of through holes 64, 64 penetrating therethrough.

On the other hand, as shown in FIGS. 6 and 11, a screw hole 66 corresponding to the bolt hole 60 and a positioning pin 67 corresponding to the positioning groove 61 are provided at the outer end portion of the cam shaft 36. It is done.

Thus, the crankshaft 12 is at a predetermined rotation position corresponding to a specific position (for example, top dead center) of the piston 25, and the camshaft 36 is at a predetermined phase relationship position with respect to the crankshaft 12. When the first and second marks 62a and 62b, bolt hole 60 and screw hole 66, positioning groove 61 and positioning pin 67 are aligned with each other on a straight line L passing through the centers of both shafts 12 and 36, There is.

[0050] In order to attach the driven pulley 46 to the camshaft 36, first, the crankshaft 12 is fixed at a rotational position corresponding to the specific position of the piston 25. Next, as shown in FIG. 12 (A), the timing belt 47 that is already hung on the drive pulley 45 while the first pulley 62a of the rim 46c is aligned with the second drum 62b of the cylinder head 5 is aligned. Insert inside. Next, as shown in FIG. 12B, the positioning pin 67 of the camshaft 36 is received in the bolt hole 60 of the driven pulley 46 and the positioning pin 67 is guided to the positioning groove 61 so as to be driven. When the rear shaft 46 is moved together with the timing belt 47, the cam shaft 36 rotates accordingly, and when the positioning pin 67 reaches the tip of the positioning groove 61, as shown in FIG. At the same time as the hub 46a is aligned on the same axis, the bolt hole 60 and the screw hole 66 are aligned with each other.

[0051] In this way, the positioning pin 67 received in the bolt hole 60 is guided to the positioning groove 61, and the first and second alignments are made on a straight line L passing through the centers of the crankshaft 12 and the camshaft 36. The marks 62a and 62b, the bolt hole 60 and the screw hole 66, the positioning groove 61 and the positioning pin 67 are arranged all at once. By visually observing this state, it can be easily confirmed that the crankshaft 12 and the camshaft 36 are in a predetermined phase relationship.

Therefore, as shown in FIG. 6, the hub 46 a is fixed to the camshaft 36 by passing the mounting bolt 68 through the bolt hole 60, screwing into the screw hole 66, and tightening. In this way, the timing transmission 37 is attached to the crankshaft 12 and the camshaft 36 that are previously mounted on the crankcase 2 and the cylinder head 5 in the predetermined phase relationship.

[0053] In this case, since the bolt hole 60 and the screw hole 66 are arranged at positions eccentric from the centers of the hub 46a and the cam shaft 36, they are driven by a single eccentric mounting bolt 68. The rotation of the pulley 46 can be reliably transmitted to the camshaft 36 and the mounting bolt 68 can be prevented from loosening.

[0054] Further, the screw hole 66 and the positioning pin 67 are arranged at positions where the central forces of the cam shaft 36 are also eccentric in opposite directions, so that the bolt hole 60 formed in the narrow end wall of the hub 46a of the driven pulley 46 is provided. In addition, a sufficient amount of eccentricity can be given to the positioning groove 61, whereby the positioning effect of the positioning groove 61 on the positioning pin 67 and the torque capacity of the mounting bolt 68 can be increased.

[0055] By the way, as described above, the outer end surface of the cylinder head 5 in which the work window 55 is opened becomes the inclined surface 5c !, so that a part of the outer periphery of the driven pulley 46 is exposed from the work window 55. Therefore, a part of the driven pulley 46 exposed outside the work window 55 can be easily grasped with a tool or the like without being obstructed by the cylinder head 5, and the cam of the driven pulley 46 is thereby It can be easily attached to the shaft 36 and can be easily removed. Therefore It can contribute to the improvement of assemblability and maintainability.

[0056] The outer end surface 5c of the cylinder head 5, that is, the side wall 73 of the lid 57 joined to the inclined surface 5c is formed so as to be inclined along the inclined surface 5c. In this way, the head of the engine body 1 is shaped so that its lateral width narrows toward the tip side, and the engine E can be made compact.

As shown in FIGS. 7 to 9, the cylinder head 5 is formed with a pair of projecting portions 70, 70 projecting outward from the work window 55 below the work window 55. The portions 70 and 70 are overlapped on the upper end surface of the cylinder block 3 outside the intermediate chamber 48b through the gasket 4 and fastened to the cylinder block 3 by auxiliary connecting bolts 7 and 7.

[0058] According to the fastening of the auxiliary connecting bolts 7 and 7, the surface of the cylinder block 3 and the cylinder head 5 with respect to the gasket 4 is located outside the intermediate chamber 48b accommodating the timing belt 47! The pressure can be increased sufficiently. In addition, the presence of the inclined surface 5c above the auxiliary connecting bolts 7 and 7 ensures a sufficient space for receiving the tool for operating the auxiliary connecting bolts 7 and 7. Can be easily performed. This also means that the amount of overhanging of the projecting portions 70, 70 to the outside of the work window 55 can be reduced, which also contributes to the compactness of the engine E.

Note that the operation of the auxiliary connecting bolts 7 and 7 is performed before the cover body 57 is attached.

Next, the lubrication of the valve gear 35 will be described.

In FIG. 1 to FIG. 3, FIG. 6 and FIG. 8, the lower chamber 48a of the timing transmission chamber 48 passes through a plurality of step portions 8, 8 ... of the inner wall of the crankcase 2 that supports the bearing bracket 10. The crankcase 2 communicates with the inside of the crankcase 9, that is, the crankcase 9.

[0062] As shown in Fig. 2, in the lower chamber 48a, an impeller-type oil slinger 72 driven from the crankshaft 12 via gears 74 and 74 'is partly stored in the lower chamber 48a. It is arranged so as to be immersed in. The oil slinger 72 causes the oil 71 to scatter to the surroundings by its rotation. The oil guiding wall 73 forces the oil slinger 72 and the drive pulley 45 side to guide the scattered oil to the timing belt 47 side. The timing belt 47 is integrally formed on the outer surface of the bearing bracket 10 so as to surround the periphery thereof. Bearing block Since the racket 10 is a relatively small part, it can be easily manufactured together with the oil guide wall 73. Also, the bearing bracket 10 has the oil guide wall 73 integrally therewith, so that its rigidity is strengthened and effective in increasing the support rigidity of the crankshaft 12.

Thus, in the lower chamber 48 a, the scattered oil from the oil slinger 72 is guided to the timing belt 47 side by the oil guide wall 73, and the oil adhering to the timing belt 47 is transferred to the upper chamber by the belt 47. When the timing belt 47 reaches the driven pulley 46 when it is transported to 48c, it is swung off by centrifugal force and scattered to the surroundings, colliding with the surrounding walls to generate oil mist, which is generated in the upper chamber 48c. As a result, the ball bearing 41 of the camshaft 36 can be lubricated as well as the entire timing transmission 37.

[0064] In particular, in the upper chamber 48c, when a part of the oil shaken off from the timing belt 47 collides with the inclined inner surface of the lid 57, it rebounds to the web 46b side of the driven pulley 46. This oil passes through the through holes 64 and 64 of the driven pulley 46 and is applied to the ball bearing 41, so that the ball bearing 41 is also lubricated. Further, a part of the oil sprinkled on the ball bearing 41 passes through the oil passage groove 76 on the outer periphery of the bearing 41 and moves to the valve chamber 49, and the ball bearing 41 is also lubricated from the valve chamber 49 side. Become . Therefore, the ball bearing 41 is lubricated very well.

[0065] As shown in Fig. 3, the bottom of the valve operating chamber 49 is connected to the crank chamber via a series of oil return passages 77 formed in the cylinder head 5 and the cylinder block 3 along one side of the cylinder bore 3a. Communicated with 9 The oil return passage 77 descends toward the crank chamber 9 so that oil flows from the valve chamber 49 to the crank chamber 9.

[0066] By the way, during the operation of engine E, in the crank chamber, a pulsation of pressure accompanying the raising and lowering of piston 25 occurs, and the pulsating pressure moves through oil return passage 77, oil passage hole 75 and oil passage groove 76. When the oil is transmitted to the valve chamber 49 and the timing transmission chamber 48, oil mist travels between the valve chamber 49 and the timing transmission chamber 48, so that the entire valve operating device 35 can be effectively lubricated.

Then, after lubrication, the oil accumulated in the valve operating chamber 49 flows down the oil return passage 77 and returns to the crank chamber 9. In addition, the bottom of the timing transmission chamber 48 is also directed downward to the lower chamber 48a. Thus, the oil accumulated in the upper chamber 48c flows down the intermediate chamber 48b and returns to the lower chamber 48a.

[0068] By using the operation of the oil slinger 72 and the timing transmission device 37 and the pulsation pressure of the crank chamber 9 as described above, the inside of the timing transmission chamber 48 and the valve chamber 49 that are partitioned from each other can be lubricated by the oil mist. This eliminates the need for a dedicated oil pump for lubrication, contributing to the simplification and compactness of the engine E structure and cost reduction. Since the camshaft 36 can maintain the overhead position with respect to the intake and exhaust valves 29i and 29e, the desired output performance of the engine can be ensured.

Note that the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the scope of the invention. For example, the belt type timing transmission 37 can be replaced with a chain type.

Claims

The scope of the claims

[1] The crankshaft (12) supported by the crankcase (2) and the valve camshaft (36) supported by the cylinder head (5) are fixed to the crankshaft (12). A driving rotary member (45), a driven rotary member (46) fixed to the camshaft (36), and an endless transmission member (47) wound around both rotary members (45, 46) (a timing transmission device) 37) to open a work window (55) for attaching / detaching the driven rotating member (46) to / from the camshaft (36) on the outer end surface (5c) of the cylinder head (5). In the engine with a lid (57) that closes the window (55),

The outer end surface (5c) of the cylinder head (5) to which the lid (57) is joined is at least part of the outer periphery of the driven rotating member (46) opposite to the driving rotating member (45). An engine characterized by being formed on an inclined surface (5c) inclined so as to be exposed from 55).

[2] In the engine according to claim 1,

The engine characterized in that the inclined surface (5c) is formed so that the driven rotating member (46) extends over a half circumference opposite to the driving rotating member (45) to expose the working window (55) force.

[3] In the engine according to claim 1 or 2,

A cylinder block (3b) connected to the crankcase (2) and having a cylinder bore (3a) and a part (48b) of a timing transmission chamber (48) on one side of which accommodates the timing transmission (37) The cylinder head (5) is overlapped with the gasket (4), and the cylinder head (5) is fastened to the cylinder block (3) with a plurality of main connecting bolts (6) arranged around the cylinder bore (3a). In addition, the cylinder head (5) is fastened to the cylinder block (3) by the auxiliary connecting bolt (7) arranged below the work window (55) on the outside of the timing transmission chamber (48). To engine.

[4] In the engine according to claim 1 or 2,

The engine characterized in that the side wall of the lid (57) is inclined along the inclined surface (5c) of the cylinder head (5).

[5] In the engine according to any one of claims 1 to 4,

The engine main body (62a) displayed on the outer surface of the driven rotating member (46) and the first mark (62a) when the crankshaft (12) is in the predetermined rotational position Displayed in 1) The second alignment mark (62b), the bolt hole (60) provided on the end wall of the hub (46a) of the driven rotating member (46), which is fitted to one end of the cam shaft (36), and the bolt hole (60) Force The positioning groove (61) extending in the radial direction and one end face of the cam shaft (36) are projected at a position eccentric from the center in a certain direction, and the cam shaft (36) A positioning pin (67) that engages with the positioning groove (61) when it has a predetermined phase relationship with respect to the crankshaft (12), and a cam shaft (36) When 36) is in a predetermined phase relationship with respect to the crankshaft (12) at the predetermined rotational position, the screw hole (66) coinciding with the bolt hole (60) and the bolt hole (60) are passed through. An engine comprising: a mounting bolt (68) that is screwed into the screw hole (66) and fixes the hub (46a) to the cam shaft (36).

[6] In the engine according to claim 5,

When the camshaft (36) has a predetermined phase relationship with the crankshaft (12) at the predetermined rotational position, the camshaft (36) is placed on a straight line (L) passing through the centers of the crankshaft (12) and the camshaft (36). An engine characterized in that the first and second alignment marks (62a, 62b), the positioning groove (61) and the positioning pin (67) are aligned.

[7] In the engine according to claim 6,

The engine characterized in that the bolt hole (60) and the screw hole (66) are arranged at positions where the central forces of the hub (46a) and the cam shaft (36) are also eccentric.

[8] In the engine according to claim 7,

The engine characterized in that the screw hole (66) and the positioning pin (67) are arranged at positions decentered in opposite directions to the central force of the camshaft (36).