JP2001090606A - Crankshaft holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crank shaft holder capable of enabling easy assembly of parts in a periphery of a crankshaft and increasing variety of material for the crankshaft holder. SOLUTION: This crankshaft holder 80 formed of a press-worked plate includes a holder body 81 having a crank shaft supporting part 83 for rotatably supporting a crankshaft 4, and a mounting part 82 having a partially cylindrical shape for supporting a bolt 85 for fixing the crank shaft holder 80 to a crank case 5. The mounting part 82 is protruded in an insertion direction of the crankshaft 4 and includes a reinforced part for enhancing flexural rigidity of the holder body 81.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crankshaft holder having a support for rotatably supporting a crankshaft in a machine having a crank mechanism such as an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, a crankshaft of an internal combustion engine is supported via a bearing in a bore formed in a crankcase as disclosed in Japanese Utility Model Publication No. 2-5041, and the rotation of the crankshaft is controlled by a clutch. And transmission to the wheels via the transmission gear. Further, in the internal combustion engine disclosed in this publication, the timing gear on the crankshaft and the cam gear on the camshaft are gear-coupled via a gear train including at least two intermediate gears meshing with each other, and The gear shaft of the gear is supported on a unit frame having a pair of holding plates made of a material having substantially the same thermal expansion coefficient as the intermediate gear at an appropriate meshing position between the intermediate gears. As a result, when the temperature of the internal combustion engine rises, the intermediate gear and the unit frame expand at the same rate, so that the proper meshing relationship between the intermediate gears does not change, and the meshing noise of the gears due to the increase in backlash increases. Occurrence can be prevented.

[0003]

By the way, in the conventional internal combustion engine, the holding portion of the crankshaft is provided on the crankshaft because the holding portion formed integrally with the crankcase forms a wall. It has been difficult to assemble parts around the crankshaft, such as a rotary shaft provided with a driven gear that meshes with the drive gear.

Further, since the holding portion is integrally cast with a crankcase made of a light alloy material, the range of selection of the material of the holding portion is limited. For example, the intermediate gear of the conventional internal combustion engine and the intermediate gear As seen in the combination with the unit frame that holds the gear shaft, the material that forms the holding portion is selected from the viewpoint of thermal expansion. It has been difficult to select a material for the holding portion that matches the function of the above.

Further, since the crankshaft is rotatably supported by a holding part cast integrally with the crankcase, the main shaft of a camshaft or a transmission gear that is drivingly connected to the crankshaft via a gear is provided. In addition, since it is attached to the engine body separately from the crankshaft, the number of assembling steps increases, and there is room for improvement in the ease of assembling those shafts to the engine body.

The present invention has been made in view of such circumstances, and the invention according to claims 1 to 7 facilitates the assembly of parts around the crankshaft, and provides the crankshaft. It is a common object to provide a crankshaft holder capable of expanding the range of selection of the material of the holder.

It is another object of the present invention to provide a crankshaft holder having rigidity for securely holding a crankshaft on which a large force acts. The invention according to claim 5 provides a crankshaft holder having improved assemblability and removability with respect to a fixed member, such as a rotary shaft driven by a crankshaft via gears.
Further, the invention described in claim 7 is to provide a crankshaft holder capable of preventing generation of gear meshing noise due to an increase in backlash due to thermal expansion when the temperature of the internal combustion engine rises. It is an object of the present invention to provide a crankshaft holder capable of holding a proper position of the crankshaft.

[0008]

Means for Solving the Problems and Effects of the Invention According to the invention as set forth in claim 1 of the present application, a holder body made of a pressed plate material, and a crankshaft formed on the holder body to rotatably support a crankshaft. A crankshaft holder comprising: a first support portion; and a mounting portion provided on the holder body and holding a stopper to a fixing member, wherein the crankshaft holder is fixed to the fixing member by the stopper. This is a crankshaft holder that can be attached and detached.

According to the first aspect of the present invention, since the holder main body in which the first supporting portion for supporting the crankshaft is formed is formed of a pressed plate material, the weight of the crankshaft holder can be reduced easily. Is possible. Further, the crankshaft holder provided with the attachment portion to the fixing member is formed of a separate member from the fixing member on which the crankshaft is arranged, and is detachably attached to the fixing member by a stopper. As a result, there is no need to form a holding portion for the crankshaft on the fixing member,
The structure of the fixing member is simplified, and the assembling of the crankshaft and parts around the crankshaft is facilitated.

The material for forming the crankshaft holder is not limited to the material for forming the fixed member. For example, a back gear due to thermal expansion between a drive gear provided on the crankshaft and a driven gear meshing with the drive gear is used. It is possible to select a material suitable for a function unique to the crankshaft, such as selecting a material for preventing the rush from increasing.

The invention described in claim 2 of the present application is claim 1
The crankshaft holder according to claim 1, further comprising a reinforcing portion that is provided on the holder main body so as to protrude radially outward of the first support portion in the axial direction of the crankshaft and that increases bending rigidity of the holder main body. .

According to the second aspect of the present invention, the holder body provided with the first support portion for supporting the crankshaft protrudes radially outward of the first support portion in the axial direction of the crankshaft. By providing the reinforcing portion, a crankshaft holder having bending rigidity capable of securely holding the crankshaft even when a large force acts on the crankshaft can be provided.

According to a third aspect of the present invention, in the crankshaft holder according to the second aspect, the mounting portion also serves as the reinforcing portion.

According to the third aspect of the present invention, since the mounting portion also serves as the reinforcing portion, a more compact crankshaft holder can be obtained, and the rigidity of the stopper itself held by the mounting portion is reduced to the holder body. In addition to the bending rigidity of the reinforcing portion, the rigidity is further increased, and a crankshaft holder having high strength can be obtained.

According to a fourth aspect of the present invention, in the crankshaft holder according to any one of the first to third aspects, the crankshaft is a crankshaft of an internal combustion engine, and a drive provided on the crankshaft. A second support portion provided with a driven gear that meshes with a gear and rotatably supporting a rotating shaft that drives a mechanism attached to the internal combustion engine is formed on the holder main body.

According to this invention, the rotary shaft provided with the driven gear meshing with the drive gear provided on the crankshaft of the internal combustion engine is a holder for supporting the crankshaft at the first support portion. Since the mechanism is supported by the second support portion of the main body, the mechanism mounted on the internal combustion engine and driven by the rotating shaft can be compactly disposed near the crankshaft, and the crankshaft and the rotating shaft driving the mechanism are connected to the crankshaft. The holder can be modularized as a common base. As a result, when the crankshaft holder is attached to and detached from the fixed member, the rotating shaft for driving the mechanism is simultaneously attached to and detached from the fixed member, so that the rotating shaft can be easily attached to and removed from the internal combustion engine. Thus, the disassembly of the internal combustion engine for assembly and maintenance is facilitated.

According to a fifth aspect of the present invention, in the crankshaft holder according to the fourth aspect of the present invention, an inner portion of the mechanism constituting at least a part of the mechanism is disposed between the pair of crankshaft holders. The pair of crankshaft holders, the crankshaft, the rotating shaft, and the holder internal part are detachably attached to the fixing member in an integrated state.

According to the fifth aspect of the present invention, a part of the mechanism driven by the rotating shaft is provided as an inner part of the holder.
Disposed between a pair of crankshaft holders, a crankshaft,
Since the rotating shaft and the holder inner portion are attached to and detached from the fixed member in a state of being integrated with the pair of crankshaft holders, the assembling and dismounting of those components with respect to the internal combustion engine are improved, and the assembly and the assembly of the internal combustion engine are improved. Easy disassembly for maintenance.

According to a sixth aspect of the present invention, in the crankshaft holder according to the fourth or fifth aspect, a coefficient of thermal expansion of a material forming the holder main body and a material forming the drive gear and the driven gear are set. Are approximately equal.

According to the present invention, the material forming the holder body and the material forming the drive gear and the driven gear have substantially the same coefficient of thermal expansion. Also, when thermal expansion occurs in the crankshaft holder, the drive gear, and the driven gear that supports the rotating shaft, it is possible to prevent an increase in backlash between the two gears, and to prevent noise due to an increase in backlash.

According to a seventh aspect of the present invention, in the crankshaft holder according to any one of the first to sixth aspects,
The pair of crankshaft holders are detachably attached to the fixing member in a state where the pair of crankshaft holders are integrated by a spacer that maintains a distance between the pair of crankshaft holders in the axial direction of the crankshaft.

According to the seventh aspect of the present invention, since the distance between the pair of crankshaft holders in the axial direction of the crankshaft is accurately defined by the spacer, the crankshaft and the like disposed between the pair of crankshaft holders The member can maintain an appropriate position in the axial direction, and the presence of the spacer suppresses deformation of the crankshaft holder caused by a load acting on the crankshaft. In this specification, “front”, “rear”, “left” and “right” mean “front”, “rear”, “left” and “right” of the vehicle body.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 9
FIG. 1 is a diagram showing a first embodiment of the present invention, and FIG.
Is a power transmission device having a spark ignition type four-cycle single cylinder forced air-cooled internal combustion engine 2 equipped with a crankshaft holder of the present invention, a swash plate type hydraulic transmission 3 and a final reduction gear (not shown). 2 is a cross-sectional view of the power unit 1 as viewed from the front, FIG. 2 is a cross-sectional view of the power unit 1 as viewed from the back, and FIG.

The power unit 1 is mounted on a motorcycle or a straddle-type vehicle, and its front end is connected to a vehicle body frame via a pivot connection, and its rear end is connected via a shock absorber. Therefore, the power unit 1 is driven in accordance with a traveling state such as traveling on an uneven road surface.
It is a swing type that can swing about a pivot with respect to the vehicle body.

The internal combustion engine 2 and the hydraulic transmission 3 will be described in detail with reference to FIGS. The internal combustion engine 2 is arranged vertically so that the axis of the crankshaft 4 points in the front-rear direction of the vehicle body, and the axis of the cylinder 6 points slightly obliquely to the right of the vehicle body. The crankcase 5 made of an aluminum alloy of the internal combustion engine 2 is one of the cases of the hydraulic transmission 3 located on the left side of the vehicle due to a split surface slightly inclined leftward of the vehicle body from a vertical plane passing through the axis of the crankshaft 4. The transmission-side crankcase 5a is also divided into an engine-side crankcase 5b in which the cylinder 6 and the cylinder head 7 of the internal combustion engine 2 are integrally formed by casting. The cylinder head cover 8 is attached to the cylinder head 7.

As shown in FIG. 3, the crankshaft 4
Through a pair of front and rear ball bearings 9, 10,
Crankshaft support portions 83 of a pair of front and rear crankshaft holders 80, 90 made of a pressed steel plate,
Each is rotatably supported by 93 and arranged in the crankcase 5. Each crankshaft holder 80, 90
The engine-side crankcase 5 is driven by through bolts 85 and 95, which are a pair of stoppers, through which the pair of mounting portions 82 and 92 are inserted.
b is fixed to the right side wall. The details of the front and rear crankshaft holders 80 and 90 which are detachable from the engine-side crankcase 5b as the fixing member will be described later.

On the other hand, a piston 1 slidably fitted in a cylinder hole of a cylinder 6 in which a number of cooling fins are formed.
The one reciprocating motion is transmitted to the crankshaft 4 via the connecting rod 12, whereby the crankshaft 4 is driven to rotate. In the crankshaft 4, the front crank web includes:
A balance weight 14 is provided and the piston 11
In addition, generation of primary vibration due to reciprocating motion of the connecting rod 12 is suppressed. On the other hand, an output gear 15 that meshes with the input gear 58 of the hydraulic transmission 3 is formed on the rear crank web.

The cylinder head 7 in which a number of cooling fins are formed is formed with two fitting holes that open to the combustion chamber, and these fitting holes are used to hold an intake valve holder 37 and an exhaust valve holder described later. The body 38 is fitted. Further, an ignition plug (not shown) for igniting a mixture of fuel and air injected from a fuel injection valve provided in an intake pipe (not shown) is attached to the cylinder head 7 so as to face the combustion chamber. Have been.

As shown in FIGS. 2 and 3, a double-acting piston type supercharger 16 is mounted above the engine side crankcase 5b and the cylinder 6. The air introduced into the supercharger 16 from the auxiliary intake passage via the intake air conduit is recharged by the rotation of a supercharger crankshaft having a supercharger drive gear 17 meshing with a cam gear 23 described later. And compressed to a high pressure,
Discharged into the discharge air conduit. The supercharger 16 opens and closes a throttle valve provided in the sub intake passage so that the supercharging operation is performed only during specific engine operation such as during engine acceleration or high output.

As shown in FIG. 3, an AC generator 18 is provided at the front of the crankshaft 4 located forward of the front ball bearing 9, and a rotor 19 of the AC generator 18 has a crankshaft. 4 is fixed to the crankshaft 4 by a nut at the front end. In addition, a cooling fan 20 that sends cooling air to the internal combustion engine 2 is attached to the rotor 19 by bolts, and rotates integrally with the rotor 19. The cooling fan 20 is covered by a fan cover 21 provided with an air intake 21a.

On the other hand, behind the rear ball bearing 10 of the crankshaft 4, a steel timing gear 22 is provided so as to rotate integrally with the crankshaft 4. The timing gear 22 constitutes a drive gear for driving a camshaft 24 which is a rotating shaft for driving a valve mechanism which is one mechanism of the internal combustion engine 2, and is press-fitted into a shaft end in front of the camshaft 24. The camshaft 24 meshes with a cam gear 23 which is a steel driven gear provided to rotate integrally with the camshaft 24, so that the camshaft 24 makes one rotation every two rotations of the crankshaft 4.

At the rear of the cylinder 6, the axis of the cylinder 6 is disposed so as to point in the front-rear direction of the vehicle body, and the front shaft end of the hollow camshaft 24 formed of a tube is connected to the front shaft end of the camshaft 24. The boss portion of the cam gear 23 fixed to the cam shaft 23 is rotatably supported by a cam shaft support portion 94 of a rear crankshaft holder 90 via a front ball bearing 25, and a rear shaft end of the boss portion is a rear ball bearing. 26 through the camshaft holder 10
The camshaft supporting portion 101 is rotatably supported.
The camshaft holder 100 is formed from a pressed steel plate, and is integrally connected to the rear crankshaft holder 90 via a pair of connecting portions described below and a pair of hollow lower rocker arm shafts formed of a tube material. . The camshaft holder 100 will be described later.

The camshaft 24 is provided with an intake / exhaust cam 30 for driving the intake valve 27 and the exhaust valve 28 to open and a supercharging cam 31 for driving the supercharge valve 29 to open. The pair of lower rocker arm shafts described above includes a lower intake rocker arm shaft 35 for swingably supporting the lower intake rocker arm 32 and the lower supercharged rocker arm 34, and a lower exhaust rocker arm for swingably supporting the lower exhaust rocker arm 33. This is the axis 36 (see FIG. 2).

The intake valve 27 and the supercharging valve 29 hold the two valves 27 and 29 and are modularized as a cylindrical intake valve holder 37 having respective valve guides and valve seats. Similarly, the exhaust valve 28
And is modularized as one exhaust valve holder 38 having a valve guide and a valve seat. Further, the intake valve holding body 37 is provided with a connection port to which an intake port and a supercharging port formed of a pipe material are connected, and similarly, the exhaust valve holding body 38 is formed of a pipe material. A connection port to which an exhaust port is connected is provided.

The intake valve holding body 37 and the exhaust valve holding body 38 are fitted into the two fitting holes of the cylinder head 7, respectively, so that the intake valve 27, the supercharging valve 29 and the exhaust valve 28 are connected to the cylinder. It is mounted on the head 7. Thereafter, the intake port, the supercharging port, and the exhaust port are connected to the three connection ports described above, respectively, so that the combustion is performed from the three ports via the intake valve 27, the supercharging valve 29, and the exhaust valve 28, respectively. An intake path, a supercharging path and an exhaust path leading to the chamber are formed.

The valve operating mechanism is of the OHV type, and FIG.
As shown in FIG. 2, the intake valve 27 is driven to open by an upper intake rocker arm 39 which is oscillated by a pull rod 77 which is pulled down by a lower intake rocker arm 32 which is oscillated in contact with the intake / exhaust cam 30. Similarly, the supercharging valve 29
The valve is driven to open by an upper supercharging rocker arm 41 which is oscillated by a pull rod 79 which is pulled down by a lower supercharging arm 34 which is oscillated in contact with the supercharging cam 31. On the other hand, the exhaust valve 28 is connected to the upper exhaust rocker arm 4 which is oscillated by a pull rod 78 which is lowered by a lower exhaust rocker arm 33 which is oscillated in contact with the intake / exhaust cam 30.
0 drives the valve to open. The upper intake and upper supercharger rocker arms 39 and 41 are swingably supported on an upper intake rocker arm shaft and an upper supercharger arm shaft fixed to the intake valve holder 37, respectively, and the upper exhaust rocker arm 40 is provided with an exhaust valve. It is swingably supported by an upper exhaust rocker arm shaft fixed to the holder 38.

As shown in FIGS. 2 and 3, an oil pump 42 is provided behind the crankshaft 4. The oil pump 42 is of a trochoid type, and a rotor attached to a hollow pump drive shaft 43 fitted from a rear end surface of the crankshaft 4 to a hole formed coaxially with the crankshaft 4 is provided with a crankcase. 5 is driven to rotate inside a pump casing 44 fixed to 5.

The oil in the oil reservoir 45 formed at the bottom of the crankcase 5 is sucked by the oil pump 42 through a suction passage 46 formed in the crankcase 5 on the engine side. The oil discharged from the oil pump 42 to the discharge passage 47 at a high pressure is supplied as hydraulic oil to the hydraulic transmission 3 through an oil passage 48 provided in the crankcase 5, while an oil pipe 49 is provided. And is supplied to a valve operating mechanism provided in the cylinder head 7 through the passage.

The oil pipe 49 is connected to an oil inflow chamber 50 located at the upper left and rear of the double head cylinder head cover 8 having an inner plate 8a and an outer plate 8b formed of a steel plate. The oil in the oil inflow chamber 50 is
In a portion of the cylinder head cover 8 facing the cylinder head 7, the oil flows into one end of a meandering oil passage 51 formed by processing the outer plate 8 b into a waveform, and the oil passage 51
From a plurality of injection holes 52 provided in the middle of
Upper supercharging and upper exhaust rocker arms 39, 41, 40
Oil is sprayed toward the valve to lubricate the sliding portion of the valve train.

The injected oil flows down the inner wall surface of the cylinder head 7 and is collected in an oil recovery chamber 53 formed at the lower right of the cylinder head cover 8 and at the rear thereof. The flow returns to the oil reservoir of the crankcase 5 via 54. The return oil pipe 54 is provided with a number of cooling fins 55 on its outer periphery.
Since the oil flowing through the pipe 4 is cooled, the return oil pipe 54 also functions as an oil cooler. Further, also in the meandering oil passage 51, since the oil is cooled while flowing through the long passage, this part of the cylinder head cover 8 also functions as an oil cooler. In addition, the outer plate 8b having a double structure is processed into a corrugated shape, and the trough of the corrugated portion comes into contact with the inner plate 8a to form a meandering oil passage 51, so that the strength of the cylinder head cover 8 is improved. Because of this, the soundproofing effect is excellent.

Further, the oil discharged from an oil passage formed inside the crankshaft 4 is supplied to the rear ball bearing 10 of the crankshaft 4 through the inside of the pump drive shaft 43. On the rear surface of the output gear 15, an annular lubrication groove 56 is formed at a position farther from the axis of the crankshaft 4 than the axis of the crankpin 13, and the center line of the groove width is located. A part of the oil that has passed through the inside of the pump drive shaft 43 is supplied to the pump. And, this lubrication groove 56
Forms a centrifugal oil strainer. In the lubrication groove 56, solid foreign matter mixed into oil is separated by centrifugal force generated by rotation of the crankshaft 4, and
The cleaned oil passes through an oil passage 57 inside the crank pin 13 communicating with the bottom of the lubrication groove 56,
The lubrication of the front and rear ball bearings 9 and 10 is performed by a part of the oil supplied to the sliding portion between the shaft and the large end of the connecting rod 12 and flowing out from the sliding portion.

On the other hand, the swash plate type hydraulic transmission 3, which is a component of the power transmission device for transmitting the power of the crankshaft 4 to the drive wheels, includes an input gear 58, a constant displacement swash plate type hydraulic pump, a variable displacement The swash plate type hydraulic motor and the output shaft 59 are provided. Note that the axis of the output shaft 59 is on a horizontal plane including the axis of the crankshaft 4.

Output gear 15 formed on crankshaft 4
Is engaged with an input gear 58 formed integrally with a front portion of a housing 60 of the hydraulic pump. A front boss portion of the input gear 58, a rear boss portion of the start driven gear 61 rotatably supported on the outer periphery of the output shaft 59 via a bearing 65, and an inner peripheral surface of the front boss portion and a rear boss portion. A one-way clutch 62 is formed by a roller (not shown) provided between the one-way clutch 62 and the outer peripheral surface.
Are formed. Therefore, the front boss of the input gear 58 forms an outer race of the one-way clutch 62, and the rear boss of the start driven gear 61 forms an inner race of the one-way clutch 62.

Further, a semi-cylindrical balance weight 63 is fixed to the outer peripheral surface of the front boss portion of the input gear 58 so that the crankshaft 4 and the input gear 58 rotate at the same speed. , Number of teeth of output gear 15 and input gear 5
8 is set equal to the number of teeth of the input gear 58.
Constitute a balancer that suppresses primary vibration generated by the rotational movement of the crankshaft 4 and the reciprocating movement of the piston 11 and the connecting rod 12.

As described above, since the balancer is formed using the boss portion of the input gear 58, a dedicated shaft and a dedicated drive mechanism for the balancer are not required, so that the number of parts is reduced and The weight of the internal combustion engine 2 can be reduced, and the crankcase 5 can be made more compact, and the internal combustion engine 2 can be made more compact.

The front boss portion of the start driven gear 61 meshing with the small gear 69 of the idler shaft constituting the reduction mechanism of the start motor is connected to the transmission shaft support portion 84 of the front crank shaft holder 80 via the ball bearing 64. It is rotatably supported. Therefore, the output shaft 59 of the hydraulic transmission 3 is supported by the transmission shaft support 84 of the front crankshaft holder 80 via the ball bearing 64, the starting driven gear 61, and the bearing 65.

At the time of starting, the rotation of the starting motor 66 causes the pinion 67, the large idler shaft gear 68, the small idler shaft gear 69, the start driven gear 61, the one-way clutch 62, the input gear 58 and the output gear 15 to rotate. And transmitted to the crankshaft 4.

On the other hand, the hydraulic pump of the hydraulic transmission 3 includes a pump-side swash plate for driving a plurality of pistons in a housing 60 thereof. The hydraulic motor includes a cylinder block having a plurality of pistons and a motor-side swash plate. Having a plate, the cylinder block is integrally connected to the output shaft 59.

When the rotation of the crankshaft 4 is transmitted to the input gear 58 via the output gear 15, the housing 60 of the hydraulic pump integrated with the input gear 58 rotates, whereby the pump-side swash plate tilts and The piston is driven and the output shaft 5
Hydraulic oil supplied from the hydraulic oil pipe at the front end of No. 9 is compressed to generate high oil pressure.

The high hydraulic pressure generated by the hydraulic pump is supplied to a hydraulic motor under the control of a control valve, and the piston is driven to abut on the motor side swash plate, whereby the cylinder block rotates and the output shaft integrated therewith. 59 rotates. The rotation of the output shaft 59 is steplessly changed by changing the angle of the swash plate by the actuator. Further, the control valve can prevent the output shaft 59 from rotating, that is, prevent the rotation of the input gear 58 from being transmitted to the output shaft 59.

The transmission output gear 70 attached to the output shaft 59 of the hydraulic transmission 3 meshes with a gear fixed to the drive shaft of the final reduction gear, and the rotation of the output shaft 59 is reduced to drive. The rear wheels, which are wheels, are driven.

Here, the front and rear crankshaft holders 80 and 90 and the camshaft holder 100 will be described with reference to FIGS. 1 to 3 and FIGS. 4 to 9.

The front crankshaft holder 80 shown in FIGS. 4 to 6 has a flat plate-shaped holder body 81 which forms a plane substantially perpendicular to the axis of the crankshaft 4, and both sides of the holder body 81 along the axis of the cylinder 6. A pair of mounting portions 82 are provided at the edges and curved in an arc shape, and are formed of a single pressed steel plate.

The holder body 81 has a crankshaft support portion 83 rotatably supporting the crankshaft 4 via a front ball bearing 9, a ball bearing 64, a front boss portion of the starting driven gear 61 and a bearing 65. The transmission shaft support 84 that rotatably supports the output shaft 59 of the hydraulic transmission 3 is formed by burring. Both support parts 83, 8
4 has a cylindrical portion projecting rearward, that is, toward the rear crankshaft holder 90 from the rear surface of the holder main body 81, that is, the surface on the side of the crankpin 13, toward the rear crankshaft holder 90. 9, 64 outer races are press-fitted, respectively.

Each of the mounting portions 82 is formed by bending a steel plate extending from a side edge of the holder main body 81 along the axis of the cylinder 6 toward the rear side of the holder main body 81 at a position radially outward of the crankshaft support portion 83. By doing so, it is formed in a partially cylindrical shape as a whole (see FIG. 6), and the through-hole 85 is inserted through the cylindrical hollow portion as described above. Therefore, each mounting portion 82 projects from the rear surface of the holder body 81 toward the rear crankshaft holder 90. And
The front crankshaft holder 8 is formed by a pair of through bolts 85.
Reference numeral 0 denotes a side edge of the holder body 81 on the cylinder 6 side, which is fixed to the crankcase 5.

Each mounting portion 82 also serves as a reinforcing portion for the front crankshaft holder 80 by being configured as follows. That is, the front crankshaft holder 80 is mounted on the engine side crankcase 5b so that the explosive force of the air-fuel mixture acting on the crankshaft 4 from the piston 11 via the connecting rod 12 does not cause bending deformation of the holder main body 81 larger than the allowable limit. In this state, each of the partially cylindrical mounting portions 82 has its axis substantially parallel to the axis of the cylinder 6 or the holder main body 81 due to explosive force.
The cylinder 6 is inclined with respect to the axis of the cylinder 6 within a range in which the bending deformation can be suppressed within an allowable limit.

Further, the length of each mounting portion 82 in the axial direction is the same as the crankshaft supporting portion 83 which is orthogonal to the axis of the cylinder 6.
Are set as appropriate so that the bending deformation of the holder main body 81 can be suppressed within an allowable limit from the plane passing through the axis of. In this embodiment, the axes of both mounting portions 82 are substantially parallel to each other, and the lengths of both mounting portions 82 are substantially equal.

As described above, the two mounting portions 82 project from the holder main body 81 in the axial direction of the crankshaft 4, which is the direction in which the crankshaft 4 passes through the crankshaft support portion 83, and extend along the axis of the cylinder 6. By having a length, it has a function of increasing the bending rigidity of the holder main body 81, and also serves as a reinforcing portion of the front crankshaft holder 80.

Further, since the bending rigidity of the through bolt 85 itself passing through the hollow portion of the mounting portion 82 is added to the bending rigidity due to the shape of the mounting portion 82, the rigidity of the holder body 81 is further increased.

On the other hand, similarly to the front crankshaft holder 80, the rear crankshaft holder 90 shown in FIGS. 7 and 9 also has a flat plate-shaped holder main body 91 which forms a plane substantially perpendicular to the axis of the crankshaft 4. The holder body 91 includes a pair of mounting portions 92 which are located on both side edges along the axis of the cylinder 6 and which are curved in an arc shape, and are formed of a single pressed steel plate.

The holder body 91 has a crankshaft support 93 for rotatably supporting the crankshaft 4 via the rear ball bearing 10 and a camshaft 24 via the front ball bearing 25 and the front boss of the cam gear 23. The rotatable cam shaft support 94 is also formed by burring. The cylindrical portions of the support portions 93 and 96 project forward from the front surface of the holder main body 91, that is, the surface on the side of the crankpin 13, toward the front crankshaft holder 80. Ball bearings 10,
Each of the 25 outer races is press-fitted.

Each mounting portion 92 is formed by bending a steel plate extending from a side edge along the axis of the cylinder 6 of the holder main body 91 at a position radially outward of the crankshaft supporting portion 93 toward the front side of the holder main body 91. By doing so, the front crankshaft holder 8
As in the case of the mounting portion 82 of No. 0, the whole is formed in a partially cylindrical shape, and the through-hole bolt 95 is inserted through the cylindrical hollow portion as described above. Therefore, the mounting portion 92
The direction in which the crankshaft 4 passes through the crankshaft support portion 93, protrudes from the front surface of the holder body 91 toward the front crankshaft holder 80.

Each mounting portion 92 has the same axial arrangement and length in the axial direction as the mounting portion 82 of the front crankshaft holder 80. Therefore, both mounting portions 92 are connected to both mounting portions 8 of front crankshaft holder 80.
Like the second embodiment, the rear crankshaft holder 90 has a function of increasing the bending rigidity of the holder main body 91, and therefore also serves as a reinforcing portion of the rear crankshaft holder 90. Since the bending rigidity of the through bolt 95 itself inserted through the hollow portion of the mounting portion 92 is added to the bending rigidity due to the shape of the mounting portion 92, the rigidity of the holder main body 91 is further increased.

As shown in FIGS. 8 and 9, the camshaft holder 10 formed of a single pressed steel plate is used.
0, a camshaft supporting portion 101 for rotatably supporting the camshaft 24 via a rear ball bearing 26 is formed by burring, and a pump casing 44 of an oil pump 42 disposed behind the crankshaft 4 is provided. An insertion hole 102 to be inserted is formed.

The camshaft support 101 has a cylindrical portion in the direction in which the camshaft 24 is inserted through the camshaft support 101, and is directed forward from the front surface of the camshaft holder 100, that is, toward the rear crankshaft holder 90. The outer race of the rear ball bearing 26 is pressed into the inner peripheral surface of the cylindrical portion.

The rear crankshaft holder 90 and the camshaft holder 100 have the same contour when viewed from the front, and are integrally connected by the pair of lower rocker arm shafts and the connecting portion as described above.

That is, in the rear crankshaft holder 90, the camshaft support portion 94 of the holder main body 91 is located radially outward and closer to the crankshaft support portion 93, the axis of the crankshaft support portion 93 and the camshaft support portion 94. A pair of front mounting holes 9 is located at a position symmetrical with respect to a plane including the
6,97 are formed, and also in the camshaft holder 100,
A pair of rear mounting holes 103 and 104 are formed by burring at positions opposed to the front mounting holes 96 and 97, and a lower intake rocker arm shaft is provided in the pair of front mounting holes 96 and 97 and the pair of rear mounting holes 103 and 104. 35 and a lower exhaust rocker arm shaft 36 are press-fitted, respectively.

Each of the rocker arm shafts 35 and 36 has a flange portion bulging out of a part of the pipe material, and the flange portion abuts on the rear surface of the holder main body 91 of the rear crankshaft holder 90, that is, the surface on the camshaft holder 100 side. The contact between them defines the distance between the holders 90 and 100. Then, the surface of the flange portion on the camshaft holder 100 side and the camshaft holder 10
The lower intake rocker arm shaft 35 has a lower intake rocker arm 32 and a lower supercharged rocker arm 34 between the rear mounting holes 103 and 104 projecting toward the rear crankshaft holder 90 from the front surface of the lower intake rocker arm 90.
The cylindrical rocking bases of the lower exhaust rocker arm 33 are fitted to the lower exhaust rocker arm shaft 36, respectively. The movement in the axial direction is restricted (see FIG. 3).

The rear crankshaft holder 90 has a holder body 91 and a camshaft holder 100 with the crankshaft 4 attached thereto.
With respect to the axis of the crankshaft support portion 93, at a position radially outward of the crankshaft support portion 93 and substantially parallel to both side edges along the axis of the cylinder 6, the crankshaft support portion 93 At a position symmetrical about the plane containing the axis of
A pair of coupling portions are formed. Each coupling portion includes a pair of cylindrical front coupling portions 98 projecting toward the camshaft holder 100 by burring the holder main body 91 of the rear crankshaft holder 90, and a rear crankshaft by burring the camshaft holder 100. It is configured by press fitting with a pair of cylindrical rear coupling portions 105 protruding toward the holder 90 side. The rear coupling portion 105 is formed as a stepped member having a large diameter portion and a small diameter portion, and the small diameter portion is press-fitted into the front coupling portion 98 so that the opening end face of the front coupling portion 98 comes into contact with the step portion. Defines the distance between the holders 90 and 100.

Further, as shown in FIG. 4, the holder main body 81 of the front crankshaft holder 80 is provided radially outward of the crankshaft support portion 83 with respect to the cylinder 6 side with respect to the axis of the crankshaft 4. At a position on the opposite side, a pair of bolt holes 86 for connecting the front crankshaft holder 80 to the crankcase cover 71 with bolts 72 (see FIG. 3) is formed. This is to prevent the opposite side of the front and rear crankshaft holders 80 and 90 from the cylinder 6 side with respect to the axis of the crankshaft 4 from being deformed away from each other due to the aforementioned explosive force.

As for the rear crankshaft holder 90, the camshaft holder 100 disposed behind the rear crankshaft holder 90 is integrally connected to the rear crankshaft holder 90 via a pair of rocker arm shafts and a pair of connecting portions. Due to the structure, the deformation in the separating direction is prevented.

Incidentally, the front and rear crankshaft holders 80 and 90, the camshaft holder 100, the material for forming the timing gear 22 and the cam gear 23, and the steel material in this embodiment have substantially the same coefficient of thermal expansion. , The holders 80, 9
0, 100 and the gears 22 and 23, when the thermal expansion occurs, between the crankshaft 4 and the camshaft 24, the amount of expansion of the timing gear 22 and the cam gear 23 that mesh with the amount of expansion of each of the holders 80, 90 and 100. Is substantially equal to each other, it is possible to prevent an increase in backlash at the meshing portion of the two gears 22 and 23, and to prevent the occurrence of noise due to an increase in backlash.

The first embodiment has the following advantages because it is configured as described above. The front and rear crankshaft holders 80 and 9 are formed by pressing the holder main bodies 81 and 91 on which the crankshaft support portions 83 and 93 for supporting the crankshaft 4 are formed, respectively, from a pressed plate material.
0 can be made lighter and easier to form. Further, since the mounting portions 82 and 92 are also formed of the plate material forming the holder main bodies 81 and 91, the crankshaft holders 80 and 90 provided with the mounting portions 82 and 92 can be formed more easily.

Attachment part 8 to engine side crankcase 5b
The front and rear crankshaft holders 80 and 90 respectively having the through-holes 85 and 9 are provided separately from the crankcase 5 in which the crankshaft 4 is disposed.
5 makes it detachable from the crankcase 5. As a result, since it is not necessary to form a holding portion for the crankshaft 4 in the crankcase 5, the structure of the crankcase 5 is simplified, and the crankshaft 4 itself is assembled to the crankcase 5 and the vicinity of the crankshaft 4 It is easy to assemble the hydraulic transmission 3, the starting driven gear 61, and the like, which are parts of the above, with the crankcase 5. Further, the transmission shaft supporting portion 84 that supports the output shaft 59 of the hydraulic transmission 3 is provided on the front crankshaft holder 80, so that the front crankshaft holder 80 meshes with the crankshaft 4 on which the output gear 15 is provided and the output shaft 59. The distance between the shaft and the output shaft 59 provided with the input gear 58 can also be set accurately.

The crankcase 5 of the internal combustion engine 2 is
The cylinder 6 and the cylinder head 7 are
The front and rear crankshaft holders 80 and 90 are separate from the crankcase 5, unlike the prior art in which the holding portion of the crankshaft is integrally formed with the crankcase while being formed integrally with the crankcase 5. Since it is composed of members, the structure of the integrated crankcase is simplified, casting and subsequent processing are facilitated, and the productivity of the integrated crankcase is improved.

Further, the front and rear crankshaft holders 80 and 90 are provided with the timing gear 22 and the cam gear 23.
As in the case where the holding portion of the crankshaft 4 is integrally cast with the crankcase 5, the aluminum alloy is formed from a steel plate having a thermal expansion coefficient substantially equal to that of the steel material as the material for forming the crankcase 5. Without being limited to the above, an appropriate material suitable for the function unique to the crankshaft 4 can be selected.

Therefore, the front and rear crankshaft holders 80 and 90 and the camshaft holder 100 are formed of a steel material having a thermal expansion coefficient substantially equal to that of the steel material forming the timing gear 22 and the cam gear 23, and thus the internal combustion When the temperature of the internal combustion engine 2 rises due to heat generation of the engine 2 and thermal expansion occurs in the holders 80, 90, 100 and the gears 22, 23, it is possible to prevent an increase in backlash between the gears 22, 23. In addition, it is possible to prevent generation of noise due to an increase in backlash. Therefore, it is not necessary to use a special gear in order to prevent backlash due to a difference in thermal expansion between the crankshaft 4 and the camshaft 24, and the cost can be reduced.

The holder bodies 81 and 91 having the crankshaft support portions 83 and 93 for supporting the crankshaft 4 are formed of a pressed steel plate.
A pair of reinforcing portions are formed on both side edges along the axis of the cylinders 1 and 91 and are partially cylindrical, and protrude radially outward of the crankshaft support portions 83 and 93 in the axial direction of the crankshaft 4. This makes it possible to reduce the weight compared to a holder made by casting, and to increase the bending rigidity that can securely hold the crankshaft 4 even when a large force such as the explosive force of an air-fuel mixture acts on the crankshaft 4. Having a crankshaft holder.

Front and rear crankshaft holders 80, 9
Reference numeral 0 denotes a more compact crankshaft holder because the pair of partially cylindrical mounting portions 82 and 89 into which the through bolts 85 and 95 pass also functions as a reinforcing portion, and is held by the mounting portions 82 and 92. Through bolts 85, 9
Since the rigidity of the 5 itself is added to the bending rigidity due to the reinforcing portions of the holder main bodies 81 and 91, the rigidity is further increased, and a crankshaft holder having high strength can be obtained.

A cam gear 23 meshing with a timing gear 22 provided on the crankshaft 4 is provided, and a camshaft 24 for driving a lower intake, lower exhaust and lower supercharged rocker arms 32, 33, 34 constituting a valve operating mechanism is provided. Is supported by the camshaft support portion 94 of the holder main body 91 of the rear crankshaft holder 90 that supports the crankshaft 4 by the crankshaft support portion 93, so that a part of the valve train can be compactly arranged near the crankshaft. With the rear crankshaft holder 90
Can be used as a common base to provide a module including the crankshaft 4 and the camshaft 24. As a result, the lower intake and lower exhaust rocker arms 3 are attached and detached by attaching and detaching both crankshaft holders 80 and 90 to and from the crankcase 5.
By performing the assembling and removing of the camshaft 24 for driving the camshafts 2 and 33 from the crankcase 5, the ease of assembling and removing the camshaft from the crankcase 5 is improved, and the assembly and maintenance of the internal combustion engine 2 are improved. For easy disassembly.

Further, the rear crankshaft holder 90 and the camshaft holder 100 are provided with a pair of rocker arm shafts 3.
5 and 36, the mechanism including the cam gear 23, the camshaft 24 and the rocker arms 32, 33 and 34 is modularized together with the front and rear crankshaft holders 80 and 90 supported by the crankshaft 4 to provide a crankcase. 5 to make it easier to disassemble the internal combustion engine 2 for assembly and maintenance.

The front crankshaft holder 80 is connected to the crankcase cover 71 by bolts 72 at a position radially outward of the crankshaft support portion 83 and opposite to the cylinder 6 side with respect to the axis of the crankshaft 4. The rear crankshaft holder 90 has a frame structure integrated with the camshaft holder 100 disposed behind the pair via the pair of rocker arm shafts 35 and 36 and the pair of coupling portions 98 and 105. As a result, it is possible to prevent the front and rear crankshaft holders 80, 90 from being deformed away from each other by the explosive force of the air-fuel mixture.

FIGS. 10 to 13 show a second embodiment, which is applied to the same internal combustion engine as the first embodiment, instead of the front and rear crankshaft holders 80 and 90. FIG. However, the output shaft 59, the camshaft 24, and the valve mechanism of the hydraulic transmission 3 are supported by different structures.

In the second embodiment, the crankshaft 4
Is held on the crankcase 5 by the front and rear crankshaft holders 110 and 120. Each of the crankshaft holders 110 and 120 is a flat plate-shaped holder main body 111 that forms a plane substantially perpendicular to the axis of the crankshaft 4, and is bent substantially perpendicularly to the holder main body 111 at the edge of the holder main body 111 on the cylinder 6 side. Mounting portion 112 and mounting portion 11
And a reinforcing portion 113 bent substantially at right angles to the holder main body 111 at both side edges along the axis of the cylinder 6 of the holder main body 111 outside the both end portions of the holder main body 111.
They are formed from a single sheet of pressed steel.

A crankshaft support 114 for rotatably supporting the crankshaft 4 via a front ball bearing 9 is formed on the holder body 111 of the front crankshaft holder 110 by burring. Crankshaft support 114
Has a cylindrical portion projecting rearward, that is, toward the rear crankshaft holder 120 from the rear surface of the holder main body 111, that is, the surface on the side of the crankpin 13, toward the rear crankshaft holder 120. Outer race is press-fitted.

The mounting portion 112 is provided with a crankshaft support portion 114.
The steel plate extending from the side edge of the holder body 111 on the cylinder 6 side at the radially outward position is bent toward the rear side of the holder body 111, so that the front crankshaft holder 110 is mounted at both ends thereof. It is formed as a flange provided with a bolt hole 116 through which a pair of mounting bolts 115, which are stoppers for fixing to the side crankcase 5b, are inserted. Therefore, the mounting portion 112 is attached to the holder main body 1.
11 protrudes toward the rear crankshaft holder 120 from the rear surface.

The pair of reinforcing portions 113 are provided at the radially outer positions of the crankshaft supporting portion 114 with steel plates extending from both side edges along the axis of the cylinder 6 of the holder main body 111, respectively, on the rear side of the holder main body 111. By bending
It is formed as a substantially rectangular flange. Therefore,
Each of the reinforcing portions 113 is formed such that the crankshaft 4 is
In the axial direction of the crankshaft 4, which is a direction in which the crankshaft 14 is inserted, the projection projects from the rear surface of the holder body 111 toward the rear crankshaft holder 120.

On the other hand, on the holder main body 121 of the rear crankshaft holder 120, a crankshaft support 124 for rotatably supporting the crankshaft 4 via the rear ball bearing 10 is formed by burring. The cylindrical portion of the crankshaft support portion 124 projects forward from the rear surface of the holder body 121, that is, toward the front crankshaft holder 110, and the outer race of the rear ball bearing is press-fitted into the inner peripheral surface of the cylindrical portion. You.

The mounting portion 122 includes a crankshaft support portion 124
The front crankshaft holder 11 is formed by bending a steel plate extending from a side edge of the holder main body 121 on the cylinder 6 side toward the front side of the holder main body 121 at a radially outer position of the front crankshaft holder 11.
0, and formed at both ends thereof with bolt holes 126 through which a pair of mounting bolts 125 which are stoppers for fixing the rear crankshaft holder 120 to the crankcase 5 are inserted. Therefore, the mounting portion 122
Project from the rear surface of the holder body 121 toward the front crankshaft holder 110.

A pair of reinforcing portions 123 are provided at the radially outer position of the crankshaft support portion 124 with steel plates extending from both side edges along the axis of the cylinder 6 of the holder main body 121, respectively. By bending to the side, it is formed as a substantially rectangular flange. Therefore, each reinforcing portion 123 protrudes from the rear surface of the holder main body 121 toward the front crankshaft holder 110.

The reinforcing portions 113 and 123 of the crankshaft holders 110 and 120 are, similarly to the reinforcing portions of the first embodiment, so that the holder bodies 111 and 121 do not bend more than the allowable limit due to the explosive force. In a state where the front crankshaft holder 110 is fixed to the engine side crankcase 5b, the bending curve corresponding to the axis of the reinforcing portion (the mounting portions 82, 92) of the first embodiment is formed with respect to the axis of the cylinder 6. They are provided substantially parallel or inclined. Further, the lengths of the bending curves of the reinforcing portions 113 and 123 also differ from the plane passing through the axis of the crankshaft supporting portions 114 and 124 orthogonal to the axis of the cylinder 6 toward the cylinder 6 side and the opposite side of the cylinder 6, respectively. The length is such that bending deformation of the main bodies 111 and 121 can be suppressed within an allowable limit.

As described above, each reinforcing portion 113, 123
As in the first embodiment, the holder main body 111 and the holder main body 111 are moved in the direction in which the crankshaft 4 passes through the crankshaft support portions 114 and 124.
It has a function of increasing the bending rigidity of the holder main bodies 111 and 121 by projecting from the 121 and having a predetermined length along the axis of the cylinder 6.

Further, as shown in FIGS. 12 and 13, each reinforcing portion 113 of the front crankshaft holder 110 is provided.
The rear part is a reinforcing part 123 of the rear crankshaft holder 120.
Overlapped with each other inside the front portion of the cylinder 6 with respect to the axis of the crankshaft support portion 114 of the cylinder.
In the vicinity of the end opposite to the side, a screw hole 11 for connecting the overlapped portion of both reinforcing portions 113 and 123 with a bolt 130.
7 are formed. And the rear crankshaft holder 1
A bolt hole 127 through which a bolt 130 is inserted is formed at a position facing the screw hole of the overlapping portion of the front crankshaft holder 110 in the overlapping portion at the front end of each reinforcing portion 123 of the front crankshaft holder 110.

Then, these overlapping portions are connected to each other by bolts 13.
0, the front and rear crankshaft holders 110 and 120 connect the crankshaft 4 to the front ball bearings 9 and 10.
And is rotatably supported via the, and is removably fixed to the crankcase 5 as a fixing member by mounting bolts 115 and 125. Also, by connecting the overlapping portions to each other with bolts 130,
The opposite sides of the front and rear crankshaft holders 110 and 120 from the cylinder 6 side with respect to the axis of the crankshaft 4 are:
This prevents deformation in the direction away from each other.

The second embodiment has the following effects because it is configured as described above. Since the holder main bodies 111 and 121 on which the crankshaft support portions 114 and 124 for supporting the crankshaft 4 are formed are formed of pressed plate materials, the weight of the front and rear crankshaft holders 110 and 120 can be reduced easily. Is possible. Further, the mounting portions 112, 122 and the reinforcing portions 113, 12
3 is also formed by the plate material forming the holder main bodies 111 and 121, so that the mounting portions 112 and 122 and the reinforcing portions 1 are formed.
Crankshaft holder 110, 1 provided with 13, 123
20 can be formed more easily.

Attachment portions 112, 12 to crankcase 5
And rear crankshaft holders 110, 1 comprising
Reference numeral 20 is formed of a separate member from the crankcase 5 in which the crankshaft 4 is disposed, and is detachably attached to the crankcase 5 by mounting bolts 115 and 125. As a result, since it is not necessary to form a holding portion for the crankshaft 4 in the crankcase 5, the structure of the crankcase 5 is simplified, and the crankshaft 4 itself is assembled to the crankcase 5 and the vicinity of the crankshaft 4 It is easy to assemble the hydraulic transmission 3, the starting driven gear 61, and the like, which are parts of the above, with the crankcase 5.

Further, since the front and rear crankshaft holders 110 and 120 are formed from a steel plate, they are formed of the crankcase 5 as in the case where the holding portion of the crankshaft 4 is integrally cast with the crankcase 5. The material is not limited to the aluminum alloy, and an appropriate material suitable for the function unique to the crankshaft 4 can be selected. For example, as in the first embodiment, noise is generated due to an increase in backlash between gears due to thermal expansion. Prevention can be achieved.

Further, holder bodies 111 and 12 having crankshaft support portions 114 and 124 for supporting the crankshaft 4 are provided.
1 is formed of a pressed steel plate, and is bent substantially orthogonally from both side edges along the axis of the cylinder 6 of the holder main bodies 111 and 121, so that the crankshaft supporting portion 1 is formed.
A pair of reinforcing portions 113, 123 projecting in the axial direction of the crankshaft 4 are provided radially outward of the portions 14, 124. As a result, a crankshaft having a bending rigidity capable of securely holding the crankshaft 4 even when a large force such as an explosive force of an air-fuel mixture acts on the crankshaft 4 while allowing the weight to be reduced as compared with the holder by casting. It can be a holder.

The front and rear crankshaft holders 110,
The overlapping portions of the reinforcing portions 113, 123 of 120 are connected by bolts 130 near the ends of the overlapping portions on the side opposite to the cylinder 6 side with respect to the axis of the crankshaft support portions 114, 124. As a result, the front and rear crankshaft holders 110 and 120 can be prevented from being deformed away from each other by the explosive force of the air-fuel mixture.

Next, referring to FIG. 14 to FIG.
An embodiment will be described. In the third embodiment, the internal combustion engine 201 is a four-cycle single-cylinder water-cooled internal combustion engine,
The internal combustion engine 201 forms a power unit together with a power transmission device having a cone type continuously variable transmission (not shown).

FIG. 14 is a cross-sectional view taken along a plane passing through the axis of the cylinder 203 of the internal combustion engine 201 and viewed from the back, and FIG. 15 is a cross-sectional view taken mainly along the line XV-XV in FIG. As shown, the internal combustion engine 201 is arranged vertically so that the axis of the crankshaft 206 is oriented in the front-rear direction of the vehicle body, and the axis of the cylinder 203 is the crankshaft 20.
It is directed slightly obliquely upward to the right with respect to the axis 6.
The crankcase 202 of the internal combustion engine 201 has a split surface slightly inclined to the left from the vertical plane passing through the axis of the crankshaft 206, so that the transmission side, which also serves as a part of the case of the continuously variable transmission, is located on the left side of the vehicle body. A crankcase 202a,
It is divided into an engine side crankcase 202b integrally formed by casting together with a cylinder 203 of the internal combustion engine 201.

A cylinder head 204 is mounted on the cylinder 203, and a cylinder head cover 205 is mounted on the cylinder head 204. Further, a power transmission device for transmitting the power of the crankshaft 206 to the rear wheels is:
It has a starting clutch 234 and the continuously variable transmission, and a main shaft 233 of the continuously variable transmission is disposed diagonally above and to the left with respect to the axis of the crankshaft 206.

The crankshaft 206 is rotatably supported on the crankshaft supporting portions of the flat front and rear crankshaft holders 240 and 260 via front and rear ball bearings 207 and 208, respectively. Placed in These pair of crankshaft holders 240,
260 is detachably fixed to the crankcase 202 and the cylinder 203, which are fixing members, by five through bolts, which are stoppers through which the five mounting portions are inserted. These through bolts have a tightening direction parallel to the axis of the crankshaft 206. The details of the front and rear crankshaft holders 240 and 260 will be described later.

The piston 209 which is slidably fitted in the cylinder hole of the cylinder 203 and reciprocates is connected to the connecting rod 2.
10 to the crankshaft 206. As in the first embodiment, a balance weight is provided on the front crank web of the crankshaft 206, and an output gear 211 is formed on the rear crank web.

The cylinder head 204 is provided with an ignition plug 212 for igniting the air-fuel mixture supplied from the intake passage, facing the combustion chamber. A double-acting piston-type supercharger 213 of the same type as that of the first embodiment is mounted directly above the engine-side crankcase 202b and the cylinder 203, and discharge air at a high pressure passes through a supercharge valve 223. And supplied to the combustion chamber. The supercharger 213 is different from that of the first embodiment in that a drive sprocket 215 serrated and coupled to a cam shaft 214 described later and a supercharger 2
The crankshaft of the supercharger 213 is rotated and driven at a rotation speed equal to that of the camshaft 214 by a belt (not shown) stretched between the driven sprocket 216 serrated and connected to the crankshaft 206 of the supercharger 13. You.

An AC generator 217 is provided at the front end of the crankshaft 206 extending forward from the front ball bearing 207, and a rotor of the AC generator 217 integrally fixed to the crankshaft 206 has a forward portion. A cooling fan 218 for blowing cooling air is integrally fixed to the arranged radiator (not shown). On the other hand, the crankshaft 206
A trochoid-type oil pump 219 is provided at the rear side of the first embodiment.

A steel timing gear 2 serrated and connected to the rear of the rear ball bearing 208 of the crankshaft 206
Reference numeral 20 denotes a drive gear that drives a camshaft 214 that is a rotation shaft that drives a valve mechanism that is one mechanism of the internal combustion engine 201, and is a driven gear made of steel that is a driven gear serrated and coupled to the camshaft 214. It is in mesh with the cam gear 221.

The cam shaft 214 is provided with three cams 224 for driving the intake valve (not shown), the exhaust valve 222 and the supercharging valve 223, respectively. The lower rocker arm shaft 225 has three cams 224. The two lower rocker arms slidably in contact with the respective 224 and constituting part of the valve operating mechanism, namely, a lower intake rocker arm 226, a lower exhaust rocker arm 227 and a lower supercharged rocker arm 228.
Are swingably supported (see also FIG. 17). Each of the cylinder heads 204 has
One upper end is swingably supported by an upper rocker arm shaft 229, and the other end is connected to the lower rocker arm via a corresponding pull rod 230 in an interlocked manner, ie, three upper rocker arms, ie, an upper intake rocker arm (not shown) and an upper exhaust rocker arm 231. And upper supercharged rocker arm 232
The upper rocker arms abut an intake valve, an exhaust valve 222 and a supercharging valve 223 slidably provided on the cylinder head 204, respectively.

Therefore, the three lower rocker arms oscillated corresponding to the three cams 224 respectively oscillate the three upper rocker arms via the three pull rods 230, and are operated by the three upper rocker arms. Intake valve,
The exhaust valve 222 and the supercharging valve 223 open and close the intake port, the exhaust port, and the opening on the combustion chamber side of the supercharging port at predetermined timing, respectively. Therefore, the valve mechanism is
A cam shaft 214, a lower rocker arm, a pull rod 230, and an upper rocker arm are provided.

The output gear 211 meshes with an input gear 235 of a centrifugal start clutch 234 rotatably mounted on a main shaft 233 of the continuously variable transmission, and the power of the crankshaft 206 is transmitted via the start clutch 234. Main shaft 2 of continuously variable transmission
33. Here, since the starting clutch 234 and the continuously variable transmission constitute a power transmission device which is a mechanism attached to the internal combustion engine 201, the input gear 235 is
The input gear 235 corresponds to a driven gear that meshes with an output gear 211 that is a drive gear provided on the crankshaft 206.
Are rotated at the same rotation speed as the primary drive gear, and the main shaft 233 corresponds to a rotation shaft that drives the power transmission device. The main shaft 233 includes a first main shaft 233a serving as an output shaft of the starting clutch 234, and a second main shaft 233 spline-coupled to the first main shaft 233a and serving as an input shaft of the continuously variable transmission.
b.

The starting clutch 234 includes a first main shaft 233a.
A bowl-shaped clutch outer 234a coupled so as to rotate integrally with the sleeve, and a sleeve 234b inside the clutch outer 234a and drivingly connected to the input gear 235 and rotatably fitted to the first main shaft 233a. , A drive plate 234c that rotates integrally with the sleeve 234b
And The input gear 235 is connected to the internal combustion engine 201.
Is rotated at a rotation speed higher than the predetermined rotation speed of the clutch spring 234d, the plurality of clutch shoes 234d supported swingably on the drive plate 234c.
e, oscillates radially outward due to the centrifugal force against the spring force, and the friction member 234f provided on the outer peripheral surface of each clutch shoe 234d comes into contact with the inner peripheral surface of the clutch outer 234a. Are connected, and the rotation of the input gear 235 is transmitted to the main shaft 233.

Here, with reference also to FIGS. 16 to 18, front and rear crankshaft holders 240, 260
This will be further described mainly. Front crankshaft holder 240
The rear crankshaft holder 260 has the same shape, and includes flat plate-shaped holder main bodies 241 and 261 each forming a plane substantially orthogonal to the axis of the crankshaft 206.
The holder bodies 241 and 261 are formed of a single pressed steel plate.

Each of the holder bodies 241 and 261 is provided with three support portions, five attachment portions, and two connection portions.
Hereinafter, the holder main body 241 of the front crankshaft holder 240
However, since the same applies to the holder main body 261 of the rear crankshaft holder 260, the configuration or reference numerals related to the rear crankshaft holder 260 are described in parentheses for convenience of description.

The three supporting portions having through holes penetrating the holder main body 241 (261) in the axial direction of the crankshaft 206 rotatably support the crankshaft 206 via front ball bearings 207 (rear ball bearings 208). And the crankshaft support 242 (262)
62), a transmission shaft support 243 (263) rotatably supporting the first main shaft 233a via a front ball bearing 280 (rear ball bearing 281) to the left, and a front ball bearing to the right. A camshaft support 244 that rotatably supports the camshaft 214 via a rear ball bearing 283.
(264). And three support parts 242 to 24
4 (262 to 264) are the crankshaft 206 and the main shaft 23.
3 and the axis of the camshaft 214 are positioned so as to be substantially on the same plane.
(262 to 264) include respective front ball bearings 207 and 282.
Outer races 207a, 282a (outer races 208a, 283) of steel (each rear ball bearing 208, 283).
a) is press-fitted, and the inner race 207b (the inner race 208b) of the front ball bearing 207 is
The inner race 282b (283b) of the front ball bearing 282 (rear ball bearing 283) is pressed into the camshaft 214, respectively.

The five mounting portions having through holes passing through the holder main body 241 (261) in the axial direction of the crankshaft 206 are provided on the transmission side crankcase 202a.
First and second mounting portions 245 and 246 forming two transmission-side mounting portions respectively corresponding to the two bolt holes (one of which is shown in FIG. 15).
(265, 266) and three bolt holes provided in the engine side crankcase 202 (FIG. 15 shows one of them).
(Three bolt holes 285 are shown), and third, fourth, and fifth attachment portions 247 to 249 (267 to 269) constituting three engine-side attachment portions. And these attachment parts 245-249 (265-269)
Are located around the front crankshaft holder 240 (rear crankshaft holder 260).

Each of the mounting portions 245 to 249 (265 to 26
9), through bolts 286 to 290 having a tightening direction parallel to the axis of the crankshaft 206 are inserted, and the through bolts 286 to 290 allow the two crankshaft holders 2 to be inserted.
40 and 260 are the crankcase 202 and the cylinder 2
03 is fixed. Among them, the third and fourth attachment portions 247,
248 (267, 268)
8,289 are located near the cylinder liner. Also, the first, second, and fourth attachment portions 245, 246, 248
(265, 266, 268) are screwed into nuts 291, 292, 294 welded to the rear crankshaft holder 260, respectively. Further, the third and fifth attachment portions 247,
249 (267, 269) have through bolts 288, 2
Knock shaft having a hollow portion through which the 90 is inserted (FIG. 1)
5 shows a knock shaft 296 through which the through bolt 290 is inserted).
8 and 290 are nuts 2 on the rear crankshaft holder 260 side.
93,295.

The two coupling portions 250, 251 (270, 271) having through holes passing through the holder main body 241 (261) in the axial direction of the crankshaft 206 are connected to the first and second coupling portions.
It is located between the line connecting the attachment portions 245 and 246 (265 and 266) and the line connecting the third and fourth attachment portions 247 and 248 (267 and 268) and is located at a position substantially opposite to the diameter of the crankshaft 206. . Then, each of the connecting portions 250 and 251
(270, 271) include both crankshaft holders 240,
260, which is a spacer for holding the interval in the axial direction of the crankshaft 206 at a set value,
298 is pinched by press fitting.

Further, a rocker arm shaft support 252 (272) having a through hole is provided in the holder body 241 (261).
Is provided, and the rocker arm shaft support portion 252 (272) is provided.
The three lower rocker arms are swingably supported by the lower rocker arm shaft 225 fitted to the arm.

As shown in FIG. 17, the front crankshaft holder 240 and the rear crankshaft holder 2
60, the camshaft 206 held by both ball bearings 207 and 208, the camshaft 214 held by both ball bearings 282 and 283, and the first shaft held by both ball bearings 280 and 281.
The main shaft 233a, the lower rocker arm shaft 225, and the starting clutch 234 are arranged, and the crankshaft holders 240, 260 are integrated with the crankcase holders 240, 260 in a state where these members and the crankshaft holders 240, 260 are integrated.
2, the third and fifth attachment portions 247, 24 from the front.
No. 9 (267, 269) is positioned on the cylinder 203 and the engine side crankcase 202b by the knock shaft (the fifth mounting portion 249 (269), the knock shaft 296 shown in FIG. 15). The fourth and fifth attachment portions 247, 248, 249 (26
7, 268, 269), the through bolts 288, 289, 290 inserted into the knock shaft from the front are temporarily tightened, so that they are temporarily fixed to the cylinder 203 and the engine side crankcase 202b. Thereafter, the transmission-side crankcase 202a is moved to the engine-side crankcase 202b.
And the first and second mounting portions 245, 246 (26
5, 266), through bolt 28 inserted from the front
6,287 are temporarily fastened, so that both crankshaft holders 240,260 are accommodated in the crankcase 202,
Next, these through bolts 286 to 290 are tightened, and both crankshaft holders 240 and 260 are
3 and the crankcase 202.

As described above, the three lower rocker arms constituting a part of the valve operating mechanism and the starting clutch 234 which is a part of the power transmission device are provided by the two crankshaft holders 24.
Since they are arranged between 0 and 260, they respectively constitute the holder internal portion of the valve train and the power transmission device holder.

Incidentally, the steel materials forming the holder main bodies 241 and 261 of the front and rear crankshaft holders 240 and 260, the timing gear 220 and the cam gear 221 have substantially the same thermal expansion coefficients. When the temperature rises, even if thermal expansion occurs in these members, the amount of extension of both crankshaft holders 240 and 260 between the crankshaft 206 and the camshaft 214 and the timing gear 220 and cam gear 22
Since the elongation amount is substantially equal to 1, the backlash of the meshing portion between the two gears 220 and 221 can be prevented from increasing, and the generation of noise due to the backlash increase can be prevented.

Each of the holder main bodies 241 and 261 and the outer races 207a and
Since the thermal expansion coefficients of the forming materials of the thermal expansion members 208a are substantially equal to each other, even if thermal expansion occurs, the change in the tightening force due to the press-fitting is small.
261 and 20 ball bearings 207 and 20
8 can be reliably held.

Since the third embodiment is configured as described above, the following effects are obtained. Since the holder main bodies 241 and 261 on which the crankshaft support portions 242 and 262 for supporting the crankshaft 206 are respectively formed are formed of pressed plates, the front and rear crankshaft holders 240 and 260 can be reduced in weight and easily formed. Is possible.

The front and rear crankshaft holders 240,
260 is formed of a separate member from the crankcase 202 in which the crankshaft 206 is disposed, and
290, the crankcase 202 and the cylinder 20
3 is detachable. As a result, the crankcase 20
2 does not need to form a holding portion for the crankshaft 206, so that the structure of the crankcase 202 is simplified, and the crankshaft 206 itself is assembled to the crankcase 202 and the cams around the crankshaft 206 are provided. Shaft 21
4. The assembling of the continuously variable transmission or the like into the crankcase 202 becomes easy.

Further, since the front and rear crankshaft holders 240 and 260 are formed from a steel plate having a thermal expansion coefficient substantially equal to the steel material forming the timing gear 220 and the cam gear 221, the holding portion of the crankshaft 206 is formed. Without being limited to the material for forming the crankcase 202, as in the case of being integrally cast with the crankcase,
An appropriate material suitable for the function unique to the crankshaft 206 can be selected.

The front and rear crankshaft holders 240,
The camshaft 214 provided with a cam gear 221 meshing with the timing gear 220 provided on the crankshaft 206 is supported by the camshaft support portions 244 and 264, and the output gear 211 provided on the crankshaft 206 has a camshaft 214. A first main shaft 233a of the continuously variable transmission that is drivingly connected via a starting clutch 234 having an input gear 235 that meshes with the first main shaft 233a;
Are supported by the transmission shaft support portions 243, 263, so that a part of the valve train and the power transmission device can be compactly disposed near the crankshaft 206.

Further, using the front and rear crankshaft holders 240 and 260 as a common base,
6, a lower rocker arm which is provided with a camshaft 214 and a first main shaft 233a and is a part of a valve mechanism driven by the camshaft 214, and a starting clutch 234 which is a part of a power transmission device driven by the main shaft 233.
Each of the holder internal parts may be a module disposed between the front and rear crankshaft holders 240, 260.

As a result, both crankshaft holders 240, 2
The cam shaft 214 and the first main shaft 233a are attached and detached to and from the crankcase 202 and the cylinder 203.
Of the camshaft 214 and the first main shaft 233a is improved and the disassembly for assembly and maintenance of the internal combustion engine 201 is improved. It will be easier. Further, the lower rocker arm and the starting clutch 234, which are internal parts of the holder disposed between the pair of crankshaft holders 240 and 260, are also integrated with the pair of crankshaft holders 240 and 260 and the crankcase 202 and the cylinder 203. The components are attached to and detached from the crankcase 202 and the cylinder 203, so that they can be easily assembled and removed from the crankcase 202 and the cylinder 203, and the internal combustion engine 201 can be easily assembled and disassembled for maintenance.

Further, the crankshaft 20 of the pair of crankshaft holders 240, 260 is moved by the spacing shafts 297, 298.
6 is precisely defined, so that the crankshaft 206, the camshaft 214, and the first main shaft 233a are disposed between the front and rear crankshaft holders 240 and 260.
In addition to being able to hold a proper position in the axial direction,
The presence of the spacing shafts 297, 298 press-fitted into the coupling portions 250, 251, 270, 271 causes the crankshaft 20
6, the deformation of both crankshaft holders 240, 260 caused by the explosion load acting on 6 is suppressed.

The front and rear crankshaft holders 2
40, 260 holder bodies 241, 261 and each ball bearing 2
Since the thermal expansion coefficients of the outer races 07 and 208 and the material of the outer races 207a and 208a are substantially equal to each other, even if thermal expansion occurs, a change in the tightening force due to press-fitting is small. The ball bearings 207, 208 can be reliably held only by the thickness of the steel plates of the main bodies 241, 261.

Furthermore, a pair of crankshaft holders 240,
260 handles most of the explosion load acting on the crankshaft 206 and
First to fifth attachment portions 245 to 24 located around 60
9, 265 to 269, the crankshaft 2 and the cylinder 203 are fixed.
Since the load acting on the crankshaft holders 240 and 260 from 2006 can be dispersed over a wide range of the crankcase 202 and the cylinder 203, the crankcase 202 can be made thinner or made of a lightweight material such as a synthetic resin. .

Next, a fourth embodiment will be described with reference to FIGS. In the fourth embodiment, the internal combustion engine includes a pair of balancer shafts 302 and 303, and a crankshaft 301 is connected to a connecting rod one end of which is connected to a piston 304 slidably fitted to a cylinder (not shown). Crank pin 301c to which the other end of 305 is connected
A front crank half 301a and a rear crank half 301b integrally connected by a
And are rotatably supported by front and rear crankshaft holders 320 and 340 via rear ball bearings 307, respectively.

In the crankshaft 301 having the disk-shaped front and rear crank webs, the crankshaft 301 between the rear crank web and the rear ball bearing 307 is made of steel, which is a drive gear provided on the crankshaft 301. The balancer drive gear 308 is press-fitted, and the rear ball bearing 30
7, a steel timing gear 309, which is a drive gear provided on the crankshaft 301, is press-fitted into a rear end portion of the crankshaft 301, and the gears 308 and 0309 rotate integrally with the crankshaft 301.

The balancer driving gear 308 meshes with steel balancer driven gears 310, 311 press-fitted into the balancer shafts 302, 303 rotatably supported by the crankshaft holders 320, 340, respectively. Both balancer shafts 3 provided with balance weights 312 and 313
02 and 303 are driven to rotate at a rotation speed equal to the rotation speed of the crankshaft 301. The timing gear 30
9 is a camshaft 31 meshed with a steel cam gear 315, which is a driven gear press-fitted into the camshaft 314, and provided with a cam 316 for driving an intake valve, an exhaust valve, and a supercharging valve, respectively.
4 is driven to rotate.

Next, the front crankshaft holder 320 and the rear crankshaft holder 340 will be described. Each of the crankshaft holders 320 and 340 has a symmetrical shape with respect to a symmetrical plane which is a plane passing through the axis of the crankshaft 301 and the axis of the cylinder, and has a flat plate shape substantially orthogonal to the axis of the crankshaft 301. Holder body 32
1 and 341, and the holder main bodies 321 and 341 are formed from a single sheet of pressed steel plate.

The holder bodies 321 and 341 of both crankshaft holders 320 and 340 are connected to the rear crankshaft holder 340.
Except that a cam shaft support 352 and a connecting portion of a cam shaft holder 380, which will be described later, are formed on the holder main body 341.
1, the common crankshaft holder 320
Of the rear crankshaft holder 340 will be described in parentheses for convenience of description.

The three supporting portions having through holes penetrating the holder main body 321 (341) in the axial direction of the crankshaft 301 rotatably support the crankshaft 301 via a front ball bearing 306 (rear ball bearing 307). And the crankshaft support 322 (342).
42), front ball bearings 360, 362 (rear ball bearings 361, 361) on the sides of the crankshaft 301, respectively.
363), and a pair of balancer shaft support portions 323, 324 (3) that rotatably support the balancer shafts 302, 303 via (363).
43, 344).

The three support portions 322, 323, 324 (3
42, 343, 344), the axes of the crankshaft 301 and the two balancer shafts 302, 303 are located on the same plane, and the axis of the crankshaft 301 and the balancer shafts 302, 30
3 are arranged so as to be equal to the axis. In addition, each of the support portions 322, 323, 324 (342, 34
3,344) includes respective front ball bearings 306, 360, 36.
2 (each rear ball bearing 307, 361, 363) made of steel outer races 306a, 360a, 362a (307a,
361a, 363a) are press-fitted and the front ball bearing 30
6 (rear ball bearing 307) of inner race 306b (30
7b) on the crankshaft 301 and on the front ball bearing 36
Inner races 360b, 362b (361b, 363b) of 0,362 (rear ball bearings 361, 363) are pressed into balancer shafts 302, 303, respectively.

The three mounting portions having through-holes penetrating the holder body 321 (341) in the axial direction of the crankshaft 301 are formed of through-holes having a center line on the symmetry plane. (Not shown) and a first mounting portion 325 (345) constituting a case-side mounting portion corresponding to a bolt hole provided at a position symmetrical with respect to the symmetry plane and provided on a cylinder serving as a fixing member. The second and third mounting portions 326 and 327 (3) constituting two cylinder-side mounting portions respectively corresponding to the two bolt holes provided.
46, 347). Second and third mounting portions 326, 3
27 (346, 347) is the holder main body 321 (34).
In 1), a pair of projections 321a, 321b (341a, 341b) projecting toward the cylinder head are provided respectively. And, these mounting portions 325
327 (345-347) are located around the front crankshaft holder 320 (rear crankshaft holder 340).

Each of the mounting portions 325 to 327 (345 to 34)
7), through bolts (not shown), which are stoppers in a tightening direction parallel to the axis of the crankshaft 301, are inserted, and the through bolts allow the front crankshaft holder 3 to be inserted.
20 (rear crankshaft holder 340) is fixed. Among them, the through bolt inserted into the first mounting portion 325 is
Nut 364 welded to front crankshaft holder 320
And a through bolt inserted into the first mounting portion 345 is screwed into a nut 365 welded to the rear crankshaft holder 340.

The front and rear crankshaft holders 320,
In order to join the 340, the holder body 321 (341) is
The four coupling portions having through holes penetrating in the axial direction of the crankshaft 301 are formed by two balancer shaft support portions 323, 324.
(343, 344) than the first mounting portion 325 (345).
The first and second coupling portions 328, 329 (34
8, 349) and both balancer shaft support portions 323, 324.
(343, 344), the second and third mounting portions 326, 3
The third and fourth coupling portions 330 and 331 (350 and 351) are located closer to 27 (346 and 347). The first joint 328 (348) and the second joint 329 (34)
9), and the third coupling part 330 (350) and the fourth coupling part 331 (351) are respectively arranged symmetrically with respect to the symmetry plane.

Then, both the first connecting portions 328 and 348, both the second connecting portions 329 and 349, and both the third connecting portions 330 and 35 are provided.
0, the rivets 366 are attached to both the fourth connecting portions 331 and 351.
369 are inserted, and the rivets 366
369, both ends of which are both crankshaft holders 320, 3
The abutting surfaces of the crankshafts 3
In the state where the cylindrical collars 370 to 373 which are spacers for holding the interval at the set value in the axial direction of 01 are inserted, one end of the rivets 366 to 369 is swaged, so that the two crankshaft holders 320 and 340 are set. Are integrated. The rivets 36 inserted into both the third connecting portions 330 and 350 and both the fourth connecting portions 331 and 351
8, 369 are a pair of connecting portions 38 of the camshaft holder 380.
2, 383 are also inserted, so that the camshaft holder 380 is fixed in contact with the rear crankshaft holder 340.

Next, the rear crankshaft holder 340 will be further described. A camshaft having a center line located on the symmetry plane and a through-hole penetrating in the axial direction of the crankshaft 301 is provided on the holder main body 341. A support portion 352 is formed, and a rivet 374 is inserted into and fixed to the camshaft support portion 352 and a camshaft support portion 381 provided on a camshaft holder 380 fixed to the rear crankshaft holder 340. A cylindrical collar 375 having both ends abutting on opposing surfaces of the rear crankshaft holder 340 and the camshaft holder 380 is fitted on the outer periphery of the rivet 374, and a cylindrical camshaft 314 is rotatable around the outer periphery of the collar 375. Is fitted to.

Further, the holder main body 341 is provided with fifth and sixth coupling portions 353 and 354 having through holes penetrating in the axial direction of the crankshaft 301. Fifth joint 35
3 is the second mounting portion 34 at one of the protrusions 341a.
The sixth connecting portion 354 is located between the third mounting portion 347 and the fourth connecting portion 351 at the other protruding portion 341b.

On the other hand, a camshaft holder 380 formed of a single pressed steel plate has a crankshaft 301.
Are provided by four through holes penetrating in the axial direction. First and second coupling portions 382, 383
The camshaft holder 380 is formed by bending a part of the camshaft holder 380 toward the rear crankshaft holder 340, and is formed on a flange portion that abuts on the rear crankshaft holder 340 in FIG. Flange portion 380a
Are shown), and the rivets 368 are located closer to the balancer shaft support portions 323, 324 (343, 344) than the cam shaft support portion 352, and are inserted through the third and fourth attachment portions 350, 351 respectively. , 369 are inserted.

Further, the third and fourth connecting portions 384, 385
Are located at positions respectively corresponding to the fifth and sixth coupling portions 353 and 354 in the rear crankshaft holder 340, and are closer to the second and third attachment portions 346 and 347 than the camshaft support portion 381. Then, the first and second connecting portions 382 and 383, the third and fourth connecting portions 384 and 3 of the camshaft holder 380 are provided.
85, and the fifth and sixth parts of the rear crankshaft holder 340.
The coupling portions 353 and 354 are arranged symmetrically with respect to the symmetry plane.

The fifth joint 353 of the rear crankshaft holder 340 and the third joint 384 of the camshaft holder 380,
Then, the sixth coupling portion 354 of the rear crankshaft holder 340
Further, bolts (not shown) also serving as spacers are inserted into the fourth coupling portions 385 of the camshaft holder 380, respectively, so that the distance between the rear crankshaft holder 340 and the camshaft holder 380 in the axial direction of the crankshaft 301 is increased. It is kept at the set value.

In the fourth embodiment, the front crankshaft holder 320 and the rear crankshaft holder 340
, The crankshaft 301 held by the two ball bearings 306, 307, the two ball bearings 360, 361, and the two ball bearings 3
A pair of balancer shafts 3 respectively supported by 62 and 363
02, 303, and further, in the rear crankshaft holder 340 and the camshaft holder 380, the camshaft 314 held by the collar 375 is arranged and integrated to be positioned at predetermined positions of the crankcase and the cylinder. Parts 325-327, both second mounting parts 326,34
6. The through bolts are tightened by the third mounting portions 327 and 347, and are fixed to the crankcase and the cylinder.

By the way, the front and rear crankshaft holders 320 and 340, the timing gear 309, the cam gear 3
15. Since the steel material forming the balancer drive gear 308 and the balancer driven gears 310 and 311 has substantially the same coefficient of thermal expansion, even if the members undergo thermal expansion when the temperature of the internal combustion engine rises. , The crankshaft holder 32 between the crankshaft 301 and the camshaft 314.
0, 340, and the balancer drive gear 308 and the balancer driven gears 310, 311 that mesh with each other are substantially equal to each other, and the crankshaft 301 and the camshaft 31 are substantially equal.
4, since the amount of extension of the crankshaft holders 320 and 340 and the amount of extension of the camshaft holder 380 are substantially equal to the amount of extension of the timing gear 309 and the cam gear 315 meshing with each other, the backlash of the meshing portions of these gears is reduced. The noise can be prevented from increasing due to an increase in backlash.

The front and rear crankshaft holders 3
The steel material forming the outer races 306a and 307a of the holder bodies 321 and 341 of the ball bearings 20 and 340 and the ball bearings 306 and 307 has substantially the same coefficient of thermal expansion. Since the change in the tightening force due to the press-fitting is small, it is not necessary to increase the press-fitting allowance, and the ball bearings 306 and 307 can be reliably held only by the thickness of the steel plates of the holder main bodies 321 and 341.

The fourth embodiment has the following effects because it is configured as described above. Since the holder main bodies 321 and 341 on which the crankshaft support portions 322 and 342 for supporting the crankshaft 301 are formed are formed of a pressed plate, the front and rear crankshaft holders 320 and 340 can be reduced in weight and easily formed. Is possible.

The front and rear crankshaft holders 320,
340 is formed of a separate member from the crankcase in which the crankshaft 301 is disposed, and is detachably attached to the crankcase and the cylinder by through bolts. as a result,
Since it is not necessary to form a holding portion for the crankshaft 301 in the crankcase, the structure of the crankcase is simplified, and the crankshaft 301 itself is assembled to the crankcase and the camshaft, which is a component around the crankshaft 301, is provided. 31
4. Assembling of the balancer shafts 302 and 303 into the crankcase becomes easy.

Further, the front and rear crankshaft holders 320 and 340 are formed of a steel plate having a thermal expansion coefficient substantially equal to that of the steel material used to form the timing gear 309 and the cam gear 315. As in the case of being integrally cast with the case, the crankshaft 3 is not limited to the material for forming the crankcase.
01 can select an appropriate material for the unique function.

The front and rear crankshaft holders 320,
340 includes balancer driven gears 310 and 31 that mesh with a balancer drive gear 308 provided on the crankshaft 301.
A pair of balancer shafts 302 and 303 provided with the crankshaft 3 are supported by the balancer shaft support, and the rear crankshaft holder 340 and the camshaft holder 380 further include a crankshaft 3.
01 is provided with the cam shaft 314 provided with the cam gear 315 meshing with the timing gear 309 provided on the cam shaft support portions 352 and 381.
303 and the camshaft 314 can be compactly arranged near the crankshaft 301. Further, a module including the crankshaft 301, the balancer shafts 302 and 303, and the camshaft 314 can be provided using the front and rear crankshaft holders 320 and 340 as a common base.

As a result, both crankshaft holders 320, 3
By attaching and detaching the balancer shafts 302 and 303 and the camshaft 314 to and from the crankcase and cylinder by attaching and detaching the crankcase and cylinder 40, the assembly and detachability of the balancer shafts 302 and 303 and the camshaft 314 are performed. Has improved,
Disassembly for assembly and maintenance of the internal combustion engine is facilitated.

Further, the rivets 366 to 369 and the collars 370 to 373 are used to set the two crankshaft holders 320,
Since the interval between the crankshafts 340 in the axial direction is accurately defined, the crankshaft 301 and the balancer shaft 30 disposed between the crankshaft holders 320 and 340 are defined.
2,303, the rivets 366 to 369 and the collar 370.
To 373, both crankshaft holders 320 and 340 generated by the explosion load acting on the crankshaft 301.
Is suppressed.

The front and rear crankshaft holders 3
20, 340 and the respective ball bearings 3
Since the thermal expansion coefficients of the outer races 306a, 307a and the outer races 306a, 307a are substantially equal to each other, even if thermal expansion occurs, the change in the tightening force due to the press-fitting is small. The ball bearings 306 and 307 can be reliably held only by the thickness of the steel plates of the main bodies 321 and 341.

Further, both crankshaft holders 320, 34
0 is responsible for most of the explosive load acting on the crankshaft 301, and is equivalent to each of the crankshaft holders 320, 340.
Mounting parts 325 to 327, 345 located around the
347, the load acting on the crankcase holders 320 and 340 from the crankshaft 301 can be distributed over a wide range of the crankcase and the cylinder. It can be made of a lightweight material such as a synthetic resin.

In the following, an embodiment in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration. Front and rear crankshaft holders 80, 110, 9
The mounting portions 82, 92, 112, 122 and the reinforcing portions of 0, 120 are respectively provided with holder main bodies 81, 91, 111, 1
Although each of the crankshaft holders is formed integrally with the holder 21, at least one of the crankshaft holders may be formed separately from the holder main body and fixed to the holder main body.

A rotation shaft rotatably supported by a support portion 96 of the rear crankshaft holder 90 and provided with a cam gear 23 which is a driven gear meshing with the timing gear 22 which is a driving gear of the crankshaft 4. Although the shaft was the camshaft 24, a driving gear was provided on the crankshaft 4, and a rotating shaft for driving a cooling water pump or an oil pump was provided as a rotating shaft provided with a driven gear meshing with the gear. It may be.

Lower intake and lower exhaust rocker arm shaft 3
5, 36 were hollow shafts formed from a tube material,
It can also be formed with a solid shaft.

Although the balance weight 63 is provided on the outer peripheral surface of the front boss of the input gear 58, when the outer race of the one-way clutch 62 is formed of a member different from the front boss of the input gear 58. The balancer can be formed by fixing a balance weight to the outer peripheral surface of the separate member.

In the above embodiment, the crankshaft holder 8
0, 90, 110, 120, 240, 260, 320,
Although 340 was used as a pair, a single crankshaft holder is used for a cantilevered crankshaft. Further, although the crankshaft is arranged in the front-back direction of the vehicle body, it may be arranged in the left-right direction of the vehicle body. Further, a gear transmission may be used as a transmission having a rotating shaft supported by the crankshaft holder. In this case, at least one of the main shaft and the sub shaft of the gear transmission is supported by the crankshaft holder. The rotation shaft of the shift mechanism may be supported by a crankshaft holder.

The crankshaft holder for the crankshaft 4 of the internal combustion engine 2 has been described. However, the crankshaft holder can be applied to a machine other than the internal combustion engine, for example, a compressor or an expander using a crank mechanism.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a power unit including an internal combustion engine including a crankshaft holder according to a first embodiment of the present invention, as viewed from the front.

FIG. 2 is a cross-sectional view of the power unit of FIG. 1 as viewed from the back.

FIG. 3 is a sectional view taken along line III-III of FIG. 1;

FIG. 4 is a front view of a front crankshaft holder.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

FIG. 6 is a sectional view taken along line VI-VI of FIG. 4;

FIG. 7 is a rear view of the rear crankshaft holder.

FIG. 8 is a rear view of the camshaft holder.

9 is a sectional view taken along line IX-IX of FIG. 7 when the rear crankshaft holder and the cam holder are integrated.

FIG. 10 is a front view of a front crankshaft holder according to a second embodiment of the present invention.

FIG. 11 is a rear view of a rear crankshaft holder according to a second embodiment of the present invention.

FIG. 12 is a view when a front and rear crankshaft holder according to a second embodiment of the present invention are integrated.

FIG. 13 is a sectional view when the crankshaft is supported by the front and rear crankshaft holders.

FIG. 14 is a view showing a cross section taken along a plane passing through an axis of a cylinder according to a third embodiment of the present invention and viewed from the back.

15 is a sectional view taken mainly along the line XV-XV in FIG. 14;

FIG. 16 is a front view of an essential part when a crankshaft, a camshaft, and a main shaft are supported by front and rear crankshaft holders.

FIG. 17 is a sectional view taken along line XVII-XVII in FIG. 16;

18 is a sectional view taken along line XVIII-XVIII in FIG.

FIG. 19 is a rear view of the fourth embodiment of the present invention when a crankshaft, a balancer shaft, and a camshaft are supported by front and rear crankshaft holders.

20 is a sectional view taken along line XX-XX in FIG.

FIG. 21 is a sectional view taken along line XXI-XXI in FIG. 19;

FIG. 22 is a sectional view taken along line XXII-XXII in FIG. 19;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Power unit, 2 ... Internal combustion engine, 3 ... Hydraulic transmission, 4 ... Crankshaft, 5 ... Crankcase, 6 ... Cylinder, 7 ... Cylinder head, 8 ... Cylinder head cover,
9, 10: ball bearing, 11: piston, 12: connecting rod, 13: crank pin, 14: balance weight, 1
5: output gear, 16: supercharger, 17: supercharger drive gear,
18 ... AC generator, 19 ... rotor, 20 ... cooling fan,
21 fan cover, 22 timing gear, 23 cam gear, 24 cam shaft, 25, 26 ball bearing, 27 intake valve, 28 exhaust valve, 29 supercharge valve, 30 intake / exhaust cam, 31 ... Supercharging cam, 32 ... lower intake rocker arm, 3
3 Lower exhaust rocker arm, 34 Lower booster rocker arm, 35 Lower intake rocker arm shaft, 36 Lower exhaust rocker arm shaft, 37 Intake valve holder, 38 Exhaust valve holder, 39 Upper intake rocker arm, 40 Upper Exhaust rocker arm, 41 ... upper supercharged rocker arm, 42 ... oil pump, 43 ... pump drive shaft, 44 ... pump casing, 45 ... oil reservoir, 46 ... suction path, 47 ... discharge pipe,
48 ... oil passage, 49 ... oil pipe, 50 ... oil inflow chamber, 51 ...
Oil passage, 52 injection hole, 54 return oil pipe, 55 cooling fin, 56 lubrication groove, 57 oil passage, 58 input gear, 59
... output shaft, 60 ... hydraulic pump housing, 61 ... starting driven gear, 62 ... one-way clutch, 63 ... balance weight, 64 ... ball bearing, 65 ... bearing, 66 ... starting motor, 6
7 pinion, 68, 69 gear, 70 transmission output gear, 71 crankcase cover, 72 bolt, 7
7, 78, 79: pull rod, 80: front crankshaft holder, 81: holder body, 82: mounting part, 83: crankshaft support, 84: transmission shaft support, 85: bolt, 8
Reference numeral 6: bolt hole, 90: rear crankshaft holder, 91: holder body, 92: mounting portion, 93: crankshaft support portion, 9
4 camshaft support, 95 bolt, 96, 97 front mounting hole, 98 front coupling, 100 camshaft holder, 10
1: camshaft support, 102: insertion hole, 103, 104
Rear mounting hole, 105: rear connecting portion, 110: front crankshaft holder, 111: holder body, 112: mounting portion, 1
DESCRIPTION OF SYMBOLS 13 ... Reinforcement part, 114 ... Crankshaft support part, 115 ... Bolt, 116 ... Bolt hole, 117 ... Screw hole, 120 ... Rear crankshaft holder, 121 ... Holder body, 122 ... Mounting part, 123 ... Reinforcement part, 124 ... Crankshaft support, 1
25 bolt, 126 bolt hole, 127 bolt hole 1
30 bolt, 201 internal combustion engine, 202 crankcase, 203 cylinder, 204 cylinder head, 2
05: cylinder head cover, 206: crankshaft, 2
07, 208: ball bearing, 209: piston, 210: connecting rod, 211: output gear, 212: spark plug, 213
... supercharger, 214 ... camshaft, 215, 216 ... sprocket, 217 ... AC generator, 218 ... cooling fan, 21
9 ... oil pump, 220 ... timing gear, 221 ...
Cam gear, 222 ... exhaust valve, 223 ... supercharging valve, 224 ...
Cam, 225: Lower rocker arm shaft, 226: Lower intake rocker arm, 227: Lower exhaust rocker arm, 228
... lower supercharged rocker arm, 229 ... upper rocker arm shaft, 230 ... pull rod, 231 ... upper exhaust rocker arm, 232 ... upper supercharged rocker arm, 233 ... main shaft, 2
34 Start clutch, 235 Input gear, 240 Front crankshaft holder, 241 Holder body, 242 Crankshaft support, 243 Transmission gear support, 244 Camshaft support, 245 to 249 Mounting part 250, 251 ...
Coupling portion, 252 rocker arm shaft support portion, 260 rear crankshaft holder, 261 holder body, 262 crankshaft support portion, 263 transmission shaft support portion, 264 camshaft support portion, 265 to 269 mounting portion, 270, 271 ...
Coupling portion, 272: rocker arm shaft support portion, 280 to 28
3: ball bearings, 284, 285: bolt holes, 286-29
0: Through bolt, 291-295: Nut, 296: Knock shaft, 297, 298: Spacing shaft, 301:
Crank shafts, 302, 303: Balancer shaft, 304: Piston, 305: Connecting rod, 306, 307: Ball bearing, 308: Balancer drive gear, 309: Timing gear, 310, 311: Balancer driven gear, 312, 31
3 ... balance weight, 314 ... camshaft, 315 ... cam gear, 316 ... cam, 320 ... front crankshaft holder,
321, a holder body, 322, a crankshaft support, 32
3,324 ... balancer shaft support, 325-327 ... mounting part, 328-331 ... joining part, 340 ... rear crankshaft holder, 341 ... holder body, 342 ... crankshaft support, 343,344 ... balancer shaft support , 345-34
7 mounting part, 348-351 coupling part, 352 camshaft support part, 353, 354 coupling part, 360-363 ball bearing, 364 365 nut, 366-369 rivet, 370-373 ... collar 374, rivet, 3
75: collar, 380: cam shaft holder, 381: cam shaft support portion, 382 to 385: coupling portion.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomomi Ishikawa 1-4-1 Chuo, Wako-shi, Saitama Pref. Inside Honda R & D Co., Ltd. (72) Inventor Toshiyuki Kase 1-4-1 Chuo, Wako-shi, Saitama Inside Honda R & D Co., Ltd. (72) Inventor Masahiro Kuroki 1-4-1 Chuo, Wako-shi, Saitama Pref. Inside the Honda R & D Co., Ltd. (72) Tsutomu Motoyoshi 1-4-1 Chuo, Wako-shi, Saitama Pref. Honda R & D Co., Ltd.

Claims (7)

[Claims] 1. A holder body made of a pressed plate material, a first support portion formed on the holder body to rotatably support a crankshaft, and a stopper provided on the holder body and fixed to a fixing member. And a mounting part for holding the crankshaft, wherein the crankshaft holder is detachable from the fixing member by the stopper. 2. A method according to claim 1, further comprising a reinforcing portion which is provided on said holder main body so as to protrude radially outward of said first support portion in the axial direction of said crankshaft and increases bending rigidity of said holder main body. The crankshaft holder according to claim 1. 3. The crankshaft holder according to claim 2, wherein the mounting portion also serves as the reinforcing portion. 4. The crankshaft is a crankshaft of an internal combustion engine, and is provided with a driven gear that meshes with a drive gear provided on the crankshaft, and is rotatable about a rotary shaft that drives a mechanism attached to the internal combustion engine. The crankshaft holder according to any one of claims 1 to 3, wherein a second support portion for supporting the crankshaft is formed on the holder main body. 5. A part inside the holder constituting at least a part of the mechanism is disposed between the pair of crankshaft holders, and the pair of crankshaft holders, the crankshaft, the rotating shaft and the part inside the holder are arranged. The crankshaft holder according to claim 4, wherein the crankshaft holder is detachably attached to the fixing member in an integrated state. 6. The material forming the holder main body and the material forming the driving gear and the driven gear have substantially the same coefficient of thermal expansion.
The crankshaft holder as described. 7. A pair of said crankshaft holders being detachably attached to said fixing member in a state where said pair of crankshaft holders are integrated by a spacer which keeps a distance between said pair of crankshaft holders in the axial direction of the crankshaft. The crankshaft holder according to any one of claims 1 to 6, wherein: