JPH1077862A - Engine unit for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid enlargement of engine width caused by a cooling water pump and enlarge a bank angle in case of mounting an engine unit on a motorcycle by axially connecting a housing of the cooling water pump and a housing of a lubricating oil pump to arrange a housing unit in a crankcase. SOLUTION: A cooling water pump 100 and a lubricating oil pump 101 are both arranged in a lower case 27, and a pump shaft 102 common to both pumps is rotatably supported on a housing unit 103 through bearings 104, 105. A rotor 106 of the lubricating oil pump 101, and an impeller 107 of the cooling water pump 100 are fixed to the right end part of the pump shaft 102. A driven sprocket 108 is bolt-fastened and fixed to the axial right end face of the pump shaft 102. The sprocket 108 is connected to a driving sprocket 110. Protrusion of a crankcase side wall is thereby eliminated, so that engine width can be reduced, and a bank angle can be set large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine unit for a vehicle, and more particularly, to an arrangement structure of a cooling water pump and a lubricating oil pump in which an engine width can be reduced when the pump is provided.

[0002]

2. Description of the Related Art Conventionally, as an engine unit having such a cooling water pump and a lubricating oil pump, conventionally, a cooling water pump and a lubricating oil pump are coaxially arranged on a common pump shaft.
A structure in which the pump shaft is driven to rotate by a crankshaft is generally used.

In the above-mentioned cooling water pump, a mechanical seal is interposed between the pump shaft to which the impeller is fixed and the housing, and a small amount of cooling water leaks from the mechanical seal to thereby seize the seal. The structure which avoids is adopted. Therefore, if the cooling water pump is housed in the crankcase, water leaked from the mechanical seal may be mixed into the lubricating oil in the crankcase. In order to avoid this problem, conventionally, a cooling water pump is generally provided outside the crankcase (for example, see Japanese Patent Application No. 63-266940).

[0004]

However, when the cooling water pump is arranged outside the crankcase as in the above-described conventional engine, there is a problem that the engine width is increased by an amount corresponding to the projection of the cooling water pump in the engine width direction. When the engine unit is mounted on a motorcycle, there is a problem that the bank angle is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and an engine unit for a vehicle which can avoid an increase in engine width by a cooling water pump and can increase a bank angle when mounted on a motorcycle. It is intended to provide.

[0006]

According to a first aspect of the present invention, there is provided a vehicle engine unit in which a cooling water pump and a lubricating oil pump are coaxially arranged. The housing and the housing are connected in the axial direction to form a housing unit 103, and the housing unit 103 is connected to the crankcase 25.
It is characterized by being arranged inside.

According to a second aspect of the present invention, a cooling water pump is disposed in a crankcase such that a rotation axis thereof is parallel to an input shaft and an output shaft of a transmission, and a maximum diameter of a housing of the cooling water pump is provided. The part is radially opposed to the minimum diameter gear of the output shaft or the input shaft which is arranged close to the output shaft or the input shaft.

According to a third aspect of the present invention, the cooling water pump is disposed in the crankcase, one end of the housing of the cooling water pump in the axial direction is fitted to the side wall of the crankcase, and the other end is formed in the crankcase. It is characterized in that it is bolted and fixed to the wall.

According to a fourth aspect of the present invention, in any one of the first to third aspects, a portion of the housing of the cooling water pump opposite to the impeller across the bearing is communicated with the outside of the crankcase by a drain pipe. It is characterized by.

[0010]

According to the vehicle engine unit 15 of the present invention, the housings of the cooling water pump 100 and the lubricating oil pump 101 are joined to form a housing unit 102, and the housing unit 102 is Since the cooling water pump is housed and disposed in the crankcase 25, the cooling water pump does not protrude outward from the side wall of the crankcase, so that the expansion of the engine width due to the protrusion of the cooling water pump can be avoided. This has the effect of increasing the bank angle. In addition, since the cooling water pump and the lubricating oil pump come close to each other, the common pump shaft can be shortened.

Further, since the housings of both pumps are combined to form the housing unit 103, even when the cooling water pump is disposed in the crankcase, water leaking from the seal does not fall into the crankcase, and lubrication is prevented. No cooling water is mixed into the oil. In general, since the pressure of the lubricating oil pump is higher than that of the cooling water pump, water leaked from the sealing portion does not flow into the lubricating oil side in the pump.

According to the second aspect of the present invention, the cooling water pump is installed in the crankcase and the maximum diameter portion 103 of the housing.
Since d is disposed so as to radially oppose the smallest diameter gear of the input shaft 71 or the output shaft 74 located closer to the transmission 70, the distance between the housing and the input shaft 71 or the output shaft 74 is reduced. By arranging the cooling water pump in the crankcase in parallel with the input shaft 71 and the output shaft 74, there is an effect of avoiding a problem that the crankcase becomes large.

According to the invention of claim 3, one end of the housing of the cooling water pump is connected to the side wall 27a of the crankcase 25.
And the other end is fixed by bolting, so that the structure when the cooling water pump is arranged in the crankcase 25 can be simplified, and the number of parts such as fixing bolts can be reduced, and the cost can be reduced. This has the effect of facilitating the mounting work.

According to the fourth aspect of the present invention, since the portion opposite to the impeller across the bearing of the housing of the cooling water pump is communicated with the outside of the crankcase through the drain pipe 117, the cooling water pump leaks. Water can be discharged to the outside, and the effect of more reliably preventing water from entering the lubrication system can be obtained.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 17 are views for explaining an engine unit of a motorcycle according to an embodiment of the present invention. FIG. 1 is a left side view of the motorcycle on which the engine unit is mounted, and FIGS. FIG. 5 is a sectional view showing a communication hole portion of a cylinder block, and FIGS. 6 to 8 are a plan view, a sectional side view, and a sectional side view of a cylinder head, respectively. Figures 9 and 9 are cross-sectional side views of a head bolt portion, Figure 10 is a plan view of a camshaft, Figures 11 and 12 are left side views and a cross-sectional rear view of a transmission, and Figures 13 and 14 are cooling water and lubrication. FIG. 15 is a rear view of the starting device, and FIGS. 16 and 17 are a plan view and a schematic configuration diagram of an intake device. Note that the terms front, rear, left and right in the present embodiment refer to front, rear, left and right when viewed in a state of sitting on a seat.

In FIG. 1, reference numeral 1 denotes a motorcycle, and a vehicle body frame 2 has a seat rail 4 extending rearward of the vehicle body at the rear ends of a pair of left and right main frames 3 having a substantially inverted L shape in side view. The fuel tank 5 is mounted on the upper part of the main frame 3, and the main seat 6 and the tandem seat 7 are mounted on the upper part of the seat rail 4, respectively.

A front fork 9 is pivotally supported by a head pipe 8 at the front end of the main frame 3, and a front wheel 10 is pivotally supported at the lower end of the front fork 9. A rear arm 11 is pivotally supported by a pivot shaft 12 on a rear arm bracket 3a below the rear end of the main frame 3 so as to be able to swing up and down.
A rear wheel 13 is pivotally supported at the rear end.

A rear cushion 14 is interposed between the rear arm 11 and the vehicle body frame 2. The lower end of the rear cushion 14 is connected to the lower end of a first link 14a that is arranged upright on the rear side and is supported by the rear arm 11, and the upper end is supported by the body frame. The upper end of the first link 14a is connected to the vehicle body frame via a second link 14b provided upright on the rear side of the rear cushion 14, and the second link 14b and the first link 14a are connected to the rear cushion 14. Is forming a triangle.
As described above, the lower end of the rear cushion 14 is supported by the first and second links 14a and 14b which are arranged upright, so that a large space is secured below the rear cushion 14 while ensuring so-called progressive characteristics. ing.

An engine unit 15 is suspended from a lower portion of the main frame 3.
A radiator 16 is provided on the front side of 5. The engine unit 15 is a water-cooled four-cycle parallel four-cylinder five-valve engine in which the cylinder axis 20 is inclined forward and the crankshaft 21 is directed in the vehicle width direction.

The engine unit 15 is shown in FIGS.
As shown in the figure, the cylinder head 23 is laminated on the upper surface of the cylinder block 22 and fastened with a head bolt, and the head cover 24 is mounted on the upper surface of the cylinder head 23,
It has a schematic structure in which a unit case 25 in which a crankcase and a transmission device case are integrated is formed under the cylinder block 22.

The unit case 25 includes upper and lower cases 2
The upper case 26 is formed integrally with the cylinder block 22. The crankshaft 21 is supported by bearings 30 on a plurality of bosses 29 formed on the surface of the upper and lower cases 26 and 27. Further, the crank chamber 19 for each cylinder is independent by the boss portion 29. An oil pan 28 is connected to a lower mating surface of the lower case 27.

Four cylinder bores (cylinders) 22a are formed in the cylinder block 22 in parallel, and a piston 31 is slidably inserted into each cylinder bore 22a. A small end of a connecting rod 32 is connected to the piston 31 via a piston pin 31b, and a large end of the connecting rod 32 is connected to a crankpin 21a of the crankshaft 21. Above piston 3
Reference numeral 1 denotes a so-called slipper type in which a notch concave portion 31c is formed at a shaft end portion of a piston pin 31b of a piston skirt 31a.

Each piston 31 of the cylinder head 23
Three intake ports 33 and two exhaust ports 34 are opened in the combustion concave portion 23a formed on the opposite surface of the fuel cell 23. Each opening can be opened and closed by an intake valve 35 and an exhaust valve 36. Cylindrical bottomed valve lifters 37, 37 are mounted on the upper ends of the valves 35, 36, respectively. The valve lifters 37 are slidably supported by lifter guide holes 23b formed in the cylinder head 23. A spring 38 is provided between each of the valves 35 and 36 and a spring seat 23c formed on the cylinder head 23 to constantly urge the valves in the closing direction.

Above the intake valve 35 and the exhaust valve 36, a camshaft 40 for pressing and driving the valves is provided.
41 are arranged in parallel with each other and in parallel with the crankshaft 21. Each of the camshafts 40 and 41 is a camshaft arrangement chamber 3 formed by the cylinder head 23 and the head cover 24.
9 and is rotatably supported by a cam bearing portion formed on the cylinder head 23 and a cam cap 48 fixed to the cam bearing portion by bolts.

The cam sprockets 40a, 41a attached to the right ends of the camshafts 40, 41 in the axial direction and the cam drive teeth 2 integrally formed at the right end of the crankshaft 21.
1b is connected by a timing chain 42. The cam sprockets 40a, 41a, the timing chain 42, and the cam driving teeth 21b of the camshaft driving mechanism configured as described above are integrated with the cylinder block 22 and the right outer end face of the cylinder head 23 in a chain arrangement chamber (cam). (Shaft drive mechanism arrangement chamber) 43. A rotor 44 having outer peripheral teeth is mounted inside the cam drive teeth 21b of the crankshaft 21, and a pickup 45 for detecting a crank rotation angle is mounted on the rotor 44.
Are facing each other. 46 is the timing chain 42
Is an automatic tensioner for automatically adjusting the tension of the chain, and 47 is a chain guide.

An opening 50 for assembling the camshaft drive mechanism is formed in a portion of the outer wall 22b of the cylinder block 22 constituting the chain arrangement chamber 43 facing the crankshaft 21. The cover member 51 is detachably bolted. The cylinder bore 22 located in the mounting opening 50 when viewed in the crankshaft direction.
A communication hole 52 communicating the adjacent crank chambers 19 is formed in the lower portion so as to form the same axis.

Each of the communication holes 52 is connected to the assembling opening 50.
The drilling is performed by machining to reduce the pumping loss due to the reciprocating motion of the piston. The inner surface of each of the cylinder bores 22a is coated with a hard plating film a in order to enhance wear resistance. The plating film a is formed by masking the communication hole portion before forming the communication hole 52 and performing plating processing in this state, thereby facilitating the plating process operation and forming the communication hole. 52 is facilitated.

That is, the plating process is performed in the cylinder bore 2
This is performed by closing the upper and lower openings of 2a and energizing while the plating space is filled in the closed space. However, if the communication hole 52 is formed first, it becomes difficult to close the hole. On the other hand, if machining is performed after plating, the hard plating film a makes processing difficult. In the present embodiment, the plating process is performed in a state where the communication hole 52 is masked, so that the above-described problem can be avoided.

As shown in FIG. 5, a lubricating oil passage 53 communicating between the bearing 30 of the crankshaft 21 and the inner peripheral surface of the communication hole 52 is formed in each boss 29 of the upper case 26. . A cooling nozzle 54 is inserted into the lubricating oil passage 53, and the injection port 54 a of the nozzle 54 is directed from the notch concave portion 31 c of the piston 31 located at the bottom dead center to the back surface of the piston. The thickness of the communication hole 52 in the direction of the crankshaft is W2 on the crankshaft side and W1 on the piston side. Therefore, the lubricating oil injected from the injection port 54a is reliably supplied to the piston back surface without being hindered by the peripheral edge of the communication hole 52 or the piston skirt, and the piston 31 can be reliably cooled.

Next, the fastening structure of the cylinder head 23 will be described. 6 to 10, a bolt insertion hole 23d is formed in the cylinder axial direction on the intake side and the exhaust side of the portion between the cylinders of the cylinder head 23, and is inserted into the cylinder block 22 in the bolt insertion hole 23d. The upper end of the provided head bolt 55 is located.

A washer mounting surface 56 is formed on the upper edge of the bolt insertion hole 23d of the cylinder head 23.
A washer 57 having a slightly smaller diameter than the washer mounting surface 56 is mounted on the mounting surface 56. The cylinder head 23 includes:
By screwing nuts 58 and 59 to the head bolt 55, the head bolt 55 is fastened and fixed to the cylinder block 22 via the washer 57. The nut 58 on the intake side has a smaller diameter than the washer 57, whereas the nut 59 on the exhaust side has the same diameter as the washer 57.

Here, if the dimension between cylinders is reduced in order to reduce the size of the engine, it becomes difficult to secure a space for mounting the head bolt 55 with a nut. In particular, since three lifter guide holes 23b are required on the intake side,
It is difficult to secure the wall thickness necessary for the rigidity of the guide hole 23b and the area required for the washer mounting surface 56 while narrowing the dimension between the cylinders.

In the present embodiment, the following structure is employed in order to secure the wall rigidity while reducing the dimension between the cylinders and to secure a necessary washer arrangement area. The above cylinder head 2
On the upper side of the suction side washer mounting surface 56 of No. 3, a washer rotating hole 60 which is slightly larger in diameter than the washer 57 and is capable of rotating the washer 57 is formed in a bag shape following the mounting surface. The washer arranging surface 56 and the washer rotating hole 60 are located below the lower edge of the lifter guide hole 23b when viewed in the height direction.

A nut insertion hole 61 is formed above the washer rotation hole 60 and has a diameter smaller than that of the washer rotation hole 60 and slightly larger than that of the nut 58. The shaft arrangement chamber 39 is open. A slit 63 having a diameter slightly larger than that of the washer 57 is formed on the inner surface of the nut insertion hole 61. The slit 63 is formed so as to pass through the center of the nut insertion hole 61 and to be perpendicular to the camshaft 40.
The length is set to be substantially the same as the radial length.

In this way, the washer 57 is inserted from the slit 63 in a state of being oriented vertically and at right angles to the camshaft, and is rotated in the washer rotation hole 60 to rotate the washer mounting surface 56.
(See FIGS. 8 and 9). The exhaust-side nut insertion hole 62 has a slightly larger diameter than the washer 57, and the nut 59 has a pressing surface having the same diameter as the washer 57.

Here, of the head bolts 55, the axis of the head bolts 55, 55 on the intake side and the exhaust side between the cylinders is separated from the axis of the cam shafts 40, 41 on the intake side and the exhaust side when viewed from a plane. , That is, slightly offset outwardly away from the center of the cylinder bore.

Since the inter-cylinder head bolt 55 is offset outward from the axis of the camshaft as described above, the wall thickness of the lifter guide hole 23b can be ensured while reducing the inter-cylinder dimension.

On the other hand, the head bolt 55 located at the end on the chain arrangement chamber 43 side is arranged so as to coincide with the cam axis. The head bolt 55 arranged at this end is
Unlike the head bolt between the cylinders, the lifter guide hole 23
Since they are not narrowed by b and 23b, they can be arranged closer to the chain arrangement 43 side, so that the wall thickness of the lifter guide hole 23b 'can be ensured without offsetting from the camshaft axis unlike that between cylinders.

The torsional torque acting on the camshafts 40 and 41 is maximum at the end of the cam chain arrangement chamber 43 side.
It becomes smaller as the distance from the arrangement chamber 43 increases. On the other hand, while the inter-cylinder head bolt is offset outward from the camshaft axis as described above, the head bolt on the side of the chain arrangement chamber 43 coincides with the camshaft axis. 64 is offset outwardly from the camshaft axis, while the tool hole 64 'at the end coincides with the camshaft axis.

As described above, since the tool hole 64 'provided at the position where the torsion torque is large is made coincident with the axis of the camshaft, the torsional rigidity of the camshaft caused by the tool hole 64' can be suppressed. Further, among the tool holes for the cylinder-to-cylinder head bolts, the tool holes located closer to the cam chain arrangement chamber 43 are offset from the cam axis axis, which is disadvantageous in torsional rigidity. However, a thrust receiving portion 65 is provided as described later. Therefore, the above reduction in torsional rigidity can be covered. The remaining tool holes do not pose a problem because the torsion torque is small.

Each of the camshafts 40, 41 is integrally formed with a thrust receiving portion 65 having a predetermined axial width for regulating the axial movement thereof. The thrust receiving portion 65 is formed to have a larger diameter than other portions except the cam nose. The thrust receiving portion 65 is formed vertically above the head bolt 55 between the first and second cylinders located at the outermost ends of the camshafts 40 and 41 on the side of the chain arrangement chamber 43 (FIG. 6). reference). A tool hole 64 is formed through the thrust receiving portion 65 in the diametric direction, and the tool hole 64 is formed so as to be coaxial with the head bolt 55. A similar tool hole 64 is formed in a portion of each of the camshafts 40 and 41 facing the other head bolt 55. Further, a tool hole 48a is formed in a portion facing each tool hole 64 of the cam cap 48, and a plug (not shown) is provided in the tool hole 48a provided at a position corresponding to a bearing portion adjacent to the cam chain. Removably inserted.

Here, the thrust receiving portion is usually formed in a flange shape having a small axial width, but in the present embodiment, the thrust receiving portion 65 is formed to have a large axial width, thereby forming a tool hole. Thus, the reduction in the torsional rigidity of the camshaft due to the formation of 64 is suppressed.

Here, when assembling the cylinder head 23 to the cylinder block 22, first, the cylinder head 23 is provided with intake and exhaust valves 34, 35, a spring 38,
And the valve lifter 37, and the washer 5
7, the nuts 58, 59 are inserted and arranged on the washer disposing surface 56, and then the camshafts 40, 41 and the cam cap 48 are assembled, so that the cylinder head 23 is sub-assembled.

Then, the sub-assembled cylinder head 23 is placed on the cylinder block 22 and the tool hole 4 is set.
8a, a fastening tool is inserted from the tool hole 64 and the nuts 58 and 59 are tightened to the head bolt 55. It is needless to say that the camshafts 40 and 41 may be assembled after the cylinder head 23 is fastened to the cylinder block 22.

As shown in FIG. 6, the camshaft bearing 6 at the end of the cylinder head 23 on the side of the chain arrangement chamber 43 is provided.
6, 66 are formed wider in the axial direction than the other bearing portions. A nut insertion hole 67 is formed in the bearing 66. The nut insertion hole 67 is provided in the bearing center line E
It is formed so as to be more offset toward the lifter guide hole 23b in the cam axis direction. Further, an oil passage 128 communicating the oil passages 127 and 129 on the intake side and the exhaust side is offset from the bearing center line E to the side opposite to the lifter guide hole 23b ', that is, in the direction perpendicular to the camshaft toward the chain arrangement chamber 43 side. It is formed so as to extend. Accordingly, the durability of the bearing portion 66 to which a large radial load is applied can be secured while forming the nut insertion hole 67, and the oil passage 127 that connects the intake side and the exhaust side can be formed without any trouble.

Next, the transmission 70 of the engine unit 15 will be described. The transmission 70 mainly includes a main shaft (input shaft) 72 having an input gear group 71 mounted above a rear portion of the crankshaft 21 as shown in FIGS. Drive shafts (output shafts) 74 each having an output gear group 73 engaged with the input gear group 71 mounted below the shaft 72 are arranged in parallel with the crankshaft 21.

The drive shaft 74 is supported via a bearing 75 on a boss formed on the surface of the upper and lower cases 26 and 27 in the same manner as the crankshaft 21. The main shaft 72 is disposed in the upper case 26, and the left end of the main shaft 72 is supported by a boss of the upper case 26 via a bearing 76. The right portion is supported by a right wall 26g of the upper case 26 via a bearing 77 and a flange 78, and the flange 78 is fixed to the right wall 26g by bolting.

The left end of the drive shaft 74 protrudes outward from the unit case 25, and a drive sprocket 79 mounted on the protrusion is connected to the rear wheel sprocket 13a of the rear wheel 13 via a chain 80. ing. A clutch mechanism 81 is mounted on the right end of the main shaft 72. The clutch mechanism 81 includes the crankshaft 21
A large number of outer drums 84 are engaged with a large reduction gear 83 supported by the main shaft 72 via a damper, and an inner drum 85 is spline-connected to the main shaft 72. It has a structure with a clutch plate 86 interposed. The clutch mechanism 81 is turned off the engine power by rotating a push lever 87 connected to the inner drum 85.

A shift drum 90, an input-side fork shaft 91, and an output-side fork shaft 92 are disposed in parallel with the main shaft 72 and the drive shaft 74 on the rear and obliquely rear side thereof. The right and left ends of the fork shafts 91 and 92 are supported by right and left bosses 26e and 26f formed integrally with the upper case 26. A bearing 90c is provided between the left end of the shift drum 90 and the left boss 26f. Reference numeral 90d denotes a retaining plate for the bearing 90c and the fork shafts 91 and 92. In FIG. 11, the retaining plate 90 is removed.

The input-side fork shaft 91 has one input-side shift fork 93 and the output-side fork shaft 9
2, two output-side shift forks 94, 94 are mounted movably in the axial direction. The shift fork 93,
The forked claw portions 93b and 94b of the input gear 94
Sliding grooves 71b, 73 formed in the gears of the output gear group 73
b and slidably engage with the shift forks 93,
The engagement pins 93a, 94a formed integrally with the base of the shift drum 94 are formed in guide grooves 9 formed on the outer peripheral surface of the shift drum 90.
0a is slidably engaged. This shift drum 90
Is rotated by a change mechanism (not shown),
The shift forks 93 and 94 slide in the axial direction to move the gears of the input gear group 71 and the output gear group 73, and as a result, switching is performed between the lowest gear and the highest gear.

The shift drum 90, the input side fork shaft 91, and the output side fork shaft 92 on the left side wall of the upper case 26.
An assembly opening 26a is formed in a portion opposed to the left end of the cover plate 95, and the cover plate 95 is formed in the assembly opening 26a.
(See FIG. 1) is detachably mounted.

Then, at the upper part in the upper case 26,
An oil breather chamber 96 is formed integrally to separate in advance the lubricating oil mixed in the air discharged from the inside of the crankcase to the outside for adjusting the pressure in the crankcase. The air from which the lubricating oil has been separated is introduced into the intake system. The bottom wall 26c of the oil breather chamber 96 is located near the upper side of the input-side fork shaft 91, and regulates the rotation angle of the fork 93 when assembling the input-side shift fork 93, as described later. It is a stopper.

Next, the procedure for assembling the transmission 70 will be described. First, the upper case 26 is turned upside down so that the distribution surface faces upward, and is placed on an assembly table or the like. Then, the main shaft 72 into which the input gear group 71 is incorporated is inserted from the right wall opening 26d of the upper case 26 through the insertion hole of the right wall 26g, and the left end is fitted into the bearing 76 and the flange 78 is fitted. Tighten the bolt to the right side wall 26g (see FIGS. 2, 4, and 12).

Next, the claw 93b of the input side shift fork 93 is engaged with the sliding groove 71b of one gear of the input gear group 71 from the distribution surface side, and is rotated about the claw 93b. The base 93c is attached to the bottom wall 2 of the oil breather chamber 96.
6c. Thereby, the input side shift fork 9
3 is held in a state shown by a two-dot chain line in FIG. 11 without disengaging the engagement of the claw portion 93b with the sliding groove 71b. At this time, the engagement pin 93a is located slightly outside the outer peripheral surface of the shift drum 90.

Subsequently, the left side wall assembly opening 26 a
From the shift drum 90 to the drum support hole of the left boss 26f.
Into the right boss portion 26b.
e, and the shift drum 90 is set by fitting the bearing 90c at the left end into the support hole of the left boss 26f. At this time, since the base 93 c of the input side shift fork 93 is held at the rotation angle position such that the engagement pin 93 a does not interfere with the outer peripheral surface of the shift drum 90, the shift drum 90 can be inserted without hindrance. It is.

The input shaft side shift fork 9
3 is rotated upward, and the engagement pin 93 is
a into the guide groove 90a of the shift drum 90. In this engaged state, the input side fork shaft 91 is inserted into the shift fork 93 from the assembly opening 26a side, and both ends of the input fork shaft 91 are raised. The case 26 is fitted into the support holes of the left and right boss portions 26f and 26e. Thus, the assembly of the main shaft 72 and the input-side shift fork 93 is completed.

Next, the output gear group 73 is incorporated and the claw portions 94 b, 9 of the output shaft side shift forks 94, 94.
4b is the drive shaft 7 engaged with the sliding grooves 73b, 73b.
4 with the engagement pin 94 of the output shaft side shift fork 94.
a is engaged with the guide groove 90 a of the shift drum 90, and is placed on the distribution surface of the upper case 26. In this state, the output-side fork shaft 92 is inserted through the assembling opening 26a into the shift fork 94, and the fork shaft 92
The left and right bosses 26f, 26e of the upper case 26
Into the support holes of the. Finally, retaining plate 90d
And a link mechanism is connected to the left end of the shift drum 90. The drive shaft 74 may be mounted after setting the shift forks 94, 94.

Next, the crankshaft 21, the main shaft 72,
The positional relationship between the drive shaft 74 and the drive shaft 74 will be described mainly with reference to FIG. In the main shaft 72, the first shaft angle θ1 formed between the crankshaft / main shaft straight line A connecting the shaft center of the main shaft and the shaft center of the crankshaft 21 and the cylinder axis 20 on the cylinder head side and the main shaft side is an acute angle. In other words, it is disposed at a position closer to the cylinder head 23 side than a straight line C passing through the axis of the crankshaft 21 and perpendicular to the cylinder axis 20.

The drive shaft 74 has a main shaft / drive shaft straight line B and a crank shaft / main shaft straight line A connecting the shaft center of the drive shaft 74 and the shaft center of the main shaft 72 on the drive shaft side and the crank shaft side. Are arranged so that the second axis angle θ2 formed by the first angle becomes an acute angle. In this manner, the main shaft 72 and the drive shaft 74 are arranged so as to be carried on the back surface of the cylinder block 22.

The maximum outer peripheral surface (the outer peripheral surface of the large reduction gear) 81a of the clutch mechanism 81 is formed by a straight line D passing through the top surface of the piston 31 'located at the bottom dead center and making a right angle with the cylinder axis 20. Located on the side. The main shaft 72, the shift drum 90, the fork shafts 91 and 92, and the drive shaft 74 are located in the axial projection plane of the large reduction gear 83 of the clutch mechanism 81.

Next, the arrangement of the cooling water pump and the lubricating oil pump will be described. As shown mainly in FIGS. 2, 13, and 14, the cooling water pump 100 and the lubricating oil pump 101 of the present embodiment are both housed in the lower case 27, and the pump shaft 102 common to both pumps is It is arranged below and parallel to the crankshaft 21 and the drive shaft 74. The pump shaft 102 is rotatably supported in the housing unit 103 via bearings 104 and 105. The right end of the pump shaft 102 is provided with a rotor 106 of the lubricating oil pump 101, and the left end is provided with cooling water. The impeller 107 of the pump 100 is fixed. A driven sprocket 1 is provided on the right axial end face of the pump shaft 102.
08 is fixed by bolting.
Reference numeral 8 denotes a drive sprocket 11 mounted on a portion of the main shaft 72 outside the flange 78 via a chain 109.
Connected to 0.

The housing unit 103 includes a main body portion 103a located at the center in the axial direction, a cooling side housing portion 103b located on the left and right sides, and a lubricating side housing portion 103.
c, and the two housing portions 10
3b and 103c are bolts 111 and 1 screwed in the axial direction.
12 fastened to the main body 103a. The maximum diameter portion 103d of the housing unit 103 is disposed at a position radially opposed to the highest-speed gear 73a (see FIG. 4) having the minimum diameter of the output gear group 73 of the drive shaft 74.

When the housing unit 103 is provided so as to be close to the main shaft 72,
The maximum diameter portion 103d is connected to the input gear group 71
Is desirably arranged so as to be radially opposed to the minimum diameter gear.

Here, the housing unit 103 is
The cooling side housing part 103 is accommodated in the lower case 27 and
b is a boss 27 formed on the left side wall of the lower case 27.
a through the O-ring 27b, and the lubricating side housing portion 103c is screwed in from below.
It is arranged and fixed in the lower case 27 by being fastened to the vertical wall of the lower case 27 by the bolts 113, 113. The vertical wall extends in a substantially vertical direction from the vicinity of the mating surface with the upper case, and functions as a rib for improving the rigidity of the case.

A seal member 114 is provided on the left side of the left bearing 104 of the pump shaft 102 in the axial direction.
A mechanical seal 115 is provided on the left side of the box at an interval. A drain hole 116 is formed between the seal member 114 at the bottom of the main body 103a and the mechanical seal 115, and a drain pipe (drain pipe) 117 is inserted into the drain hole 116. The lower end of the drain pipe 117 communicates with the outside through a drain passage 28a formed in the oil pan 28. Thereby, the water leaking from the cooling water pump 100 is discharged to the outside of the engine. The drain pipe 117 is provided between the housing unit 103 supported by the lower case 27 and the oil pan 28 attached to the lower case from below via the O-ring 117a without using a special support member. It is pinched.

A cooling water return hose 118 is provided at the suction port 103e of the cooling side housing part 103b,
A cooling water supply pipe 119 is connected to 3f. The cooling water supply pipe 119 is led out to the front of the engine, and is connected to a cooling jacket inlet (not shown) on the front wall of the cylinder block 23 via a cooling hose 123a and a water supply pipe 123b. Therefore, the crankcase 25 is located between the outlet of the supply pipe 119 from the pump to the front wall of the engine.
Since it passes through the inside, the portion exposed to the outside, the cooling hose 123a, and the water supply pipe 123b are also short, so that the appearance of the engine is improved.

An oil strainer 120 disposed in the oil pan 28 is connected to the lubricating oil suction port 103g of the lubricating side housing portion 103c.
An oil filter 121 connected to the front wall of the lower case 27 is connected to the lubricating oil discharge port 103h. The lubricating oil leaving the oil filter 121 is supplied to the main gallery 1
The oil is supplied to each engine lubrication unit such as the crankshaft 21, the main shaft 72, the drive shaft 74, and the camshafts 40 and 41 through the motor 22.

Here, the camshaft path of the lubricating oil opens between the first cylinder intake side of the cylinder head 23 and the chain arrangement chamber 43 as shown in FIGS. 3, 6 to 8 and 16. A discharge port 126a of the first oil passage 126 communicates with a first oil passage 127 extending along the intake camshaft 40, and a fourth oil passage 129 extending along the exhaust camshaft 41 through the third oil passage 128. And the first and fourth oil passages 127 and 129 communicate with a camshaft bearing. Each camshaft 40, 41
The lubricating oil that has been lubricated is recovered into the oil pan 28 through an oil return passage 130 formed between the exhaust sides of the third and fourth cylinders of the cylinder head 23.

In the above embodiment, the cooling water pump and the lubricating oil pump are integrated and arranged in the clan case. However, only the cooling water pump may be arranged in the crank case.

Next, a starting device of the engine unit 15 will be described mainly with reference to FIGS. The starting motor 135 is arranged on the back surface of the cylinder bore of the upper case 26 in parallel with the crankshaft 21. The motor 135 is connected to the rear case 135a by the upper case 2.
6 and the front end boss 135b
Is fitted into the boss portion of the upper case 26 to be supported.

The output gear 136 of the starting motor 135
Project into the upper case 26, which
8 with the large-diameter gear 138a. This intermediate gear 1
Reference numeral 38 denotes an intermediate shaft 137 which is bolted and fixed above the main shaft 72 in the upper case 26. The intermediate shaft 137 is a shaft of the largest diameter portion (large reduction gear 83) of the clutch mechanism 81. It is arranged so as to be located in the direction projection plane.

The small-diameter gear 138b of the intermediate gear 138 meshes with a starting gear 139. The starting gear 139 has a one-way clutch 140 interposed between the boss portion of the large reduction gear 83 supported by the main shaft 72. Connected.
The one-way clutch 140 is configured to transmit the torque from the starting motor 135 to the large reduction gear 83 and not to transmit the torque from the crankshaft 21 to the starting motor 135.

The exhaust device of the engine unit 15 is as follows.
Mainly, an exhaust pipe 141 connected to each exhaust port 34 opening to the front wall of the cylinder head 23, a first muffler 142 disposed between the engine unit 15 and the rear wheel 13 and below the rear cushion 14, and The second muffler 143 is provided on the upper right side of the rear wheel 13.

Each exhaust pipe 141 is bent downward from the exhaust port 34 and extends rearward below the oil pan 28. The first muffler 142 is disposed by utilizing a space created by arranging the rear cushion link mechanism between the oil pan 28 and the rear wheel 13 upright. Is provided with a muffling mechanism and a catalyst (not shown).

Next, the intake device of the engine unit 15 will be described mainly with reference to FIGS. Each of the intake ports 33 led to the rear wall of the cylinder head 23 is connected to a quadruple carburetor unit 151 via a joint 150. This carburetor unit 151 is a first carburetor corresponding to the first to fourth cylinders from the right.
To the fourth vaporizers 151a to 151d. Each of the vaporizers 151a to 151d has a butterfly throttle valve 152 that opens and closes by a throttle operation.
And an automatic variable venturi type having a piston valve (not shown) that opens and closes automatically by the negative pressure of the intake air of the engine. Rotational force can be transmitted by a connecting member 154 between the valve shafts 153 of the throttle valves 152. It is configured to be connected to.

A throttle opening sensor 155 for detecting the opening of the throttle valve 152 is connected to the right end of the carburetor unit 151 in the vehicle width direction.
Numeral 5 is arranged on the side of the chain arrangement chamber 43 of the cylinder head 23, that is, on the rear surface of the rightward projecting portion of the chain arrangement chamber 43. In addition, the first vaporizer 1
A throttle pulley 156 is mounted on a connecting member 154 between the first carburetor 51a and the second carburetor 151b. The throttle pulley 156 is connected to a throttle grip (not shown) of a steering handle via a throttle cable 157. I have. Each of the throttle valves 152 is opened and closed in synchronization with the rotation of the throttle grip.

Here, the carburetor unit 151 has a dimension W1 from the vehicle center line L to the right outer end of the throttle opening sensor 155, and a carburetor unit 1 from the vehicle center line L.
51 are arranged so that the dimension W2 up to the left outer end is the same. Thus, the vehicle center line L and the carburetor unit 1
The center line 51 corresponds to the center line in the vehicle width direction.

Then, the first and second vaporizers 151a, 151
The axes X1 and X2 passing through the center of the intake passage 51b and parallel to the vehicle body center line L are separated from the axis Y1 and Y2 passing through the cylinder axis 20 of the first and second cylinders and parallel to the vehicle body center line L. 43 is slightly offset (specifically, about 2 mm). On the other hand, the third and fourth vaporizers 151
The axes X3 and X4 of c and 151d are separated from the corresponding axes Y3 and Y4 of the third and fourth cylinders by the chain arrangement chamber 43.
On the side, it is larger than the first and second vaporizers 151a and 15b. Specifically, the third carburetor 15c is 7
mm and the fourth vaporizer 15d is offset by about 14 mm. The throttle pulley 156 causes the pitch between the carburetors to be increased. In the present embodiment, the throttle pulley 156 is disposed between the first and second carburetors whose pitches are increased by the offset. I have.

Next, the operation and effect of this embodiment will be described. In the present embodiment, the communication hole 52 that connects the crank chambers 19 is located in the mounting opening 50 of the camshaft drive mechanism provided on the outer wall 22b of the cylinder block 22 when viewed in the crankshaft direction. Since the communication hole 52 can be formed by machining using the assembly opening 50, there is no need to perform extra processing such as separately forming an opening for machining. Therefore, it is not necessary to close the processing opening with the exclusive lid member, and the manufacturing cost can be reduced.

In forming the hard plating film on the inner surface of the cylinder bore 22a, the plating process is performed prior to the machining of the communication hole 52, so that the plating operation can be simplified and the communication hole can be formed. 5
2 can facilitate the processing operation. That is, the plating process is performed by closing the upper and lower openings of the cylinder bore 22a and supplying a current in a state where the closed space is filled with a plating solution. If so, the above-mentioned blockage becomes difficult. On the other hand, if machining is performed after the plating treatment, the processing becomes difficult due to the hard plating film. In the present embodiment, the plating process is performed in a state where the communication hole 52 is masked, so that the above-described problem can be avoided.

In the case where the lubricating oil passage 53 is formed in each boss portion 29 of the upper case 26 so as to open to the inner peripheral surface of the communication hole 52, and the lubricating oil is injected to the back surface of the piston through the passage 53. The width W of the upper part of the communication hole 52
1 is smaller than the lower width W2, the injected lubricating oil is reliably supplied to the back surface of the piston without being interrupted by the upper edge of the communication hole 52. The notch need not be formed,
The piston 31 can be efficiently cooled without increasing the cost.

Further, in this embodiment, a slipper-type piston 31 having a cut-out recess 31c formed in the piston skirt 31a is employed, and the injection port 54a of the lubricating oil passage 53 is connected to the piston 31 positioned at the bottom dead center. Since the piston skirt 31a is directed toward the back surface of the piston through the cutout recess 31c, the injection flow of the lubricating oil is not interrupted, and the cooling efficiency can be improved in this respect as well. Further, since the notch recess 31c is provided, the piston skirt 3
The problem that the effective area of the communication hole 52 is reduced by 1a can also be avoided. Alternatively, it is not necessary to lengthen the connecting rod in order to avoid area reduction due to the skirt.

According to the cylinder head fastening structure of the present embodiment, the washer mounting surface 56 is formed below the lower edge of the lifter guide hole 23b of the cylinder head 23, and is larger than the washer 57 following the mounting surface 56. A washer rotation hole 60 having a diameter is formed, and a nut insertion hole 61 into which a nut 58 can be inserted is formed following the washer insertion hole 60. Further, the nut insertion hole 61 has substantially the same radial dimensions as the washer rotation hole 60. Slit 6 with
Since the washer 3 is formed, the washer 57 can be seated on the mounting surface 56 by inserting the washer 57 from the slit 63 with the washer 57 in the vertical direction and falling down by the washer rotating hole 60. As a result, the dimensions between the adjacent lifter guide holes 23b can be reduced while securing the necessary wall thickness of the lifter guide portion and the area of the nut tightening seat surface, whereby the cylinder pitch can be reduced and the engine width can be made compact. it can.

In this embodiment, when the camshafts 40 and 41 are formed through the tool holes 64 for tightening the head bolts disposed between the cylinders, portions of the camshafts 40 and 41 close to the chain arrangement chamber 43. That is, since the tool hole 64 formed at the portion where the torsion torque is increased and the formation position of the wide thrust receiving portion 65 are matched, the tool hole 6 is formed.
4, the reduction in torsional rigidity of the camshaft can be suppressed by the wide and large-diameter thrust receiving portion 65.

In the transmission of this embodiment, the upper case 26
The bottom wall 26c of the oil breather chamber 96 is used as a stopper for restricting the rotation angle position of the input-side shift fork 93.
Input-side shift fork 9 without complicating the structure
3 can be improved in assemblability.

That is, as described in the above-described assembling procedure, when the input side shift fork 93 is rotated downward while the claw portion 93b is engaged with the sliding groove 71a of the main shaft 72, the base portion 93c is formed. Abuts on the bottom wall 26c and is temporarily held at a predetermined position. Therefore, when the engagement pin 93a of the shift fork 93 is engaged with the guide groove 90a of the shift drum 90, the assembly opening on the side of the upper case 26 is opened. It can be assembled by inserting the input-side fork shaft 91 from the 26a side. Conventionally, an opening for assembling was formed in the top wall of the crankcase. However, in the present embodiment, such an opening can be made unnecessary.
Since the number of assembling steps is not required, the cost can be reduced, and the rigidity of the ceiling portion of the crankcase can be prevented from being reduced by forming the assembling opening.

The height of the bottom wall 26c of the oil breather chamber 96 functioning as the stopper is set at a position where the locking pin 93a of the input side shift fork 93 is disengaged from the guide groove 90a of the shift drum 90. With the side shift fork 93 temporarily held, the shift drum 90
Can be inserted from the assembly opening 26a side without any trouble, and the assembling work can be easily performed from this point as well.

Further, since the stopper portion is constituted by the bottom wall 26c of the oil breather chamber 96 integrally formed with the upper case 26, it is not necessary to form the stopper portion specially.
It is possible to avoid cost increase and case enlargement.

According to the present embodiment, the crankshaft 21, the main shaft 72, and the drive shaft 74 are connected to the first shaft angle θ1 between the crankshaft / main shaft straight line A and the cylinder axis 20, and the shaft straight line A. Since the second shaft angle θ2 between the main shaft and the drive shaft straight line B is arranged so as to form an acute angle, the distance between the crankshaft 21 and the drive shaft 74 can be reduced, and the longitudinal length of the engine unit 15 can be reduced accordingly. Can be shortened.

Since the front-rear length of the engine unit can be reduced, the rear arm pivot portion can be located forward, and the length of the rear arm 11 can be extended when the wheel base is set in the same manner as in the prior art. The angle can be reduced, and running stability can be improved.
When the length of the rear arm is set to be the same as that of the related art, the wheelbase can be shortened, and the maneuverability can be improved.

Further, since the length of the rear arm 11 can be set large, an empty space can be secured between the engine unit 15 and the rear wheel 13, and the first muffler 142 can be disposed by effectively utilizing the space. . As a result, the exhaust noise silencing effect can be improved, and the center of gravity can be reduced.

In this embodiment, as shown in FIG.
Although the second muffler 143 is connected to the rear of the first muffler 142 via the exhaust pipe 144, the second muffler may be omitted depending on the capacity of the first muffler.

Further, since the main shaft 72 is arranged closer to the cylinder head 23 side than the right-angled straight line C passing through the crankshaft 21, the main shaft 72 is arranged to be carried on the back of the cylinder block 22. 15 can be further reduced. Further, since the clutch mechanism 81 is disposed such that its maximum outer peripheral surface 81a is located on the cylinder head 23 side with respect to the right-angled straight line D passing through the piston top surface at the bottom dead center, the engine unit 15 can be downsized from this point as well.

Since the main shaft 72, the shift drum 90, the fork shafts 91 and 92, and the drive shaft 74 are arranged in the axial projection plane of the largest diameter portion of the clutch mechanism 81,
The arrangement of each shaft is compact, the protrusion of the unit case 25 can be reduced, and the engine can be downsized from this point as well.

In this embodiment, both the cooling water pump 100 and the lubricating oil pump 101 are connected to the common housing unit 1.
Since the housing unit 103 is disposed in the unit case 25, the protrusion from the crankcase side wall can be eliminated, so that the engine width can be reduced and the bank angle can be set large.

Further, since the largest diameter portion 103d of the housing unit 103 is radially opposed to the highest-speed gear 73a having the smallest diameter of the drive shaft 74, the distance between the pump shaft 102 and the drive shaft 74 can be reduced. In this respect, the size can be reduced.

The left end of the housing unit 103 in the axial direction was fitted to the boss 27a of the lower case 27 via an O-ring 27b, and the right end was fixed to the lower case 27 by bolts to support the cantilever. In addition, it is possible to reduce the number of fixing bolts while securing both the mounting strength and the sealing property without applying a radial offset load to the O-ring, thereby reducing the cost and simplifying the mounting structure.

Further, since the drain pipe 117 is inserted between the cooling water pump 100 and the lubricating oil pump 101 of the housing unit 103 and the drain pipe 117 is communicated to the outside, the water leaking from the cooling water pump 100 And water can be reliably prevented from mixing into the lubricating oil while the cooling water pump 100 is arranged in the crankcase.

According to the starting device of this embodiment, the output gear 136 of the starting motor 135 is connected to the intermediate gears 138a and 138.
b, a one-way clutch 140 is interposed between the starting gear 139 mounted on the main shaft 72 and the large reduction gear 83 meshed with the crankshaft 21. Is the starting gear 139,
Since the intermediate gears 138a and 138b and the output gear 136 do not rotate, the loss horsepower can be reduced.

The start gear 139 and the one-way clutch 140 are connected to the large reduction gear 83 of the main shaft 72 and the input gear group 7.
1, the space can be compactly arranged by effectively utilizing the axial dead space of the main shaft 72. Further, the crankshaft can be shortened as compared with the one-way clutch provided on the crankshaft. The axial length and the position of the main shaft 72 are determined by the vehicle width direction position of the reduction small gear 82 disposed at the end of the crankshaft 21, the vehicle width direction position of the drive sprocket 79 for the rear wheel 13, and the speed change. The dead space is inevitably determined by the number of stages and the like, and therefore, in the case of an engine having the same specifications as in the present embodiment, the dead space often occurs in the inner portion of the clutch mechanism of the main shaft 72.

Since the intermediate shafts 137 of the intermediate gears 138a and 138b are arranged in the axial projection plane of the large reduction gear 83, the layout of the starting device can be made compact, and the size of the engine can be reduced. Also, interference with the connecting rod of the starting gear 139 can be avoided while reducing the pitch between the crankshaft and the main shaft.

According to the intake system of this embodiment, the throttle opening sensor 155 is arranged at the end of the carburetor unit 151 on the side of the chain arrangement chamber 43, and the throttle pulley is arranged between the first and second carburetors. A dimension W1 from the vehicle center line L to the outer end of the opening sensor 155;
The throttle opening sensor 155 is arranged in a vacant space at the end of the chain arrangement chamber 43 side so that the dimension W2 from the front to the outer end of the carburetor unit 151 on the side opposite to the opening sensor 155 is substantially the same. Each carburetor 151a can be made without increasing the vehicle width dimension of the main frame 3.
-X1 to X4 and the axis Y1 to Y4 of each cylinder.
And the total amount of offsets can be minimized. As a result, it is possible to reduce the intake passage resistance while reducing the vehicle width and improving the riding position.

The connecting member 15 between the first and second carburetors 151a and 151b located on the chain arrangement chamber 43 side.
Since the throttle pulley 156 is disposed at the position 4, the total amount of offset between the carburetor and the cylinder can be minimized while avoiding an increase in the width of the vehicle body, and the tuning accuracy of each carburetor can be improved. That is, for example, when a pulley is disposed at the left end of the carburetor unit, it is necessary to increase the offset amount between the third and fourth cylinders and the carburetor in order to avoid an increase in the width of the vehicle body. Tuning accuracy of the vaporizer is reduced.

[Brief description of the drawings]

FIG. 1 is a left side view of a motorcycle equipped with an engine unit according to an embodiment of the present invention.

FIG. 2 is a right side view of the engine unit.

FIG. 3 is a right side view showing a structure around a chain arrangement chamber of the engine unit.

FIG. 4 is a sectional rear view of the engine unit.

FIG. 5 is a sectional view showing a communication hole portion of the engine unit.

FIG. 6 is a plan view of a cylinder head of the engine unit.

7 is a sectional view of the cylinder head (VII-VII in FIG. 6).
(Line sectional view).

FIG. 8 is a sectional view of the cylinder head (VIII-VII in FIG. 6).
FIG.

9 is a sectional view of a fastening portion of the cylinder head (FIG. 8)
IX-IX sectional view of FIG.

FIG. 10 is a plan view of an intake camshaft of the engine unit.

FIG. 11 is a left side view of an upper case portion of the engine unit.

FIG. 12 is a sectional view of a transmission of the engine unit.

FIG. 13 is a sectional view of a cooling water pump and a lubricating oil pump of the engine unit.

FIG. 14 is a side view of a lubricating oil pump portion of the engine unit.

FIG. 15 is a developed rear view of the starting device of the engine unit.

FIG. 16 is a schematic plan view of an intake device of the engine unit.

FIG. 17 is a schematic configuration diagram of the intake device.

[Explanation of symbols]

15 Engine Unit 25 Unit Case (Crankcase) 27a Boss (Sidewall) 70 Transmission 73a Highest Speed Gear 74 Drive Shaft (Output Shaft) 100 Cooling Water Pump 101 Lubricating Oil Pump 103 Housing Unit 103d Maximum Diameter Part 117 Drain Pipe ( Drain pipe)

Claims (4)

[Claims] 1. A vehicle engine unit in which a cooling water pump and a lubricating oil pump are coaxially arranged, wherein the housing of the cooling water pump and the housing of the lubricating oil pump are axially connected to form a housing unit. An engine unit for a vehicle, wherein the engine unit is disposed in a crankcase. 2. A cooling water pump is disposed in a crankcase such that a rotation axis thereof is parallel to an input shaft and an output shaft of a transmission, and a maximum diameter portion of a housing of the cooling water pump is close to the cooling water pump. An engine unit for a vehicle, wherein the engine unit is radially opposed to a minimum diameter gear of the output shaft or the input shaft arranged. 3. A cooling water pump is arranged in a crankcase, one axial end of a housing of the cooling water pump is fitted to a side wall of the crankcase, and the other end is bolted to a wall of the crankcase. An engine unit for a vehicle, which is fastened and fixed. 4. The vehicle according to claim 1, wherein a portion of the housing of the cooling water pump opposite to the impeller across the bearing is communicated with the outside of the crankcase by a drain pipe. Engine unit.