JPH1037731A - Engine for outboard motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize an oil pump and an engine itself by enabling driving of an oil pump with the same driving speed as a crankshaft. SOLUTION: An engine 3 is so mounted on an outboard motor that a crankshaft 6 is perpendicularly arranged. A balancer shaft 40 is journalled inside an engine case 23 parallely to the crankshaft 6. Rotation of the crankshaft 6 is constant-speed transmitted to the balancer shaft 40. In such a case, an oil pump 58 is arranged near the balancer shaft 40, and directly driven thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine of an outboard motor used for propulsion of a ship.

[0002]

2. Description of the Related Art Many outboard motor engines are mounted vertically on an outboard motor such that its crankshaft is oriented vertically, and the rotation of the crankshaft is performed via a drive shaft that extends long downward. The power is transmitted to a propeller for propulsion provided at the bottom of the outboard motor.

[0003] When the engine is a four-stroke engine, a camshaft for driving a valve train is supported inside the engine. The camshaft drives an oil pump for lubrication in many cases. For example, an outboard motor described in Japanese Patent Publication No. 3-3904 is provided with an oil pump near the lower end of a camshaft, and the oil pump is driven by the camshaft.

[0004]

However, since the rotation speed of the camshaft is half the rotation speed of the crankshaft,
In order to drive the oil pump with the cam shaft that rotates slowly as described above, it is necessary to increase the capacity of the oil pump, which leads to an increase in the size of the oil pump and, consequently, the size of the engine.

On the other hand, if the oil pump is directly driven by the crankshaft, the drive rotation speed of the oil pump is increased and the size of the oil pump can be reduced. However, the drive shaft is connected to the lower end of the crankshaft. Since a flywheel magneto device and starting device are provided at the upper end, it is necessary to provide a special gear device etc. in the middle of the crankshaft to extract the rotation of the crankshaft. This leads to shape and structural complexity.

The outboard motor engine according to the present invention has been invented in order to solve such a problem. The first object of the present invention is to operate an oil pump at a drive rotational speed equal to that of a crankshaft. An object of the present invention is to reduce the size of the oil pump and the engine itself by making it drivable.

A second object of the present invention is to simplify the structure of an oil passage formed inside an engine case to facilitate manufacture of an engine.

Further, a third object of the present invention is to improve the lubrication state of a balancer shaft supported in an engine case.

A fourth object of the present invention is to improve the accuracy of oil pressure measurement of an oil pressure regulator for monitoring oil pressure, and to improve the maintainability of an engine by improving the removability of the oil pressure regulator. is there.

[0010]

According to a first aspect of the present invention, an engine for an outboard motor according to the present invention is provided with an outboard motor mounted vertically so that a crankshaft is oriented vertically. In an engine of an outboard motor, the balancer shaft is supported in parallel with the crankshaft in the engine case, and the rotation of the crankshaft is transmitted to the balancer shaft at a constant speed. The pump is installed near the balancer shaft, and the oil pump is directly driven by the balancer shaft.

As described above, if the oil pump is directly driven by the balancer shaft to which the rotation of the crankshaft is transmitted at a constant speed, the oil pump can be driven at the same driving speed as the crankshaft. In addition, the oil pump and the engine itself can be downsized by reducing the capacity of the oil pump accordingly.

Further, the engine of the outboard motor according to the present invention includes:
As described in claim 2, the balancer shaft is formed in a hollow shaft shape, one end of the hollow portion communicates with the discharge side passage of the oil pump, and the other end of the hollow portion communicates with the lubrication portion of the engine. .

With this configuration, the hollow portion of the balancer shaft is used as it is as the oil passage, so that the number of oil passages formed inside the engine case can be reduced and the configuration of the oil passage can be simplified. Can be easily manufactured.

Further, in the engine for an outboard motor according to the present invention, the oil pump is installed at the bottom of the engine case, and the suction side passage and the discharge side passage of the oil pump are connected to the engine case. And a separate oil gallery block fixed on the bottom of the oil gallery block, a bearing portion for supporting the lower end of the balancer shaft is provided in the oil gallery block, and this bearing portion is communicated with the discharge side passage. Was.

Thus, a part of the suction side passage and the part of the discharge side passage of the oil pump can be formed as separate oil gallery blocks, so that the structure of the oil passage formed inside the engine case can be simplified. This also makes engine production easier. In addition, the discharge side passage of the oil pump and the bearing portion that supports the lower end of the balancer shaft are provided in one oil gallery block and communicate with each other, and high-pressure oil flowing through the discharge side passage is directly supplied to the bearing portion. Therefore, the lubrication state of the balancer shaft can be kept good.

In the outboard motor engine according to the present invention, the oil pressure regulator for monitoring the oil pressure in the oil passage is mounted upward with respect to the oil passage.

This makes it difficult for oil bubbles to get caught in the oil pressure regulator, thereby improving the accuracy of measuring the oil pressure of the oil pressure regulator and, at the same time, improving the maintainability of the engine by improving the attachment and detachment of the oil pressure regulator.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a right side view showing an example of an outboard motor according to the present invention. FIG. 2 is a longitudinal sectional view of an engine portion of the outboard motor, and FIG.
FIG. 3 is a cross-sectional view along the line III.

The outboard motor 1 has a box-shaped engine cover 2 at the uppermost part, and an engine 3 is housed inside the cover. A steering handle 4 extends forward from the front of the engine cover 2 and has an engine 3
The throttle grip 5 for adjusting the output is provided. The engine 3 is mounted vertically so that its crankshaft 6 is oriented vertically.

A drive housing 7 is connected to a lower portion of the engine cover 2, and a gear housing 8 is provided below the drive housing 7. A propeller shaft 10 is supported inside the gear housing 8, and a propeller 11 is provided at a rear end of the propeller shaft 10.

On the other hand, a drive shaft extending vertically downward from the lower end of the crankshaft 6 of the engine 3 is provided in the drive housing 7.
A lower end of the drive shaft 12 is supported by a forward / reverse switching device 13 composed of a bevel gear or the like.
Works with 10.

The output of the engine 3 is transmitted to the propeller shaft 10 through the drive shaft 12 and the forward / reverse switching device 13, and the switching operation of the forward / reverse switching device 13 switches the rotation direction of the propeller shaft 10 and the propeller 11 or shifts the rotation to neutral. can do.

The upper portion of the drive housing 7 is rotatably supported by a rotation support portion 16 of a clamp bracket 15, and the clamp bracket 15 is fixed to a transom (stern portion) 18 of a boat 17. Therefore, the outboard motor 1 is provided so as to be able to rotate 360 ° with respect to the hull 17, and the steering of the hull 17 can be performed by turning the steering handle 4 to change the direction of the entire outboard motor 1.

The engine cover 2 has a structure in which, for example, a synthetic resin upper cover 2b is detachably mounted on a metal lower cover 2a with a seal member 19 interposed therebetween. Engine 3 on
Has been fixed. In addition, the steering handle 4 is provided integrally with the lower cover 2a, and a waterproof cover 21 which serves as an air intake 20 and also serves as a handle is provided at the rear upper portion of the upper cover 2b.

The engine 3 is a single-cylinder engine of, for example, a 4-cycle OHV type, and is configured as follows.

First, the lower cover 2 of the engine cover 2
The engine case 23 is fixed on a. The engine case 23 is configured by joining a lower crankcase 23a and an upper cylinder b block 23b. A cylindrical cylinder sleeve 24 extending horizontally rearward is formed integrally with the cylinder block 23b, and a cylinder head 25 and a head cover 26 are fixed to the rear end of the cylinder sleeve 24.

A cylinder bore 27 is formed inside the cylinder sleeve 24, and a cylinder bore 27 is formed in the cylinder head 25.
Is formed. In addition, an intake port 29 and an exhaust port 30 connected to the combustion chamber 28 are formed in the cylinder head 25, and these two ports 29, 3
An intake valve 31 and an exhaust valve 32 for opening and closing the valve 0 are set, and a valve train 33 for opening and closing the valves 31 and 32 is further incorporated. Note that an ignition plug 34 is provided in the combustion chamber 28.

On the other hand, the crankshaft 6 is
The metal bearing 35 provided on the a side and the cylinder block 23
It is rotatably supported by a bearing 36 provided on the b side. A pair of upper and lower crank webs 6a and 6b are formed at an intermediate portion of the crankshaft 6, and a crank pin 6c is eccentrically provided therebetween.

A piston 37 is slidably inserted into the cylinder bore 27, and a piston rod 37a provided on the piston 37 and a crankpin 6c of the crankshaft 6 are connected by a connecting rod 38. Cylinder bore
The reciprocating motion of the piston 37 in the shaft 27 is converted into the rotational motion of the crankshaft 6. Since the upper end of the drive shaft 12 is integrally connected to the lower end of the crankshaft 6 by spline fitting or the like, the rotation of the crankshaft 6 is transmitted to the drive shaft 12 as it is.

FIG. 4 is a plan view of the crankcase 23a taken along the line IV-IV in FIG. 2, and FIGS.
FIG. 6 is a longitudinal sectional view taken along line VV and line VI-VI in FIG. 4.

As shown in FIG. 3 and FIG.
Inside 23 is a balancer shaft 40 and a cam shaft parallel to the crankshaft 6.
41 is supported. The lower ends of the two shafts 40, 41 are supported by bearings 42, 43 provided on the crankcase 23a side, and the upper ends are supported by bearings 44, 45 provided on the cylinder block 23b side. ing.

The balancer shaft 40 is a rotating shaft for canceling engine vibration generated due to the inertial force caused by the reciprocating motion of the piston 37 and the rotating motion of the crank webs 6a and 6b. Are located. On the other hand, the camshaft 41 is a rotary shaft for driving the valve train 33 incorporated in the cylinder head 25, and is disposed, for example, on the right side of the crankshaft 6.

The upper crank web 6a of the crankshaft 6
Above the balancer drive gear 47 is fixed,
The balancer drive gear 47 meshes with a balancer driven gear 48 provided on the balancer shaft 40. A cam drive gear 49 is fixed below the crank web 6b on the lower side of the crank shaft 6, and the cam drive gear 49 meshes with a cam driven gear 50 provided on the cam shaft 41.

The number of teeth of the balancer drive gear 47 and the number of teeth of the balancer driven gear 48 are set to be the same, and the number of teeth of the cam drive gear 49 is set to half the number of teeth of the cam driven gear 50. Therefore, when the crankshaft 6 rotates, the rotation of the crankshaft 6 is transmitted to the balancer shaft 40 at a constant speed, and the rotation of the crankshaft 6 is transmitted to the camshaft 41 at a reduced speed of one half.

The balancer shaft 40 is formed in a hollow shaft shape having a hollow portion 40d.
a and 40b are integrally formed. An eccentric cam 40c is formed between the upper and lower balance weights 40a, 40b.

Then, as shown in FIG.
Since the driven rod 51a of the plunger type fuel pump 51 provided on the abutment 23 is in contact with the eccentric cam 40c, the balancer shaft
When the 40 rotates, the driven rod 51a is periodically pressed by the eccentric cam 40c to discharge the fuel, and the fuel is supplied to a fuel supply device such as a carburetor.

On the other hand, an intake cam 41a and an exhaust cam 41b are formed on the camshaft 41, and the movement of the intake cam 41a and the exhaust cam 41b accompanying rotation of the camshaft 41 causes two tappets 52 and two pushes. The transmission is transmitted to the valve train 33 via the rod 53, and the valve train 33 is driven to open and close the intake valve 31 and the exhaust valve 32.

By the way, as shown in FIGS. 4 and 5,
An oil pump housing 55 is formed in a pedestal shape at the bottom of the engine case 23 (crankcase 23 a), and a separate oil gallery block 56 is fastened on the oil pump housing 55 by three bolts 57. . Further, a bearing portion 42 that supports the lower end of the balancer shaft 40 is formed on the upper portion of the oil gallery block 56 as described above.

Inside the oil pump housing 55, for example, a trochoid type oil pump 58 is provided.
The main shaft 58a of the oil pump 58 extends upward to
Of the oil pump 58 when the balancer shaft 40 rotates.
Is driven directly.

The suction side passage 58b and the discharge side passage 58c of the oil pump 58 are formed between the oil pump housing 55 and the oil gallery block 56. The oil gallery block 56 is provided with an oil passage 59 connected to the suction-side passage 58b, and a pipe-shaped oil strainer 60 connected to the oil passage 59 is bent downward and extends near the bottom surface of the crankcase 23a.

On the other hand, an oil filter housing 61 is provided outside the crankcase 23a, and an oil filter 62 is housed inside. Oil filter 62
Can be taken out by removing the upper lid 63 of the oil filter housing 61, and can be washed or replaced.

Then, the discharge side passage 58c of the oil pump 58
An oil passage 65 extending horizontally from the oil filter housing 61 is connected to an inlet passage 66 provided at the bottom of the oil filter housing 61, and an oil passage 68 extending from an outlet passage 67 also provided at the bottom of the oil filter housing 61 is located below the crankshaft 6. Connected to a metal bearing 35.

The crankshaft 6 extends obliquely upward from the position of the lower metal bearing 35 so as to extend into the crankshaft 6.
An oil passage 69 opening to c is formed. The end of the oil passage 69 is closed by a plug 70.

On the other hand, as shown in FIG. 5, a small hole 72 is formed in the oil gallery block 56 to connect the discharge side passage 58c to the bearing portion 42. The small holes 72 allow the discharge-side passage 58c to communicate with the lower end of the hollow portion 40d of the balancer shaft 40 via the bearing portion 42.

An oil passage 73 extending horizontally is formed above the cylinder block 23b. The oil passage 73 is formed so as to connect the bearing 44 supporting the upper end of the balancer shaft 40, the bearing 36 above the crankshaft 6, and the bearing 45 supporting the upper end of the camshaft 41. In addition,
An oil groove 74 is formed around the bearing 36, and both ends of the oil passage 73 are closed by plugs 75.

A small hole is formed at the upper end of the hollow portion 40d of the balancer shaft 40.
76 is drilled, and the balancer shaft 40 is
The hollow portion 40d communicates with the oil passage 73. Accordingly, one end (lower end) of the hollow portion 40d of the balancer shaft 40 communicates with the discharge side passage 58c of the oil pump 58 through the small hole 72, and the other end (upper end) communicates with the engine 3 through the small hole 76 and the oil passage 73. (Bearings 36, 44, 45).

By the way, as shown in FIG.
An oil pressure regulator 79 for monitoring oil pressure is provided upward at an intermediate part of the oil passage, and an oil pressure switch 80 is provided at a tip of the oil passage 68. A predetermined amount of oil 81 is stored at the bottom of the engine case 23 as shown in FIGS.

The engine 3 is configured as described above. A flywheel magneto device 82 for power generation and a low pre-coil type starting device 83 are provided above the engine 3.

When the engine 3 starts, the balancer shaft 40 is driven to rotate by the rotation of the crankshaft 6, and two balance weights 40a, 40b provided on the balancer shaft 40 are provided.
Centrifugal force cancels engine vibration generated due to the inertial force accompanying the reciprocating motion of the piston 37 and the rotational motion of the crank webs 6a, 6b. Therefore, the quietness of the engine 3 is greatly improved.

At the same time, the rotation of the balancer shaft 40 drives the oil pump 58, and the oil 81 stored in the bottom of the engine case 23 is supplied to the oil pump 58 via the oil strainer 60, the oil passage 59, and the suction side passage 58b. Inhaled. The oil sucked into the oil pump 58 is discharged to the discharge side passage 58
The oil is pressure-fed to the side c, and flows therefrom into an oil passage 65 and a small hole 72.

The oil 81 flowing into the oil passage 65 is an inlet passage.
After flowing into the oil filter housing 61 from the oil filter 66 and being filtered by the oil filter 62, the oil flows through the outlet passage 67 and the oil passage 68, and a part thereof is supplied to the metal bearing 35 below the crankshaft 6. Most of the remaining oil 81 flows through the oil passage 69 in the crankshaft 6 to lubricate between the crankpin 6c and the large end of the connecting rod 38.
Scattered into the crankcase 23 due to the rotational centrifugal force of the cylinder shaft 27, between the sliding surface between the cylinder bore 27 and the piston 37, between the piston pin 37a and the small end of the connecting rod 38, and further between the camshaft 41
The lubrication of the intake cam 41a, the exhaust cam 41b, the tappet 52, the push rod 53, etc., of the camshaft flows down to the bottom of the crankcase 23.

The oil 81 flowing into the small hole 72 from the discharge side passage 58c of the oil pump 58 has a part thereof
And the other flows upward through the hollow portion 40d of the balancer shaft 40, flows from the small hole 76 to the oil passage 73,
The bearing 44 on the upper side of the balancer shaft 40, the bearing 36 supporting the upper end of the crankshaft 6, and the bearing 45 on the upper side of the camshaft 41 are lubricated.

An oil pressure regulator 79 provided in the oil passage 68 monitors the oil pressure in the oil passage 68. For example, when the oil pressure becomes too high, an alarm such as a buzzer or a lamp provided on a control panel or the like of the outboard motor 1 is provided. Activate the means.
Further, the oil pressure switch 80 activates the alarm means when the oil pressure in the oil passage 68 drops too much.

If the oil pump 58 is driven directly by the balancer shaft 40 rotating at the same speed as the crankshaft 6 as in the engine 3, the oil pump 58 is driven at the same driving rotation speed as the crankshaft 6. It can be driven fast. For this reason, compared with the case where the oil pump 58 is driven by the camshaft 41 rotating at half the rotation speed of the crankshaft 6,
Even if the capacity of the oil pump 58 is small, a sufficient oil discharge amount can be obtained. Therefore, the size of the oil pump 58 and the engine 3 can be reduced.

In this engine 3, the balancer shaft 40
Is formed in a hollow shaft shape, and one end (lower end) of the hollow portion 40d communicates with the discharge side passage 58c of the oil pump 58,
The other end (upper end) of the hollow portion 40d is connected to the engine lubrication portion (36,44,
45), the balancer shaft
The 40 hollow portions 40d are used as they are as oil passages. Therefore, the number of oil passages formed inside the engine case 23 can be reduced, and the manufacture of the engine 3 is facilitated.

Further, in the engine 3, the suction side passage 58 b and the discharge side passage 58 c of the oil pump 58 are connected to the bottom (oil pump housing 55) of the engine case 23 and the separate oil gallery block 56 fixed thereon. Therefore, it is not necessary to form the suction side passage 58b and the discharge side passage 58c all on the bottom side of the engine case 23. In this regard, the structure of the oil passage formed inside the engine case 23 is simplified. And the manufacture of the engine 3 is facilitated.

Moreover, the discharge side passage 58c of the oil pump 58
And a bearing portion 42 for supporting the lower end of the balancer shaft 40 is provided in one oil gallery block 56 and communicates with each other through the small hole 72, so that high-pressure oil flowing through the discharge side passage 58c is small. The oil is supplied directly to the bearing portion 42 through the hole 72. For this reason, the lubrication state of the balancer shaft 40 can be favorably maintained.

In the engine 3, the oil passage 68
Since the oil pressure regulator 79 that monitors the oil pressure inside the oil pressure regulator 79 is mounted upward with respect to the oil passage 68, it is difficult for oil bubbles to get caught in the oil pressure regulator 79. Therefore, the accuracy of measuring the oil pressure of the oil pressure regulator 79 is improved, and at the same time, the detachability of the oil pressure regulator 79 is improved, so that the maintainability of the engine 3 is also improved.

In this embodiment, the engine 3 is a four-cycle OHV single-cylinder engine. However, if the engine 3 has a balancer shaft rotating at the same speed as the crankshaft, for example, a multi-cylinder four-cycle OHV engine is used. Engine and OHC
The configuration according to the present invention can also be applied to a type of engine or the like. Further, the configuration according to the present invention can be applied to an engine used other than the outboard motor.

[0060]

As described above, the engine of the outboard motor according to the present invention is mounted vertically on the outboard motor so that the crankshaft is oriented vertically, and is parallel to the crankshaft in the engine case. In an engine of an outboard motor configured to support the balancer shaft and transmit the rotation of the crankshaft to the balancer shaft at a constant speed, an oil pump is installed near the balancer shaft, and the oil pump is mounted on the balancer shaft. It is characterized in that it is configured to be directly driven by a shaft.

As described above, if the oil pump is directly driven by the balancer shaft to which the rotation of the crankshaft is transmitted at a constant speed, the oil pump can be driven at the same speed as the crankshaft. In addition, the oil pump and the engine itself can be downsized by reducing the capacity of the oil pump accordingly.

Further, the engine of the outboard motor according to the present invention
The balancer shaft was formed in a hollow shaft shape, and one end of the hollow portion was connected to the discharge side passage of the oil pump, and the other end of the hollow portion was connected to the lubrication portion of the engine.

In this case, since the hollow portion of the balancer shaft is used as it is as the oil passage, the number of oil passages formed inside the engine case can be reduced, and the configuration of the oil passage can be simplified. Can be easily manufactured.

Further, in the outboard motor engine according to the present invention, the oil pump is installed at the bottom of the engine case, and the suction-side passage and the discharge-side passage of the oil pump are fixed to the bottom of the engine case and above. The oil gallery block is provided between the oil gallery block and a separate oil gallery block. The oil gallery block is provided with a bearing portion for supporting the lower end of the balancer shaft, and the bearing portion is communicated with the discharge side passage.

Thus, a part of the suction side passage and the part of the discharge side passage of the oil pump can be formed in a separate oil gallery block, so that the configuration of the oil passage formed inside the engine case can be simplified. This also makes engine production easier. In addition, the discharge side passage of the oil pump and the bearing portion that supports the lower end of the balancer shaft are provided in one oil gallery block and communicate with each other, and high-pressure oil flowing through the discharge side passage is directly supplied to the bearing portion. Therefore, the lubrication state of the balancer shaft can be kept good.

In the outboard motor engine according to the present invention, since the oil pressure regulator for monitoring the oil pressure in the oil passage is mounted upward with respect to the oil passage, oil bubbles are caught in the oil pressure regulator. This makes it difficult to improve the oil pressure measurement accuracy of the oil pressure regulator and improves the detachability of the oil pressure regulator, thereby improving the maintainability of the engine.

[Brief description of the drawings]

FIG. 1 is a right side view showing an example of an outboard motor according to the present invention.

FIG. 2 is a longitudinal sectional view of an engine portion of the outboard motor.

FIG. 3 is a transverse sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a plan view of the crankcase taken along the line IV-IV in FIG. 2;

FIG. 5 is a longitudinal sectional view taken along line VV of FIG. 4, showing an embodiment of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outboard motor 3 Engine 6 Crankshaft 23 Engine case 36,44,45 Bearing part which is a lubrication part of an engine 40 Balancer shaft 40d Hollow part of balancer shaft 41 Camshaft 42 Bearing part which supports the lower end of balancer shaft 55 Oil Pump housing 56 Oil gallery block 58 Oil pump 58b Intake side passage of oil pump 58c Discharge side passage of oil pump 59,65,68,69,73 Oil passage 79 Oil pressure regulator 81 Oil

Claims (4)

[Claims] An outboard motor 1 is mounted vertically on the outboard motor 1 so that the crankshaft 6 is oriented vertically, and a balancer shaft 40 is supported in the engine case 23 in parallel with the crankshaft 6. In an outboard motor engine configured so that the rotation of the crankshaft 6 is transmitted at a constant speed to the oil pump 40, an oil pump 58 is installed near the balancer shaft 40.
The outboard motor engine 3 is configured to be directly driven by the balancer shaft 40. 2. The balancer shaft 40 is formed in a hollow shaft shape, one end of the hollow portion 40d communicates with the discharge side passage 58c of the oil pump 58, and the other end of the hollow portion 40d is connected to a lubricating portion of the engine 3 (for example, The engine 3 of the outboard motor according to claim 1, which is in communication with the outboard motor (36, 44, 45). 3. An oil pump 58 is provided at the bottom of the engine case 23, and the suction side passage 58b and the discharge side passage 58c of the oil pump 58 are separated from the bottom (55) of the engine case 23 and fixed thereto. The oil gallery block 56 is provided with a bearing 42 for supporting the lower end of the balancer shaft 40, and the bearing 42 and the discharge side passage 58c are communicated with each other. Outboard engine 3 as described. 4. The outboard motor engine 3 according to claim 1, wherein an oil pressure regulator 79 for monitoring the oil pressure in the oil passage 68 is mounted upward with respect to the oil passage 68.