JPH04292514A - Oil returning structure for engine - Google Patents

Abstract

PURPOSE:To provide the oil returning structure of an engine which is simple in structure and can prevent air from getting mixed in oil sucked from an oil pump inlet port. CONSTITUTION:In an engine 1 in which a return oil from a cylinder head 3 is returned to a crank case chamber 111 on one side, and an oil pump 20 is provided on the other side in a crank section 14, an oil reservoir 47 below a cranck case 5 is partitioned from a crank chamber 10 with a partition 49, which is provided with a hole 50d to make at least the crank case chamber 111 communicate with the oil reservior 47.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of an oil return section provided at the bottom of a crankcase of an engine, to which oil that has lubricated various parts of the engine returns.

0002

[Prior Art] Normally, in a four-stroke engine, the oil that lubricates various parts of the engine is returned to the crankcase, and is stored in an oil reservoir at the bottom of the crankcase, forming an oil surface, and this stored oil is pumped into the oil pump. The oil is recirculated to various parts or returned to the oil tank.

By the way, the liquid level of the above-mentioned stored oil fluctuates under the influence of the piston that reciprocates above it, the crank that rotates, etc., so that the liquid level in the stored oil is sucked into the oil pump from the oil pump suction port. Air tends to get trapped in the oil. For this reason, some oil pumps have an arc-shaped rib between the crank and the oil pump suction port so as to cover the lower part of the crank.

[0004] Furthermore, Japanese Patent Application Laid-open No. 1-273815 discloses a system that occupies a predetermined volume in the space between the crankshaft and the oil level of the stored oil, and that moves up and down on the oil level according to changes in the oil level. A movably disposed volume body and a means for restricting the upward movement of the volume body are provided, and when the oil in the oil reservoir moves to one side when the vehicle turns or accelerates or decelerates, the volume body A part of the oil sinks below the oil level and raises the oil level,
This shows an oil reservoir structure for a vehicle engine that allows sufficient oil to be sucked from the oil pump suction port.

[0005]

[Problem to be Solved] However, even if an arcuate rib is provided between the crank and the oil pump suction port as described above, the pumping action of the piston is applied to the oil surface of the stored oil, and both sides of the rib, i.e. The oil level on the crankcase cover side on both sides of the crankcase rises, and the liquid level in the central crankcase decreases accordingly, which tends to cause air to become trapped in the oil pump suction port provided in this area. . Furthermore, as the oil level on the crankcase cover side rises, the breathing performance of the crankcase decreases.

[0006] In the oil described in the above-mentioned Japanese Patent Application Laid-Open No. 1-273815, since the oil surface is almost entirely covered by the volume body, such a problem is unlikely to occur.
On the other hand, the structure becomes complicated.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an oil return structure for an engine which has a very simple structure and can effectively prevent air from being mixed into the oil sucked from the oil pump suction port.

[0008]

[Means and effects for solving the problem] Therefore, in the present invention, the return oil of the cylinder head is returned to one side in the crankshaft direction with respect to the crank in the crankcase, and an oil pump is provided on the other side with respect to the crank. In the engine, an oil reservoir in a lower part of the crankcase is partitioned from the crank chamber by a partition, and the partition is provided with an oil passage communicating at least the inner portion of the crankcase on one side with the oil reservoir.

According to the present invention, since the oil reservoir is separated from the crank chamber by the partition wall, the oil level of the oil stored in the oil reservoir decreases due to the pumping action of the piston and the stirring action caused by the rotation of the crank. Therefore, oil that does not trap air is stably sucked into the oil pump from the oil pump suction port provided in the oil reservoir. In addition, the oil level on the crankcase cover side does not particularly rise, improving crankcase breathing performance and reducing oil agitation, which lowers the maximum oil temperature, leading to improved engine performance and reliability. . Furthermore, in an engine in which the return oil from the cylinder head is returned to one side in the crankshaft direction with respect to the crank in the crankcase, and an oil pump is provided on the other side with respect to the crank, the inner part of the crankcase on the one side is A large amount of oil around the cam is returned, and this large amount of oil must pass under the crank and be sucked into the oil pump on the opposite side.At this time, it is agitated by the crank and tends to trap air, but this is not the case. According to the invention, the oil returned to the inner part of the crankcase passes through the oil passage provided in the partition wall, enters the oil reservoir section partitioned from the crank chamber, passes through the oil reservoir section, and is drained by the rotation of the crank. The oil is sucked into the oil pump on the opposite side without being disturbed, so no air is trapped.

The oil return structure of the present invention can be constructed extremely simply by integrally forming the partition wall with the crankcase.

[0011]

[Embodiment] Fig. 1 is a longitudinal sectional side view of an engine 1 according to an embodiment of the present invention, and Fig. 2 is a sectional view taken substantially along line II-II in Fig. 1, in which 2 is a cylinder head cover, 3 is a cylinder head, 4 is a cylinder block, and 5 is a crankcase.

The crankcase 5 is composed of left and right case bodies 7l and 7r that abut against each other at the mating surface 6, and left and right case covers 8l and 8r that cover the sides of these bodies, respectively. The interior of the crankcase 5 is divided into a central crank chamber 10 and left and right crankcase chambers 11l, 11r by case side walls 9l, 9r integrally formed with the case bodies 7l, 7r, respectively. A crank unit 14 consisting of a disc-shaped crank arm 12 and a crank pin 13 is housed in the crank chamber 10, and a crank shaft is rotatably supported on case side walls 9l and 9r via main bearings 15. 16 protrudes into the crankcase chambers 11l and 11r on both sides. crankshaft 16
A generator 17 is attached to the end that protrudes into the crankcase chamber 11l, and a drive gear 19 that transmits rotation to the gear transmission mechanism 18 is attached to the end that protrudes into the crankcase chamber 11r.
is installed. An end of the crankshaft 16 in the crankcase chamber 11r is connected to a rotor shaft 21 of an oil pump 20 provided in the case cover 8r, and the oil pump 20 is driven by the crankshaft 16.

A large end of a connecting rod 22 is pivotally connected to the crank pin 13 via a bearing 23, and a small end of the connecting rod 22 is pivotally connected to a piston pin 24 and is connected to a piston 25 via the pin 24. connected.

The cylinder head 3 is provided with an intake passage 26 and an exhaust passage 27, as well as an intake valve 28 and an exhaust valve 29 for opening and closing these passages. Also cylinder head 3
The cam chamber 30 is formed by the upper part and the cylinder head cover 2.
is formed, and a cam shaft 31 is horizontally installed in the cam chamber 30 so as to be freely rotatable. Then, as the camshaft 31 rotates, the intake valve 28 and the exhaust valve 29 are operated via the cam 32 and the rocker arm 33, and the intake passage 26 and the exhaust passage 27 are opened and closed with respect to the combustion chamber 34 as appropriate. The camshaft 31 is driven by the crankshaft 16. For this reason, a driving sprocket 35 is provided on the portion of the crankshaft 16 that protrudes into the crankcase chamber 11l, and a driven sprocket 36 is provided on the camshaft 31 at a position corresponding to the driving sprocket 35. Sprocket 35, 3
A cam chain 37 is wound between the 6 parts. The cam chain 37 is disposed in a cam chain chamber 38 formed by vertically passing through the cylinder head 3 and cylinder block 4 from the cam chamber 30 to the crankcase chamber 11l.

Oil discharged from the oil pump 20 driven by the crankshaft 16 first enters a filter chamber 39 and is filtered. The filter chamber 39 is also covered by the case cover 8r.
is integrally formed. A part of the oil that has left the filter chamber 39 is transferred from the oil passage 40 to the rotor shaft 21 of the oil pump 20.
The oil passes through the inside and enters the oil passage 41 bored in the crankshaft 16, and then passes through the inside of the crank pin 13 and reaches the crank pin bearing 23 to lubricate the bearing, and then is splashed into the cylinder hole 42 and the piston 25 and the wall surfaces of the cylinder hole 42 and fall into the crankcase 5. The remainder of the oil that has left the filter chamber 39 passes through an oil passage 43 (not shown) bored in the case body 7r and the cylinder block 4, and then passes through an oil passage (not shown) bored in the center of the camshaft 31 in the axial direction. The oil is fed to the oil supply passage 44 under pressure. Then, the oil is ejected from the oil supply port 45 to the surroundings to lubricate the necessary parts of the valve mechanism within the cam chamber 30. After lubrication, this oil falls from the cam chamber 30 through the cam chain chamber 38 into the crankcase chamber 11l, but the amount thereof is quite large. The oil discharged from the oil pump 20 is also supplied to each shaft of the gear transmission mechanism 18 and a water pump drive shaft 62 which also serves as a balancer shaft, which will be described later.

Bottom wall 46l of left and right case bodies 7l and 7r
, 46r to protrude downward from the oil reservoir portion 4.
7l and 47r are provided, and these left and right oil reservoir portions abut against each other at the mating surface 6 to form an oil reservoir 47. Openings 48 are provided in the bottom walls 46l and 46r at the portions that define the crank chamber 10, but the oil reservoir 4
7 does not communicate directly with the crank chamber 10 through these openings 48, but there is a partition wall 4 above the openings 48.
9, and the oil reservoir 47 is separated from the crank chamber 10 by this partition wall 49. The partition wall 49 is a rib portion 4 that protrudes from the left and right case side walls 9l and 9r and surrounds the lower part of the crank arm 12 in an arc shape.
9a, and one end edge in the circumferential direction of the rib portion 49a is connected to the bottom wall 46.
partition wall portion 49b connected to l, 46r, and rib portion 49
A partition wall portion 49c that connects the other edge of a to the bottom walls 46l and 46r, and an end wall portion 49d that closes the left and right opening portions.
, 49e, and the left and right end wall portions 49d, 49e are formed by case side walls 9l, 9r, respectively. The inside of the partition wall 49, that is, the oil reservoir 47, is connected to the left crankcase chamber 11l through a hole 50d provided in the left end wall portion 49d, and into the right crankcase chamber 11l through a hole 50e provided in the right end wall portion 49e. 11r and further communicates with the crank chamber 10 through holes 50b and 50c provided in partition wall portions 49b and 49c, respectively.

The oil reservoir 47 is divided into three upper and lower compartments by horizontal partition plates 51, 51, and adjacent compartments are communicated with each other through communication holes 52 provided in the partition plates 51, 51, respectively. Further, the oil reservoir 47 is provided with an oil suction passage 53 that extends vertically along one side wall thereof, and communicates with the lowermost compartment through an oil suction port 54 provided at the lower end of the oil suction passage 53. There is. The upper part of the oil suction passage 53 communicates with the suction port of the oil pump 20 via a suction oil passage 55 provided in the case body 7r and a suction oil passage 56 provided in the case cover 8r.

After the oil around the crank pin 13 or the camshaft 31 has been lubricated as described above, the oil that has returned to the bottom of the crank case 5 is drained through the holes 50 provided in the partition wall 49 and the bottom wall of the case body. The oil enters the oil reservoir 47 through the opening 48, where it forms an oil surface and is stored there. And the oil suction port 54 from the bottom compartment
The oil is sucked into the oil suction passage 53 through the suction oil passages 55 and 56, and then sucked into the oil pump 20 through the suction oil passages 55 and 56, where it is recirculated to each lubricating section.

In the oil return structure of this embodiment configured as described above, the oil reservoir 47 is separated from the crank chamber 10 by the partition wall 49, so that the oil reservoir 47 is separated from the crank chamber 10 by the partition wall 49.
The oil level of the oil stored in 7 does not drop or fluctuate due to the pumping action of the piston or the stirring action due to crank rotation, and is always stable. Therefore, air is not mixed into the oil sucked from the oil suction port 54. Furthermore, since the oil level in the crankcase chambers 11l and 11r does not rise, the breathing performance of the crankcase does not deteriorate, and since there is little oil stirring, the maximum oil temperature can be maintained low. In particular, from the cylinder head section to the crankcase chamber 11l on the opposite side of the oil pump 20 with respect to the crank section 14, the cam chain chamber 3
A large amount of oil returns through the partition wall 4 through the hole 50d from the crankcase chamber 11l.
Oil reservoir 47 separated from the crank chamber 10 by 9
The oil is sucked into the oil pump 20 on the opposite side through the oil reservoir 47, and the oil does not directly pass through the crank chamber 10 and be agitated by the rotation of the crank part 14, which has a large air entrapment prevention effect. is obtained.

FIGS. 3 and 4 show another embodiment of the invention. In addition, in these drawings, the same reference numerals are given to the same parts as in the above embodiment, and detailed explanations are omitted. In this embodiment, the box-shaped oil reservoir 47 protruding from the lower surfaces of the bottom walls 46l, 46r of the left and right case bodies 7l, 7r as in the previous embodiments is not provided. The oil reservoir 67 in this embodiment is formed in the lower part of the crank chamber 10 along the inner wall surfaces of the bottom walls 46l, 46r, extending between the left and right crankcase chambers 11l, 11r.
It is separated from the crank chamber 10 by a partition wall 49 similar to the previous embodiment. The oil in the oil reservoir 67 is supplied to the oil suction port 54, the oil suction passage 53, and
The oil is sucked into the oil pump through the suction oil passage 55 and the suction oil passage 56, but is returned to the separately provided oil tank by the oil pump 20-1, and from the oil tank to the engine side by the oil pump 20-2. Return, filter 39
Each part of the engine is supplied with oil.

FIG. 5 is a partially cutaway side view of the engine of this embodiment as seen from the case cover 8l side, FIG. 6 is a sectional view taken along line VI-VI in FIG. 5, and FIG. 7 is a side view of the crankcase. FIG. 3 is a plan view showing a mating surface with a cylinder block. As can be seen from these drawings, this engine is provided with a water pump 57 on the side opposite to the oil pumps 20-1 and 20-2, that is, on the side of the case cover 8l. For this reason, a water pump support part 58 is integrally formed on the case cover 8l, a water pump 57 is supported in this part, and the outside is covered with a water pump cover 59. The water pump cover 59 has a suction passage 60 leading to the pump chamber of the water pump 57, which suction passage 60 is connected to a radiator. The water pump 57 has bearings 61 mounted on the case side walls 9l and 9r.
It is driven by a water pump drive shaft 62 which is rotatably supported via a water pump drive shaft 62 and extends parallel to the crankshaft 16 and also serves as a balancer shaft. The water pump drive shaft 62 includes a gear 63 that meshes with the drive gear 19 and is driven by the crankshaft 16. The cooling water discharged from the water pump 57 passes through the water passage 64a formed by the water pump support part 58 and the water pump cover 59, and then passes through the water passage 64a formed in the case body 7l.
b, and further enters a water passage 64c formed in the case body 7r via a water passage 64b. Water passages 64b, 64
c are openings 68 on the end faces of the case bodies 7l and 7r, respectively.
b, 68c are open. and these openings 6
8b and 68c are the water passages 6 on the cylinder block side, respectively.
It communicates with 9b and 69c. Cooling water is provided through water passage 69b,
The water is led from 69c to the water jacket 65 on the outer periphery of the cylinder hole 42, cools the cylinder portion, and then flows back to the radiator via the cooling water outlet 66 on the exhaust passage 27 side.

[0022]

According to the present invention, since the oil reservoir is separated from the crank chamber by the partition wall, the oil level of the oil stored in the oil reservoir is increased by the pumping action of the piston and the stirring action caused by the rotation of the crank. Oil that does not drop or fluctuate and therefore does not entrap air is stably sucked into the oil pump from the oil pump suction port provided in the oil reservoir. Furthermore, the breathing performance of the crankcase is improved and the maximum oil temperature is lowered.

In particular, a large amount of oil returned from the cylinder head to the crankcase on the opposite side of the oil pump is
The oil is drawn into the oil pump on the opposite side through an oil reservoir partitioned off from the crank chamber without being disturbed by crank rotation, effectively preventing air from getting trapped in the oil pump. The structure of the oil reservoir is therefore extremely simple.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of an engine according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken approximately along line II-II in FIG. 1;

FIG. 3 is a longitudinal sectional side view similar to FIG. 1 showing another embodiment of the present invention.

FIG. 4 is a sectional view taken substantially along the line IV-IV in FIG. 3;

FIG. 5 is a partially cutaway side view of the engine.

6 is a cross-sectional view taken along line VI-VI in FIG. 5. FIG.

FIG. 7 is a plan view showing a mating surface of the crankcase and the cylinder block.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...Engine, 2...Cylinder head cover, 3...Cylinder head, 4...Cylinder block, 5...Crank case, 6...Mating surface, 7...Case body, 8...Case cover, 9
...Case side wall, 10...Crank chamber, 11...Crank case chamber 11, 12...Crank arm, 13...Crank pin, 14...Crank section, 15...Main bearing, 16...Crankshaft, 17...Generator, 18...Gear shifting Mechanism, 19... Drive gear, 20... Oil pump, 21... Rotor shaft, 22... Connecting rod, 23... Bearing, 24... Pin, 25... Piston, 26... Intake passage, 27... Exhaust passage, 28... Intake valve, 29 ...Exhaust valve, 30...Cam chamber, 31...Camshaft, 32...Cam, 33...Rocker arm, 34...Combustion chamber, 35...Drive sprocket,
36... Driven sprocket, 37... Cam chain, 38
...Cam chain chamber, 39...Filter chamber, 40, 41...Oil passage, 42...Cylinder hole, 43...Oil passage, 44...Oil supply passage, 45...Oil supply port, 46...Bottom wall, 47...Oil reservoir, 48 ... opening, 49 ... partition, 50 ... hole, 51 ... partition, 52 ... communication hole, 53 ... oil suction passage, 54 ... oil suction port, 55, 56 ... suction oil passage, 57 ... water pump, 58
...Water pump support part, 59...Water pump cover, 60...Suction passage, 61...Bearing, 62...Water pump drive shaft, 63...Gear, 64...Water passage, 65...Water jacket, 66...Cooling water outlet, 67... Oil reservoir, 68...opening, 69...water passage.

Claims (1)

[Claims] Claim 1: In an engine in which return oil from a cylinder head is returned to one side in the crankshaft direction with respect to the crank in the crankcase, and an oil pump is provided on the other side with respect to the crank, an oil reservoir in the lower part of the crankcase is used. An oil return structure for an engine, characterized in that the oil return structure for an engine is partitioned from a crank chamber by a partition wall, and the partition wall is provided with an oil passage that communicates at least the inner portion of the crankcase on one side with the oil reservoir.