JP3713251B2 - Crankshaft end seal structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a seal structure for a crankshaft end of an internal combustion engine, particularly a diesel engine.
[0002]
[Prior art]
In general, the rear end of the crankshaft of a small diesel engine protrudes from the frame without the coupling coupling flange, and an oil drain cover with an oil seal is inserted from the rear end of the crankshaft. By fixing to the end face of the frame, the lubricating oil leaking to the outside from the crank chamber in the frame through the crankshaft is sealed with an oil seal.
[0003]
[Problems to be solved by the invention]
However, in medium and large diesel engines, there is a large-diameter flange for connecting the flywheel at the rear end of the crankshaft, so a small-diameter oil seal cannot be inserted from the end of the shaft. There is a problem that the lubricating oil cannot be prevented from leaking unless the other sealing means is used. In addition, the oil seal is relatively simple and inexpensive. However, the oil seal contacts the outer periphery of the rotating crankshaft and seals the lubricating oil. In particular, medium-sized and large-sized diesel engines with a large output have a problem that the service life is shortened.
[0004]
Therefore, an object of the present invention is to devise a structure that seals the crankshaft end having the flange portion in a non-contact manner, thereby preventing leakage of lubricating oil to the outside for a long time even in a high-power diesel engine or the like. Another object of the present invention is to provide a crankshaft end seal structure that can be prevented over a wide range.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an outer periphery of an end portion of a crankshaft that protrudes from a frame having at least a large diameter portion and a medium diameter portion that are successively connected in the axial direction through a first radial step portion. In the seal structure of the crankshaft end that covers and seals with an oil drain cover attached to the end surface of the frame, and has a hole that fits with a gap in the outer periphery of the large diameter portion, and is a partition attached to the frame An oil drain flange provided on the oil drain cover and having a radially opposed surface facing the plate and the radial step with a gap in the axial direction, and the crank shaft end side of the oil drain flange An annular chamber formed between the inner periphery and the outer periphery of the medium-diameter portion, and provided in the oil drain cover in the radial direction, with one end opening at the lower portion of the annular chamber and the other end having a diameter from the opening. Communicating oil that opens into the frame at the outside in the direction and forms a U-shaped tube Characterized by comprising and.
[0006]
In the seal structure of the crankshaft end of claim 1, the lubricating oil in the frame tends to leak along the surface of the rotating crankshaft in the axial direction. Lubricating oil to be leaked is attached to the frame, blocked by a partition plate that fits with a gap around the outer periphery of the large diameter part of the crankshaft, and part of it is blown outward in the radial direction by centrifugal force Then, the remaining lubricating oil that has been returned into the frame and passed through the partition plate is directed to the first radial stepped portion that continues to the middle diameter portion on the shaft end side. The first radial step is stepped radially inward as opposed to the centrifugal force acting on the lubricating oil by the rotating crankshaft, and the oil cut provided on the oil cut cover attached to the frame end surface. The radially opposing surfaces of the flanges face each other with a gap in the axial direction. Therefore, most of the lubricating oil is blown radially outward by centrifugal force and returns to the inside of the frame, and only a part of the lubricating oil passes through the radial step, and the outer circumference of the medium diameter portion and the inner circumference of the oil drain flange Enter the annular chamber formed between the two.
The mist-like minute amount of lubricating oil that has entered the annular chamber gradually becomes a liquid and accumulates in the lower part of the annular chamber, and fills the communicating oil path that forms a U-shaped tube with one end opened in the lower part. Here, since the other end of the communication oil path is opened in the frame at the outer side in the radial direction from the one end, the lubricating oil filling the communication oil path is returned from the other end into the frame, and the annular chamber However, the pressure is maintained at a pressure equal to the substantially atmospheric pressure lower than that in the frame by the difference in the oil column of the communication oil passage as the U-shaped pipe. Therefore, the increase / decrease in the pressure difference between the inside and outside of the frame due to fluctuations in the operating conditions of the internal combustion engine and atmospheric pressure can be automatically adjusted by the increase / decrease in the oil column difference of the lubricating oil that fills the communication oil passage, and the lubricating oil leaking out of the frame The amount of can be greatly reduced.
[0007]
In the seal structure of the crankshaft end according to claim 2, a small diameter portion is provided on the crankshaft end side of the medium diameter portion via a second radial step portion, while an axial direction is provided on the second radial step portion. The oil drain cover is provided with a second radially opposing surface that faces the gap.
[0008]
In the crankshaft end seal structure according to claim 2, a second radial step is provided between the medium diameter portion and the small diameter portion on the shaft end side, and the second radial step is a rotating crank. Contrary to the centrifugal force acting on the lubricating oil by the shaft, a step is formed inward in the radial direction, and the second radial facing surface provided on the oil drain cover is opposed with a gap in the axial direction. . Therefore, the mist-like minute amount of lubricating oil that has entered the annular chamber is blown outward in the radial direction by centrifugal force, and is prevented from leaking to the outside by the gap, and most of it becomes liquid and becomes a liquid in the annular chamber. The oil is collected by entering a communication oil passage that forms a U-shaped tube from the lower opening, and returned to the frame from the opening at the other end. Therefore, the amount of lubricating oil leaking out of the frame can be further greatly reduced.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to illustrated embodiments.
FIG. 1 is a side view of an essential part of a diesel engine employing a crankshaft end seal structure according to the present invention. From the rear end surface 1a of the frame 1 of the diesel engine, an end portion of a crankshaft 2 having a connecting flange 3 protrudes from the front end. The outer periphery of the end portion of the crankshaft 2 is connected to the rear end surface 1a of the frame and the oil. The pan 4 is covered and sealed with an oil drain cover 5 fixed to the upper surface of the pan 4.
[0010]
The end portion of the crankshaft 2 includes a radial metal bearing 6 that receives a radial load and a bearing portion 8 that is supported by the frame 1 via thrust metal bearings 7 and 7 on both sides that receive the axial load. A large-diameter portion 9 connected to the rear of the portion 8 and located in the vicinity of the rear end surface 1a of the frame 1, a medium-diameter portion 11 connected to the rear of the large-diameter portion 9 via a first radial step portion 10, The small diameter portion 13 is connected to the rear of the diameter portion 11 via the second radial step portion 12, and the tip of the small diameter portion 13 is the flange 3.
The large-diameter portion 9 includes a parallel portion 9a substantially parallel to the axis of the crankshaft 2 and an enlarged-diameter portion 9b connected to form a conical surface spreading toward the rear, and the intermediate-diameter portion 11 is formed in a round shape. The diameter-reducing portion 11a to be inserted and the diameter-enlarging portion 11b connected to form a conical surface spreading toward the rear are formed. The small-diameter portion 13 includes a central parallel portion 13b, small round portions 13a on both sides, and large round portions 13c. On the other hand, the first and second radial stepped portions 10 and 12 are formed of annular surfaces orthogonal to the axis of the crankshaft 2.
[0011]
In the parallel portion 9a of the large-diameter portion 9, a central hole 14a of a partition plate 14 whose upper portion is fixed to the rear end surface 1a of the frame 1 with a bolt 15 is inserted with a slight gap therebetween, and the large diameter of the crankshaft 2 is inserted. Lubricating oil flowing rearward through the portion 9 is blocked, and the upper space of the frame 1 and the oil drain cover 5 is separated into a front chamber 16 and a rear chamber 17. A lower portion in the frame 1 is a crank chamber 18 that is not separated by the partition plate 14.
[0012]
On the other hand, the oil drain cover 5 can be divided into two sides (in a direction perpendicular to the paper surface) by the paper surface of FIG. 1, and is fitted on the crankshaft 2 so as to cover substantially the center of the medium diameter portion 11 and the small diameter portion 13. The oil drain cover 5 is provided with an oil drain flange 19 having a first radial facing surface 19a facing the first radial step portion 10 of the crankshaft 2 with a slight gap in the axial direction. An annular chamber 20 is formed on the rear outer periphery of the ring 19 so as to guide the lubricating oil downward. The annular groove 20 extends from the rear inner periphery of the oil drain flange 19 and the outer periphery of the medium diameter portion 11 of the crankshaft 2 to form a conical surface that spreads toward the end. 21 are provided.
Further, behind the annular chamber 21 of the oil drain cover 5, a second radial facing surface 22 that faces the second radial step portion 12 of the crankshaft 2 with a slight gap in the axial direction, and a small diameter portion 13. Three annular labyrinth grooves 23 are provided on the inner peripheral surface surrounding the small round portion 13a and the parallel portion 13b to prevent the lubricating oil from leaking out of the frame 1.
[0013]
Further, one end 24a is opened inside the oil drain cover 5 at the lowermost part of the annular chamber 21, and the other end 24b is opened to the crank chamber 18 in the frame 1 on the radially outer side from the one end 24a. A communication oil passage 24 is provided.
[0014]
The crankshaft end seal structure in the diesel engine operates as follows. When the diesel engine is operated, a part of the lubricating oil supplied from the oil pan 4 to the piston and the crank pin through the oil supply system is transmitted to the surface of the rotating crankshaft 2 in the axial direction, and from the crank chamber 18. Trying to leak out of frame 1. The lubricating oil that is about to leak is attached to the rear end surface 1a of the frame and is blocked by a partition plate 14 that fits with a small gap around the outer periphery of the parallel portion 9a of the large-diameter portion 9, and is caused by centrifugal force. A part of the lubricant is blown away radially outward and returns to the front chamber 16 and the crank chamber 18, and only the lubricating oil that has passed through the partition plate 14 moves from the enlarged diameter portion 9 b to the first radial step portion 10.
[0015]
Since the rotating diameter-expanded portion 9b forms a conical surface that widens at the end, the lubricating oil is further accelerated radially outward as it moves backward due to centrifugal force, and the first radial step 10 is opposite to the centrifugal force. A step is formed inwardly in the radial direction, and a radial facing surface 19a of the oil drain flange 19 provided in the oil drain cover 5 is opposed to the first radial step portion 10 with a slight gap in the axial direction. Therefore, most of them are blown off by the centrifugal force so as to return to the crank chamber 18 through the rear chamber 17 or through the annular groove 20 of the oil draining flange 19, and only a part passes through the gap. It enters an annular chamber 21 formed between the outer periphery of the diameter portion 11 and the inner periphery of the oil drain flange 19.
[0016]
The rear end of the annular chamber 21 is formed by the second radial step surface 12 and the second radial facing surface 22 facing the second radial step portion 12 in addition to the conical surface in which the enlarged diameter portion 11b of the middle diameter portion 11 widens toward the end. Since the same slight annular gap and the three labyrinth grooves 23 formed between the small-diameter portion 13 and the oil drain cover 5 behind the same, a small amount of lubricating oil entering the annular chamber 21 is The air is blown outward in the radial direction by the centrifugal force, and the leakage to the outside of the frame 1 is almost prevented by the slight gap, and gradually becomes liquid to form a U-shaped tube from the lowermost opening 24a of the annular chamber 21. It enters the oil passage 24 and is collected and accumulated, and returned to the crank chamber 18 from the opening 24b at the other end. Here, since the other end 24 a of the communication oil passage 24 is open to the crank chamber 18 below the one end 24 a in the vertical direction, the internal pressure of the annular chamber 21 is different from the internal pressure of the crank chamber 18. The pressure is kept lower than ΔH and higher than the atmospheric pressure by a predetermined pressure due to the sealing action of the labyrinth groove 23. If the pressure difference between the inside and outside of the frame increases due to fluctuations in the operating conditions of the diesel engine and atmospheric pressure, more lubricating oil accumulates and ΔH increases, and if the pressure difference decreases, the lubricating oil enters the crank chamber 18 accordingly. It is returned and ΔH decreases. Thus, the amount of lubricating oil that leaks out of the frame 1 is greatly reduced.
[0017]
As described above, since the large-diameter flange 3 is provided at the projecting end of the crankshaft, even in an internal combustion engine where it is difficult to use an oil seal, the above-described non-contact type crankshaft end seal structure ensures the leakage of lubricating oil. Of course, there is no problem of wear as in the case of an oil seal, so that the useful life of the seal structure is naturally extended.
In the above embodiment, since the latter half of the large-diameter portion 9 is the enlarged-diameter portion 19a that forms a conical surface that widens toward the end, the lubricating oil is scattered more vigorously outward in the radial direction to the first radial step portion 11. Therefore, the leakage of the lubricating oil to the outside of the frame 1 can be further suppressed. Further, since the same second radial step 12 is provided behind the first radial step 11 and the labyrinth groove 23 is provided around the small diameter portion 13, the internal pressure of the annular chamber 21 is sealed to the labyrinth groove 23. The predetermined pressure due to the action can be maintained at a pressure higher than the atmospheric pressure, and the leakage of the lubricating oil to the outside of the frame 1 can be further suppressed.
Needless to say, the present invention is not limited to the diesel engine of the embodiment, but can be applied to seals of crankshaft ends of various internal combustion engines.
[0018]
【The invention's effect】
As is apparent from the above description, claim 1 of the present invention is a crank that has at least a large-diameter portion and a medium-diameter portion that are successively connected in the axial direction through the first radial step portion and protrudes from the frame. In the seal structure of the crankshaft end that covers and seals the outer periphery of the end portion of the shaft with an oil drain cover attached to the end surface of the frame, the partition plate having a hole that fits with a gap in the outer periphery of the large diameter portion An oil drain flange having a radially opposing surface that is attached to the frame and faces the radial step portion with a gap in the axial direction is provided on the oil drain cover, while the inner periphery of the oil drain flange on the crankshaft end side and the above An annular chamber is formed between the outer periphery of the medium diameter portion, one end opens in the lower portion of the annular chamber, and the other end opens in the frame on the radially outer side from the opening to form a U-shaped pipe. Route the road in the oil drain cover in the radial direction Therefore, the lubricating oil that tries to leak through the surface of the crankshaft in the axial direction is blocked by the partition plate and only partially passes through the hole, followed by the radial step and this. Since the passage between the opposing oil drain flanges in the radial direction is blocked, leakage of lubricating oil to the outside can be effectively prevented for a long time with a non-contact sealing structure. A small part of the lubricating oil that has entered the annular chamber after passing through the gap is also accumulated in the communication oil passage that forms a U-shaped pipe, and the annular chamber is maintained at a lower pressure than the inside of the frame by the oil column difference. While the pressure fluctuation is automatically adjusted, it is returned to the frame from the other end of the communication oil passage.
[0019]
In the crankshaft end seal structure according to the second aspect of the present invention, a small-diameter portion is provided on the crankshaft end side of the medium-diameter portion via a second radial step portion, while a shaft is provided on the second radial step portion. Since the above-mentioned oil drain cover is provided with the second radially opposing surfaces that face each other with a gap in the direction, the lubricating oil leaking out of the frame can be further reduced.
[Brief description of the drawings]
FIG. 1 is a side view of an essential part of a diesel engine employing a crankshaft end seal structure of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Frame 2 Crankshaft 3 Flange 4 Oil pan 5 Oil drain cover 6 Radial metal bearing 7 Thrust metal bearing 8 Bearing part 9 Large diameter part 10 1st radial direction step part 11 Medium diameter part 12 2nd radial direction step part 13 Small diameter part 14 Partition plate 14a Center hole 16 Front chamber 17 Rear chamber 18 Crank chamber 19 Oil drain flange 20 Annular groove 21 Annular chamber 22 Second radial facing surface 23 Labyrinth groove 24 Oil passage 24a Opening at one end 24b Opening at the other end

Claims (2)

An oil drain cover that attaches the outer periphery of the end of the crankshaft that protrudes from the frame and has at least a large diameter portion and a medium diameter portion that are successively connected in the axial direction through the first radial step portion to the frame end surface. In the seal structure of the crankshaft end that covers and seals,
A partition plate attached to the frame, having a hole that fits with a gap on the outer periphery of the large-diameter portion;
An oil drain flange provided on the oil drain cover, having a radial facing surface facing the radial step portion with an axial gap therebetween;
An annular chamber formed between the inner circumference of the crankshaft end side of the oil drain flange and the outer circumference of the medium diameter portion;
A communicating oil passage provided in the oil drain cover in a radial direction, having one end opened at a lower portion of the annular chamber and the other end radially opened from the opening in the frame to form a U-shaped tube; A crankshaft end seal structure characterized by comprising: 2. The crankshaft end seal structure according to claim 1, wherein a small-diameter portion is provided on the crankshaft end side of the medium-diameter portion via a second radial step portion, while a shaft is provided on the second radial step portion. A crankshaft end seal structure, wherein the oil drain cover is provided with a second radial facing surface facing each other with a gap in the direction.

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