JPH0552442U - Crankshaft end seal structure for diesel engine - Google Patents

Abstract

(57) [Abstract] [Purpose] The non-contact sealing structure effectively prevents the lubricating oil transmitted through the crankshaft from leaking to the outside for a long time. [Structure] Large-diameter portion 6 protruding from the end surface 1a of the frame 1,
On the outer circumference of the small diameter portion 8 at the end of the crankshaft 2 consisting of the radial step portion 7 and the small diameter portion 8, two adjacent annular grooves 9 (9 ') sandwiching an adjacent portion 9a having the same diameter as this are formed. One pair is provided at a predetermined distance in the axial direction. On the inner circumference of the oil drain cover 5 that covers the outer circumference of the crankshaft end, a radial step portion 10 facing the radial step portion 7 with a slight gap, and a pair of two annular grooves 9, 9 are provided. '
There are provided inner and outer annular grooves 11 and 11 ′ facing each other, and a labyrinth groove 12 facing the outer circumference of the small diameter portion 8 between them. The inner annular groove 11 communicates with the crank chamber 13 through the oil drain hole 14 in the oil drain cover 5, and the outer annular groove 1
1'communicates with the crank chamber 13 through a U-shaped communication oil passage 15.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a crankshaft end seal structure for a diesel engine.

[0002]

[Prior Art]

 Generally, the rear end of the crankshaft of a small diesel engine protrudes from the frame without the flange of the coupling for coupling, and the oil drain cover equipped with an oil seal is inserted from the rear end of the crankshaft. By fixing it to the end surface of the frame, lubricating oil that leaks from the crank chamber in the frame to the outside through the crankshaft is sealed with an oil seal.

[0003]

[Problems to be solved by the device]

 However, in medium- and large-sized diesel engines, a large-diameter flywheel connecting flange for connection is located at the rear end of the crankshaft, so a small-diameter oil seal cannot be inserted from the shaft end. However, there is a problem that the leakage of lubricating oil cannot be prevented unless a sealing means other than an oil seal is used. The oil seal has a relatively simple structure and is inexpensive, but since it contacts the outer circumference of the rotating crank shaft and seals the lubricating oil, the lip, which is the contact part, is subject to severe wear. However, there is a problem that the service life is shortened for medium and large diesel engines, especially with high output.

Therefore, an object of the present invention is to improve the leakage of lubricating oil to the outside even in a high-power diesel engine by devising a structure in which the crankshaft end having the above-mentioned flange portion is sealed in a non-contact manner. (EN) It is intended to provide a crankshaft end seal structure for a diesel engine that can be prevented over a period of time.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the crankshaft end seal structure of the diesel engine of the present invention comprises a large diameter portion and a small diameter portion that is continuous in the axial end direction of the large diameter portion through a radial step, and protrudes from the frame. In a structure in which the outer circumference of the end of the crankshaft is covered with an oil drain cover attached to the end surface of the frame for sealing, the outer circumference of the small diameter portion of the crankshaft is adjacent to the outer circumference of the small diameter portion, and the adjoining portions are adjacent to each other. A pair of annular grooves are provided at a predetermined distance in the axial direction, and at the inner circumference of the oil drain cover, a radial step portion is provided to face the radial step portion of the crankshaft with an axial gap. And an inner and outer annular groove facing the pair of two annular grooves of the crankshaft, respectively, and an annular labyrinth facing the outer periphery of the small diameter portion of the crankshaft between the inner and outer annular grooves. Set up a groove and Inside the oil drain cover, a radial oil drain hole that communicates the inner annular groove with the space inside the frame, one end opens to the outer annular groove, and the other end is located radially outside of this opening. A U-shaped communication oil passage opening in the frame is provided.

[0006]

[Action]

 The lubricating oil in the frame tries to leak along the surface of the rotating crankshaft in the axial direction. The lubricating oil that is about to leak is first blocked by the inner end surface of the oil drain cover that fits on the large diameter portion of the crankshaft, and part of it is blown radially outward into the frame to reduce it. Leakage is further reduced by being blocked by the gap between the radial step of the crankshaft and the radial step of the oil drain cover that axially opposes the radial step. Lubricating oil that leaks from the above-mentioned gap reaches the two annular grooves inside the small diameter part of the rotating crankshaft, and is attracted to the adjacent parts of both grooves with the maximum diameter and the maximum peripheral speed, and then outward in the radial direction. After being collected in an annular groove inside the oil drain cover, it is returned to the inside of the frame through the oil drain hole in the radial direction. By the above sealing process, the lubricating oil that leaks out is considerably reduced to a low-concentration mist, but this mist is decompressed one after another by the action of the labyrinth groove of the oil drain cover that continues in the shaft end direction, and most of the mist does not pass through. It will be stopped. Furthermore, the small amount of mist that has passed through the labyrinth groove enters the two annular grooves on the outside of the small diameter portion of the crankshaft, and is collected as liquid in the annular groove on the outside of the oil drain cover as described above. The annular groove is filled with a U-shaped communication oil passage having one end open. Here, since the other end of the communication oil passage opens in the frame radially outside of the one end, the collected lubricating oil is returned to the frame and the inside of the annular groove is A pressure equal to the atmospheric pressure, which is lower than that in the frame, is maintained by the column difference, and the oil column prevents the jetting of the lubricating oil due to the reverse flow. Thus, the amount of lubricating oil that finally leaks out of the frame is greatly reduced.

[0007]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a side view of a diesel engine that employs the crankshaft end seal structure of the present invention. In this figure, the parts that are not directly related to the present invention are not shown in detail and only the outline is shown. This diesel engine is a medium- and large-sized row 6-cylinder engine, and is used mainly for driving a land-based generator. An end of a crankshaft 2 having a flywheel 3 at its tip projects from the rear end surface 1a of the frame 1 of the diesel engine. The outer periphery of the crankshaft 2 is the rear end surface 1a of the frame and the inside is an oil pan. It is covered and sealed with an oil drain cover 5 fixed to the upper surface of the base plate 4 which has become.

As shown in FIG. 2, the end portion of the crankshaft 2 has a large-diameter portion 6 located near the inner side of the rear end surface 1 a of the frame 1, and a radial step portion outside the large-diameter portion 6. 7 and a small diameter portion 8 connected to each other, and two annular grooves 9 having a semicircular cross section that are adjacent to each other through an adjacent portion 9a having the same diameter as the small diameter portion 8 are formed on the outer circumference of the small diameter portion 8 in the axial direction. One pair are provided at a predetermined distance. The flywheel 3 is fixed to the tip of the small diameter portion 8 with a bolt (not shown). On the other hand, the oil drain cover 5 is divided into two parts on both sides (in a direction perpendicular to the paper surface) of the paper surface of FIG. 2 and is divided into an end portion of the large diameter portion 6 of the crankshaft 2, a radial step portion 7 and a small diameter portion 8. Fit it so that it covers most of it. On the inner periphery of the oil drain cover 5, there are a radial step portion 10 facing the radial step portion 7 of the crankshaft with a slight gap in the axial direction, and the above two inner and outer portions of the crankshaft. Inner and outer annular grooves 11, 11 'respectively facing the annular grooves 9, 9', and four annular labyrinths facing the outer periphery of the small diameter portion 8 of the crankshaft between these annular grooves 11, 11 '. Grooves 12 and are provided respectively. Further, in the oil drain cover 5, a vertical oil drain hole 14 for communicating the bottom of the inner annular groove 11 with the crank chamber 13 in the frame 1 and one end 15a of the outer annular groove 11 'are formed. A U-shaped communication oil passage 15 is provided, which is open at the bottom and the other end 15b is open to the crank chamber 13 radially outside the one end 15a.

The U-shaped communication oil passage 15 is opened linearly from the surface of the oil drain cover 5 as shown in FIG. 2 due to drilling work, and the opening is closed by plugs 16 and 17. A flange portion 20 is formed on the end surface of the oil drain cover 5 that faces the crank chamber 13 so that the lubricating oil that has propagated on the surface of the large diameter portion 6 of the crankshaft 2 is dammed and scattered outward in the radial direction. On the other hand, an annular groove 21 for collecting lubricating oil is provided inside the end face, and the bottom of the annular groove 21 communicates with the crank chamber 13 through an oil drain hole 22.

The crankshaft end seal structure in the above diesel engine operates as follows. When the diesel engine is operated, a part of the lubricating oil supplied from the oil pan in the base plate 4 (see Fig. 1) to the piston and the crank pin through the oil supply system moves the surface of the rotating crank shaft 2 to the shaft end. It is transmitted in the direction and tries to leak from the crank chamber 13 to the outside of the frame 1. The lubricating oil that is about to leak out is first dammed by the flange portion 20 on the end surface of the oil-draining cover 5 that is fitted onto the large-diameter portion 6 of the crankshaft 2, and part of it is radially outward in the crank chamber 13. It is skipped by and decreases. Since the flange portion 20 projects radially outward from the outer periphery of the oil drain cover 5, the lubricating oil that flows down along the surface of the oil drain cover is blocked by the protrusion portion and is blocked by the crank chamber 13. To the large diameter portion 6 and does not flow into the gap of the large diameter portion 6. Next, the lubricating oil is blocked by a small gap between the radial step portion 7 of the crankshaft and the radial step portion 10 of the oil drain cover 5 that faces the crankshaft in the axial direction, further reducing leakage. To do. Here, the blocked lubricating oil is collected in the annular groove 21 on the inner circumference of the oil drain cover 5, and then returned to the crank chamber 13 through the oil drain hole 22 at the bottom. The lubricating oil leaking from the gap reaches the two annular grooves 9 inside the small-diameter portion 8 of the rotating crankshaft 2 and is attracted to the adjacent portion 9a of both grooves having the maximum diameter and the maximum peripheral speed, and the diameter is increased. After being blown outward in the direction, and collected in the opposing inner annular grooves 11 of the oil drain cover 5, it is similarly returned to the crank chamber 13 via the oil draining hole 14 in the vertical direction at the bottom.

By the above sealing process, the lubricating oil that leaks out is considerably reduced and becomes a low-concentration mist. This mist flows in the axial end direction and flows into the four labyrinth grooves 12 of the oil drain cover 5. By the action, the pressure is reduced one after another, and the passage is almost blocked. Further, the small amount of mist that has passed through the labyrinth groove 12 enters two annular grooves 9'outside the small diameter portion 8 of the crankshaft, and the adjacent portions 9'a thereof face the oil drain cover 5 in the same manner as described above. Is collected in the outer annular groove 11 'as a liquid, and the bottom end of the annular groove 11' fills a U-shaped communication oil passage 15 having one end 15a opened. Here, since the other end 15b of the communication oil passage 15 opens into the crank chamber 13 vertically below the one end 15a, the internal pressure of the annular groove 11 'is higher than the internal pressure of the crank chamber 13 by the oil pressure. It is maintained at a pressure approximately equal to atmospheric pressure, which is lower by the column difference ΔH. If the pressure difference between the inside and the outside of the frame increases due to the operating conditions of the diesel engine and changes in atmospheric pressure, more lubricating oil accumulates and ΔH increases. If the pressure difference decreases, the amount of lubricating oil in the crank chamber 13 increases. ΔH is reduced by being returned. Thus, the amount of lubricating oil that finally leaks out of the frame 1 is greatly reduced.

As described above, even in a diesel engine in which it is difficult to use an oil seal because the flywheel 3 having a large diameter is provided at the protruding end of the crankshaft 2, the non-contact type crankshaft end seal structure described above is used for lubricating oil. Can be surely sealed, and there is no problem of wear as in the case of an oil seal, so that the service life is extended significantly. In the above-described embodiment, since the inner peripheral annular groove 21 having the collar portion 20 and the oil drain hole 22 is provided on the end surface of the oil drain cover 5 on the crank chamber side, the lubricating oil which is about to leak out is not removed. There is an advantage that it can be dammed, scattered, and returned to the crank chamber 13, and the sealing effect can be further enhanced. Although the land type diesel engine has been described in the above embodiment, it goes without saying that the crankshaft end seal structure of the present invention can be applied to other types of diesel engines.

[0013]

[Effect of the device]

 As is clear from the above description, the crankshaft end seal structure of the diesel engine of the present invention has the above-mentioned small diameter portion of the crankshaft end portion including the large diameter portion, the radial step portion and the small diameter portion protruding from the end surface of the frame. A pair of two adjacent annular grooves are provided on the outer periphery of the crankshaft so as to sandwich an adjacent portion of the same diameter at a predetermined distance in the axial direction. On the inner circumference, a radial step portion that faces the radial step portion with a gap, an inner and outer annular groove that faces the pair of two annular grooves, respectively, and the small diameter portion between them. A labyrinth groove facing the outer periphery of the frame is provided, the inner annular groove is communicated with the frame through an oil drain hole in the oil drain cover, and the outer annular groove is communicated with the U-shaped oil passage through the frame. Since it communicates with the inside, the lubricating oil transmitted through the crankshaft to the outside It is out of, it is possible to prevent the sealing structure of the non-contact across the effective and long term.

[Brief description of drawings]

FIG. 1 is a side view of a diesel engine that employs a crankshaft end seal structure of the present invention.

FIG. 2 is an enlarged cross-sectional view of section II of FIG.

[Explanation of symbols]

1 ... Frame, 2 ... Crankshaft, 3 ... Flywheel,
4 ... Base plate, 5 ... Oil cover, 6 ... Large diameter portion, 7 ... Radial step portion, 8 ... Small diameter portion, 9 ... Two inner annular grooves, 9a ... Adjacent portion, 9 '... Outside 2 Book circular groove, 10 ... radial step, 1
1 ... Inner annular groove, 11 '... Outer annular groove, 12 ... Labyrinth groove, 13 ... Crank chamber, 14 ... Oil drain hole, 15 ...
U-shaped communication oil passage, 15a ... One end, 15b ... Another end.

Claims (1)

[Scope of utility model registration request] 1. An oil comprising a large-diameter portion and a small-diameter portion continuous in the axial end direction of the large-diameter portion via a radial step, the outer periphery of the end of the crankshaft protruding from the frame being attached to the end surface of the frame. In a crankshaft end seal structure for a diesel engine, which is covered with a cut cover and sealed, in the outer periphery of the small diameter portion of the crankshaft, two adjacent annular grooves having adjoining portions having the same diameter as the small diameter portion are axially arranged. The pair of pairs of the crankshaft and the radial step portion that faces the radial step portion of the crankshaft with a gap in the axial direction are provided on the inner circumference of the oil drain cover while the pair of crankshafts are provided at a predetermined distance. Inner and outer annular grooves facing the two annular grooves, respectively, and annular labyrinth grooves facing the outer circumference of the small diameter portion of the crankshaft are provided between the inner and outer annular grooves, respectively, and the oil Inside the cutting cover, A radial oil drain hole that communicates the groove with the space in the frame, and a U-shaped communication hole that has one end open to the outer annular groove and the other end that opens radially outside the opening into the frame. A crankshaft end seal structure for diesel engines characterized by the provision of an oil passage.