JPH0557341U - 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] A crankshaft 2 protruding from a frame 1 is composed of a large-diameter portion 8, a medium-diameter portion 10 and a small-diameter portion 11, which are successively connected in the axial direction via first and second radial step portions 9 and 11. The outer periphery of the end is sealed with an oil drain cover 5 attached to the frame end surface 1a. An annular groove 13 having an inner diameter equal to the outer diameter of the middle diameter portion 10 and an outer diameter equal to or less than the outer diameter of the large diameter portion 8 is axially formed in the first radial step portion 9. The oil drain cover 5 is provided with a cylindrical portion 14 whose front end 14a fits in the annular groove 13 and whose rear end 14b fits outside the small diameter portion 12 in a protruding manner. 1
The annular labyrinth groove 15 is made to face 0, and then the second
Each of the annular oil reservoir grooves 16 is formed so as to oppose the radial stepped portion 11 of the first oil tank, and one end 17a of the oil drain cover 5 is opened to the oil reservoir groove 16 and the other end 17b of the oil drain cover 16 is radially extended from the opening 17a. A U-shaped communication oil passage 17 that opens into the crank chamber 18 on the outer side is provided.

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 flange portion for connecting the flywheel is located at the rear end of the crankshaft, so a small-diameter oil seal cannot be inserted from the shaft end. 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 part, a medium diameter part, and a small diameter part which are successively connected in the axial end direction through first and second radial steps. In the case where the outer periphery of the end of the crankshaft protruding from the frame is covered with an oil drain cover attached to the end face of the frame for sealing, the outer diameter of the middle diameter part is the same as the outer diameter of the middle diameter part in the first radial step. An annular groove that has an inner diameter and is formed in the axial direction so as to have an outer diameter that is smaller than the outer diameter of the large diameter portion and the oil drain cover is protrudingly provided, and the tip fits into the annular groove. A tubular portion whose end is fitted onto the small diameter portion, a labyrinth groove formed annularly on the inner peripheral surface of the tubular portion facing the middle diameter portion, and an axially continuous portion of the labyrinth groove and the first portion. An annular shape is formed on the inner circumference of the cylindrical portion so as to face the radial step portion A reservoir groove and a U-shaped communication oil passage that is provided in the oil drain cover in the radial direction and has one end that opens into the oil reservoir groove and the other end that opens radially inside the opening into the frame. It is characterized by having.

[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 goes from the large-diameter portion of the crankshaft to the middle-diameter portion through the first radial step portion, but is directed to the first radial step portion in the direction opposite to the shaft end direction. An annular groove is formed in the annular groove, and the tip of the tubular portion of the oil drain cover is fitted into the opening of the annular groove with a slight gap. Therefore, most of the lubricating oil returns to the inside of the frame along the outer periphery of the tubular portion having a diameter smaller than the tip of the tubular portion due to the above-mentioned gap, and only a part thereof enters the annular groove. The lubricating oil that has entered the annular groove is in the form of a mist and is transmitted through the medium diameter portion, but the labyrinth groove of the opposing oil drain cover reduces the pressure one after another, and almost completely prevents passage. Furthermore, a small amount of mist that has passed through the labyrinth groove reaches the second radial step of the crankshaft and is collected as a liquid in the oil reservoir groove of the opposing oil drain cover. Fills a U-shaped communication oil passage with an opening. Here, since the other end of the communication oil passage is opened in the frame at the outer side in the radial direction from the one end, the collected lubricating oil is returned to the frame and the inside of the oil reservoir groove is A pressure equal to the atmospheric pressure, which is lower than that in the frame by the column difference, is maintained, and the oil column prevents ejection of the lubricating oil due to the reverse flow. Thus, the amount of lubricating oil that eventually 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-speed, medium- and large-sized in-line 6-cylinder engine, and is mainly used for driving a ship or a land-based generator. From the rear end surface 1a of the frame 1 of the diesel engine, an end portion of a crank shaft 2 having a flange 3 for connection at the tip projects from the rear end surface 1a and the oil pan. 4 is covered with an oil drain cover 5 fixed to the upper surface of 4 for sealing.

As shown in FIG. 2, the end portion of the crankshaft 2 is connected to the support portion 7 supported by the frame 1 via the bearing metal 6 and is located near the outer side of the rear end surface 1a of the frame. The large-diameter portion 8 is composed of a large-diameter portion 8, a medium-diameter portion 10 and a small-diameter portion 12 which are successively connected to the large-diameter portion 8 in the axial end direction via a first radial step 9 and a second radial step 11. Is the flange 3 above. An annular groove 13 having the same inner diameter as the outer diameter of the middle diameter portion 10 and having an outer diameter smaller than the outer diameter of the large diameter portion 8 is formed in the first radial step portion 9 in the axial direction. On the other hand, the oil drain cover 5 can be bisected on both sides (in the direction perpendicular to the paper surface) according to the paper surface of FIG. 2, and is fitted onto the crankshaft 2 so as to cover the base end portion of the small diameter portion 12. In the portion surrounding the small diameter portion 12 of the oil drain cover 5, the tip 14a is fitted into the opening of the annular groove 13 of the crankshaft 2 with a slight gap, and the rear end 14b is fitted onto the small diameter portion 12 outside. A cylindrical portion 14 is formed so as to project inward in the axial direction, and three annular labyrinth grooves 15 are formed on the inner peripheral surface of the cylindrical portion 14 so as to face the intermediate diameter portion 10. The annular oil reservoir grooves 16 are provided so as to be continuous in the direction and face the second radial step portion 11.

Further, in the oil drain cover 5, one end 17a is opened at the lowest portion of the oil reservoir groove 16, and the other end 17b is opened at a crank chamber 18 in the frame 1 radially outside of the one end 17a. A letter-shaped communication oil passage 17 is provided. This U-shaped communication oil passage 17 is opened linearly from the surface of the oil drain cover 5 as shown in FIG. 2 due to the drilling process, and the opening at the time of processing is closed with plugs 18, 19 and 20. is doing. On the inner circumference of the upper part of the oil drain cover 5, an oil drain flange 21 is provided so as to project in the radial direction so as to sandwich the tip of the large diameter portion 8 of the crank shaft between the tip of the cylindrical portion 14a. There is.

The crankshaft end seal structure in the above diesel engine operates as follows. When the diesel engine is operated, part of the lubricating oil supplied from the oil pan 4 (see Fig. 1) to the piston and crank pin through the oil supply system moves the surface of the rotating crankshaft 2 in the axial direction. It is transmitted and tries to leak from the crank chamber 18 to the outside of the frame 1. The lubricating oil which is about to leak out goes from the large diameter portion 8 of the crankshaft 2 to the first radial step portion 9, but is damped by the oil drain flange 21 of the oil drain cover 5 fitted on the tip of the large diameter portion 8. It is stopped, and a part thereof is blown radially outward into the crank chamber 18 to decrease. An annular groove 13 is provided in the first radial step portion 9 toward the inner side in the axial direction, and the tip end 14a of the tubular portion of the oil removing cover 5 is fitted into the opening thereof with a slight gap. There is. Therefore, most of the lubricating oil that has passed through the oil drainage flange 21 also travels along the outer periphery of the tubular portion 14 having a diameter smaller than the tip of the tubular portion 14 into the crank chamber 18, and only a part thereof. Penetrates into the annular groove 13.

The lubricating oil that has entered the annular groove 13 travels through the medium diameter portion 10 in the form of a mist, but is depressurized one after another by the action of the labyrinth groove 15 of the facing oil drain cover 5, and almost completely passes through. Be blocked. Further, a small amount of mist that has passed through the labyrinth groove 15 reaches the second radial step portion 11 of the crank shaft and is collected as a liquid in the oil sump groove 16 of the opposed oil drain cover 5, and this oil is collected. The reservoir groove 16 is filled with a U-shaped communication oil passage 17 having one end 17a opened. Here, since the other end 17b of the communication oil passage 17 is opened in the crank chamber 18 vertically below the one end 17a, the internal pressure of the oil reservoir groove 16 is lower than that of the crank chamber 18. The pressure is maintained at a pressure substantially equal to the 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 operating conditions of the diesel engine and atmospheric pressure fluctuations, more lubricating oil accumulates and ΔH increases, and if the pressure difference decreases, the lubricating oil is correspondingly increased in the crank chamber 18 Is reduced to ΔH. Thus, the amount of lubricating oil that finally leaks out of the frame 1 is greatly reduced.

[0012] Thus, since the protruding end of the crankshaft 2 has the large-diameter flange 3, even in a diesel engine where it is difficult to use an oil seal, the non-contact type crankshaft end seal structure is used to supply the lubricating oil. Of course, the service life of the seal structure is greatly extended because it can be surely sealed and there is no problem of wear as in the case of the oil seal. In the above-described embodiment, the oil drain flange 21 which is externally fitted to the tip of the large diameter portion 8 of the crankshaft is provided on the inner periphery of the upper portion of the oil drain cover 5, so that the lubricating oil that is about to leak out is blocked. There is an advantage that it can be scattered and returned to the crank chamber 18, and the sealing effect can be further enhanced. In addition, in the above-mentioned embodiment, the description is given of the medium-speed and medium-sized diesel engine of the row type, but it goes without saying that the crankshaft end seal structure of the present invention can be applied to other types of diesel engines. Absent.

[0013]

[Effect of the device]

 As is clear from the above description, the shaft end sealing structure of the diesel engine of the present invention has a large diameter portion, a medium diameter portion, and a small diameter portion that are successively connected in the shaft end direction via the first and second radial step portions. In the case where the outer circumference of the crankshaft end is sealed with an oil drain cover attached to the frame end surface, the first radial step has the same inner diameter as the outer diameter of the middle diameter portion or less than the outer diameter of the large diameter portion. An annular groove having the outer diameter of is formed in the axial direction, while the oil drain cover is provided with a cylindrical portion whose front end fits into the annular groove and whose rear end fits over the small diameter portion. An annular labyrinth groove is formed on the inner peripheral surface of the portion so as to face the intermediate diameter portion, and an annular oil reservoir groove is formed so as to face the second radial step portion, and at the same time, inside the oil drain cover, A U-shaped communication oil passage is formed, one end of which opens into the oil reservoir groove and the other end of which opens radially outside the opening into the frame. Because only in that, it is possible to prevent over the Shi leaks to the outside of the lubricating oil traveling through the crankshaft, effective and long term sealing structure of the non-contact.

[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 ... crank shaft, 3 ... flange, 4 ... oil pan, 5 ... oil cover, 7 ... support portion, 8 ... large diameter portion,
9 ... 1st radial step, 10 ... medium diameter part, 11 ... 2nd radial step, 12 ... small diameter part, 13 ... annular groove, 14 ... cylindrical part, 1
4a ... front end, 14b ... rear end, 15 ... labyrinth groove, 16 ...
Oil reservoir groove, 17 ... U-shaped communication oil passage, 17a ... One end, 17b
... the other end, 18 ... crank chamber.

Claims (1)

[Scope of utility model registration request] 1. An outer circumference of an end portion of a crankshaft, which is composed of a large diameter portion, a medium diameter portion, and a small diameter portion which are successively connected in the axial end direction via first and second radial step portions, and which protrudes from a frame, In a crankshaft end seal structure for a diesel engine, which is covered with an oil drain cover attached to an end face of a frame for sealing, the first radial step portion has the same inner diameter as the outer diameter of the middle diameter portion, and the large diameter portion. An annular groove formed in the axial direction so as to have an outer diameter smaller than the outer diameter of the above, and a protruding end provided on the oil drain cover, a front end of which fits into the annular groove, and a rear end of which fits over the small diameter portion. A tubular portion, a labyrinth groove formed in an annular shape on an inner peripheral surface of the tubular portion facing the medium diameter portion, an axially continuous labyrinth groove and facing the second radial step portion. As described above, the oil reservoir groove formed in an annular shape on the inner circumference of the tubular portion and the diameter inside the oil drain cover are A crank of a diesel engine, which is provided in a U-shaped communication oil passage, which is provided in an opposite direction, one end of which opens to the oil reservoir groove, and the other end of which opens radially inside the opening into the frame. Shaft end seal structure.