JPH04370306A - Crankshaft end structure of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent leakage of lubricating oil travelling along a crankshaft with a flange at a protruded edge to the exterior part effectively by means of a non-contact type enclosing structure and for a long time. CONSTITUTION:The first stepped part 6 of large diameter and the second stepped part 7 of small diameter connected thereto in the direction of the shaft end are formed to the end part of a crankshaft 2 protruded from a frame edge surface 1a. An annular labyrinth groove 19 opposite to the first stepped part 7, and an annular oil groove 24 connected thereto in the direction of the shaft end are formed to the end of the crankshaft 2. A U-shaped communicating oil passage 25 one end 25a of which opens to the oil groove 24, and other end 25b of which opens to a crank chamber 18 on the outside in the radial direction of this opening is provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crankshaft end structure for internal combustion engines, particularly diesel engines.

0002

[Prior Art] Generally, the rear end of the crankshaft of a small diesel engine protrudes from the frame without a connecting flange, and an oil drain cover equipped with an oil seal is attached to the rear end of the crankshaft. The oil seal seals lubricating oil that leaks from the crank chamber in the frame to the outside through the crankshaft by inserting it through and fixing it to the end face of the frame.

0003

[Problem to be Solved by the Invention] However, in medium-sized and large-sized diesel engines, since there is a large-diameter flange for connection at the rear end of the crankshaft, it is difficult to insert a small-diameter oil seal from the shaft end. There is a problem in that leakage of lubricating oil cannot be prevented unless a sealing means other than an oil seal is used. In addition, although oil seals have a relatively simple and inexpensive structure, they seal the lubricating oil by contacting the outer periphery of the rotating crankshaft, so the contact parts, such as the lip, are subject to severe wear. In particular, large diesel engines with high output have a problem of shortened service life.

Therefore, an object of the present invention is to prevent leakage of lubricating oil to the outside for a long period of time even in a high-output internal combustion engine by devising a structure that seals the end of a crankshaft having a flange in a non-contact manner. An object of the present invention is to provide a crankshaft end structure for an internal combustion engine that can prevent the above problems from occurring.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the crankshaft end structure for an internal combustion engine of the present invention includes an oil cutter attached to the end surface of the crankshaft that extends from the outer periphery of the end of the crankshaft protruding from the end surface of the frame. In the cover, a large-diameter first step portion is provided on the protruding crankshaft near the end surface of the frame, and a small-diameter second step portion continues from the first step portion in the axial end direction; A labyrinth groove is provided in an annular shape on the inner circumferential surface of the oil drain cover opposite to the outer circumferential surface of the second stage, and a labyrinth groove is provided on the inner circumferential surface of the oil drain cover so as to be connected to the labyrinth groove in the direction of the end of the crankshaft. An annular oil sump groove,
A U-shaped communicating oil passage is provided in the oil drain cover in a radial direction, one end of which opens into the oil sump groove, and the other end of which opens into the frame on the outside of the opening in the radial direction. Features.

[0006]

[Operation] The lubricating oil leaking from the gap between the bearing on the end face of the frame and the crankshaft is transmitted along the surface of the crankshaft, and a part of the lubricating oil leaks from the outer periphery of the large-diameter first stage part that rotates at a high circumferential speed due to centrifugal force. It is blown into the inside of the cutter cover and collected in the crank chamber inside the frame. Next, the remaining lubricating oil is transmitted toward the end of the crankshaft, and is successively reduced in pressure by the action of the labyrinth groove of the oil drain cover that faces the small-diameter second stage portion of the crankshaft, thereby suppressing the amount of leakage. moreover,
A small amount of lubricating oil that leaks from the labyrinth groove toward the end of the crankshaft is collected in an oil sump groove on the inner circumference of the oil drain cover, and fills this oil sump groove with a U-shaped communicating oil passage with one end open. . Here, since the other end of the communicating oil passage opens into the frame, that is, the crank chamber, on the outside in the radial direction than the one end, the internal pressure of the oil sump groove is smaller than the internal pressure of the crank chamber. The difference in oil column on the oil sump groove side relative to the chamber side is maintained low. If the internal pressure of the oil sump groove increases or decreases due to the operating conditions of the internal combustion engine, the oil column difference decreases and a corresponding amount of lubricating oil is returned to the crank chamber, or the oil column difference increases. do. In this way, the amount of lubricant that ultimately leaks to the outside is significantly reduced.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below with reference to illustrated embodiments. FIG. 1 is a side view of a diesel engine employing the crankshaft end structure of the present invention, and in this figure, the details of parts not directly related to the present invention are omitted and only the external shape is shown. This diesel engine has 6 cylinders on each side, 12 cylinders in total.
It is a medium-sized diesel engine with a V-shaped cylinder, and is 4500~
It has an output of 6000 PS and is used to drive a land-based generator. An end of a crankshaft 2 having a connecting flange 3 at its tip protrudes from the rear end surface 1a of the frame 1 of the diesel engine.
The outer periphery of is covered with an oil drain cover 5 fixed to the rear end surface 1a and the upper surface of a base plate 4 whose interior is an oil pan.

As shown in FIG. 2, the end of the crankshaft 2 has a first step 6 with a narrow width and a large diameter provided close to the rear end surface 1a of the frame, and a first step 6 with a large diameter. It consists of a wide small-diameter second step portion 7 that continues in the direction of the shaft end, and a shaft portion 8 that reaches the flange 3. Both step portions 6 and 7 are connected by an annular arc surface with a small radius of curvature. There is an annular protrusion 7 approximately in the center of the
A is provided. Further, the shaft portion 8, the second step portion 7, and the flange 3 are connected to each other at an annular R portion. On the other hand, as shown in FIG. 3, the oil drain cover 5 has left and right half covers 5a and 5b divided into two by a vertical plane passing through the center of the crankshaft 2, which are inserted horizontally into the upper and lower vicinity of the shaft hole 5c. Long bolt 9a,
9b and four short bolts 10 via packing, and are fixed to the rear end surface 1a of the frame 1 with a large number of bolts 11 and bolts 12 passed through the outer periphery.
It is fixed to the upper surface of the base plate 4 with a large number of bolts 13 passed through the lower edge. Note that the oil drain cover 5 prevents lubricating oil transmitted through the crankshaft 2 from leaking to the outside, and the crankshaft 2 itself is supported by a bearing within the frame 1.

As shown in FIG. 2, the inside of the oil drain cover 5 is similar to the first bearing part 14 and the shaft part 8 which are fitted onto the second step part 7 of the crankshaft 2 with a slight gap. The fitted second bearing portion 15 separates the inner chamber 16 into an inner chamber 16 communicating with the oil pan via the crank chamber 18 and a closed outer chamber 17. Three labyrinth grooves 19 and 20 are formed in an annular shape on the inner peripheral surfaces of the first bearing part 14 and the second bearing part 15, respectively.
The central labyrinth groove 19 fits into the convex portion 7a of the second step 7 and communicates with the inner chamber 16 via a radial passage 21, while the two inner labyrinth grooves 20 communicate with the inner chamber 16 via a similar passage 22. It communicates with the outer room 17. Note that a flange 23 is formed at the inner end of the first bearing portion 14 to guide lubricating oil splashing outward in the radial direction from the first step portion 6 of the crankshaft. In the outer chamber 17, an annular oil sump groove 24 is formed that extends in the axial direction toward the base of the second bearing part 15, and one end 25a is connected to the oil sump groove 24 in the left and right half covers 5a, 5b. A U-shaped communication oil passage 25 which is open and whose other end 25b opens into the inner chamber 16 radially outward from the one end 25a.
are provided in the radial direction (see Fig. 3).

The crankshaft end structure in the diesel engine operates as follows. When a diesel engine is operated, some of the lubricating oil supplied from the oil pan in the bed plate 4 (see Figure 1) to the piston pin and crank pin via the oil supply system is transmitted to the surface of the rotating crankshaft 2. Then, it leaks out from the gap between the rear end of the frame 1 and the bearing. A part of the leaked lubricating oil is transferred to the first bearing part 14 by centrifugal force on the outer periphery of the large-diameter first stage part 6 that rotates at a high circumferential speed.
The oil is blown along the flange 23 of the oil drain cover 5 into the inner chamber 16 and collected in the oil pan at the bottom of the crank chamber 18. The lubricating oil remaining without being blown away is transmitted to the small-diameter second stage part 7 toward the end of the crankshaft, and is transferred to the first stage part 7 opposite to this
The three labyrinth grooves 19 on the inner periphery of the bearing portion 14 reduce the pressure one after another, suppressing leakage toward the shaft end. Here, the lubricating oil accumulated in each labyrinth groove 19 flows down into the inner chamber 16 through the passage 21 of the central groove, but this passage 21 has a small diameter and is small in number, and the convex portion 7a into which the gap of the central groove fits Since the labyrinth groove 19 is narrow, the above-mentioned sealing effect by the labyrinth groove 19 is hardly hindered.

Further, a small amount of lubricating oil that leaks out through the labyrinth groove 19 is collected in an oil sump groove 24 connected to the outer chamber 17 of the oil drain cover 5, and a U with one end 25a opened in the oil sump groove 24 is collected. It fills the letter-shaped communication oil passage 25. As shown in FIG. 2, the communicating oil passage 25 has the other end 25b opening into the inner chamber 16 on the radially outer side than the one end 25a, so that the internal pressure of the oil sump groove 24 is lower than that of the inner chamber 16, that is, the crank chamber 18. The oil column difference ΔH on the oil sump groove side with respect to the inner chamber side of the communicating oil passage 25 is maintained lower than the internal pressure of . When the internal pressure of the oil sump groove 24 increases or decreases due to the operating conditions of the diesel engine, the oil column difference ΔH decreases and a corresponding amount of lubricating oil is returned to the crank chamber 18 from the other end 25b. Alternatively, more lubricating oil accumulates in the communication oil passage 25, and the oil column difference ΔH increases. Here, since the oil sump groove 24 and the outer chamber 17 are sealed from the outside by the second bearing part 15 having three labyrinth grooves 20, there are oil drain passages 22 in the two inner grooves. also exhibits sufficient sealing action for the same reason as mentioned above,
Eventually, almost no lubricant oil leaks out. Furthermore, since the internal pressure of the outer chamber 17 can be maintained higher than atmospheric pressure, the internal pressure of the crank chamber 18 can be further increased, the number of labyrinth grooves 19 in the first bearing part 14 can be reduced, and the oil column difference ΔH can be reduced. It also has the advantage of being easy to process.

As described above, in the present invention, the end of the crankshaft 2 protruding from the end face 1a of the frame is provided with a large-diameter first step 6 and a small-diameter second step 7 extending therefrom in the direction of the shaft end. On the other hand, an annular labyrinth groove is formed on the inner circumferential surface of the oil drain cover 5 divided into left and right halves, which is fixed to the end surface 1a of the frame so as to cover the outer periphery of the end of the crankshaft, facing the first step. 19 and an annular oil sump groove 24 that extends in the axial end direction, and in the oil cutter cover 5, one end 25a opens into the oil sump groove 24, and the other end 25b connects the frame radially outward from this opening. 1 is provided with a U-shaped communication oil passage 25 that opens into the interior of the crankshaft 2, a non-contact sealing structure prevents lubricating oil from leaking to the outside through the crankshaft 2, which has a connecting flange 3 at the protruding end. It can be prevented effectively and for a long period of time.

In the above embodiment, since the shaft portion 8 outside the oil sump groove 24 is also sealed from the outside by the second bearing portion 15 having the labyrinth groove 20, leakage of lubricating oil to the outside is prevented. This has the advantage that it is possible to further reduce the overflow, to further increase the internal pressure of the crank chamber 18, and to facilitate machining. Further, the left and right half covers 5a and 5b, which are divided into two, are connected to long bolts 9a through packings in the upper and lower vicinity of the shaft hole 5c.
, 9b, etc., and is fixed not only to the end surface 1a of the frame but also to the upper surface of the base plate 4 with a large number of bolts 11, 12, 13, so that the rigidity of the oil drain cover 5 is improved and the lubricating oil is removed. It can be effectively sealed within the frame 1. In the above embodiments, a V-shaped land diesel engine has been described, but it goes without saying that the crankshaft end structure of the present invention can be applied to other diesel engines and other internal combustion engines.

[0014]

As is clear from the above explanation, the crankshaft end structure of the internal combustion engine of the present invention has a large-diameter first stage portion and a shaft attached to the end portion of the crankshaft that protrudes from the end surface of the frame. While forming a small-diameter second stage section that extends in the end direction, an oil drain cover that is fixed to the end surface of the frame so as to cover the outer periphery of the end of the crankshaft is provided with a second stage section that faces the first stage section. An annular labyrinth groove and an annular oil sump groove connected to the axial end direction are formed in the oil drain cover, one end of which opens into the oil sump groove, and the other end of which is connected to the frame on the outside in the radial direction from this opening. Since it has a U-shaped communication oil passage that opens inward, the non-contact sealing structure effectively prevents the lubricating oil that is transmitted through the crankshaft, which has a connecting flange on the protruding end, from leaking to the outside. Moreover, it can be prevented for a long period of time.

[Brief explanation of drawings]

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

FIG. 2 is an enlarged side sectional view of section II in FIG. 1.

FIG. 3 is an enlarged front view of section II in FIG. 1.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Frame, 2... Crankshaft, 3... Flange, 4... Base plate, 5... Oil drain cover, 6... First stage part, 7... Second stage part, 1
4...First bearing portion, 18...Crank chamber, 19...Labyrinth groove, 24...Oil sump groove, 25...U-shaped communication oil passage.

Claims (1)

[Claims] 1. A crankshaft end structure for an internal combustion engine in which the outer periphery of the end of the crankshaft protruding from the end face of the frame is covered with an oil drain cover attached to the end face, wherein the protruding crankshaft is close to the end face of the frame. a large-diameter first step section provided as a cylindrical section; a small-diameter second step section connected to the first step section in the axial end direction; and an inner side of the oil drain cover facing the outer circumferential surface of the second step section. A labyrinth groove annularly provided on the circumferential surface,
An annular oil sump groove is provided on the inner circumferential surface of the oil drain cover so as to be connected to the labyrinth groove toward the end of the crankshaft; 1. A crankshaft end structure for an internal combustion engine, comprising a U-shaped communicating oil passage which is open and whose other end opens into the frame radially outward from the opening.