GB2031112A

GB2031112A - Gudgeon pin

Info

Publication number: GB2031112A
Application number: GB7930016A
Authority: GB
Original assignee: NOHAB DIESEL AB
Current assignee: NOHAB DIESEL AB
Priority date: 1978-09-06
Filing date: 1979-08-30
Publication date: 1980-04-16
Also published as: FR2435640B1; FI792711A; SE7809366L; DK148169C; DE2936068C2; IT7950148A0; DE2936068A1; IT1120554B; FI64446B; FR2435640A1; SE422979B; FI64446C; DK371879A; DK148169B; GB2031112B

Abstract

A gudgeon pin 2 for internal- combustion engines with oil-cooled pistons is made in one piece with a number of oil channels communicating with each other running diagonally through the otherwise solid core of the gudgeon pin to conduct cooling oil from a feed channel 10 in the connecting rod to the top of the piston. <IMAGE>

Description

SPECIFICATION Gudgeon pin The present invention relates to internal-combustion engines in which the pistons of the engine are force cooled by means of a cooling oil flow circulating through the tops of the pistons. In more detail, the invention relates to a method of and a device for conducting such a cooling oil flow from the connecting rods of the engine, which are provided with cooling oil channels, through the respective gudgeon pin to cooling channels made in the corresponding top of a piston. The device according to the invention could also be defined as a so-called floating gudgeon pin provided with channels designed in a special way for transportation of cooling oil from the oil channel of the connecting rod to the cooling channel of the top of the piston.

According to a technique hitherto used, cooling oil is conveyed from the oil pump of the engine via a channel made in the crankshaft via grooves in the connecting rod bearings to the cooling oil channels of the connecting rods and from these connecting rod channels via grooves in the gudgeon pin bearings of the connecting rods through the gudgeon pins and from there on through grooves in the bearings for the gudgeon pins in the piston to the end cooling channels in the top of the piston.

To convey the flow of cooling oil from the channel in the crankshaft to the channels in the connecting rods does not involve any actual difficulties, as the crankshaft and the connecting rods are constantly in well-defined angular positions in relation to each other. In the case of so-called floating gudgeon pins, however, which are permitted to turn freely in their bearings in relation to both the piston and the connecting rod, it is not such a simple matter to arrange for a connection with a constant flow of cooling liquid between the connecting rod channel and the piston with an unchanged flow area.The conventional method of arranging for this connection in engines with floating gudgeon pins is to make the gudgeon pins with an internal cavity with which via openings arranged along the periphery of the gudgeon pin, uniformly distributed and on a level with its bearings in the connecting rod and piston, respectively, always one opening, regardless of how the gudgeon pin turns, is in connection with the groove in the gudgeon pin bearing of the connecting rod, while a second opening at the same time is in connection with the corresponding groove in the bearing for the gudgeon pin in the piston.

The problem involved with the design described above is that the inner cavities of the gudgeon pins must be sealed at the ends of the gudgeon pin, so that oil shall not leak out into the cylinder. As a rule, the gudgeon pin is made in the form of a thick-walled tube, closed at each end by means of a special cover. These covers can either be fastened by means of threads, or can be upset in grooves in the material. However, when extreme loads often occur on the engine, the gudgeon pins can be deformed, i.e. become oval, to such a great extent that oil begins to leak out of their end seals in such large quantities that the function of the engine is impaired. It has even happened that gudgeon pins have been deformed to such a great extent that the covers have been fragmented, which has led to severe damage.

According to another, relatively often used variant, the hollow gudgeon pin is provided with a pressed-in inner sleeve, which leaves a certain free space between this and the inside of the gudgeon pin, and which at its ends is upset in grooves in the inner wall of the gudgeon pin. The space between the sleeve and the inner wall of the gudgeon pin then provides free passage for the cooling oil between a number of openings made in the periphery of the gudgeon pin.

The disadvantage of this design is about the same as with the one previously described, viz. that when the engine is subjected to extreme loads, the gudgeon pin can easily become oval to such a degree that oil begins to leak out between the sleeve and the inner wall of the gudgeon pin. Such oil leakage almost always causes serious breakdowns unless the necessary measures are taken.

The present invention now offers a gudgeon pin made in one piece, whereby leakage and improper functioning caused by play between the different parts of a gudgeon pin made of several parts have been eliminated.

In the gudgeon pin according to the invention, the passage of the cooling oil through the gudgeon pin has been solved by the gudgeon pin which is made in one piece having been provided with a number of channels running diagonally through the gudgeon pin which otherwise is solid, which channels are in connection with each other from the periphery of the gudgeon pin on a level with the bearing for the gudgeon pin in the connecting rod to the periphery of the gudgeon pin on a level with at least one of its bearings in the piston. These channels can then most simply consist of holes drilled diagonally through the gudgeon pin, which are in connection with each other in that they, in pairs, can have common openings on the periphery of the gudgeon pin, and in that they intersect each other.These intersections should appropriately be made around the centre line of the gudgeon pin, where the forces acting upon the gudgeon pin are smallest.

The number of channels of this kind, intersecting each other, which are required for a continuous and unchanged oil supply to the top of the piston regardless of its position, when floating gudgeon pins are used, de pends upon the design of the oil feed and the outlets arranged in the gudgeon pin bearing in the connecting rod and the top of the piston. As a rule, it is then an advantage to design these feed and outlet openings in the way previously described, which is known in itself which involves that in the respective bearing surfaces there are peripheral grooves which cover a greater or lesser portion of the periphery of the bearing surface and which through one or a plurality of openings are in connection with further cooling oil channels.If these grooves made in the bearings cover approx. 120-180" of the periphery of the bearing surface, which can be considered to be normal, three inlets are required for the oil channels through the gudgeon pin on a level with the groove in the bearing for the gudgeon pin in the connecting rod, and three outlets on a level with the bearing for the gudgeon pin in the piston. With a floating gudgeon pin, this variant thus gives an unchanged flow of cooling oil through the piston, as the inlet and outlet, respectively, in the gudgeon pin which are in contact simultaneously with the further channels in the connecting rod and the piston, are always unchanged. As the channels through the gudgeon pin intersect each other, it is thus of no significance which openings in the inlet and the outlet sides, respectively, are in contact with the further channels.As this variant is preferred, an embodiment in accordance with it will be described in more detail with reference to the attached drawings, in which: Figure 1 shows a section through a diesel engine piston having a gudgeon pin in accordance with this invention.

Figure 2 shows a part section A-A at right angles to the plane of the Figure applicable to Fig. 1.

Figures 3, 4 and 5, respectively, show a section through a gudgeon pin according to the invention, an end view of same, and a cross section B-B through same.

The piston 1 shown in a sectioned condition in Fig. 1 is connected with the gudgeon pin 2 by means of the connecting rod 3, only partly shown in the Figure. In the left part of Fig. 1 the gudgeon pin and the connecting rod are shown in a sectioned condition. The floating gudgeon pin 2, arranged in a known way, is secured at its two ends longitudinally in the gudgeon pin bearing 4, 5 in the piston by means of two securing rings 6, 7.

The connecting rod 3 is provided with a bearing bushing 9 for the gudgeon pin 2, secured by means of a set screw 8 in the connecting rod. The connecting rod has a feed channel 10 for cooling oil.

The piston h'as a transport channel 11 which leads from the bearing 5 for the gudgeon pin to a cooling oil channel 12 applied in the top of the piston.

The passage of the oil through the bearing bushing 9 in the connecting rod to the gud geon pin 2 and from the gudgeon pin to the transport channel 11 in the piston will be clearly noted if Fig. 1 is supplemented with Fig. 2, which according to section A-A shows sectioned part projections of both the connect ing rod and the piston.

The bushing 9 of the gudgeon pin bearing in the connecting rod thus has an external peripheral groove 1 3 which covers 180 of the outer periphery of the bearing bushing and an inner peripheral groove 14 which covers the 180 of the internal peripheral bearing surface of the bushing which consists of the part which does not have any external grooves. These two grooves are in connection with each other via openings 1 5 in the ends of the grooves. (Only one of the openings is shown in the Figure).

The feed channel 10 of the connecting rod goes to the outer of the bushing grooves 13, and the cooling oil continues to the inner groove via the openings 1 5. There is thus cooling oil available in the groove 14 within 180 of the internal bearing surface of the bushing.

In the gudgeon pin 2, on a level with said channel 14, there are three inlet openings 16, 1 7 and 1 8 distributed over the periphery of the gudgeon pin, spaced 120 . From each of these openings there are two channels 19, 20, 21, 22, 23, 24 drilled obliquely from each each other towards the ends of the gudgeon pin diagonally through same and which emerge at the periphery of the gudgeon pin on a level with its two bearings in the piston.

The channels running in pairs from the same outlet opening follow the same central plane through the centre axis of the gudgeon pin, and therefore the outlets will also be distribut ed along the periphery of the gudgeon pin, spaced 120 . The channels also emerge at the same distance from the ends of the gud geon pin, which involves that the channels intersect each other around the centre axis of the gudgeon pin, i.e. where the gudgeon pin is subjected to the least load. The openings 19-24 emerge at the periphery of the gud geon pin on a level with grooves 25, 26 of the same type as the groove 14 in the gud geon pin bearing in the connecting rod, ar ranged in the gudgeon pin bearing 4, 5 in the piston. From at least one of these grooves, in Fig. 1 groove 25, the transport channel 11 runs for onward transport of cooling oil to the cooling channel 1 2 in the top of the piston.

The dash lines 27 indicate the outlet of the cooling channel 1 2. As all of the channels 19-24 of the gudgeon pin are connected with each other via intersections and common inlets, the transport capacity for cooling oil through the gudgeon pin is independent of the turning of the gudgeon pin in the bear ings. The number of inlets and outlets and their positions in relation to each other combined with the design of the grooves 14, 25 and 26 also involve that the transport capacity to and from the gudgeon pin is constantly unchanged, regardless of the turning of the gudgeon pin.

The flow directions of the cooling oil have been indicated with arrows in Figs. 1 and 2.

The right and left halves, respectively, of Fig. 3, show two different variants, of which the right-hand one is provided with weightsaving holes 28 in its ends.

Claims

1. A gudgeon pin, for an internal-combustion engine with an oil-cooled piston, having means for conducting cooling oil from a channel made in the connecting rod via its bearing around the gudgeon pin to the piston via at least one of the gudgeon pin bearings in the piston, wherein the gudgeon pin is made in one piece and said oil conducting means comprises a plurality of inter-communicating channels running diagonally through the otherwise solid core of the gudgeon pin from the peripheral section of the gudgeon pin which is to be received within the bearing for the gudgeon pin in the connecting rod, to at least one of the peripheral sections of the gudgeon pin to be received in the piston.

2. A gudgeon pin according to claim 1, characterized in that the channels which run diagonally from the periphery of the gudgeon pin on a level with the gudgeon pin bearing in the connecting rod to the periphery of the gudgeon pin at one and the same of its bearings in the piston intersect each other around the centre line of the gudgeon pin where the load changes arising in the gudgeon pin will be smallest.

3. A gudgeon pin according to claims 1 or 2, characterized in that the cooling oil channels run diagonally through the gudgeon pin in pairs from common openings in the periphery of the gudgeon pin on a level with the gudgeon pin bearing in the connecting rod towards the periphery of the gudgeon pin at its respective ends and the bearings arranged there in the piston.

4. A gudgeon pin according to claim 3, characterized in that the channels running in pairs from common openings run diagonally through one and the same parting line running through the centre axis of the gudgeon pin.

5. A gudgeon pin according to claim 4, characterized in that it has six such channels running in pairs from the same openings for cooling oil, the three parting lines in which these six channels are distributed then intersecting each other with a 60 angle which gives a 120 angle between the openings of the channels at the respective bearings in the piston and the connecting rod.

6. A gudgeon pin according to claim 5, characterized in that it is arranged to coact with bearings made in a known way to conduct cooling oil to and from the cooling oil passage through the gudgeon pin which bearings have grooves in the bearing surfaces which each cover at least 120-180" of the internal periphery of the bearing surface on a level with openings to the cooling oil passage through the gudgeon pin and these grooves then being in connection with the cooling oil channels through the connecting rod and the piston.

7. A gudgeon pin according to claim 6, characterized in that it is arranged to coact with bearing cups made in a known way for its bearings in the connecting rod and piston and these bearing cups in their outer and inner peripheries having grooves for conducting cooling oil which grooves each cover at least 120-180 of said peripheries and which are in connection with each other at the ends of the grooves so that they together form a coherent oil groove which runs around the bearing cup on its outside as well as on its inside, and the groove on the inside then being on a level with the openings for the cooling oil channels of the gudgeon pin and the groove on the outside of the bearing cup being on a level with the cooling oil channels in the connecting rod and the piston, respectively.

8. A gudgeon pin according to any one of the foregoing claims, characterized in that the ends of the gudgeon pin where no cooling oil channels are running are lightened by means of axially drilled cavities.