US1916292A

US1916292A - Internal combustion engine

Info

Publication number: US1916292A
Application number: US74722A
Authority: US
Inventors: Lionel M Woolson
Original assignee: Packard Motor Car Co
Current assignee: Packard Motor Car Co
Priority date: 1925-12-11
Filing date: 1925-12-11
Publication date: 1933-07-04
Anticipated expiration: 1950-07-04

Description

July 4, 1933. M, WOOLLSON 1,916,292

INTERNAL COMBUSTIOVN ENGINE Filed Dec. 1l, 1925 Patented July 4, 1933 UNITED STATES PATENT OFFICE LIONEL M. WOOLSON, OF DETROIT, MICHIGAN, ASSIGNOR T PACKARD MOTOR CAB COMPANY, 0F DETROIT, MICHIGAN, A. CORPORATION OF MICHIGAN INTERNAL COMBUSTION ENGINE Application led December 11, 1925. Serial No. 74,722.

This invention relates to internal Combustion engines and particularly to large high speed engines such as are used in the propulsion of aircraft. In such engines reliability, compactncss and a low ratio of weight to power developed are prime requisites, but because of the light construction and the high power developed, and also by reason of the high speeds employed, they are frequently subject to severe vibration which tends .to weaken the engine and adversely affect its reliability.

Engines of this nature are usually of the i V type, having a single crankshaft mounted in bearings which are supported on webs cast integral with the crankcase and transversely disposed therein. In the interest of lightness it has become the practice to cast the crankcase from aluminum and to form the bearing caps of duraluniin or similar material, these caps being carried by studs which are screwed into the webs of the crankcase.V It has been found that in structures of this nature the heavy stresses caused by the explosion load are concentrated on the threads in the stud holes of the crankcase webs, and these stresses, when rapidly reversed at high engine speeds, tend to cause the formation of minute cracks in the crankcase adjacent the stud holes, which rapidly spread and may cause the complete failure of the engine. It has heretofore been proposed to carry the bearing caps of internal combustion engines on bolts verticallv arranged in the crankcase and passing therethrough, but in the type of engine under discussion the cylinders are usually so closely spaced in the interest of compactness that such construction is impractical, there being no room for the heads of such bolts. 1

One of the objects of the present invention is to provide an engine of the character designated in which the loads on the crankcase and its webs, caused by the explosions in the engine cylinders, shall be taken by members in direct tension, and the members beingarranged parallel to the axes of the cylinders.

Another object of the invention is to provide such an engine having a crankcase of aluminum or similar material, in which the loads imposed upon such crankcase shall not be communicated thereto through threads cut in the aluminum itself.

Another object of the invention is to provide. an internal combustion engine with a bearing cap support -in which the bending moment is a minimum.

A further object of the invention is to provide such an engine with a bearing cap support which is carried by bolts or other tension members in such a manner that localization of stresses in the threaded portion of the bolts is impossible and which shall yield in elongation rather than by fracture.

Other objects of the invention will appear from the following description taken in connection with the drawing, which forms a part of this specification and in which:

Fig. 1 is a view in vertical longitudinal section through a portion of an internal combustion engine, taken substantially on the line 1-1 of Fig. 2;

Fig. 2 is a transverse vertical section through a portion of the internal combustion engine shown in Fig. 1 and substantially on the lines 2 2 of Figs. 1 and 3, showing the application of the invention thereto;

Fig. 3 is a detail section taken substantially on the line 3-3 of Fig. 2, and

Fig. 4 is a detail section showing the pre` ferred arrangement at one end of the engine crankcase, substantially on the lines 4.-4 of Figs. 1 and 3.

Referring to the drawing, at 10 is shown a portion of an internal combustion engine of the well known V type, having a crankcase 11 on which are mounted inclined banks of

cylinders

12 and 13, in a manner well known in the art to which this invention relates. The crankcase 11 is provided with suitable feet or lugs 14 by means of which the engine may be mounted in the vehicle which it is intended to propel and it is also provided with suitable internal webs l5, disposed transversely of the crankcase and preferably cast integral therewith. The webs 15 are provided with suitable openings 16 to lessen their weight and have downwardly disposed faces 17 inclined to the longitudinal median plane of the engine. These faces form, in effect, an inverted V, the sides of which are normal to the axes of the

cylinders

12 and 13 respectively. The central portion of the webs 15, approximately at the apex of this V, is provided with a cutout portion 18 of semi-circular contour, adapted for the reception of the upper half of a crankshaft bearing 19. The bottom of the crankcase is covered with a removable oil pan 20, forming a sump for the lubricating system of the engine.

In the bearing 19 is journaled the engme crankshaft 21 having cranks 22 which are adapted for connection by connecting rods 23 to suitable pistons (not shown), disposed in the

cylinders

12 and 13 in the well known manner. Each of the cranks 22 is adapted for operation by two of the connecting rods `23, one of which is disposed in a cylinder of each of the cylinder banks, in the well known manner, and which maybe of the forked construction shown, or connected to the crank pin in any vother suitable manner desired.

Below each of the webs 15 is arranged a bearing cap member 24 which may be formed of forged duralumin, or of any other suitable material, and which is provided with upwardly disposed inclined faces 25, arranged in the general form of an inverted V to coact with the downwardly disposed faces 17 of the crankcase web 15. It will be observed that by reason of the shape of the cap member 24 it is wider at its upper portion adjacent the faces 25 than itis at its lower portion and it is provided at the center of its upper portion, approximately at the apex of the V with a cutout portion 26 of semi-circular contour adapted to complement the portion 18 and receive the lower half of the crankshaft bearing 19.

The crankcase web 15, and its co-operating cap member 24 are each provided with oppositely disposed aligned holes 27 in which tension members 28 are disposed. These members 28 have a main body portion of a diameter to fit the holes 27 and extending through the cap 24 into the webs 15, thus serving as dowels to positon the cap member against longitudinal and lateral displacement with respect to the web 15. They are also provided with a reduced neck portion 29 of a diameter less than that of the hole 27 and are threaded at their upper ends, beyond the neck portion 29, on a portion having a diameter substantially equal to the main body portion of the bolt. By means of this construction the localization of stresses in the threaded portion of the bolt 28 is avoided, the neck portion 29 being adapted to yield in elongation before the bolt will break or the threads thereof be stripped. The lower ends of these bolts are provided with suitable heads 31 adapted to bear against washers 32 which are seated on small inclined shoulders or faces 33 formed at the lower end of the cap member 24. The upper ends of the bolts 29 extend through the' crankcase 15 and are fitted with nuts 34 adapted to coact with the threaded portion 30 thereof and to seat on the outer face of the crankcase. By means of these nuts tension can be placed on the bolts in such a manner as to draw the co-operating faces 17 and 25 of the web and the cap member respectively tightly into engagement and thereby clamp the crankshaft bearing 19 firmly there between. The nuts 34 may be provided with any suitable locking means such as the lock nuts 36 if desired.

It will be observed that by reason of the disposal of the webs' 15 between adjacent cylinders in either bank, the ends of the bolts 28 project through the upper face of the crankcase 11 at points between such cylinders, as clearly shown in Fig. 3, so that there is plenty of room for the application and removal of the nuts 34. For this purpose, and to provide a good square seat, the base flanges 37 of the

cylinders

12 and 13 comprising the cylinder banks, which are preferably secured to the -crankcase 11 by means of studs 38, may be cut away adjacent the nuts 34 as indicated at 39 in Fig. 3. It will likewise be noticed that the arrangement of the bearing ca 24 and its support bolts 28 in no Wise inte eres with the lubrication of the bearing 19, which 1s preferably effected through suitable ducts 41 formed in the flanges 15 and communicating with a conduit 42 disposed longitudinally of the crankcase 11.

In Figs. 1 and 4 are illustrated a modified arrangement of the bearing support above described, which is especially adapted for use at the reduced end 43 of the crankcase 11, which is adapted to house a thrust bearing 44 at either or both ends of the crankshaft 21. In this arrangement a shoulder 45 is formed on the crankcase web 46, which is of less size than the webs 15, and this shoulder 45 is adapted to form a seat for a nut 47 on the end of a tension member 48. The bolt 48 is disposed in the web 46 and its co-operating bearing cap 49 in a manner similar to that which the bolt 28 is disposed in the web 15 and its co-operating cap 24.

It will be readily seen that the bearing cap support 24 forms a beam member carried at lts outer ends by the bolts 28 and loaded intermediate its ends by the crankshaft 21, and that this beam is wider at its upper than at its lower portion, the supports being located almost directly under the load. In this way the bending moments on the member 24 are reduced to a minimum and the stiffness of this part is greatly increased.

It will also be apparent that the loads caused by the firing of the

cylinders

12 and 13 are taken in almost direct tension on the bolts 28, the loads shifting from one bolt to the other as the cylinders fire alternately in the respective c linder banks.

It will be un erstood that various forms of the invention other than those described may be used without departing from the spirit or scope of the invention.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent, is:

1. The combination in an internal combustion engine having a crankcase and banks of cylinders thereon of Webs arranged transversely of the orankcase, a cap member in the vertical plane of each web, a bearing supported between each web and its cap member and oppositely inclined bolts passing through each cap member and web parallel to the respective cylinder banks, said bolts having LIONEL M. WOOLSON.