US3066449A

US3066449A - Engine foundation and mounting assembly

Info

Publication number: US3066449A
Application number: US777742A
Authority: US
Inventors: Jr Robert Cramer
Original assignee: Nordberg Manufacturing Co
Current assignee: Nordberg Manufacturing Co
Priority date: 1958-12-02
Filing date: 1958-12-02
Publication date: 1962-12-04
Anticipated expiration: 1979-12-04

Description

Dec. 4, 1962 R. CRAMER, JR

ENGINE FOUNDATION AND MOUNTING ASSEMBLY Filed Dec. 2, 1958 /3 INVENTOR.

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rates Fatent a B @fi'rte 3,tl 3,4- l9 ENGENIE FGUNDATEGN MQUNTING ASEEEMELY Robert Cranmer, l ra, Hales (Corners, Wis., assignor to Nordherg Manufacturing Company, Milwaukee, Wis

a corporation of Wisconsin Filed Dec. 2, W53, Ser. No. 777,742 1 (Iiaim. (Ci. 56-485) This invention relates to reducing the distortion in engine bedplates mounted on concrete foundations.

One purpose of the invention is to reduce the heat transfer between an engine bedplate and the foundation supporting the engine.

Another purpose is an engine foundation having air circulation passages therein to remove heat from be neath the engine.

Another purpose is a means for reducing engine foundation shear stresses caused by expansion of the foundation from engine heat.

Another purpose is a method of reducing the distortion of an engine bedplate due to expansion of the concrete.

Another purpose is an engine foundation adaptable for use with engines operating at higher temperatures.

Another purpose is an engine foundation in which the expansion due to engine heat is reduced.

Other purposes will appear in the ensuing specification, drawings and claim.

The invention is illustrated diagrammatically in the following drawings, wherein:

FIGURE 1 is a perspective view of an engine foundation block;

FIGURE 2 is a top plan view of an engine foundation block; and

FIGURE 3 is a partial lateral half section, on an enlarged scale, of the foundation shown in FIGURE 1, showing the engine foundation block with the engine secured thereto.

Referring now to the drawings and in particular to FIGURE 1, a generally rectangular foundation block in, usually made of concrete, may have flanges 12 projecting from opposite sides of the bottom to form a firm base for the foundation, although the flanges are not necessary. A centrally disposed longitudinal trench 14 has generally vertical side walls 15, and outwardly slanting side walls 16 which run into a shelf or ledge 18 below the top of the foundation block. One end of the trench 14 may open into a generally rectangular opening 2i which is adapted to receive a generator or the like fixed to one end of the engine. The generator opening is optional and forms no part of the present invention.

One or more lateral bores or holes 22 extend through the foundation block and communicate with the longitudinal trench 14. Vertical holes 22a extend downwardly from the trench 14 and communicate with holes 22. This is clearly shown in FIGURE 2. The holes 22 in cooperation with the trench 14 provide an air circulation means for heated air. The hot air rises from the holes 22 into the trench 14 and from there it flows out of the open end of the trench into the surrounding atmosphere. The holes are below the level of the trench so that the heated air may rise from the holes into the trench.

Interposes between adjacent holes are lateral slots 24 extending downwardly from the top and between opposite sides of the cement block. The slots 24 may terminate in a bore or hole 26 having a diameter slightly greater than the width of the slot. In the preferred form, the slots will extend downward from the top of the foundation a distance equal to one-half to one-third of the depth of the foundation. Satisfactory results have been obtained when the distance between adjacent slots or between a slot and the end of the block is generally equal to the depth of the foundation. However, the invention is not limited to either this depth of slot or this particular distance between slots and the dimensions given are only illustrative.

Referring now to FIGURE 2, sole plates 28, which are adapted to be interposed between the engine bedplate and the concrete foundation, have been shown as divided into three longitudinal sections, each of which could correspond to a section of the concrete foundation formed by the slots 24. Suitable bolts or the like, indicated generally at 39, may be used in mounting an engine bedplate 33 to the sole plates and to the concrete foundation. As seen in both FIGURES 2 and 3, shims 31 are interposed between the bedplate and the sole plate. In the preferred form, the width of the shims will constitute between ten to twenty-five percent of the length of the bedplate. This will keep heat transfer between the bedplate and the sole plate at a minimum. As shown clearly in FIGURE 2, the shims may be placed on either or both sides of the bolts or, in some instances, it may be desirable to place an additional shim between adjacent bolts.

Referring now to FIGURE 3, the details of the engine mounting are shown. A first wedge 32 is mounted on the shelf 18 of the concrete foundation. A second wedge 34 is mounted on top of the first wedge, the two cooperating to form a level surface for the sole plate. The height of the two wedge members may be varied by moving the second wedge member laterally on the upper surface of the first wedge member. The sole plate 28 is placed on top of the second wedge member, and the shims are placed on top of the sole plate.

Any suitable means may be used for levelling, and as such this does not constitute a necessary part of the invention. Any method may be used for initial alignment.

The bedplate 33 is sea ed upon the shims with its center extending down into the trough 14. The bolts 30 pass through the bedplate, sole plate, between the wedge members and down into the concrete foundation. After the sole plate has been laid on the wedges, grout, indicated at 35, is poured around the sole plate and wedges. The grouting material is usually a non-reinforced concrete which is quite rich in cement. It should be noted that the grout does not contact the engine bedplate. This reduces heat transfer from the engine to the foundation.

In some foundations it is also desirable to use retaining blocks 35 which fasten to the sole plate at the corners of the engine. These blocks are an additional means for preventing movement of the engine and for initial positionin of the engine.

The invention is not restricted to any particular type or style of engine but may be used with diesel, dual fuel or gas engines or others, whether supercharged or not, twocycle, four-cycle, etc. However the problem arises primarily in connection with engines having long bedplates.

The use, operation and function of the invention are as follows:

In recent years the temperatures of engines have been increasing due to supercharging, more horsepower, cost of cooling equipment, and other factors. For example, older types of engines operated with bedplate temperatures of 120 degrees F. at full load. Assuming an ambient temperature of F. the rise in bedplate temperatures was about 40. In present engines the full load bedplate temperatures may reach 180 F. or higher. Again assuming an ambient temperature of 80 F. this gives a rise in bedplate temperature of F. from starting to full load. The increase in temperature has caused increased distortion in the bedplate due to more expansion of the bedplate and corresponding increased expansion of the concrete foundation upon which the bedplate rests. Ac-

asses-as cordingly, it is a purpose of this invention to minimize or reduce the distortion in engine bedplates.

In engine mounting structure the bedplate is sometimes mounted upon a sole plate, shims being placed between the sole plate and bedplate to level the engine. Quite often the bedplate is grouted directly. In any event, if a sole plate is used, it may be placed on wedges which in turn are placed on a concrete foundation. There is usually heat transfer from the bedplate to the concrete through the grout. The coefficient of expansion of steel or cast iron, which is usually used to form the engine bedplate, is approximately 6 per degree F., and the coelficient of expansion of concrete is approximately 8 lO per degree P, so that a corresponding increase in temperature of the concrete and the bedplat will give a greater expansion in the concrete than in the steel. This causes distortion in the steel or cast iron bedplate. There is another form of distortion in the concrete itself. Concrete is a poor conductor of heat. Therefore the lower layers of the concrete foundation will be at a lower temperature than the upper portions which are adjacent the engine and bedplate. This temperature differential in the concrete foundation will cause high shear stresses to be set up within the foundation, and will deflect the concrete block upwards at the middle of its length.

In order to both reduce the distortion of the engine bedplate and the shear stresses in the concrete foundation, I have placed a plurality of lateral slots in the foundation. These slots will divide the top of the foundation into longitudinal segments. Each of these concrete segments will expand when the temperatures are raised, but the expansion of each segment Will be a fraction of the expansion of a foundation without slots. The amount of expansion of each segment will depend on the number of slots. For example, if there were two slots, each section would have an expansion equal to one-third of the expansion of a similar member without slots. By reducing the amount of the expansion of each part of the concrete, the cumulative shear stresses in the concrete and the upward deflection are reduced.

The sole plates may be divided for ease of installation, and if desired the sole plates may be made to correspond to the sections of the foundation so that expansion in these plates will be similarly reduced. By seotionalizing the concrete, and sole plates, if desired, the expansion of the bedplate will more nearly correspond with the ex pansion of the corresponding segment of concrete. This will cut down the amount of distortion in both the sole plates and bedplate.

In order to form the slots described above, I use a split pipe with Cellotex soaked in asphalt placed in the open slot of the pipe. Or I may use any suitable material such as used by building contractors for expansion joints. The concrete is then cast around the pipes and the material to complete the structure. The material and pipes, which remain in the concrete after it is cast, are compressible so that when the sections of concrete expand they will not be restricted.

In the prefered form, the depth of the slots is from one-half to one-third of the total depth of the concrete foundation, and the longitudinal distance between slots is generally equal to the depth of the concrete. Although this form of construction has been found to give satisfactory results, the invention is not limited to these dimensions.

Another method of decreasing the distortion in the bedplate and shear stress in the concrete is to reduce their temperatures. This can be done by providing a means for ambient air to circulate through and beneath the bedplate. For example, I provide a plurality of holes or bores extending through the concrete foundation and communicating with the trench. The holes being beneath the trench provide a chimney-like effect in that hot air from the hole is drawn up into the trough or trench and from there flows out of the open end of the trench into mounted.

the atmosphere. The air flow will cause a continuous circulation of air underneath the engine and will have a cooling effect on the 'bedplate and concrete foundation.

An additional way to decrease the distortion of the bedplate and the shear stress of the concrete is to reduce the heat transfer from the bedplate to the concrete. In the usual engine foundation, shims are placed between the bedplate and the sole plate to level the engine when it is Usually these shims extend the length of the sole plate and bedplate. in my mounting structure, however, the shims are made into a plurality of small members so that the heat transfer from the bedplate to the sole plate will be greatly reduced. For example, shims can be placed on either side of the mounting bolts and if desired additional shims can be placed between adjacent bolts. The total area of the shims should be from ten to twenty-five percent of the total area of the sole plates. This will cause a decrease in the heat transfer from the bedplate to the sole plate, and a corresponding decrease in the temperature of the concrete foundation. An additional advantage of the spaced shims is that this construction provides air passages between the bedplate and sole plate, these air passages connecting with the iongitudinal trench in the concrete foundation. This will provide additional means for the passage of heated air from underneath the engine.

There are many modifications, alterations and substitutions possible without departing from the scope of the invention. For example, the drawings show a plurality of slots and holes in the concrete foundation, but the number of slots and holes should depend upon the length of the foundation. A shorter foundation may require only one hole and one slot, whereas longer foundations require a plurality of slots and holes. Also the drawings show a shim placed on each side of the mounting bolts and an additional shim placed between adjacent bolts. However, the exact number and position of the shims is not essential to the invention, as the important point is that the total width of shims be much smaller than the length of bedplate.

As the specification and drawings are broadly illustrative and diagrammatic, the invention should only be limited by the following claim.

I claim:

Means for mounting an engine which, in operation, generates a substantial amount of heat, said mounting m ans being designed to prevent distortion caused by the engine heat and including a monolithic concrete foundation having a centrally disposed longitudinal trench, a plurality of slots extending between opposite sides of said foundation and downwardly from the top thereof to a level below the longitudinal trench, said slots dividing that portion of the concrete foundation adjacent the engine into sections to reduce the heat expansion stresses in the concrete caused by differential co-efficients of expansion of the concrete and metal engine parts, the distance be tween adjacent slots being generally equal to the depth of the foundation and the depth of said slots being generally equal from one-half to one-third the depth of the foundation, a plurality of generally horizontal holes extending between opposite sides of said foundation and positioned below the level of said trench, said holes being positioned between adjacent slots, a plurality of vertical holes in said foundation, one connecting each horizontal hole with said trench, said holes and trench forming an air circulation path so that engine heat may be dissipated to the atmosphere, a sole plate positioned on top of said foundation, means for adjusting the position of the sole plate relative to the foundation, a plurality of relatively narrow shim members intermittently spaced on the sole plate providing substantial air space between the sole plate and an engine bed plate generally co-extensive with the sole plate and seated on the shim members, the air space between adjacent shim members providing an air circula;

5 6 tion path in cooperation with the trench for dissipating 2,535,691 Miller Dec. 26, 1950 engine heat. 2,568,783 Woodrufi Sept. 25, 1951 2,709,571 Mafera May 31, 1955 Reference. Cnted 1n the file of th1s patent 2,842,955 Pedersen July 15' 1958 UNITED STATES PATENTS 5 596,280 Short Dec. 28, 1897 FOREIGN PATENTS 687,106 Anderson Nov. 19, 190 735,068 Great Britain 9