US2251696A - Piston expander and method of installation - Google Patents

Description

All@ '5, 1941- R. M. ULRICH l n 2,251,696

l PISTON EXPANDER AND METHOD OF INSTALLATION I Filed April 26, 1938 2 Sheets-Sheet l Aug. 5, 1941. R. M. ULRICH PISTON EXPNDER AND METHOD OF INSTALLATION Filed April- 26, 1938 2 Sheets-Sheet 2 Wm M d. w H @u Patented vAusg. 5, 1941 PISTON EXPANDER AND METHOD OF INSTALLATION Raymond M. Ulrich, Shelbyville, Ill., assigner to Alois W. Graf, Strasburg, Ill.

Application April 26, 1938, Serial No. 204,272

S Claims.

My invention relates to piston expanders and method of installation, and more particularly to piston expanders which cooperate with the slot of the expansible piston skirt.

This application is a continuation in part of my copending application, Serial No. 48,312, filed November 5, 1935, and entitled Piston expander, now Patent No. 2,209,432, granted July 30, 1940, and Which is assigned to the same assignee as the present application.

Other features which are related to the present invention and the invention described in the above mentioned patent will be found in my copending applications, Serial No. 247,089, filed December 24, 1938 for the Method of and means for expanding piston skirts; and Serial No. 247,- 088, filed December 2l, 1938 for Piston drill guide block, now Patent No. 2,209,433, granted July 30, 1940, both of which applications were assigned to the same assignee as the present application.

Heretofore numerous piston expanders and expansible pistons have been proposed. Such devices, however, have often been characterized by a complex structure which necessitated lspecial machining of the pistons and special tools for the installations of such devices. It, of course, would be desirable to provide a simple piston expander suitable for pistons of various sizes and of different thicknesses of piston Walls which Would serve to produce an expansion fit within the piston cylinder without the use of special adjustable devices.

It is, therefore, an object of my invention to provide an improved piston expander and method of installation which will overcome many of the disadvantages inherent in the devices of the prior art and which will be simple and reliable in operation.

It is another object of my invention to provide an improved piston expander which can be installed in pistons without the use of special tools other than those usually found in automotive repair shops.

It is still another object of my invention to provide an improved piston expander and method of installation which Will produce the same degree of expansion fit within the piston cylinder in the case of thick Walled pistons as is the case in thin Walled pistons.

The novel features which I believe to be characteristic of my invention, are set forth with particularity in the appended claims. My invention itself, however, both as to its organization y and Imethod of operation, 'together with further `bearing surfaces and concave inner surfaces.

objects and advantages thereof, will be understood better by reference to the following description taken in connection with the accompanying drawingsl in which Figs. 1 and 42 lshow one embodiment of my piston expander; Figs. 3 and 4 show alternative embodiments of my piston expander; Fig. 5 shows an exterior view of the piston skirt provided with my expander; Fig. 6 shows a perspective view of my piston drill guide block; Fig. '7 shows the application of my drill guide block to the skirt of a piston; Figs. 8 and 9 explain the operation of the drill guide block in connection with thin walled pistons; Figs. 10 and 1l explain the operation of the drill guide block in connection with thick walled pistons; Fig. 12 shows a perspective view of an expander utilized in one method of preparing piston skirts for reception of my piston expander; Figs. 13 and 14 are explanatory of the operation of the method of producing an expansion lit, Where -there has been appreciable Wear of the piston skirt; and Figs. 15 and 16 show another embodiment of my piston expander.

Referring to Figs. 1 and 2 of the drawings, I have illustrated therein one embodiment of my piston expander comprising an arcuate shaped body member l preferably of spring steel, provided With a plurality of projections or lugs 2 in the proximity of the ends of the body l, and a projection or lug 3 at an intermediate portion thereof. The projections 2 near the end of the body l are cut back froms the extremities thereof so as to leave a flat rportion 4, the purpose of which subsequently will become apparent. The projecting members 2 and 3 are arranged substantially perpendicular to the plane of the -arc of the body of the expander, but preferably the the the the at a slight `angle to the perpendicular of plane, so that the 'curved outer 'portion of projections 2 and 3 form slight angles to right; and left of the line perpendicular to plane of the arc of the body l.

In Fig. 3 there is shown a'modification of my piston expander which is made of thinner material, and the projections thereof have convex In this figure those portions of the expander cor- Vresponding to portions in Figs. 1 and 2, have been given the sante reference characters together with the subscript a. In Fig. 4 a still further modification of my invention -is shown in which parts corresponding to the expander shown in Figs. 1 and 2 have been given similar reference characters together Ywith the subscript b, In this instance, however, the member In is arcuate in one direction to the greater portion of its length, and near each extremity thereof the member Ib is bent over in the reverse direction in a U shape. Thus, in this embodiment the hat portions of the expander corresponding to 4 in Figs. 1 and 2, and to is in Fig. 3, are now displaced to a point on the opposite side of the projection 2b as indicated by the flat surface 4b in the figure. 1f desired, the curvature of the body member Ib, may be made such that the projections 2b and 3b are in the same relative po-A sitions as the projections 2 and S oi" Fig. 1. Each of the projections in these tvvo figures is also placed at slight angles to the perpendicular to the plane of the curvature of the body members Ia and Ib.

Fig. 5 discloses a piston having an expansible skirt provided with a slot therein. The faces of the slot have indentations therein which have surfaces corresponding to sections of a cylindrical surface which are bounded by planes which are oblique angled to the axis of said surface. The expansible piston skirt 5 which is nominally provided with a slot 6 having indentations I on the faces thereof, is shown with an expander of the type disclosed in Figs. l and 2 arranged within the piston skirt 5, and having the projections 2 and 3 extending into the indentations 1. The

vflat end portions 4 of the body member I of the expander, serve as bearing surfaces adjacent the inside wail of the pist-on skirt, thereby preventing any possible change in the position or shape of the expander, due to temperature variations which would tend to cause the end projections 2 to extend through the wall 0f the piston an undesired amount. Flat portions 4 and the body 'member I, are therefore contiguous to the inside wall of the piston skirt.

It of course will be apparent that expanders of the type shown in Figs. 3 and 4, can likewise be utilized in a manner similar to that shown in Fig. 5. Due to the simplicity of the expanders, it will be found that the expander is adaptable to all types of pistons, regardless of the inside shape ofthe piston, with reference to strengthening struts and ribs. Y

Reference may now be had to Fig. 6, in which I haveshovvn'a piston drill guide block comprising an elongated body portion 8, having a concave rto maintain the block 8 in proper operative position on the piston skirt. The head member I2 bears against the ,inside surface of the piston skirt, While the at portion I3 is located between the. faces of the piston slot. The body portion 8 Vis furthermore provided With a plurality of drill bit guide openings 16, i I'I and I3 respectively, which are spaced apart and extend from the con- `cave face 9 through the block. The axis of each guide opening forms an acute angle with the ,perpendicularto the tangent of the curvature of the concave face 9 at the center line extending between the projections Ii!V and Il. The alternate axes of the openings I6, Il and I8 are so ,placed vto theY right and left of the center line, aso 'that driilibitsoperating Within the guides siderable Wear of the piston skirt, or Where it is Will produce indentations in the faces of the slot which are sections of a cylindrical surface which are bounded by planes which are oblique angled to the axis of the surface. Fig. 7 shows the drill guide block 3 in operative relation with respect to the piston skirt 5 and from this View it is apparent that the axes of the drill bit guide openings I and I8 are in the same plane, which is at an acute angle to the right of a plane perpendicular to a plane tangent to the curvature of the piston skirt at the slot whereas the axis of the driil bit guide opening H, is in a plane Which is at an acute angle to the left of the plane perpendicular to a plane tangent to the curvature of the piston skirt 5 at the slot.

Thus from Fig. 5 it will become apparent that the axes of the surfaces of the indentations on the one face of the slot 6, which are engaged by the projections 2 of the expander, are at an acute angle to the axis of the surface of the indentation on the opposite face of the siot 6, which is engaged by the projection 3 of the expander. By forming the operative indentation on one face of the slot in a piane at a slight angle to the plane of the radius of the piston skirt at the slot, and forming the other operative indentation on the opposite face of the slot in a plane at a slight angle to and on the other side of the plane of the radius of a piston skirt at the slot, the degree of expansive force exerted by the installed piston expander becomes proportional to the thickness of the piston skirt walls.

From Figs. 8 and 9 which are respectively sectional vieWs along the lines A-B and C-D of Fig 7 it will be seen that in a thin walled piston skirt the inside viev/` of the arcuate indentations in the faces of the slot would represent indentations in staggered relation so that if tangents to the indentations are drawn on the inside of the skirt parallel to the faces of the piston slot 6, they are spaced apart an appreciable amount. Thus in a thin Walled piston, skirt expanders of the type shown in Figs. 1, 2 and 3, do not exert as great a tension on the piston skirt, as Would be the case in thick walled piston skirts. Figs. 10 and 11 are sectional vievvs respectively along the lines A-B and C-D' of Fig. 7, in the instance Where thick Walled pistons are utilized. In this instance it will be apparent from the figures, that When vievved from the inside of the piston skirt7 the arcuate indentations will appear to be more nearly in line, and hence if tangents to the indentations are drawn parallel to the piston slot on the inside of the piston skirt, these tangents will be closer together than was the case in a thin walled piston. Thus an expander such as shown in Figs. 1, 2 and 3, when inserted in the indentationsv thus made, will exert a greater force on a thick Walled piston than on a thin walledY piston. The angles at which the drill bit guide openings l5, I7 and I8 have been arranged, are so chosen that any expander of the types shown in Figs. 1, 2, 3, 4, 15 and 16 will always produce the proper biasing effect against the slot faces at the indentations, to produce the proper expansion fit of the piston within the piston cylinder. From this it is apparent that a single type of piston expander, .produces the proper lexpansion in both thin Walled and thick Walled piston skirts. Thus no compensation or adjustment is required on the part of the person installing these expanders, to provide for the variation in the thickness of vpiston jIn vsome ,instances Wherethere has been condesired to obtain a tighter expansion t of the piston Within the cylinder, a somewhat different method of preparing the piston and installing the expanders may be utilized. In such case the piston is inserted in the piston cylinder and eX- panded by means of an auxiliary expander, so that theproper fit of the piston skirt is obtained. Such an auxiliary expander is disclosed in Fig. 12, and it comprises a base or support member i9, supporting at either extremity thereof one of a pair of levers 2U and 2| which are each pivoted at one end. The inside or adjacent surfaces 22 and 23- respectively of the levers 20 and 2|, comprise cam surfaces which are actuated by an actuating means 24 which is supported by the adjusting means or screw 25, which is located at an intermediate point in a support member I9. When the unexpanded piston is inserted into its cylinder as shown in Fig. 13, it will be apparent that there is considerable clearance between the skirt and the cylinder Walls. Obviously, of course, for the purpose of clear illustration, this has been greatly exaggerated in the drawing. Fig. 14 shows how the expander shown in Fig. 12 has been inserted within the piston skirt, and adjusted so as to expand the skirt sufficiently to contact the cylinder walls to form a snug expansion fit. The expanded piston is then removed from the cylinder, and a drill guide block shown in Fig. 6 is applied to the slot of the piston in a manner shown in Fig. 7. Since the piston skirt has been expanded by the auxiliary expander, it will be apparent that the indentations made by the drill passing through the drill guide block, will be much less in the faces of the piston slot than would be the case if the piston had not been expanded by the auxiliary expander. After the drill bits have been passed through the drill guide block and the indentations formed in the faces of the piston slot, the auxiliary expander and the drill guide block are removed, and a piston expander of any of the types shown in the drawings, is inserted on the inside of the piston skirt. This will then expand the piston to such degree, as to maintain substantially the same type of expansion t within the cylinder wall as was obtained by the auxiliary expander.

In Figs. and 16 there is shown a further modification of my piston expander, having an arcuate shaped body member 26, provided with a plurality of projections or lugs 21, 28 in the proximity of the ends of the body member 26, and a projection or lug 29 at an intermediate portion thereof. The projections 21 and 28 near the ends of the body member 26, are set back from the extremities thereof, so as to leave flat bearing portions 3l). The body portion 2B, as will be apparent from Fig. 16, has a greater mass at the center than near the ends, so as to distribute the stress evenly, thereby increasing the flexibility and elasticity of the expander.

While I have shown and described my invention in connection with certain specific embodiments, it will, of course, be understood that I do not wish to be limited thereto, since it is apparent that modifications may be made in the instrumentalities employed, without departing from the spirit and scope of my invention as set forth in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The combination with a piston having in the expansible skirt thereof a slot provided with indentations on the faces of said slot, said indentations comprising concave cylindrical surfaces the axes of which are in planes at acuteangles to each other and to the plane of the radiusof the piston skirt at the slot, a spring expansion member located within said skirt and being provided with a plurality of projections engaging said indentations, said projections each havingv an arcuate-surfacev at such an angle that a substantial portion of said arcuate surface is in contact with said surface of said indentation of said slot.-

2. The combination of a piston skirt having, a slot therein, at least three indentations inthe faces of said slot, said indentations each having al surface comprising a section of a cylindrical surface, the axis of an indentationl on one face of the slot being at an acute angle to the axis of an indentation on the opposite face of the slot, thereby to predetermine the degree of force to be exerted by the expander, an expander cooperating with said slot and comprising a spring body member provided with a plurality of members projecting into said indentations, at least two of said projecting members engaging indentations on one side of said slot and at least one member 'engaging an indentation on the other side of said slot.

3. The combination of al piston skirt having a slot therein, at least three indentations in the faces of said slot, said indentations each having a surface comprising a section of a cylindrical surfacey the plane of the axes of the indentations on one face of the slot being at an acute angle to the indentation on the opposite face of the slot, thereby to predetermine in accordance with the thickness of said skirt the degree of expansive force to be exerted by the expander, an expander located in the proximity of said slot and comprising a spring body having a projection near each extremity of said body and a projection at an intermediate portion thereof, said end projections engaging indentations on one face of said slot and said intermediate projection engaging an indentation in the opposite face of said slot.

4. The combination of a piston skirt having a slot therein, at least three indentations in the faces of said slot, said indentations each having a concave surface comprising a section of a cylindrical surface, the plane of the axes of the indentations on one face -of the slot being at an acute angle to the indentation on the opposite face of the slot, thereby to predetermine in accordance with the thickness of said skirt the degree of expansive force to be exerted by the expander, an expander cooperating with said indentations andv comprising a spring body provided with a plurality of members projecting into said indentations, at least two of said projecting members engaging indentations in one face of said slot and at least one projecting member engaging an indentation on the other face of said slot, said projections having convex engaging surfaces each comprising a section of said cylindrical surface.

5. The combination of a piston skirt having a slot therein, at least three indentations in the faces of said slot, said indentations being arranged in alternate planes at slight angles to the plane of the radius of said piston skirit at said slot, an expander `cooperating with said piston skirt slot and being arranged inside said skirt, said expander comprising a spring body member provided with a plurality of members projecting into said slot, at least two of said projecting members engaging some of said indent-ations on one side of said slot and the remaining memofv said slot..

6. nThe combination with a piston having in theA other side Vthe expansible skirt thereof a slot provided with .indentations on the faces of said slot, said indentations comprising concave surfaces Which are sections of a cylindrical surface, the axis of an indentation on one face of the slot being at an acute angle to the axis of an indentation on the opposite face of the slot, thereby to predetermine the degree of force to be exerted by the expander, a spring expansion member comprising a resilient curved body portion having a greater mass at its center than at its ends, a transversely disposed lug adjacent each end of said body and at an intermediate portion thereof, said expansion member being located within said skirt and said 'lugs engaging said indentations on the faces of said piston slot, said lugs each having an arcuate surface at such an angle that a substantial portion of said arcuate surface is in contact With the surf-ace ofthe indentations of said piston Slot.

. 7. The combination with a piston having in the expansible skirt thereof a slot provided With indentations onrthe faces of said slot, said indentations comprising concave surfaces which are sections of a cylindrical surface, the axis of an indentation on one face of the slot being at an acute angle to the plane of the radius ofthe piston skirt at the slot, and the axis of an indentation on the opposite face of the slot being ata like angle on the opposite side of said plane,

whereby 'the degree of expansive force to lbe exerted upon the piston skirt by an expander Willbe proportional to the thickness of said skirt, a spring expansion member located Within said skirt and having a body portion provided with a transversely disposed lug adjacent each end of said body, said lugs engaging said indentations, said lugs each having a convex surface at such an angle that it is complementary to the concave surface of said indentation.

8. The combination with a piston having in the expansible skirt thereof a slot provided with indentations on the faces of said slot, said indentations comprising concave surfaces which are sections of a cylindrical surface, the axis of an indentation on one face of the slot being at acute angle to the plane of the radius of the piston skirt at the slot, and the axis of an indentation on the opposite face of the slot being at a like angle on the opposite side of said plane, whereby the degree of expansive force to be exerted upon the piston skirt by an expander will be proportional to the thickness of said skirt, a spring expansion member located Within said skirt and being provided with a plurality of projections engaging said indentations, said projections being transversely disposed adjacent to the free ends of said expansion member, said projections each having a convex surface at such an angle that a substantial portion of said convex surface is in contact With the surface of said slot indentation.

RAYMOND M. ULRICH.

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