US1510760A - Piston for fluid-pressure engines - Google Patents

Description

F. T. BURGESS PISTON FOR FLUID PRESSURE ENGINES Filed July 2'7. 1923 %ZJwz 444: @M #3444 Fatentfi Got. 7, i224.

UNET@ED STATS FREDERICK TASKER BURGESS, OF LONDON, ENGLAND.

PISTON FOR FLUID-PRESSURE ENGINES,

Application filed July 27, 1923. Serial No. 654,254.

I '0 all whom it may concern:

Be it known that I, FREDERICK TASKER BURGESS, a subject of the King of England, residing at London England, have invented certain new and useful Improvements in Pistons for Fluid-Pressure Engines, of which the following is a specification.

This invention relates to pistons for fluid pressure engines, and it has for its principal object to provide a construction which will have but small clearance at the skirt and thus will avoid piston slap, and also ensure an effective scraper action on the cylinder walls. A further object 'is to minimize transfer of heat from the head to the skirt.

In the accompanying drawings,

Figure 1 is a central vertical section, and

Figure 2 a horizontal section on the line 2-2 of Figure 1, illustrating one construction.

Figure 3 is a central vertical section, and

Fi re 4 a horizontal section on the line 4-4; of Figure 3, illustratingan alternative construction.

Like letters indicate like parts throughoutthe drawings.

In the construction shown in Figures 1 and 2, the web-portion is in the form of a hollow neck A of relatively small diameter where it unites with the crown B, but, with an easy sweep therefrom, it increases in diameter to unite with the skirt portion C, serving at the junction to stiffen the piston in bosses D thereon, and preferablymeet- 'mg the skirt at or near-the level of the piston pinraxis. In this way an annular channel E is formed between the neck and the adjacent edge of the skirt, and this edge is so formed as to have a scraping action which collects into the channel excess lubricant from the walls of the cylinder. Perforations .F ma be provided on the side or base of the c annel to allow the collected lubricant to pass to the working faces of the piston pin, and also to drain back to the sump.

p, e skirt of the piston is slit from end to end, in this case at two places G and H oppos'ite one another and between the piston pin bosses. These slits extend into the neck A, terminating in circular holes J drilled or cored in the neck'at .a point between the crown and the skirt. Thus the web A is divided into two parts and resilience is imparted to the opposite sides 0" and C of the skirt which carry the bosses D not merely for a part of its length but for the whole thereof, ensuring close contact with the cylinder walls and an avoidance of piston bevelled edge C and C so that a scraping action takes place both on instroke and outstroke of the piston.

The neck web portion A is made of small diameter and with thin sides and thus the passage of heat from the head ,to the skirt is minimized.

In the construction shown in Figures 3 and 4, the design is substantially the same, but the web portion, instead of beingoriginally of circular or similar contlnuous shape, is divided into two separate-webs A and A each of which unites with one skirt part. Thus the web A? unites with the skirt art C and the web A with the skirt part If desired, each web portion A or'A may be divided vertically into two parts one lying on each side of the gudgeon pin boss F. The web portions A and A may be curved as shown, or may be flat. According to the sectional shape the desired stiffness of the webs can be obtained, as it will be clear that where' the webs are of curved section they are stifier than where they are of flat formation.

Preferably in each case the webs A and A incline towards one another at the top, so that when the piston is under load the tendency is for the skirt parts C and C, to spread and to work closely in the cylinder bore.'

Although it has been stated that the skirt parts in both constructions are separated from one another, as by the slits H, .-m some designs, where the piston pin bosses F are low down, it might not be essential that the skirt portion should be slit from end to end, and I wish to make it clear that .my invention covers constructions in which the skirt is split substantially fromend to end so that t e desired separating efiect of the skirt side can be obtained.

Again, in some cases the skirt may be split-at a single point between the piston pin bosses, the skirt being still free to expand and the bosses to move towards and away from one another, as will be readily understood.

In the construction shown in Figures 3 and 4 the skirt is formed with a number of grooves C and oil holes'C whilst the edges C and C are so bevelled as to encourage theoil to flow alongthe'skirt and pass away to the interior through the grooves C and holes C. g

In manufacturing a piston of this kind in aluminium alloy, the skirt can be machined cylindrical to the exact bore of the cylinder, or with only a very small running clearance, such as is used with pistons having cast iron skirts. If the fit is too tight the skirt will contract slightly, but if too loose it will "expand,- and, during the firing stroke, and probably also during the compression stroke, when the loads are hi hest, the pressure on the crown causes the ower ends of the webs to tend to spread, so that any clearance is taken up and the skirt fits the cylinder the whole way round, ensuring distribution of the wear and absence of noise. In addition, it will be clear that there can be no slap or noise of the piston in the cylinder walls and that, in spite of the close fit, seizure of the piston is pre-' vented owing to its ability to yield inwards. Again, distortion of the skirt in the neighbourhood of the piston bosses is reduced to will fit worn or over-size cylinders, which is a-great saving in repair work.

What I claim as my invention and desire to secure by Letters Patent of the United States is I 1. In a piston, in combination, a crown, a separate expansible skirt having bosses for the piston pin, inclined webs connecting the crown and the skirt in such a manner that pressure on; the crown causes expansion of the skirt. I

2. In a piston, in combination, a crown,

a separate skirt divided into two parts by longitudinal slits, a piston pin boss in each part, a web portion connecting each part of the skirt to the underside of the crown, uniting with the skirt parts close to the piston pin bosses and forming the sole connection between the crown and skirt.

.3. In a piston, in combination, a crown, a separate two part skirt, a piston pin boss in each part, an inclined web portion connecting each part of the skirt to the underside of the crown and forming the sole connection between said parts.

4. In a piston, in combination, a crown,

a separate expansible skirt having bosses for the piston pin, inclined curved webs connecting the crown and the skirt in such a manner that pressure on the crown causes expansion of the skirt.

5. In a piston, in combination, a crown, a se arate skirt divided into two parts by longitudinal slits, a piston pin boss in each part, a curved web portion connecting each part of the skirt to the underside of the crown, uniting with the skirt parts close to thepiston pin bosses and forming the sole connection between the crown and skirt.

In testimony whereof I afiix my signature.

FREDERICK IASKIER BURGES.

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