US2266192A

US2266192A - Wrist pin construction

Info

Publication number: US2266192A
Application number: US283689A
Authority: US
Inventors: Grieshaber Emil
Original assignee: Nordberg Manufacturing Co
Current assignee: Nordberg Manufacturing Co
Priority date: 1939-07-10
Filing date: 1939-07-10
Publication date: 1941-12-16
Anticipated expiration: 1958-12-16

Description

Dec. 16,1941.

E. IGRIEISHABER 2,

WRIST PIN CONSTRUCTION Filed July 10, 1939 I 3 Sheets-Sheet l 6mm BB J (Ittornegs Dec. 16, 1941. E. GRIESHABER WRIST PIN CONSTRUCTION Filed July 10, 1939 3 Sheets-Sheet 2 Patented Dec. 16, 1941 WRIST PIN CONSTRUCTION Emil Grieshaber, Milwaukee, Wis., assignor to Nordberg Manufacturing Company, Milwaukee, Wis., a corporation of Wisconsin Application July 10, 1939, Serial No. 283,689 6 Claimsc1. 309-15) This invention relates to reciprocating engines and particularly to piston and wrist-pin constructlons intended primarily for use in Diesel en- Engines of this type have commonly been constructed with trunk pistons, in which the wrist pin is mounted in the piston proper. In such case, the piston performs also the functions of a. cross-head. In some cases, however, it is desirable to use a cross-head and guides distinct from the piston. The wrist pin constructions heretofore used for these two types of engine have been quite distinct, each being affected markedly in design by the environment in which it is used.

The present invention is based on the concept that substantial manufacturing economies can be eflfected when a manufacturer produces both types of engine, by producing a standardized wrist pin construction capable of use with either type of engine. To do so is not a simple problem, because loads are heavy, the space limitations are severe (particularly in a. trunk piston), accessibility is essential, and means must be provided to supply through the wrist pin the cooling fluid (oil) required by the piston head. bviously, a heavily loaded wrist pin must be manufactured with precision and hence isan expensive component. Standardization of design thus results in unusual savings of cost and reduces the risk of failur because the performance of a standardized design is predictable after adequate standardizing tests.

A preferred embodiment as applied to trunk pistons and to cross-heads will now be described by reference to the accompanying drawings, in which:

Figure 1 is an axial section through a trunk piston having the invention incorporated. The plane of section is on the axis of the wrist pin.

Figure 2 is a similar section, the plane of section being normal to the axis of the wrist pin.

Figure 3 is a section on the line 3-3 of Figure 1.

Figure 4 is a section on the line 44 of Figure 2.

Figure 5 is a section on the line 5-5 of Figure 1.

and connected piston. The wrist pin and connecting rod are identical with corresponding parts in Figures 1-6. I v

Figure 9 is a section (drawn on a somewhat enlarged scale) showing the piston and wrist pm of Figure 8. The section is on the plane common to the axis of the piston and the axis of the wrist pin.

Referring first to Figures 1 to 7, inclusive, the.

trunk piston is comprised of two major components, a head portion II, and a main sleeve portion l2, the head portion ll having ring grooves l3 for the usual piston rings, and the sleeve portion having grooves M for other rings which usually are oil scraping rings.

A circular shoulder is formed at l5 to center the head and the sleeve, and these are held to- Figure 6 is a perspective view of the wrist pin.

gether by six studs it, two of which appear on the plane of section of Figure 2. These studs are threaded into the head, extend through a thickened portion of the sleeve, and their ends are exposed in pockets l1. Two of these pockets appear in Figure 2, and all are clearly shown in Figure 4.

Within each pocket, a main nut l8 and a check nut is are applied to the studs. Since the piston is single acting, the load carried by the studs is not great.

Mounted in under-cut grooves in the circumference of the sleeve, there are wearing rings indicated generally at 2|, the provision of such rings being standard construction.

Extending across the sides of the interior of the sleeve l2, and bounded by parallel secant lines, are two lugs 22 against which the wrist pin indicated generally by the numeral 23 seats. These lugs are flat on their lower faces and deliver thrust directly to flattened end portions 24 of the wrist pin 23.

As is best shown in Figure 6, the wrist pin is of generally cylindrical contour having a cylindrical journal or bearing surface indicated by the numeral 25 in Figure 6 and having cylindrical ends conforming to the interior circumference of the sleeve l2 and indicated in Figure 6 by the numeral 26. In this way, a maximum seating area is secured at 24 within the limitation afforded by the internal dimensions of the sleeve l2. The wrist pin is fastened to the lugs 22 by four studs 21. Construction of these'studs and the nuts mounted thereon can best be explained by reference to Figure 7.

Each stud has a threaded end 28 and a flange 29, the threaded portion entering threaded holes gin frame with cross-head guide, cross-head in a corresponding lug 22,'the flange 29 being seated in a countersink formed in the latter. Below the flange 29, each stud is relieved and then enlarged at 3| to form a centering element for aligning the wrist pin. Below the portion 3| there is a short taper leading to reduced portion 32. At a distance corresponding to the thickness of the end portion of the wrist pin, the stud is provided with threads 33 to receive a sleeve nut 34. This nut is elongated as shown and terminates in a hexagonal wrench grip 35. Beyond the threads 33, the stud is further reduced and its end is threaded as indicated at 36 to receive a check nut 31. The use of the sleeve nut 34 brings the wrench grip 35 below the journal surface 25 of the wrist pin and near enough to the lower end of the skirt I2 to permit it to be reached by an extension socket wrench. It is contemplated that a special wrench will be made for tightening these sleeve nuts and another for tightening the check nuts 31.

It will be observed that the studs are symmetrically arranged in the plane of the flattened end portions 24 and the arrangement is such as to facilitate assembly and to avoid the transmission of bending stresses to the studs.

The connecting rod which is generally indicated by the numeral 38 is provided with a hearing bushing 39 pressed to place and held by a cates with annular channel 60. Below this is a second annular channel 6| formed as an internal groove in the head II. The channel 6| and the lower portion of channel 66 encircle the enlargement 56 of the hollow filler piece 55. The channel 60 communicates with the channel 6| by means of a tube 62 pressed into the intervening flange. The top of tube 62 is located close to the top of channel 60 so that the spiral passage and passage 60 must substantially fill with oil befor discharge commences.

The path of oil circulation is as follows:

Oil flows upward through the port 42 and through the port, 43, groove 44 and port 46, to

' tube 52, t0 tube 5|.

staking screw 4i (see Figs. 1 and 2) Connecting rod 38 has an axial bore 42 which, in accordance with past practice, receives oil under pressure from the crank pin (not shown). From the bore 42, a drilled port 43 leads to a groove 44 in the inner face of the bushing 39, and this groove communicates with an axial bore 45 in the wrist pin 24 by means of a drilled port 46. The ends of the bore 45 are closed by threaded plugs 41 (see Figs. 1 and 6).

As best illustrated in Figure 5, the holes formed in the ends of the wrist pin 24 to receive the studs 21 do not enter the bore 45. A drilled port 48 leads from the bore 45 and communicates with a drilled port 49 in the left-hand lug 22 of Figure 1. A. drilled port similar to the port 48, but larger, is formed in the other end of the wrist pin and extends clear through the end of the pin. It is, however, isolated from the bore 45 by tube 5|, pressed to place and making a fluid-tight connection with the wrist pin. The tube 5I is clearly shown at th right of the wrist pin in Figure 1, and also in Figure 5. The tube 5i is in direct communication with a tube 52 of the same diameter, pressed to place, in bores formed in the sleeve I2 (see Figure 1).

. Formed integrally with the sleeve I2 and extending upward from the bosses 22 is a conical barrier open at its center and indicated by the numeral 53. Mounted on the upper margin of the barrier 53 and connected thereto by machine screws 54 is a cup-shaped filler piece 55 having an enlarged upper end 55 and a diagonal tubular passage 51 formed integrally therewith, and arranged as shown in Figures 1 and 2. This filler piece coacts with flanges and ribs formed on the interior of head II, and with portions of sleeve I2 to form oil chambers and passages through which oil is circulated.

The head ii is of generally cup-shaped con figuration and the enlarged head 55 on the member 55 lies within the head II. On the inner face of the head II is a spiral baffle indicated at 58 and arranged to provide, in filler piece 55, a spiral passage 59 with theinner end of which the tubular duct 51 communicates. The spiral passage 59 at its outer end communiconjunction with the bore 45 of the wrist pin. Thence it flows through the

ports

46, 49 to the annular space 56 within the sleeve I2 aroundthe lower portion of the filler 55. From this annular space, the oil flows through the tubular passage 51 to the inner end of the spiral passage 59 and thence through the spiral passageto channel 60 through the tube 62, thence through channel 6| to the The tube 5| discharges through the lower end of the piston directly into the crank case (not shown). It follows that the circulating oil not only lubricates the wrist pin but also flows through the upper part of the piston skirt and then in a sinuous path through the piston head, ultimately discharging back to the crank case from which the circulating oil is drawn.

In Figures 8 and 9, a modified construction is shown which, however, uses certain components used in Figures 1 and 2. Where the components are the same, the same reference numerals are used in Figures8 and 9. Other components are given distinctive numerals. The cylinder head portion II is the same as in Figures 1 and 2 and is provided with ring grooves I3 as before. It has the annular groove passage 6|, channel 60, spiral rib 56, spiral passage 59, and connecting tube 62. These'passages are completed by an inserted cup I56 which performs th same function as the enlarged head 56 shown in Figures 1 and 2.

The sleeve portion II2 of the piston is ribbed on its inner surface as indicated at H4 and has no ring grooves. It is connected by the studs II6 (see Fig. 8) with a cross-head indicated at H. 'I'he*crcss-head is guided in the cross-head guide 12 which is carried by a portion of the engine frame 13. The particular form of the cross-head guide and engine frame are not material, but are clearly indicated in the drawings.

The cross-head H is formed with two parallel shoulders I22, functionally similar to the lugs 22 in Figures 1 and 2. Mounted against these lugs is the wrist pin 23 which is identical with the wrist pin shown in Figures 1 and 2. It is associated with connecting rod 36 which may be identical with and, in any event, is functionally identical with the connecting rod shown in Figures 1 and 2. This being the case, there is an axial bore 42, port 43, groove 44, axial bore 45', port 46, and plugs 41, port 48 and inserted tube 5I. is functionless, as hereafter explained.

The port 46 communicates with a port I49 in the cross-head, and this is connected by a pipe I51, to a passage leading through cup I56 to the inner end of the spiral passage 59 in head I I.

The discharge port .from channel 6I which in the embodiment of Figures 1 and 2 communicates with the pipe 52, in Figures 8 and 9 communicates with a port in the sleev II2 with which In this environment, however, the tube 5| is connected a pipe I52. The lower end of pipe I52 communcates with a passage I53 in the second lug I22 on the cross-head. The lower end of the port I53 is closed by a screw plug I54,

and the port has a lateral discharge leading to' an elbow I55.

The elbow I55 carries a discharge pipe I56 whose end is housed within the pipe I51 leading to the oil-sump of the engine.

It follows that assuming a cylinder bore of given size, the piston head component, the wrist pin, and, in certain cases, the connecting red, are interchangeable and may be manufactured to a single standard for use in either type of engine.

It is deemed unnecessary to trace the circulation of oil with reference to Figure 9 because it follows very closely the circulation characteristics of Figures 1 and 2, and the only difference is that ther is no chamber corresponding to the chamber 50 (Figs. 1 and 2) so that the piston is not charged with oil through any portion of the skirt II2. Instead, the cooling circulation is confined to the head I I.

The purpose of the design is to secure the maxi- 'mum practicable seating area at 24, for a wrist pin of a maximum practicable diameter. On these dimensions the trunk-type piston imposes the closest limitations, but since the effective piston area is the same whether or not a crosshead is used, any wrist pin which will withstand the stresses encountered in one type of engine will be adequate to withstand similar stresses encountered in the other. Y

The studs 32 hold the parts in assembled relation, but since the piston. is single-acting, the studs never transmit the working thrust developed upon the piston head.

The use of the elongated sleeve nuts 34 makes these accessible, even in the trunk piston, and ,it is highly advantageous to be able to use the same studs, nuts andvcheck nuts in both types of engine, because, as in the case of the wrist pin, standardization results in predictable performance.

When used with trunk pistons, the invention has the advantage that no part of the wrist pin extends through sleeve I2, nor does it require any opening to be formed in that sleeve. The wrist pin may be dismounted and reconnected while the piston is in the cylinder which is a great advantage from the maintenance standpoint, because it permits the connecting rod to be dismounted without pulling the piston and permits the piston to be pulled through the head end of the cylinder without dismounting the connecting rod. This permits reduction in the height of the engine room, because it is necessary to provide space to pull only the piston, not as heretofore the piston and connecting rod.

The arrangement here disclosed to secure the cylinder whose diameter is somewhat less than i the diameter 'of the piston head and whose axis is coincident with the axis of such head, the end portions of said wrist pin being cut away to afford seats for engaging said parallel lugs, said wrist pin having an oil passage leading through it from the journal surface to one'of said seats in position to register with the passage in the corresponding lug; threaded connections engaging saidlugs and the end of said pin; and a connecting rod including a bearing joumaled on said pin and having an oil passage leading to said bearingand communicating with the oil passage in said wrist pin 2. The" combination of a trunk piston includ-' 'ing a head and a guiding sleeve forming a reciprocating unit, there being an oil circulating passage in the head and wrist, pin supporting lugs in the sleeve, said lugs being formed with passages which communicate with opposite ends of the passage in the head; a wrist pin having a cylindrical journal at its mid-portion and rounded ends which are portions of a ,right cylinder whose diameter approximates the internal diameter of the sleeve with which it is co-axial, the end portions of said wrist pin being cut away to afford seats for engaging said lugs, said wrist pin having an oil passage leading through it from the journal surface to one of said seats in posiing a bearing journaled on said pin and having maximum possible dimensions of wrist pin within an oil passage leading to said bearing and communicating with theoil passage in the wrist pin. 3. A wrist pin for use with pistons of the oil cooled type, comprising a member having a cy1indrical journal for a connecting rod at its midportion and rounded ends which ends are portions of a right cylinder whose diameter does not exceed the 'internal diameter of a trunk piston for which the pin is suited, and whose axis is perpendicular to the axis of said journal, the end portions of said member being cut away to parallel planessecant to said cylindrical ends to afford seats for mounting the member, said member having an oil passage leading through it from the journal surface to one of said seats, and a distinct oil passage leading through the other end from the other of said seats, each of said passages terminating at the middle of the seat, and the pin having bolt holes, two in each seat located at opposite sides of the passage aforesaid.

'4. A wrist pin for use with pistons of the oil cooled type, comprising a pin having a cylindrical /journal for a connecting rod at its mid portion v I and rounded'ends, which ends are portions of a right cylinder whose diameter does not exceed the internal diameter of the piston for which the pin is suited and whose axis is perpendicular to the axis of said journal, the end portions of said pin being shouldered to form seats for mounting said pin in such piston, said pin having an oil'passage leading through it from its journal surface to one of saidseats, said'passage including'a bore substantially coaxial with'the journal surface of the pin and extending substantially from end to end of the pin but closed at each end, the pin having bolt holes out of communication with said axial bore.

5. The combination of a trunk piston comprising a head formed with a head cooling passage for oil, and a guiding sleeve having wrist pin supporting lugs wholly internal to the sleeve, one of said lugs being provided with a port connected with the entrance end of said cooling passage in the head; a wrist pin wholly internal to said sleeve and having seats at its ends for engaging said lugs, said pin having a journal for the connecting rod intermediate said lugs, said wrist pin'having an oil passage leading through it from the surface of the journal to that seat which engages the ported lug, said passage in the wrist pinincluding a chamber which extends nearly but not quite from end to end of the wrist pin; means for rigidly connecting the ends of said pin to the lugs within said skirt; a connecting rod including a bearing journaled on said pin; and means for supplying oil to the chamber in the wrist pin.

6. The combination or a trunk piston comprising ahead formed with a head cooling passage for oil, and a guiding sleeve having wrist pin supporting lugs wholly internal to the sleeve, said lugs being provided with ports connected with the respective ends of .the cooling passage in the head; a wrist pin wholly internal to said sleeve and having seats at its ends for engaging said lugs, said pin having a journal for the connecting rod intermediate said lugs, said wrist pin having an oil passage leading through it from the surface of the journal to one of said seats to communicate with the port therein, said passage in the wrist pin including a chamber which extends nearly but not quite from end to end or the wrist pin and the wrist pin having a second passage. distinct from the one just defined which communicates with the passage in the other lug; means for rigidly connecting the ends of said pin to the lugs within said skirt, and a connecting 'rod including a bearing journaled on said pin and having an oil passage leading to said bearing and communicating with the oil passage which leads from the surface of the journal.

' EMIL GRIESHABER.