US3920098A

US3920098A - Pressurized lubricating system for a reciprocating compressor drive

Info

Publication number: US3920098A
Application number: US419148A
Authority: US
Inventors: Walter Schroeder
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-03-03
Filing date: 1973-11-26
Publication date: 1975-11-18
Anticipated expiration: 1992-11-18

Abstract

A reciprocating compressor drive for driving a pair of opposed horizontally arranged compressor pistons. The pistons are carried by a pair of coaxial horizontal piston rods which are fixed to a crosshead situated between the piston rods and formed with a vertical slot receiving a slide block connected to a crank pin which is driven by a rotary crank drive. A pair of guide bars, which are parallel to the piston rods, extend through upper and lower bores of the crosshead, these bores carrying suitable bearings which slide along the guide bars. A pressurized lubricating system is provided for lubricating components such as the bearings which slide on the guide bars and the crank pin which is received in the slide block, the crosshead preferably being made of a light-weight material such as a plastic and carrying steel guide strips which slidably engage the slide block, the latter as well as the bearings which engage the guide bars preferably being made of bronze while the guide strips which engage the slide block and the guide bars which engage the bearings are preferably made of steel.

Description

United States Patent Schroeder 22 Filed:

[4 1 Nov. 18, 1975 PRESSURIZED LUBRICATING SYSTEM FOR A RECIPROCATING COMPRESSOR DRIVE Nov. 26, 197 3 21 Appl. No.:419,148

Related US. Application Data [63] Continuation-in-part of Ser. No. 119,478, March 1,

1971, Pat. NO. 3,779,672.

[30] Foreign Application Priority Data 308/238, DIG. 9, 493; 417/534, 535, 536; 74/44, 49, 50; 184/5, 100, 6

Primary E.\'aminer-Richard C. Pinkham Assistant ExaminerMarvin Siskind Attorney, Agent, or Firm-Steinberg & Blake [57] ABSTRACT A reciprocating compressor drive for driving a pair of opposed horizontally arranged compressor pistons. The pistons are carried by a pair of coaxial horizontal piston rods which are fixed to a crosshead situated between the piston rods and formed with a'vertical slot receiving a slide block connected to a crank pin which is driven by a rotary crank drive. A pair of guide bars, which are parallel to the piston rods, extend through upper and lower bores of the crosshead, these bores carrying suitable bearings which slide along the guide bars. A pressurized lubricating system is provided for lubricating components such as the bearings which slide on the guide bars and the crank pin which is received in the slide block, the crosshead preferably being made of a light-weight material such as a plastic R f C d and carrying steel guide strips which slidably engage 1 UNITE]; gszr fg LZ the slide block, the latter as well as the bearings which engage the guide bars preferably being made of 2,183,878 12/1939 Young 184/5 bronze while the guide Strips Which engage the Slide 3 block and the guide bars which engage the bearings 3:033:312 5/1962 Enders .1: 1:: 74/50 are preferably made of Steel 3,162,268 12/1964 Short 184/5 9 Claims, 4 Drawing Figures 3,779,672 12/1973 Schroeder 417/493 11 I 1 1 m111ll 30 flIIl/l 1 1 1 '11 1 1? end 1 i 2;

\1: 1111 $1 8 42 a4 44 v 28 H v I Ill-III" a EEITTITTAEVAR 7 luv lg WA, 2. 1. I "f 7 v r I "I I I" "QYA J 'lilllll,lllzl'l 36 l {4 6 V E J 4 Iili'AV/l US. Patent Nov. 18, 1975 Sheet 1 of3 3,920,098

US. Patent Nov. 18, 1975 FIG. 3

U.S. Patent Nov. 18, 1975 Sheet 3 of3 3,920,098

lllu PRESSURIZED LUBRICATING SYSTEM FOR A RECIPROCATING COMPRESSOR DRIVE CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of application Ser. No. 119,478, filed Mar. 1, 1.971, and entitled AIR COMPRESSOR, now U.S. Pat. No. 3,779,672.

BACKGROUND OF THE INVENTION The present invention relates to reciprocating drives, and in particular to reciprocating drives for compressors having horizontally arranged opposed pistons.

For certain purposes it is desired to arrange compresduly stressed. Also it is essential to provide parts which will not rapidly wear, so that a long operating life can be assured for drives of this type.

SUMMARY OF THE INVENTION It is accordingly a primary object of the present invention to provide a drive of the above type which will solve the above problems.

In particular, it is an object of the invention to provide a reciprocating drive, particularly adapted for opposed compressor pistons, capable of operating extremely high speeds without subjecting the components to excessive stresses or wear so that a long operating life is assured.

Furthermore it is an object of the present invention to provide for a drive of the above type alubricating system which will assure a long operating life.

Also it is an object of the present invention to provide for a reciprocating drive of the above type components made of materials which will contribute to a highly effective operation with minimum maintenance.

According to the invention the opposed compressor pistons are carried by a pair of horizontal coaxial piston rods fixed to a crosshead means which is situated between the piston rods and which is formed with a verti- 'cal slot. A slide block is received in this vertical slot and is operatively connected with a crank pin which in turn is connected to a rotary crank drive. The crosshead means is formed with upper and lower bores which are parallel to the common axis of the piston rods and which carry in their interiors bearings which surround and are slidable along a pair of guide bars carried by a housing means in which the guide bars as well as the crosshead means and the rotary crank drive are situated. A pressurized lubricating system is also carried by the housing means for lubricating such components as the crank pin and the bearings which slide along the guide bars.

BRIEF DESCRIPTION OF DRAWINGS The invention is illustrated by way of example in the accompanyingdrawings which form part of this application and in which: I

FIG. 1 is a simplified schematic front elevation of a compressor provided with the reciprocating drive of the invention;

FIG. 2 is a fragmentary sectional plan view taken along line 2-2 of FIG. 1 in the direction of the arrows and showing components of the invention at a scale which is considerably enlarged compared to FIG. 1;

FIG. 3 is a fragmentary sectional elevation taken along line 3-3of FIG. 2 in the direction of the arrows and showing further details of the drive of the invention; and

FIG. 4 is a sectional elevation taken along line 44 of FIG. 1 in the direction of the arrows and also showing further details of the structure of the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. 1, there is illustrated therein a compressor 10 which is provided with the dirve of the invention. This compressor 10 has a pair of pipes 12 which feed compressed air to a common pipe 14. From the pipe 14 the compressed air may be delivered to a suitable tank, for example. The pipes 12 receive the compressed air from a pair of cylinders 16 which house in their interiors a pair of reciprocating pistons 18 one of which is indicated at the left of FIG. 2 and the other of which is indicated at the right of FIG. 3. These pistons 18 reciprocate back and forth with suitable clearance in the cylinders 16, air being drawn into the interior of the cylinders in an unillustrated manner through filters 20, one of which is shown in section in FIG. 3. These filters 20 are carried by suitable tapered supports 22. During the pressure strokes of the pistons, air is delivered therefrom into the interiors of the pipes 12 throughsuitable discharge valves 24, one of which is shown at the right of FIG. 3.

For compressors of the above type, it is important to reciprocate the pistons 18 at extremely high speeds. For example, each piston should be reciprocated back and forth through approximately 3,000 operating cycles per minute, or more. The reciprocating drive of the invention is capable of achieving these results in an outstanding manner.

Thus, the pistons 18 are respectively fixed to the opposed ends of a pair of coaxial horizontally extending piston rods 26. These piston rods extend slidably through suitable sealing glands 28 carried by a housing means 30 at opposed end wall portions thereof. Suitable compression springs 32 surround the piston rods 26 and maintain the sealing glands 28 compressed so that a tight sliding fit is assured around the piston rods 26-so as to maintain the pistons .18 operating at all times in a perfectly dry space.

The piston rods 26 are fixed at their inner ends, which are always in the interior of the housing means 30, to a crosshead means 34 which is made of a lightweight material inasmuch as the crosshead means 34 will reciprocate back and forth at high speed, and because of the inertia associated therewith will create undesirably large forces unless it is made of a light-weight material. Preferably the crosshead 34 is made of a synthetic resin. Many plastics are available for this purpose.

The plastic croshead means 34 is formed with a vertically extending slot 36 which receives a slide block 38.

Because. the crosshead means 34 is made of a lightweight material such as-a suitable synthetic plastic, the opposed .sides of the slot 36 fixedly carry guide strips 40 fixed. to thecrosshead means 34 in any suitable way as by the countersunk screws 42 indicated in FIG. 2. In order to assure a proper connection of the screws 42 with the crosshead means 34 as well as a proper connection of the piston rods 26 with the crosshead means .34, the plastic crosshead is molded around internally threaded sleeves such as the sleeves 44 and 46 (FIG. 2) into which the piston rods 26 and screws 42 are respectively threaded as illustrated. An effective sliding engagement between the guide strips 40 and the slide block 38 is achieved by a suitable choice of materials for these components. It is preferred to make the guide strips 40 of steel and the slide block 38 of bronze, preferably phosphor bronze.

A crank pin 48, which is also made of steel, is operatively connected with the bronze slide block 38. This crank pin 48 forms part of a rotary crank means 50 which carries the crank pin 48 at a suitable radial distance from the axis of rotation of the crank means 50, this axis of rotation being horizontal and perpendicular to the common axis of the piston rods 26. As is shown most clearly in FIG. 4, the rotary crank means 50 is in the form of a disc, preferably made of steel, and having a sleeve 52 which surrounds and is fixed with a drive shaft 54 driven by a suitable driving motor 56 which is fixed to the housing 30. The sleeve 52 may have a splined or other type of keyed connection with the drive shaft 54 so as to rotate therewith, and a suitable screw 58, for example, maintains the rotary crank means 50 on the drive shaft 54.

The plastic crosshead means 34 is formed at its upper and lower ends with a pair of bores 60 which extend parallel to the common axis of the piston rods 26. The crosshead means 34 fixedly carried in the bores 60 elongated bearings 62 which form a bearing means surrounding and slidably engaging a pair of stationary guide bars which extend parallel to the common axis of the piston rods 26 and which are fixedly mounted on the housing means 30, extending between the opposed end walls thereof in the manner shown most clearly in FIG. 3. In this case also it is preferred to make the guide bars 64 of steel and the bearings 62 of bronze, preferably phosphor bronze.

According to a further feature of the invention a pressurized lubrication is provided for components such as the crank pin 38 at its connection with the slide block 38 and the bearings 62 at their slidable engagement with the guide bars 64. For this purpose the housing 30 carries at its front wall an oil pumping unit 66 including a suitable driving motor 68 and a pump and filter assembly 70 situated in the interior of the housing 30 in the manner shown in FIG. 4 with the unillustrated inlet of the pump communicating with an unillustrated oil supply which is maintained in any suitable way in communication with the pump inlet. The oil is pumped under pressure through a suitable pipe system 74.

One part of the pipe system 74 communicates with a stationary oil-distributing ring 76 which also is preferably made of a bronze such as phosphor bronze and which surrounds the rotating steel sleeve 52 at the exterior thereof. A suitable bracket 78 is fixedly carried by the housing in the interior thereof (FIG. 4), this bracket 78 being fixed to and supporting the stationary oil ring 76. The oil is delivered from the pipe system 74 in the manner illustrated in FIG. 4 to an internal groove 80 which is formed in the interior of the oil ring 76. The sleeve 52 is formed with a bore which communicates with the groove 80 to receive oil therefrom. Thus the bore in the sleeve 52 includes the axial bore portion 82 closed at its right end by a plug 84 communicating with a radial bore 86 which opens into the groove to receive the pressurized oil therefrom. The disc 50 is formed with a radial bore 88 closed by a plug 90. This bore 88 extends across an opening 92 in the crank disc 50. The opening 92 is filled by a cylindrical portion 94 of the crank pin 48, and the crank pin 48 is held onto the disc 50 by way of a suitable nut and washer assembly 96 carried by a threaded portion of the crank pin 48. The portion 94 which is thus journaled in the disc 50 is formed with an axial bore 98 which extends through the interior of the crank pin 48 all the way up to the region thereof which is surrounded by the slide block 38. The slide block is held on the crank pin 48 by a second nut and washer assembly 100. The axial bore 98 is in communication with radial bores 102 formed in the part 94 of the crank pin 48, this part 94 having the radial bores 102 in communication with the radial bore 88 of the crank disc 50. The axial bore 98 of the crank pin 48 also communicates with radial bores 104 which communicate at their outer ends with external grooves 107 (FIG. 2) and an internal circumferential groove 106 formed in the slide block 38. In this way a forced lubrication is provided at the connection between the crank pin 48 and the slide block 38.

The pipe system 74 also communicates with a pair of fittings 108 (FIG. 3) which deliver the oil under pressure to axial bores 110 which are respectively formed in the steel guide bars 64. These axial bores 110 in turn communicate with radial bores 112 distributed along the guide bars 64 and communicating with the axial bore 110, so that this way the oil under pressure is delivered to the exterior surfaces of the guide bars 64 in order to lubricate the bearings 62 as they slide along the guide bars 64.

Thus, with the above-described pressurized lubricating means it is possible to maintain the slidable engagement between the bearings 62 and the guide bars 64 suitably lubricated, and of course with the pressurized lubricating system it is also possible to lubricate the drive transmission which is deilvered to the slide block 38. Moreover, with the above-described transmission the parts do not develop inertia forces which are sufficiently great to provide undue stresses.

It has been found from experience that with a system as described above it is possible to rotate the shaft 54 at a speed of 3,500 revolutions per minute, with the bearings 62 travelling along the guide bars 64 and the slide block 38 sliding along the guide strips 40 at linear speeds on the order of 62 feet per second. In practice it is possible to recipiocate the pistons at cycles of between 3,000 and 6,000 cycles per minute. The hydraulic pressurized lubricating means of the invention is self-contained and is capable of operating at pressures of 2,000 psi. The bronze used for the slide block 38, the oil ring 76, and the bearings 62 is a special high quality phosphor bronze with an extremely high strength achieved by cold-working. In practice it has been found that the thermal stability of this bearing material is constant up to 572F (300C) with the stability then decreasing only slowly beyond this temperature.

In practice an unlimited working life for the entire drive mechanism can be assured because of the negligible wear achieved with the invention.

It will be noted from FIG. 2 that the exterior surface of the crank pin, where it is surrounded by the slide block 38, is formed with a spiral groove 107 communicatingwith bore 104 to improve the distribution of the lubricant.

What is claimed is: v

1. For use with horizontally arranged opposed compressor pistons, a pair of coaxial horizontal piston rods,

. crosshead means situated between and fixed to said piston rods, said crosshead means being formed with a vertically extending slot and having opposed upper and lower ends respectively formed with bores extending therethrough parallel to said piston rods, a pair of bearing means respectively situated in said bores and fixed to said crosshead means, a pair of guide bars extending parallel to said piston rods through said bearing means, said bearing means having sliding engagement with respect to said guide bars, housing means carrying said guide bars and housing said guide bars and crosshead means in the interior of said housing means, a slide block situated in said slot of said crosshead means for slidable movement vertically along said slot, rotary crank means carried by said housing means and having a horizontal axis of rotation which is perpendicular to the common axis of said piston rods, said rotary crank means including a crank pin displaced by a predetermined radial distance from said axis of rotation of said rotary crank means and operatively connected with said slide block for reciprocating the latter vertically in said slot of said crosshead means while displacing said crosshead mean back and forth along said guide bars, and pressurized lubricating means operatively connected with said crank pin and said pair of bearing means for lubricating said crank pin and said pair of bearing means, said pressurized lubricating means including a pump means carried by said housing means and communicating with a lower interior portion thereof where an oil bath is located, an oil ring carried by said housing means in the interior thereof and surrounding said rotary crank means, said oil ring communicating with said pump means to be fed with pressurized oil thereby and said oil ring having an interior groove provided by said pump means with a supply of oil, said rotary crank means being formed with an inter- 6 nal bore communicating with said groove "of said oil ring and receiving pressurized oil therefrom, and said crank pin being formed with internal bores communicating with said bore of said rotary crank means and with an inner surfacae of said slide block which surrounds said crank pin so that the presssurized oil is delivered from said rotary crank means along the interior of said crank pin to the inner surface of said slide block which surrounds said crank pin.

.2. The combination of claim 1 and wherein said crosshead means is made of a light-weight material and carries a pair of guide strips extending along opposed parallel vertical sides of said slot, said guide strips slidably engaging said guide block.

3. The combination of claim 2 and wherein said guide strips are made of steel while said slide block is made of bronze.

4. The combination of claim 1 and wherein said guide bars are made of steel and saidpair of bearing means are made of bronze.

5. The combination of claim 1 and wherein said rotary crank means and crank pin are made of steel while said slide block is made of bronze.

6. The combination of claim 5 and wherein a pair of steel guide strips are carried by said crosshead means along opposed vertical sides of said slot and slidably engage said bronze slide block.

7. The combination of claim 1 and wherein said guide bars are respectively formed with bores communicating with the outer surface of said guide bars and also communicating with said pump means to receive pressurized oil therefrom to be delivered to the outer surface of said guide bars for lubricating said bearing means.

8. The combination of claim 1 and wherein said crosshead means is made of a plastic material.

9. The combination of claim 1 and wherein a pair of sealing gland means respectively slidably engage and surround said piston rods for maintaining pistons connected to said piston rods in a dry condition.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3-920'098 DATED November 18, 1975 |N\/ ENTOR(S) Walter Schroeder It is certi fied that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading, after the inventor's name, the address should read: --6 s. Coria St., Brownsville, Texas 78520--.

Signed and Scaled this Twenty-sixth Day of April 1977 [SEAL] Arrest:

RU'IH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of Parents and Trademarks

Claims

1. For use with horizontally arranged opposed compressor pistons, a pair of coaxial horizontal piston rods, crosshead means situated between and fixed to said piston rods, said crosshead means being formed with a vertically extending slot and having opposed upper and lower ends respectively formed with bores extending therethrough parallel to said piston rods, a Pair of bearing means respectively situated in said bores and fixed to said crosshead means, a pair of guide bars extending parallel to said piston rods through said bearing means, said bearing means having sliding engagement with respect to said guide bars, housing means carrying said guide bars and housing said guide bars and crosshead means in the interior of said housing means, a slide block situated in said slot of said crosshead means for slidable movement vertically along said slot, rotary crank means carried by said housing means and having a horizontal axis of rotation which is perpendicular to the common axis of said piston rods, said rotary crank means including a crank pin displaced by a predetermined radial distance from said axis of rotation of said rotary crank means and operatively connected with said slide block for reciprocating the latter vertically in said slot of said crosshead means while displacing said crosshead mean back and forth along said guide bars, and pressurized lubricating means operatively connected with said crank pin and said pair of bearing means for lubricating said crank pin and said pair of bearing means, said pressurized lubricating means including a pump means carried by said housing means and communicating with a lower interior portion thereof where an oil bath is located, an oil ring carried by said housing means in the interior thereof and surrounding said rotary crank means, said oil ring communicating with said pump means to be fed with pressurized oil thereby and said oil ring having an interior groove provided by said pump means with a supply of oil, said rotary crank means being formed with an internal bore communicating with said groove of said oil ring and receiving pressurized oil therefrom, and said crank pin being formed with internal bores communicating with said bore of said rotary crank means and with an inner surfacae of said slide block which surrounds said crank pin so that the presssurized oil is delivered from said rotary crank means along the interior of said crank pin to the inner surface of said slide block which surrounds said crank pin.

2. The combination of claim 1 and wherein said crosshead means is made of a light-weight material and carries a pair of guide strips extending along opposed parallel vertical sides of said slot, said guide strips slidably engaging said guide block.

4. The combination of claim 1 and wherein said guide bars are made of steel and said pair of bearing means are made of bronze.