US3545891A

US3545891A - Compressor crankshaft arrangement

Info

Publication number: US3545891A
Application number: US772496A
Authority: US
Inventors: Sidney A Parker
Original assignee: Lennox Industries Inc
Current assignee: Lennox Industries Inc
Priority date: 1968-11-01
Filing date: 1968-11-01
Publication date: 1970-12-08
Anticipated expiration: 1987-12-08

Description

Dec. 8,1970 4 s. A. PARKER 3,545,891A

COMPRESSOR CRANKSHAFT ARRANGEMENT Filed NOV. 1, 1968 lli-5.1

TTO/Q/VE YS United States Patent O 3,545,891 COMPRESSOR CRANKSHAFT ARRANGEMENT Sidney A. Parker, Fort Worth, Tex., assignor to Lennox Industries Inc., a corporation of Iowa Filed Nov. 1, 1968, Ser. No. 772,496 Int. Cl. F04b 39/02; B23b 15/00 U.S. Cl. 417--372 9 Claims ABSTRACT F THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to an improved crankshaft arrangement for a compressor.

The crankshaft is one of the more expensive components of a refrigerant compressor, along with the electric-drive motor and the basic casting for compressor block. Prior crankshafts were commonly forged for high strength requirements and cast for lesser strength requirements. After initial forming, the crankshaft is rough ground. Pump passages are then drilled in the crankshaft. The exterior surface of the crankshaft is then coated and a portion of the coating is cut away to expose surfaces to be plated with copper which will prevent heat treatment of such surfaces. The crankshaft is heat treated and straightened. Portions of the exterior surface are then finish ground to the close tolerances required.

Special xturing is required to grind the crankshaft since the centerline of the eccentric portion of the crankshaft differs from the centerline of the main shaft portion. It is apparent from the foregoing that the manufacture of conventional .cast or forged crankshafts is relatively complex, time-consuming and, therefore, expensive.

An object of the present invention is to provide an improved compressor crankshaft arrangement, wherein the cost of fabrication is materially reduced.

A further object of the present invention is to provide an improved crankshaft arrangement for a compressor, including separate relatively inexpensive centerless ground components prehardened, and then joined to one another by electron beam welding without adversely affecting the prior heat treating.

Yet another object of the present invention is to provide an improved method for fabricating an inexpensive crankshaft for a compressor. Other objects and advantages of the present invention will become more apparent hereinafter.

BRIEF DESCRIPTION OF THE DRAWING There is illustrated in the attached drawing a presently preferred form of the present invention, wherein:

FIG. 1 is a cross-sectional view of a compressor embodying an improved crankshaft of the present invention;

FIG. 2 is an enlarged fragmentary cross-sectional vieW of the compressor of FIG. 1;

FIG. 3 is a plan view of the flywheel of the crankshaft of FIGS. 1 and 2; and

FIG. 4 is a detail sectional view taken generally along the line 4-4 of FIG. l and illustrating a method of securing the compression mechanism within the outer housing of the compressor.

3,545,891 Patented Dec. 8, 1970 DESCRIPTION OF THE PREFERRED EMBODI- MENT OF THE INVENTION Referring to FIGS. 1 and 2, there is illustrated a compressor which embodies the crankshaft arrangement of the present invention. The compressor comprises a gastight outer housing which includes an upper shell 12 and a lower shell 14 integrally joined to one another, as, for example, by welding. To the bottom of the exterior surface of the lower shell 14 are Welded a plurality of suitable supports or legs (not shown) by means of which legs the compressor may be supported in upright position within a condensing unit or an air-conditioning unit.

Resiliently supported within the outer housing or casing of the compressor 10 by means which will be more fully described hereafter is a compression mechanism 16 which includes a compressor block 18. Formed in the compressor block is a cylinder 20 having a cylinder liner 22 disposed therein for slidingly receiving a piston 24. The end of the cylinder liner 22 is closed by a discharge and suction valve assembly 26 retained in place within the compressor block 18 by means of a cylinder head 28. The cylinder head is held in place in the compressor block by suitable means, including a Belleville spring 29 and a retaining ring 30.

Journaled within the compressor block 18 is the crankshaft arrangement 32 of the present invention. The crankshaft 32 is driven by electric drive motor 36. The motor includes rotor 34 secured to the upper end of the crankshaft arrangement 32 for rotating same and stator 35 which is inductively connected to the rotor 34. 'Ihe stator 35 is xedly secured within the compressor block 18.

The means for actuating piston 24 include pistonconnecting rod 38 which is aflixed to the lower end of the crankshaft arrangement 32. Upon rotation of the crankshaft 32, the connecting rod 38 will be moved to reciprocate piston 24 Within the cylinder liner 22.

Suction gas enters the compressor from a suction line and passes into the space between the compressor block 18 and the outer housing 12. The suction gas ilows through the opening 44 in the end cap 46 over the motor 36 for cooling same and through the opening 47 in the compressor block to the discharge and suction valve assembly 26. During the suction stroke, suction gas is drawn through the suction valve in the discharge and suction valve assembly 26 into the chamber defined between the liner 22, piston 24 and assembly 26. On the discharge or compression stroke, the piston 24 forces the compressed gases through the discharge valve in the discharge and suction valve assembly 26 and through the opening in cylinder head 28 into the discharge line 48 and through the muffler 49 in the discharge line to the discharge conduit 50 extending from the top of the compressor. The discharge conduit 50, which is adapted to be connected in a refrigeration system, forms an extension of the discharge line.

Turning now to a further more detailed consideration of the compressor crankshaft or drive shaft arrangement 32, it is seen that the crankshaft is fabricated from a plurality of components suitably joined to one another to provide a unique arrangement. The crankshaft arrangement 32 includes a hollow shaft portion 52 which is adapted to be journaled by

bearings

54 and 56 within the compressor block 18. The shaft portion 52 can be made from cold extruded high carbon steel, cut to length, heat treated and then centerless ground to close tolerances. A separate mass or ywheel 58 is secured to the bottom of the shaft 52 by electron beam welding. Such ywheel can be made from powdered metal or may be forged, for example. An opening 92 is provided in mass 58 for reducing the weight thereof, as desired.

The crankshaft arrangement 32 further includes a tubular centerless ground part 60 affixed within an opening 67 in the mass 58 by electron beam welding. The part 60 can also be made from steel, for example, high carbon steel, with the exterior surface thereof being heat treated to harden same. The axis of the tubular part 60 is parallel to the axis of the hollow shaft 52. Depending from the bottom of the tubular part 60 is a tube y62 which is adapted to be connected to the tubular part 60 through the fitting 61. Tube 62 and fitting 61 are joined as a subassembly and are connected to part 60 so as to retain an end of connecting rod 38 journaled on part 60. The free end 62a of the tube 62 is adapted to extend downwardly into a lubricant sump 64 defined in the lower end of the compressor casing or shell 14 and is adapted to lie in the axis of the hollow shaft 32, so as to ingest lubricant from the sump during operation of the compressor. The tubular part 60 is provided with generally transverse or radially disposed openings 66 adjacent the upper end thereof which are in communication with a transverse or radial opening 68 in the mass 58. The opening 68 in the mass 58 is adapted to communicate with an annular groove or recess `69 defined in the compressor block 18 which groove 69, in turn, communicates with passage means 70 formed in the compressor block. The passage means 70 may comprise separate interconnected passages drilled in the compressor block, with the ends of the passages then being plugged to provide a continuous passage means communicating the crankshaft passage with annular space 72 between the hollow shaft 52, the compressor block 18 and

bearings

54 and 56. lt will be seen that in normal operation, lubricant ingested by the tube 62 from the sump 64 will pass through the tube 62, fitting 61, tubular part 60 and through the opening 68 and passage means 70 into the annular space 72 for pressurized lubrication of the crankshaft bearing surfaces.

A vent opening 74 is provided in the top of the tubular part 60 such that at start-up of the compressor, any refrigerant in the tubular part 60 will be vented through the vent opening 74 into the space between the compressor block 18 and the outer housing. Thus, at start-up of the compressor, lubricant will ow to the bearing surfaces, so as not to starve the bearing surfaces. If refrigerant were carried to the bearing surfaces at start-up, rather than lubricant, it would be possible to damage the bearing surfaces. Also, some lubricant or oil will be emitted from the groove 69 opening 74 during normal operation and will help lubricate the Wrist pin 37 which joins the connecting rod 38 to piston 24.

The drive shaft 32 is readily fabricated as follows. Hollow shaft 52 may be made from cold extruded steel cut to length, heat-treated and then centerless ground to close tolerance. Part 60 is suitably formed and heattreated. The ywheel portion or mass 58 is forged or can be made from powdered metal. Shaft 52 is inserted into opening 59 in flywheel 58 and electron beam welded into place. Since the heat from such welding is extremely localized the heat-treated exterior surface portions of the shaft 52 are not adversely affected. Tubular part 60 which comprises the eccentrically disposed member for driving connecting rod 38 is positioned in opening 67 in liywheel 50 and electron beam welded in place so as not to adversely affect the heat-treated exterior of part 60. Part 60 is secured in opening 67 with opening 66 in the part 60 aligned with passage 68 in the flywheel or mass 58. Opening 67 extends through the mass 58 such that vent opening 74 in the top of part 60 can properly function. The connecting rod 38 is journaled on lthe part 60 and fitting 61 is secured to the part 60 so as to retain the connecting rod 38 on part 60.

By this construction the diicult fixturing for grinding of the eccentric portion of a conventional crankshaft is avoided. The surface finishes of a crankshaft made by the present method are consistently better than that of a conventionally formed crankshaft. The components of the new crankshaft are easily formed and are relatively inexpensive. The overall cost of the crankshaft is materially reduced. It is also noted that the electron beam welded joint is strong and that no splined connection is needed to transmit the high torque from the electric-drive motor 36 and shaft 52 to mass 58 and eccentric post part 60 to which the connecting rod 38 is operatively secured.

Referring to FIG. 4, there is better illustrated the arrangement for resiliently supporting the compressor block 18 within the outer housing. The resilient supporting means includes a bracket 82 suitably secured to the compressor block 18 by means of a bolt `83, a bracket 84 and a resilient block 86 secured between the brackets 82 and 84. A stirrup-like member 88 which is atiixed to the lower shell 14 of the housing receives the bracket 84 and guides same for up and down movement. The member 90, which is suitably secured to the upper shell 12 provides a stop for limiting upper movement of the resilient supporting means. Thus, it will be seen that the bracket 82 is secured to the compressor block, such that the compression mechanism 16 is atiixed thereto. The bracket 84 is movably received within the stirrup 88 which limits downward movement thereof. Upward movement of the resilient means 80 is restricted by the stop 90.

There has been provided by the present invention an improved low-cost crankshaft arrangement for cornpressors. The crankshaft is fabricated from inexpensive components that are readily assembled. The parts comprising the crankshaft are joined by electron beam welding so as not to adversely affect the heat-treated exterior surfaces of the hollow shaft or eccentric post part. The components can be separately centerless ground prior to assembly, obviating the need for complex ixturing for grinding the eccentric part of the crankshaft such as is needed in making a conventional crankshaft.

While I have shown and described a presently preferred form of my invention, it will be understood that the invention is not limited thereto, since it may be otherwise embodied within the scope of the attached claims.

I claim:

1. In a compressor, a crankshaft comprising a shaft having separate mass means secured at one end thereof, conduit means secured to said mass means including a tube extending from the mass means, with the free end of the tube disposed in the axis of the shaft and passage means in the mass means adapted to communicate with the tube, there being a vent hole in the mass means communicating with the passage means, and the shaft comprisin g a hollow tubular member.

2. A compressor as in claim 1, wherein the mass means includes a iiywheel portion, a tubular part secured to the flywheel portion and extending downwardly from the flywheel portion and a fitting aliixed to the tubular part for securing the tube to the flywheel portion.

3. A compressor as in claim 2, wherein the hollow tubular member and the tubular part are made from high carbon steel.

4. A compressor as in claim 2 wherein the exterior surface of the hollow tubular member is heat-treated and is connected to the flywheel portion by electron beam welding so as not to destroy the heat treat of the exterior surface.

5. A compressor as in claim 1, including a casing having a lubricant sump defined therein, compressor block means for receiving the crankshaft in said casing, bearing means for journaling the crankshaft and passageway in the compressor block means communicating with the passage means inthe mass means, the tube being disposed in the lubricant sump, whereby in operation, lubricant is ingested through the tube and passed through the passage means in the mass means and the passageway in the compressor block means to the bearing means for lubricating the bearing surfaces.

6. A method of fabricating a multiple component crankshaft for a compressor comprising aixing a separate mass means having passage means therein to the end of a shaft by electron beam welding, securing conduit means, including a tube, to the mass means with the free end of the tube disposed in the axis of the shaft and with the tube communicating with the passage means.

7. A method of fabricating a crankshaft for a compressor as in claim 6 including forming a vent hole in the mass means communicating with the passage means.

8. A method of fabricating a crankshaft for a compressor as in claim 6 wherein the shaft is hollow including the steps of securing a tubular part in an opening extending through the mass means, with the axis of the tubular part being parallel with the axis of the hollow shaft and affxing a fitting to the tube and connecting same to the tubular part, the tubular part including opening means aligned with the passage means in the mass means and a vent passage at the top thereof.

9. In a compressor, hollow tubular crankshaft means having a heat-treated exterior surface and a fly wheel portion connected to the crankshaft by electron beam welding so as not to destroy the heat treat of the exterior surface, a tube secured to the crankshaft means and extending downwardly therefrom, with the free end of the tube having an opening disposed in the longitudinal axis of the crankshaft means, and vent means in the crankshaft means for venting material within the crankshaft means to exterior of the crankshaft means at startup of the compressor.

References Cited UNITED STATES PATENTS 2,766,929 10/ 1956 Rusch et al. 230-206 3,049,285 8/ 1962 Doeg 230-206 3,075,686 1/1963 Steinhagen 230-58 ROBERT M. WALKER, Primary Examiner U.S. Cl. X.R. 29-156.4