Oil Pumping System

Abstract

A centrifugal refrigerant compressor has an internal oil pump consisting of an oil pumping plate on the shaft of its impeller, and a thrust plate. At startup of the compressor, an external oil pump circulates oil through the internal pump and the bearings of the compressor. When the compressor speed approaches normal, an oil pressurestat opens a switch which turns off the external pump, and the internal pump circulates the oil.

Description

BACKGROUND OF THE INVENTION

The field of the invention is centrifugal refrigerant compressors of the type disclosed in the U.S. Pat. No. 3,163,999 of J. L. Ditzler and R. T. Kirchner, in which an impeller is driven by stepup speed gearing by an enclosed electric motor. In the past, such compressors have been lubricated, during operation, by external oil pumps driven by electric motors.

This invention uses such an external pump for startup, and uses an internal oil pump for circulating the oil through the bearings of the compressor after startup.

SUMMARY OF THE INVENTION

A centrifugal refrigerant compressor has its gas impeller driven by stepup speed gearing by an internal electric motor. The shaft of the impeller and that of the motor have bearings. The impeller shaft has attached thereto an oil-pumping plate, which with an associated thrust plate, acts as an oil pump when the compressor is operating at normal speed. An external oil pump driven by an electric motor, circulates oil through the internal oil pump and the bearings at startup of the compressor. When the compressor reaches operating speed, a pressurestat responsive to the oil pressure, opens a normally closed switch that turns off the motor of the external oil pump, although both pumps could be continued in operation if that is desired.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B together are a diagrammatic view of a centrifugal refrigerant compressor, and a lubrication system of the latter, embodying this invention, with an external oil pump and gas and oil separator unit shown, on FIG. 1B, in section;

FIG. 2 is an enlarged side view, in section, of the oil-pumping plate; its associated thrust plate, and the adjacent compressor structure, of FIG. 1A;

FIG. 3 is a view along the lines 3-3 of FIG. 2, of the face of the oil-pumping plate that faces the thrust plate;

FIG. 4 is a section along the lines 4-4 of FIG. 3; and

FIG. 5 is an enlarged side view, in section, of the check valve within the external oil pump and gas and oil separator unit of FIG. 1B.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to FIGS. 1A and 1B of the drawings, centrifugal compressor C is of the type disclosed in the previously mentioned patent. It has an impeller 10, has a gas inlet passage 11 aligned with the inlet of the impeller 10, and has a scroll-shaped wall 12 around the impeller 10. The impeller 10 has a shaft 13 with bearings 14 and 15, and having a pinion gear 16 attached thereto between the bearings 14 and 15. The inner end of the shaft 13 has an oil-pumping plate 18 attached thereto. A thrust plate 19 extends around the shaft 13 closely adjacent to the plate 18. A speed stepup gear 20 is meshed with the gear 16, and is attached to motor shaft 21 having bearings 22 and 23 on opposite sides of the gear 20. The inner end of the shaft 21 has rotor 25 of compressor motor CM attached thereto. The motor CM has a stator 26 with windings 30, and has lead wires 27, 28 and 29 connected to the windings 30.

The bearing 14 has an oil supply passage 33, and an oil drain passage 34. The bearing 15 has an oil supply passage 35, and an oil drain passage 36. The bearing 23 has an oil supply passage 40, and an oil drain passage 41. The oil supply passages 33, 35, 37 and 40 connect with a common oil supply passage 43. The oil drain passages 34, 36, 38 and 41 connect with a common oil drain passage 44.

The thrust plate 19 has an oil inlet passage 52 which connects through tube 55 with the outlet of a conventional jet pump 56, and has an oil outlet passage 57 which connects through tube 58, filter 59, cooler 60, check valve 61 and tube 62 with standby oil supply tank 63. The latter has a piston-type plate 64 therein, and between the bottom of the latter and the bottom of the tank 63 is a coiled spring 65 which urges the plate 64 upwardly. A tube 66 connects the tube 62 to the internal oil supply passage 43. Tube 67 connects with the tube 66, and connects through check valve 68 with the inlet of the jet pump 56. The latter has a nozzle 70 therein which converges from its inlet towards and discharges into cylindrical outlet passage 71 within the pump 56. Tube 72 connected to the oil outlet of a conventional, external, oil pump and oil and gas separator unit 73, connects with the interior of the pump 56 between the nozzle 70 and the passage 71. The internal oil drain passage 44 is connected by tube 74 to the oil inlet of the unit 73. The latter is similar in construction and operation to the unit 47 disclosed in the previously mentioned patent. Refrigerant is separated from the oil within the unit 73, and passes through tube 76 into the gas inlet passage 11 of the compressor C. The unit 73 contains a centrifugal oil pump 77 driven by shaft 78 of electric motor 79. The outlet of the pump 77 is connected by tube 81 and check valve 80 to the tube 72. The details of the check valve 80 are shown by FIG. 5 of the drawings. A pressurestat 83 having a normally open switch 84, and another pressurestat 85 having a normally closed switch 86, are connected by tube 87 to the tubes 67 and 74.

The compressor motor wires 27, 28 and 29 are connected by wires 88, 89 and 90 respectively, to switches 91, 92 and 93 respectively, of compressor motor starter CMS. The switches 91, 92 and 93 are connected to electric supply lines L3, L2 and L1 respectively. The starter CMS has an energizing winding 94 connected through switch 95 of control thermostat 96 and through the pressurestat switch 84 to the line L1, and connected directly to the line L2. The motor 79 of the pump 77 within the unit 73, is connected by wire 97 and the thermostat switch 95 to the line L1, and by wire 98 and the pressurestat switch 86 to the line L2.

Referring now to FIG. 2, the oil inlet passage 52 connects through passages 100 and 101 with passage 102 within the thrust plate 19. The passage 102 connects with passages 103 within the plate 19, which converge towards the shaft 13, and which connect with annular passage 104 around the shaft 13. The passage 104 connects with the space between the plates 18 and 19, and through passages 105 extending through the plate 18, with the space between the plate 18 and a thrust plate 106 attached to inner wall 107, and connects with passage 108 around the plate 18. The passage 108 connects through passage 109 within the plate 19, and through passages 110 and 111 with the oil outlet passage 57.

Referring now to FIGS. 2, 3 and 4 of the drawings, the oil pumping plate 18 has radial slots 114 closed at their outer ends, and connecting at their inner ends with the passage 104. Between adjacent slots 114 are flat outer face portions 115, each containing a dimple 116.

Referring now to FIG. 5 of the drawings, the check valve 80 (within the unit 73) has an oil inlet opening 140 in its inner end and which connects with the oil tube 81 of FIG. 1B; has an oil inlet opening 141 in its outer end and which connects with the oil sump of the unit 73, and has an oil outlet opening 142 in its top which connects with the oil outlet tube 72. The check valve 80 has a cylindrical passage 144 near its inner end; has a cylindrical passage 148 coaxial with and having a smaller diameter than the passage 144, near its longitudinal center, and has a cylindrical passage 145 near its outer end coaxial with and having a smaller diameter than the passage 148. The passage 145 connects with the oil inlet opening 141 and with the oil outlet opening 142. A piston rod 146 is slidable within the passage 145, and has a piston head 147 on its inner end which is slidable within the passage 144. The head 147 and the inner end portion of the piston rod 146 have an axial passage 150 which connects with the inlet opening 140. The rod 146 has an annular slot 149 which connects with the outer ends of radial passages 151, the inner ends of which connect with the passage 150. A coiled spring 155 extends around the piston rod 146; has its inner end within a slot in the head 147, and has its outer end within the passage 146 in contact with wall 157 at the outer end of the passage 146.

OPERATION

When the thermostat 96 calls for cooling, it closes its switch 95 which energizes, through the closed switch 86 of the pressurestat 85, the motor 79 of the external oil pump 77. The closed thermostat switch 95 also energizes, after a time delay, the winding 94 of the compressor motor starter CMS, through the switch 84 of the pressurestat 83, which closes when the oil pressure from the pump 77 has increased to normal pressure.

The external oil pump 77 draws drained oil from the bearings of the compressor C through the tubes 74 and 44. When the pump 77 is up to speed, the oil pressure against the piston head 147 within the check valve 80 within the unit 73, causes the piston rod 146 to move to the left (facing FIG. 5), covering with its left end, the oil inlet opening 141 which connects with the oil sump of the unit 73. The spring 155 is compressed by this movement. This movement of the piston rod 146 aligns the annular slot 149 with the oil outlet opening 142 so that oil entering the inlet opening 140 flows through the passages 150 and 151 into the slot 149 and from the latter into the oil outlet opening 142, and from the latter through the tube 72 into the jet pump 56. Oil flows from the jet pump 56 through the tube 55 and the passages 52, 100, 102 and 103 into the passage 104. Oil flows from the passage 104 through the passages 105 into the space between the inner face of the plate 18 and the adjacent face of the thrust plate 106. When the compressor rotor comes up to speed, the plate 18 moves from closely to the plate 106 to closely adjacent to the plate 19.

Oil flows from the passage 104 into the inner ends of the radial slots 114. Since the outer ends of the latter are closed, centrifugal force causes pressure to be built up within them, causing oil to flow from them onto the flat faces 115 of the plate 18, and then into the dimples 116. The pressure built up in the dimples 116 causes oil to flow from them into the space between the oil-pumping plate 18 and the thrust plate 19, and through the passages 108, 109, 110 and 111 into the oil outlet passage 57. Oil flows from the latter through the tube 58, the filter 59, the cooler 60, the check valve 61 and the tube 62 into the tank 63, and through the tube 66, the internal oil supply passage 43, and the internal passages 33, 35, 37 and 40 to the bearings 14, 15, 23 and 22 respectively. Oil also flows from the tube 66 through the tube 67, and the check valve 68 into the inlet of the jet pump 56. The oil flowing from the external pump 77 through the tube 72 into the jet pump 56, also by injector action, aids in producing the above described flow through the check valve 68, the tubes 67, 66, and 62 etc.

When the oil pressure is normal, the oil flowing into the tank 63 forces the piston-type plate 64 downwardly against the resistance of the spring 65, storing oil within the space between the plate 64 and the top of the tank 63. When the oil pressure within the lubrication system decreases below normal as caused by power failure or any other reason, the spring 65 forces the plate 64 upwardly, supplying oil under pressure back into the lubrication system.

When the rotor of the compressor C is up to speed, the oil pressure produced by its oil-pumping plate 18 added to that produced by the external oil pump 77 provides an oil pressure sufficiently above normal for the pressurestat 85 to open its switch 86, deenergizing the motor 79 of the external oil pump 77, stopping the latter. The reduced oil pressure at the oil inlet 140 of the check valve 80 within the unit 73, permits the spring 155 to move the piston rod 146 to the right (facing FIG. 5) to the position shown by FIG. 5, uncovering the oil inlet opening 141 connecting with the oil sump of the unit 73, and moving the slot 149 from alignment with the oil outlet opening 142. The outlet opening 142 and the tube 72 are connected through the passage 145 and the oil inlet opening 141 with the oil within the oil sump. The oil flowing from the oil-pumping plate 18 through the tube 67 and the check valve 68 into the jet pump 56 induces through the tube 72, the opening 142 in the check valve 80, and the opening 141 in the latter, the flow of oil from the oil sump within the unit 73 into the jet pump 56, and forces that oil through the tube 55 and the following tubes and passages into the passage 104. Makeup oil flows into the oil sump within the unit 73 from the bearings of the compressor through the passage 44 and the tube 74.

If it is desired to provide higher than normal oil pressures, the pressurestat 85 and its switch 86 can be omitted so that the pump 77 operates continuously while the compressor is operating.

The mixture of refrigerant with the lubricating oil of a refrigerant compressor makes the stability of the oil supply critical to pressure drops. This invention reduces the chances of such pressure drops, and enables a smaller and less expensive external pump to be used at startup.

Claims

We claim:

1. A lubrication system for a refrigerant compressor having a first electric motor, having means including a rotary shaft for driving said compressor by said motor, and having bearings around said shaft, comprising:

an oil-pumping plate on said shaft;

a thrust plate around said shaft adjacent to said pumping plate;

said pumping plate having centrifugal oil-pumping means facing said thrust plate;

said pumping means having an oil inlet at said shaft;

said pumping means having an oil outlet around the periphery of said pumping plate;

means connecting said outlet to the oil inlets of said bearings;

an external oil pump;

a second electric motor for driving said pumps;

means for supplying oil drained from said bearings to the inlet of said pump;

means for connecting the outlet of said pump to said oil inlet of said pumping means;

means for energizing said second motor;

means for energizing said first motor after said second motor is energized;

and means for connecting said outlet of said pumping means to said outlet of said pump comprising, a jet pump having its outlet connected to said inlet of said pumping means, having a first inlet connected to said outlet of said pumping means, having an internal nozzle converging towards said outlet of said jet pump, and having a second inlet connecting with space within said jet pump around the inner end of said nozzle, and connected to said outlet of said external pump.

2. A lubrication system as claimed in claim 1 in which:

said external pump is within a unit having an oil sump into which said oil drained from said bearings is supplied, and with which said inlet of said external pump connects;

said means for energizing said second motor includes means for deenergizing said second motor after said first motor is energized;

and said second inlet of said jet pump is connected to said outlet of said external pump by a check valve having a first inlet opening connecting with said outlet of said external pump, having a second inlet opening connecting with said sump, having an outlet opening connecting with said second inlet of said jet pump, and having means responsive to oil pressure at said first inlet opening for connecting said first inlet opening with said outlet opening, and closing off said second inlet opening when said second motor is energized, and for disconnecting said first inlet opening and said outlet opening, and connecting said second inlet opening with said outlet opening when said second motor is deenergized.

3. A lubrication system as claimed in claim 2 in which:

a standby oil tank is connected to said means for connecting said outlet of said pumping means to said outlet of said external pump, to receive oil from said outlet of said pumping means;

and in which said tank has a spring-loaded piston therein which is depressed by entry of oil into said tank.

4. A lubrication system as claimed in claim 1 in which:

a standby oil tank is connected to said means for connecting said outlet of said pumping means to said outlet of said external pump, to receive oil from said outlet of said pumping means;

and in which said tank has a spring-loaded piston therein which is depressed by entry of oil into said tank.

5. A lubrication system as claimed in claim 1 in which:

said means for energizing said first motor comprises a pressurestat responsive to the pressure of the oil from said outlet of said pumping means, and having a normally open switch which closes when said pressure increases to a predetermined pressure;

6. A lubrication system for a centrifugal refrigerant compressor having an impeller, having a first shaft with a pinion gear thereon for driving said impeller, having bearings around said shaft, having a second shaft with a gear thereon having a larger diameter than and meshed with said pinion gear, having bearings around said second shaft, and having a first electric motor having its rotor on said second shaft, comprising:

an oil-pumping plate on said first shaft;

a thrust plate around said first shaft adjacent to said pumping plate;

said pumping plate having centrifugal oil-pumping means facing said thrust plate;

said pumping means having an oil inlet at said first shaft;

said pumping means having an oil outlet around the periphery of said pumping plate;

means connecting said outlet to the oil inlets of said bearings;

an external oil pump;

a second electric motor for driving said pump;

means for supplying oil drained from said bearings into the inlet of said pump;

means for connecting the outlet of said pump to said oil inlet of said pumping means;

means for energizing said second motor;

means for energizing said first motor after said second motor is energized; and

means for connecting said outlet of said pumping means to said outlet of said pump comprising, a jet pump having its outlet connected to said inlet of said pumping means, having a first inlet connected to said outlet of said pumping means, having an internal nozzle converging towards said outlet of said jet pump, and having a second inlet connecting with the space within said jet pump around the inner end of said nozzle, and connected to the outlet of said external pump.

7. A lubrication system as claimed in claim 6 in which:

said external pump is within a unit having an oil sump into which said oil drained from said bearings is supplied, and with which said inlet of said external pump connects;

said means for energizing said second motor includes means for deenergizing said second motor after said first motor is energized;

and said second inlet of said jet pump is connected to said outlet of said external pump by a check valve having a first oil inlet opening connecting with said outlet of said external pump, having a second inlet opening connecting with said sump, having an outlet opening connecting with said second inlet of said jet pump, and having means responsive to oil pressure at said first inlet opening for connecting said first inlet opening with said outlet opening and closing said second inlet opening when said second motor is energized, and for disconnecting said first inlet opening from said outlet opening and connecting said second inlet opening with said outlet opening when said second motor is deenergized.

8. A lubrication system as claimed in claim 6 in which:

a standby oil tank is connected to said means for connecting said outlet of said pumping means to said outlet of said external pump, to receive oil from said outlet of said pumping means;

and in which said tank has a spring-loaded piston therein which is depressed by entry of oil into said tank.

9. A lubrication system as claimed in claim 6 in which:

said means for energizing said first motor comprises a pressurestat responsive to the pressure of the oil from said outlet of said pumping means; and having a normally open switch which closes when said pressure increases to a predetermined pressure;

and said means for energizing said second motor comprises a pressurestat responsive to said pressure, and having a normally closed switch which opens when said pressure increases to a predetermined pressure above said first-mentioned predetermined pressure.