CN1074092C - Mechanical oil pump for a variable speed hermetic compressor - Google Patents

Abstract

The present invention relates to a mechanical oil pump for variable speed hermetic compressors, which comprises a hermetic shell (1), wherein the hermetic shell limits a lubrication groove (2) at the bottom, and a cylinder body (3) supporting an eccentric vertical shaft (5) is arranged in the hermetic shell. A rotor (8) of a motor (6) is arranged on the vertical shaft, and the vertical shaft is provided with a lower end (5b) and an upper end (5a). The lower part of a rotor assembly of the eccentric vertical shaft is connected with axial extension parts of the upper parts of pump rotors (10, 10'); the pump rotors are provided with at least one oil transportation path (12, 12') at least one part of which is limited along the axial extension parts, and pipe-shaped sleeves (20, 20') connected to the inertia part of a compressor; dragging oil cavities (21, 21') immersed into one part of a lubrication groove (2) around the pump rotors (10, 10') are limited in the pipe-shaped sleeves, and the dragging oil cavities are provided with at least one oil inlet (21a, 21a') communicated with the lubrication groove (2) and oil outlets (21b, 21b'). The ends of the pump rotors (10, 10') in the dragging oil cavities are provided with at least one dragging blade (14, 15) with ends which are always in contact with the inner walls of the dragging oil cavities (21, 21') in order that oil received through the oil inlets (21a, 21a') can be conveniently driven to the oil outlets (21b, 21b') of the dragging oil cavities (21, 21') with an angle in the radial direction.

Description

Mechanical oil pump for variable speed hermetic compressors

This invention relates to mechanical oil pumps for variable speed hermetic compressors, and more particularly to mechanical oil pumps for variable speed hermetic compressors having a vertical shaft, such as those used in small refrigeration appliances such as refrigerators and freezers.

The above-mentioned equipment requires its hermetic compressor to provide the precise cooling power required to remove the internal heat from the medium that needs cooling. Since the cooling power is directly proportional to the refrigerant flow pumped by the compressor, a change in the cooling power means a change in the flow pumped by the compressor. The technique of continuously obtaining the above-mentioned changes in flow rate is carried out by changing the motor speed.

Studies have shown that variable speed compressors require a working range of 15Hz to 100Hz, that is, 900 to 6000 rpm, in order to achieve good cooling performance. The aforementioned rotational speed changes affect the mechanical operation of the compressor, especially the operation of the oil pump, which is responsible for delivering oil to the compressor's bearings and other areas requiring lubrication such as connecting rods and pistons. Centrifugal pumps are the usual oil pumping mechanism in hermetic compressors because they are inexpensive and suitable for operation at 3000 to 3600 rpm as a result of the frequency of the grid. However, the above mechanism is not suitable for working at low rotational speeds.

Common centrifugal oil pumps, such as the one currently in use as shown in Figure 1, cannot pump oil to the bearings when the compressor needs to run at low speeds.

The working limitation of the centrifugal oil pump is related to the difference between its larger radius (R) and smaller radius (r).

It is not feasible to increase the efficiency of an oil pump by simply increasing the larger radius (R) of the pump, since such an increase is certainly critical to achieve the required pumping work, and it also affects the compressor shaft The outer diameter, therefore, affects the entire manufacturing process of the compressor and its performance, increasing losses due to friction. Clearly, at speeds near or below 900 rpm, small diameter changes are not sufficient to achieve the desired degree of centrifugal pumping.

As disclosed in patent documents US 4,478,559; US 4,569,639; DT 209,877 and FR 2,492,471, etc., common centrifugal pumps widely used in hermetic compressors show poor performance when pumping at low speeds.

In another technical solution described in the applicant's co-pending patent application, the oil can be effectively pumped at about 60 rpm, and the oil is pumped through the screw grooves provided in the rotor along the pump. achieved by dragging.

It is therefore an object of the present invention to provide a propelling mechanical oil pump for reciprocating hermetic compressors, having a vertical shaft, required to operate over a wide range of rotational speeds, promoting sufficient lubrication also at low speeds, which pumps oil The flow is proportional to the rotational speed of the shaft.

A second object of the present invention is to provide the above-mentioned oil pump in which the pumping power is increased without structural changes or changes in dimensions of the cylinder parts.

A third object of the present invention is to provide an oil pump as described above which is simple to manufacture and assemble.

A fourth object of the present invention is to provide an oil pump which does not generate an oil vortex in the oil sump of the compressor as occurs in some conventional hermetic compressor oil pumps.

The foregoing and other objects and advantages are achieved by an oil pump for a variable speed hermetic compressor comprising: a mechanical oil pump for a variable speed hermetic compressor including a seal housing defining a lubricating oil sump at the bottom and Which is equipped with: a cylinder supporting the eccentric vertical shaft, a motor rotor mounted on the eccentric vertical shaft, the eccentric vertical shaft is provided with at least one oil passage, the lower end of which is connected to the lower end of the eccentric vertical shaft, and the upper end is connected to the lower end of the eccentric vertical shaft. To the outside of the upper middle of the eccentric vertical shaft, the eccentric vertical shaft-rotor assembly is connected at its lower part to the upper axial extension of the pump rotor and to a tubular sleeve connected to an inertial part of the compressor and surrounding the At least part of a pump rotor immersed in oil, said oil pump being characterized in that it comprises:

- a drag oil chamber defined in the tubular sleeve for housing part of the oil-immersed part of the pump rotor, and having at least one oil inlet and one oil outlet communicating with the oil sump, said pump rotor being connected to the tubular sleeve The barrel is in axial sealing contact somewhere;

- at least one drag vane, which has an end mounted in said lower end portion of the pump rotor in the drag oil chamber and an end that is always in contact with the inner wall of the drag oil chamber so as to radially and angularly pass through the oil inlet Receiving oil from the oil sump is forced to the opposite end of the oil outlet of the drag oil chamber;

- at least one oil delivery passage, defined along at least a part of the axial extension of the pump rotor, so that its lower end is in fluid communication with the oil outlet of the drag oil chamber through a connecting oil passage carried by the tubular sleeve, and its upper end to the lower end of the oil passage.

The oil pump described above exhibits sufficient pumping capacity for a rotational speed of about 300 rpm without impairing its operation, and can also be applied to a compressor mounted in the usual way, ie, with the motor in the lower part of the body.

The present invention is now described with reference to the accompanying drawings:

Figure 1 shows in longitudinal section a prior art oil pump installed in a hermetic compressor with dimensions h ₁ , h ₂ , R and r.

Figures 2a and 2b show enlarged views of a prior art oil pump during pumping of oil at normal angular velocity (2a) and at reduced velocity (2b), respectively.

Figures 3 and 3a are an enlarged longitudinal sectional view of the oil pump of the present invention and a sectional view along line III-III in Figure 3, respectively.

Figures 4 and 4a correspond to Figures 3 and 3a and show another structural option of the oil pump according to the invention.

According to the above-mentioned drawings, the variable-speed hermetic compressor of the vertical shaft includes: a sealed shell 1, forming a lubricating oil groove 2 at the bottom thereof, and a cylinder body 3 is housed in the sealed shell, which has an integral body for supporting the eccentric vertical shaft Bearing 4 of 5, the vertical shaft is provided with upper end 5a and lower end 5b, and is provided with motor 6, and motor 6 has the stator 7 that is installed in cylinder block 3 and the rotor 8 that is installed on the part of eccentric vertical shaft 5, eccentric vertical shaft 5 Extending downward from the bearing 4 to form an eccentric vertical shaft-rotor assembly, the eccentric vertical shaft 5 is provided with at least one oil passage 9, the oil passage has a lower end 9b and an upper end 9a, the lower end 9b leads to the lower end 5b of the eccentric vertical shaft 5, The upper end 9a passes to the outside of the upper middle part of the bearing 4 on the eccentric vertical shaft 5, which is fitted at its lower end 5b with the upper end 10a of the pump rotor 10, the lower end 10b of which is immersed in the oil in the oil sump 2 .

In the compressor shown in Figures 2a and 2b, the lubrication of the pistons and other parts is accomplished centrifugally during the rotation of the eccentric vertical shaft-rotor assembly, which is about 3000-3600 revolutions during normal operation of the compressor /minute.

However, at low speeds, usually below 2000 rpm, the lubrication of the parts is poor, sometimes not at all, because the oil column formed in the oil passage 9 due to centrifugal action can no longer reach the upper end of the oil passage 9 9a's sake.

According to the drawings, the oil pump of the present invention comprises a pump rotor 10 and a tubular sleeve 20 permanently immersed in the oil in the oil sump 2 . The pump rotor 10 is connected to the eccentric vertical shaft-rotor assembly for rotation therewith when the oil pump is in operation. In this embodiment, the connection is achieved by direct contact between the outer sidewall of the upper end 10a of the pump rotor 10 and the adjacent inner sidewall of the lower end 9b of the oil passage 9 . The upper end 10a may also define a connector 11, as shown in FIG. 4, the embodiment of which will be described below. The reference numerals used to indicate the structural aspects of the technical solutions in FIGS. 3 and 4 are the same, and the only difference is that the symbol "'" is added to the reference numerals in the structure of FIG. 4 .

The tubular sleeve 20 is connected to the inertial part of the motor or compressor housing so as not to rotate with the pump rotor 10 by suitable means, such as the one described in the applicant's Brazilian patent application PIP201761. In the illustrated embodiment, the above-mentioned connection is connected to the compressor casing 1 through the connection wall 50 .

However, other configurations of the upper part 10a of the pump rotor 10 and other technical solutions for its fixation on the eccentric vertical shaft-rotor assembly can also be used to obtain the same effect.

The pump rotor 10 has an inner axially arranged oil supply channel 12 which is concentric to the geometric axis of the pump rotor 10 and which communicates the oil in the oil sump 2 with the oil channel 9 .

Although not shown, the oil delivery passage can also adopt other structures, such as multiple external and/or internal oil passages arranged along the axial length of the pump rotor 10 . Obviously the structure can also have external oil passages, which are formed sealingly along at least part of their length, functioning as a structural feature of the tubular sleeve 20 .

The structure of the tubular oil passages in the body of the pump rotor 10 can also make the above-mentioned oil passages form bundles diverging upwards at least from the lower end of the pump rotor 10 . In the structural solution shown in FIG. 3, the lower end 10b of the pump rotor 10 has a pair of radial grooves 13 diametrically opposed to each other, extending radially from the periphery of the lower end 10b to a predetermined distance from the geometric axis of the pump rotor 10. In this structure, the oil delivery channel 12 is located between the edge of the lower end 10b and the upper end 10a of the pump rotor 10 .

Although not shown, other structures can be used without changing the effect, for example, a plurality of grooves 13, which are preferably radial, can communicate in the center of the region of the pump rotor 10.

The aforementioned radial limitation of the radial grooves 13 is due to the fact that there is always oil on the adjacent part of the oil delivery channel 12 in this area. The communication between the aforementioned grooves would allow oil to flow away through the radial grooves 13, causing a loss of pumping power. When the oil transfer channel 12 starts above the region of the radial grooves of the pump rotor 10, communication between said grooves can occur without impairing the performance of the oil pump. The height and width of the radial grooves 13 are also defined in accordance with the desired performance of the pump and the desired structural features of the tubular sleeve 20, which will be described in more detail below.

Each radial groove 13 fits therein a respective sliding vane 14 which is freely placed in the radial groove 13 so as to pass through the radial groove between the dragged working position and the retracted non-working position. Moving radially, in the operative position said blades tend to protrude radially outwards from the associated radial groove 13 , whereas in the inoperative position the blades 14 are housed in the associated radial groove 13 . The role of the vane-groove will be described below.

The tubular sleeve 20 has a central upper opening 20a facing the rotor-eccentric vertical shaft assembly and a lower opening 20b which is offset from a portion of the lower surface or from a portion of the peripheral surface of said tubular sleeve 20 . Through the central upper opening 20a, the tubular sleeve 20 receives the lower end 10b of the pump rotor 10 with a sufficiently slight clearance therebetween to prevent the tubular sleeve 20 from rotating with the pump rotor 10.

A cylindrical dragging oil chamber 21 is defined between the upper opening 20a and the lower opening 20b, its diameter is larger than that of the pump rotor 10, and its height corresponds to the height of the radial groove 13, and the dragging oil chamber 21 has a tube shape The lower opening 20b of the barrel 20 communicates with an oil inlet 21a and an oil outlet 21b that communicates with the oil delivery passage 12 of the pump rotor 10 through a connecting oil passage 22 supported by the tubular sleeve 20 . A section of the connecting oil passage 22 is arranged below the dragging oil chamber 21; an oil receiving part receives oil from the oil outlet 21b of the dragging oil chamber 21, and supplies the oil to the lower part of the connecting oil passage 22; and an oil lifting part The oil from the lower part of the connecting oil passage 22 is sent to the oil delivery passage 12.

The oil inlet 21a and the oil outlet 21b are defined in such a manner that during the movement of the sliding vane 14 between the rest position and the operative position, downstream of the oil outlet and upstream of the oil inlet Only a thin oil film is left in the dragging oil chamber, which will not affect the pump oil efficiency, and further lubricates the lower part of the pump rotor 10 located in this area and the adjacent part of the inner wall of the dragging oil chamber 21 . The proximity between said walls is due to the eccentricity of the pump rotor 10 relative to the drag oil chamber 21 .

The above-mentioned lubrication is necessary in order to avoid the wear caused by the frictional contact of the parts due to the rotation of the pump rotor 10 .

The pumping of oil from the oil sump 2 to the bearing 4 and other parts to be lubricated during operation of the compressor is accomplished in the following manner. Rotation of the rotor-eccentric vertical shaft assembly and pump rotor 10 induces a centrifugal force on the sliding vanes 14, forcing said vanes to move away from the associated grooves 13 during a portion of the compressor's rotation and causing the outer ends of said vanes to always abut against Lean against the wall of the drag oil chamber 21. Acting as a vane within the drag oil chamber 21, the vane 14 forces the oil from the oil sump 2 to flow toward the oil outlet 21b when passing through the inlet hole 21a of the drag oil chamber 21 .

Due to the eccentricity between the pump rotor 10 and the dragging oil chamber 21, during the half-turn of the pump rotor 10, that is, at the tangential position of the pump rotor relative to the inner wall of the dragging oil chamber 21 and between the pump rotor 10 and the dragging oil chamber Between the 21 maximum spacing positions, each sliding vane 14 is pressed outwards from the associated radial groove 13 . From the region of the maximum distance, although the sliding vane 14 is still pressed outward from the relevant radial groove 13 under the action of centrifugal force, due to the eccentricity of the pump rotor and the dragging oil chamber, the blade begins to shrink toward the inside of the radial groove. Back to sports.

In this structure, the centrifugal force and eccentricity of the relevant parts act as elastic elements on the sliding vanes 14, as if provided between the inner end of each sliding vane 14 and the bottom end of each radial groove 13. The same is true for springs.

When reaching the oil outlet 21b of the dragging oil chamber 21, the oil carried by the sliding vane 14 is brought to the connecting oil passage 22, from where the oil is sent from the oil delivery passage 12 to the oil passage 9 for distribution to the bearing and adjacent Component.

In the structural scheme shown in Fig. 4, the lower end 10b' of the pump rotor 10' is preferably provided with three radial blades 15 as a whole, and these blades are fixed, hard, and distributed at equiangular distances from each other, from the oil delivery channel 12' The lower part extends and sweeps the inside of the drag oil chamber 21'. Although not shown, other configurations can be used without altering the effect, wherein one or more vanes are rigid or flexible, integral or attached to the pump rotor.

As shown in FIG. 4, the tubular sleeve 20' has an upper inlet 20a', which is formed in the central opening of the tubular sleeve 20' so as to fit concentrically into the lower end 10b' of the pump rotor 10', and also has a lower outlet. 20b'. The upper inlet 20a' also forms an oil inlet 21a' in this structure, and the oil comes from the oil sump 2 and is pumped to the oil delivery channel 12. The lower inlet 20b' communicates with the oil from the dragging oil chamber 21' through the oil delivery passage 12'.

The dragging oil chamber 21' also has an oil outlet 21b', which communicates with the oil dragged by the radial vanes 13' through the connecting oil passage 22' of the tubular sleeve 20', and the connecting oil passage 22' is arranged in the dragging oil chamber 21' Below, the connecting oil passage has an oil receiving part facing the oil outlet 21b' and an oil sending part facing the lower end of the oil delivery passage 12', which is the same as the previous description of the structural solution shown in FIG. 3 .

In this configuration, during the rotation of the eccentric vertical shaft-rotor assembly and the pump rotor 10', the oil entering the upper inlet 20a' of the tubular sleeve 20' flows to the drag oil chamber 21' and is then driven by the radial vanes. 15 is dragged on the inner wall of the drag oil chamber 21' until it reaches the connecting oil passage 22', from where the oil is delivered to the oil passage 9 as previously described.

Claims (10)

1. Mechanical oil pump for variable speed hermetic compressors, comprising a sealed casing (1) defining at the bottom a lubricating oil sump (2) and housing therein: a cylinder supporting an eccentric vertical shaft (5) ( 3), the rotor (8) of a motor (6) is installed on the eccentric vertical shaft, and the eccentric vertical shaft (5) is provided with at least one oil passage (9), and its lower end (9b) leads to the eccentric vertical shaft ( 5) the lower end 5(b), the upper end of which opens to the outside of the upper middle of the eccentric vertical shaft (5), the eccentric vertical shaft-rotor assembly is connected at its lower part to the upper axial extension of the pump rotor (10, 10') and a tubular sleeve (20, 20') connected to an inertial part of the compressor and surrounding at least a part of the pump rotor (10, 10') immersed in oil, said oil pump being characterized in that it includes: - a drag oil chamber (21, 21') defined in the tubular sleeve (20, 20') for housing part of the oil-immersed part of the pump rotor and having at least one inlet port communicating with the oil sump (2) oil ports (21a, 21a') and an oil outlet port (21b, 21b'), said pump rotor is in axial sealing contact with the tubular sleeve somewhere; - at least one drag vane (14, 15), which has an end mounted in said lower end portion of the pump rotor (10, 10') in a drag oil chamber (21) and an end always in contact with the drag oil chamber (21 , 21') in contact with the inner wall so as to radially and angularly force the oil from the oil groove (2) received through the oil inlet (21a, 21a') to the oil outlet of the dragging oil chamber (21, 21') opposite ends of (21b, 21b'); - at least one oil delivery channel (12, 12'), defined along at least a part of the axial extension of the pump rotor (10, 10'), so that its lower end passes through a tube carried by a tubular sleeve (20, 20') The connecting oil passage (22, 22') is in fluid communication with the oil outlet (21b, 21b') of the dragging oil chamber (21, 21'), and its upper end is connected to the lower end (9b) of the oil passage (9). 2. The oil pump according to claim 1, characterized in that each drag vane (14) is formed by a sliding vane fitted in a respective groove on a part of the lower end (10b) of the pump rotor (10) (13). 3. The oil pump according to claim 2, characterized in that: each sliding vane (14) is freely installed in its respective groove (13), so that when the rotor rotates, it can move radially against the rotor under centrifugal force. Lean against the inner wall of the drag oil chamber (21). 4. The oil pump according to claim 3, characterized in that the pump rotor is eccentrically arranged in the drag oil chamber (21). 5. The oil pump according to claim 2, characterized in that the pump rotor (10) is provided with a pair of grooves (13), which are diametrically opposed to each other. 6. Oil pump according to claim 1, characterized in that each drag vane (15) is connected to the lower end of the pump rotor (10'). 7. The oil pump according to claim 6, characterized in that: the oil inlet (21a') of the dragging oil chamber (21') is defined by the upper opening (20a') of the tubular sleeve (20'), the tubular Sleeve (20') surrounds pump rotor (10') 8. The oil pump according to claim 1, characterized in that: the oil delivery channel (12, 12') is inside the pump rotor (10, 10') body. 9. The oil pump according to claim 8, characterized in that: said oil delivery passage (12, 12') has an upper end and a lower end, which lead to the upper end (10a, 10a') of the pump rotor (10, 10') respectively ) and the lower end (10b, 10b') 10. The oil pump according to claim 9, characterized in that the oil delivery channel (12, 12') is concentric with the geometric axis of the pump rotor (10, 10').

Images