JPH01167488A - Oiling structure of horizontal type rotary type compressor - Google Patents

Abstract

PURPOSE: To rapidly and securely supply oil in actuation by forming an annular space between a bearing surface and a corresponding outer peripheral surface of a shaft, and forming a helical oil supply groove having a certain depth in the outer peripheral surface of the shaft. CONSTITUTION: An annular space 33 is formed between a bearing surface and a corresponding outer peripheral surface of a shaft 30. A helical oil supply groove 30a is formed in the outer peripheral surface of the shaft 30 to communicate the annular space 33 with a bearing outside. The depth h of the oil supply groove 30 is defined to be h<=[(6μωR/ρgH)cotθ.L]<1/2> , wherein μ is viscosity coefficient of a coolant; ω is an angular velocity of the shaft; R is the radius of the shaft; ρ is the density of lubricating oil; g is acceleration of gravity; H is a height from the surface of the lubricating oil till the bearing surface; θis an angle of the oil supply groove against the shaft axis; and L is the length of the shaft portion where the oil supply groove is formed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a refueling structure for a horizontal bed rotary compressor, and particularly to a horizontal rotary compressor used for compressing refrigerant in refrigerators, air conditioners, etc. This article relates to the oil supply structure for pressure S machines.

<Prior Art> A lubricating oil storage chamber formed in the bottom of a casing, a journal bearing formed in the middle part of the casing to rotatably support the middle part of the shaft extending in the horizontal direction, A horizontal layer rotary compressor for compressing refrigerant, which has a rotary compression pump unit provided at one end of a shaft and an electric motor provided at the other end of the shaft, includes a refrigerator,
These rotary compressors have become widely used in air conditioners, etc., but because they are installed horizontally, they have advantages such as saving installation space and reducing vibration and noise. Because it is necessary to maintain a low lubricating oil level to prevent lubricating oil from flowing into the rotor of a horizontally installed electric motor, a separate oil supply device is required to supply lubricating oil to the sliding parts of the rotating shaft. There is a problem with that.

Therefore, for example, in Japanese Patent Application Laid-Open No. 60-30495, a refueling device as shown in FIG. 5 of the present specification is proposed as a prior art. In this oil supply device, a helical coil surrounded by a tube and immersed in the oil surface at the lower end is connected to the tip of the shaft having the oil supply groove, so that the coil and the shaft are connected to each other. As the tube rotates, the helical movement of the coil and the viscosity of the lubricating oil causes the lubricating oil to rise along the inner peripheral surface of the tube and reach the sliding portion of the shaft.

The fluid diode system shown in FIG. 6 is disclosed in, for example, JP-A-59-218389 or JP-A-60-30495, in which the tip of a shaft has an axial passage for oil supply and a groove for oil supply. An oil supply pipe that communicates with a fluid diode type lubricating oil pump device driven by the shaft is coupled to the portion.

These conventional oil supply systems have complicated structures, increase the size of the compressor due to the increased number of parts, raise manufacturing costs, and are difficult to improve reliability and durability. There was a problem.

Japanese Unexamined Patent Publication No. 62-58086 discloses a differential pressure type oil supply structure as shown in FIG. In this structure, a certain sealed cavity is formed between the journal bearing and the shaft, and this cavity is communicated with the part below the lubricating oil level via the oil supply passage, and the initial stage of the compressor is Lubricating oil is supplied to the bearing sliding portion through the oil supply passage due to the pressure difference between the pressure that is created inside the casing during startup and the low pressure that is sealed and maintained in the sealed cavity. Although this type of differential pressure system is simpler than other types of oil supply structures, it tends to delay the supply of lubricating oil to the sliding parts when the compressor is started, and it is also difficult to lubricate the sliding parts. Since it is difficult to supply oil evenly and reliably, partial wear of the sliding parts may occur in some cases, and a pressure difference required for oil supply within the compressor is generated. However, there are problems in that the lubricating oil may not reach the sliding parts because such high pressure is not generated.

That is, the journal bearing 1a provided in the center of the wall 1
An annular cavity 5 is formed between the inner circumferential surface of the shaft 2 and the outer circumferential surface of the shaft 2. It communicates with the upper part of the passage 1b. A helical coil 2a is formed in a part of the sliding portion of the shaft 2. Therefore, the sealed chamber 5 and the oil supply passage 1b are isolated from other parts of the compressor, and an airtight state is maintained, so that the pressure inside the casing 4 generated when the compressor is started is transferred to the same parts through the lubricating oil. It will be transmitted.

That is, when the compressor is started, the raised casing 4
Due to the internal pressure, lubricating oil 9 is forcibly supplied to the sealed space 5, which maintains the atmospheric pressure before starting the compressor, through the oil supply passage 1b, thereby achieving lubrication between the shaft 2 and the journal bearing 1a. . However, since the sealed chamber 5 is already filled with refrigerant gas, the refrigerant gas is compressed, thereby preventing the lubricating oil from flowing into the closed chamber 5. Therefore, a larger pressure difference is required to ensure that the lubricating oil reaches the sliding parts. Therefore, it takes a relatively long time for the lubricating oil to reach the sliding parts of the bearing, and in some cases, a problem arises in that a sufficient pressure difference is not generated and lubricating oil is not supplied to the sliding parts. It is possible. In addition, since the oil supply groove is formed only in a part of the shaft sliding part, the lubricant cannot be reliably supplied to the outer sliding part where the oil supply groove is not formed, causing wear and tear in that part. In some cases, this may shorten the life of the compressor. In order to prevent this, additives have been conventionally added to the lubricating oil, but this has only increased the manufacturing cost of the compressor and has not been able to achieve a sufficient effect. Furthermore, because the oil supply groove is formed only on a portion of the sliding part of the shaft to maintain the airtightness of the sealed chamber, fine cutting chips and other hard foreign matter may get mixed into the lubricating oil. When foreign matter enters the sliding part, it is not discharged to the outside of the sliding part and is trapped in the sliding part between the bearing and the shaft.
In some cases, this causes the shaft to seize, which is a fatal failure of the compressor, and causes large abrasion scars on the sliding parts, which drastically shortens the life of the compressor. In order to avoid such problems, it is necessary to thoroughly clean the parts before assembling the compressor, and to strictly select the lubricating oil or control the residue, which results in an increase in the manufacturing cost of the compressor.

<Problems to be Solved by the Invention> In view of the problems of the prior art, the main purpose of the present invention is to supply lubricating oil quickly and reliably to the bearings even when the compressor is started up. The object of the present invention is to provide an oil supply structure for a horizontal layer rotary compressor that is improved so that lubricating oil is supplied over the entire sliding surface of the shaft.

A second object of the present invention is to provide an oil supply structure for a horizontal bed rotary compressor that can reduce the burden of managing lubricating oil residue and cleaning parts.

A third object of the present invention is to provide an oil supply structure for a horizontal rotary press machine that is simple in structure, easy to manufacture, and has a low failure rate.

<Means for Solving the Problems> According to the present invention, the purpose is to provide a lubricating oil storage chamber formed at the bottom of the gauging and an intermediate portion of the shaft extending in the horizontal direction to be freely rotatable. a horizontal layer for compressing refrigerant having a journal bearing formed in the middle part of the casing for support, a rotary compression pump unit provided at one end of the shaft, and an electric motor provided at the other end of the shaft; The oil supply structure for a rotary compressor includes an oil supply passage that communicates a bearing surface of the journal bearing with a portion below the oil level of the lubricating oil storage chamber, and a correspondence between the bearing surface of the journal bearing and the shaft. an annular cavity defined between the shaft and the outer peripheral surface; and a spiral additional oil groove formed on the outer peripheral surface of the shaft to communicate the annular cavity with the outside of the bearing; Depth h is 6 μωR1/2 h ≦ (cotθ・L) ρgH (where μ is the viscosity coefficient of the refrigerant, ω is the angular velocity of the shaft,
R - radius of shaft, ρ - density of lubricating oil, g - gravitational acceleration, H - height from lubricating oil surface to bearing surface, θ - angle of oil groove with respect to shaft axial direction, L - formation of oil groove This is achieved by providing an oil supply structure for a horizontal rotary press machine, which is characterized in that the length of the shaft portion is determined to be the same.

<Operation> According to this structure, the casing rises at the start of compression by utilizing the pumping action of the oil groove due to inertia accompanying rotation of the shaft and the laminar movement of refrigerant flowing between the oil groove and the inner peripheral surface of the bearing. The refrigerant is discharged while overcoming the internal pressure, so that the lubricating oil present at the bottom of the casing is sucked into the oil supply groove through the oil supply passage and the annular cavity. Thereafter, regardless of the high pressure inside the casing, the pumping action of the oil supply groove due to inertia accompanying the rotation of the shaft continues to supply lubricating oil smoothly into the oil supply groove. In addition, since the oil supply groove formed on the outer peripheral surface of the shaft communicates with the outside of the sliding part,
Cutting chips, hard foreign objects, etc. mixed in the lubricating oil are easily discharged to the outside of the sliding part along with the lubricating oil, which prevents seizure of the shaft and minimizes damage to the shaft outer circumferential surface. .

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, inside a casing 10 of a rotary compressor according to the present invention, a stator 20, a rotor 21
An electric motor M having a shaft 30 and a shaft 30 is installed.

The shaft 30 is horizontally supported in a cantilevered manner by a journal bearing 50a provided on a wall 50 that divides the inside of the casing 10 into left and right parts. A pump unit 40 is provided in a portion of the shaft 30 that protrudes to the other side of the wall 50. The pump unit 40 includes a rotary piston 43 having an annular shape, a cylinder 42, a cover plate 41 on which a sub-bearing 41a for pivotally supporting the free end of the shaft 30 is formed, and a cover plate 41 that is elastically mounted on one side of the cylinder 42. It has a blade 44 and an eccentric cam 31 that is located within the cylinder 42 and is integral with the shaft 30 that is fitted into the rotary piston 43. The above-described structure of the pump unit 40 is similar to the basic structure of a conventional horizontal rotary pressure machine.

An oil supply passage 51 that communicates between the lower part of the casing 10 and the inside of the journal bearing 50a is provided inside the wall 50, and an annular passage 51 that communicates with the upper end of this oil supply passage 51 is provided between the journal bearing 50a and the shaft 30. A vacant room 33 has been constructed. This annular cavity 33 consists of an annular groove 32 formed in the outer peripheral surface of the shaft 30, but it may also be formed by a similar groove formed in the inner peripheral surface of the journal bearing 50a. good. Also, if desired, the shaft 3
The annular cavity 33 can also be formed by forming grooves on both the outer circumferential surface of the bearing and the inner circumferential surface of the bearing.

Further, over the entire length from the sliding surface of the shaft 30 supported by the journal bearing 50a to the sliding part supported by the sub-bearing 41a, there are spiral oil supply grooves 30a to 30c communicating with the annular cavity 33. It is formed on the outer peripheral surface of the shaft 30. Therefore, the oil supply passage 51 and the annular cavity 33 communicate with the space outside the sliding portion of the shaft via the oil supply grooves 30a to 30c.

When the compressor starts and the shaft 30 rotates, the oil supply groove 3
The refrigerant gas that had filled 0a to 30c overcomes the rising pressure inside the casing and is discharged into the space outside the sliding part, and then the lubricating oil 60 that remains at the bottom of the casing 10 is refilled. Oil supply groove 3 via passage 51 and annular cavity 33
It is attracted to 0a-30c. For this purpose, the depth of the oil supply groove is preferably set to a certain value or less as described below.

That is, when the compressor is initially stopped, the space defined between the upper space of the oil supply passage 51, each bearing, and the shaft 30 is filled with refrigerant gas.

When the compressor is started and the shaft 30 begins to rotate at high speed, the refrigerant gas must be discharged to the outside of the sliding portion through the spiral oil supply grooves 30a to 30c. That is, the oil supply groove plays the role of a kind of blade and discharges refrigerant gas, and at the same time sucks lubricating oil through the partial oil supply passage 51 and the annular cavity 33, and supplies this lubricating oil toward the sliding part of the shaft. do.

However, as the compressor starts up, the air pressure inside the casing increases rapidly, so it is conceivable that a pressure difference will occur that causes the refrigerant in the oil supply groove to flow backwards. In other words, if the force that attempts to cause the refrigerant to flow backwards due to the action of the pump unit 44 is greater than the force that attempts to discharge the refrigerant to the outside of the sliding part by the oil supply groove of the shaft that rotates at high speed, the oil supply groove This makes it impossible to discharge refrigerant. However, in the present invention, focusing on the laminar flow phenomenon caused by the viscosity of the refrigerant, the depth of the oil supply groove is limited to a certain value or less so that the lubricating oil reaches the sliding parts. The lubricating oil must be pumped to a certain height h before the force that causes it to flow backwards becomes dominant.
The aim is to obtain a pressure difference that can be increased to .

That is, in FIG. 4, when the height from the lubricant oil level 60 to the sliding part is H, the pressure difference Δp due to the refrigerant flow must be at least ρgH in order for the lubricant to rise by H. (however,
ρ must reach the density of the lubricating oil). However, since the shaft is rotating relative to the bearing, the refrigerant flow due to inertia based on the rotation of the shaft can be regarded as a laminar flow between parallel plates in which one plate moves in parallel at a constant speed. The backflow of the invading refrigerant due to the pressure difference can be
It can be regarded as laminar flow between fixed flat plates. Therefore, the refrigerant discharge amount QO per unit time and per unit width of the oil supply groove generated by the rotational inertia of the shaft can be expressed by the general formula given by the following equation (1), ρ′ωRh Qo = cosθ ( 1) The amount of refrigerant intrusion Qi due to the pressure difference between the inside and outside of the sliding part is calculated using the following formula (
2) can be expressed by the general formula given by:

ρ'h3 dP Qi = −(−) sinθ (2) 12
μ dL (where ρ' - density of refrigerant, ω - angular velocity of shaft, R
- Radius of the shaft, h - Depth of the oil groove, μm Refrigerant viscosity coefficient, I - Height from the lubricating oil surface to the bearing surface, θ - Angle of the oil groove with respect to the shaft axis direction, L - Formation of the oil groove This is the length of the shaft section. ) Here, the refrigerant intrusion amount Qi increases at the same time as the compressor is started, and the refrigerant discharge iQo is constant. Therefore, in order to raise the lubricating oil to a certain height H, the required pressure difference Δp must be obtained before or before the above-mentioned Qi and QO reach an equilibrium state. Therefore, the depth h of the oil supply groove that satisfies this requirement
To calculate, if we balance equations (1) and (2), we get (the following margins) dP 6μωR = -cotθ (3) dL
h2, and therefore 6μωR ΔP = cotθ·L (4). Furthermore, since it is necessary that Δp≧ρgH, the depth h of the oil supply groove is limited by 6μωR1/2 h≦(−cotθ−L) (5) ρgH from equation (4).

The above formula (5) is a general formula for raising the lubricating oil by a certain height H, and the amount of lubricating oil supplied per unit time is adjusted by the width of the oil supply groove and the formation angle θ of the oil supply groove. According to the inventor's experiments based on the above equation, the following results were obtained in the case of a compressor for a general household refrigerator.

Although the depth h and width of the oil groove according to the present invention can be made constant as shown in FIG. 2, in order to obtain a greater oil supply effect, it is necessary to It is also possible to gradually reduce the size of the oil supply groove. This is achieved by greatly increasing the dynamic pressure on the lubricating oil outlet side.
This is a slug that effectively prevents the refrigerant from flowing backwards due to the pressure difference by reducing the pressure difference between the casing and the casing, thereby allowing the lubricating oil to reach the sliding parts within the earliest possible time.

Furthermore, as shown in FIG. 3, if a small diameter portion 55 is formed in a part of the intermediate part of the sliding outer peripheral surface of the shaft to store a certain amount of lubricating oil flowing through the oil supply groove, a larger amount of lubricating oil can be stored. Lubricating oil can be supplied more appropriately and effectively.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of the horizontal rotary compressor of the present invention. FIGS. 2 and 3 are perspective views showing different embodiments of the shaft applied to the oil supply tR structure according to the present invention. FIG. 4 is a perspective view showing in detail a part of the shaft in which a certain amount of oil supply groove is formed. 5 to 7 are side sectional views showing a conventional oil supply structure. 10...Casing 20...Stator 21...
・Rotor 30...Shaft 30a to 30c・
... Oil supply groove 31 ... Eccentric cam 32 ... Annular groove 33 ...
・Annular empty chamber 40...Pump unit 41...
Cover plate 41a...Sub bearing 42...Cylinder 43...Rotating piston 44...Blade
50...Wall 50a...Journal bearing 51...Oil supply passage 55...Small diameter portion 60...
Lubricating oil patent applicant Daewoo Electronics Company
limited

Claims (3)

[Claims] (1) A lubricating oil storage chamber defined at the bottom of the casing;
a journal bearing formed in the middle part of the casing to rotatably support the middle part of the shaft extending in the horizontal direction; a rotary compression pump unit provided at one end of the shaft; and the other end of the shaft. An oil supply structure for a horizontal rotary compressor for compressing refrigerant, the oil supply structure having an electric motor installed in the refrigerant compressor, the oil supply passage communicating a bearing surface of the journal bearing with a portion below the oil level of the lubricating oil storage chamber. , an annular cavity defined between the bearing surface of the journal bearing and a corresponding outer peripheral surface of the shaft; and an annular cavity formed in the outer peripheral surface of the shaft to communicate the annular cavity with the outside of the bearing. a spiral oil supply groove, and the depth h of the oil supply groove is h≦{(6μωR/ρgH)cotθ・L}＾1＾/＾
2 (However, μ - viscosity coefficient of refrigerant, ω - angular velocity of shaft, R - radius of shaft, ρ - density of lubricating oil, g - gravitational acceleration, H - height from lubricating oil surface to bearing surface, θ - 1. An oil supply structure for a horizontal rotary compressor, characterized in that the angle of the oil supply groove with respect to the shaft axial direction is determined to be (L - the length of the shaft portion in which the oil supply groove is formed). (2) The oil supply structure for a horizontal rotary compressor according to claim 1, wherein the cross-sectional area of the oil supply groove is gradually decreased in the lubricating oil advancing direction. (3) The oil supply structure for a horizontal rotary compressor according to claim 1 or 2, characterized in that a small diameter portion is formed in a part of the sliding surface of the shaft.