JP2840396B2 - Hermetic compressor having a rotary rolling piston - Google Patents

Description

The present invention relates to a hermetic compressor having a rotary rolling piston and a high internal pressure, which is usually used in a small refrigerator and an air conditioner. It should be understood that in a rotary rolling piston hermetic compressor with a high internal pressure, the compressor casing will experience the condensing pressure of the system in which the compressor is used.

BACKGROUND OF THE INVENTION In a rotary rolling piston sealed compressor having a high internal pressure in a casing, lubricating oil flows into the cylinder,
The phenomenon of entering (entering) the suction and discharge chambers occurs. Lubricating oil contained in the bottom of the casing and subject to high gas pressure in the casing is raised by the lubricating oil pump means until it reaches the crankshaft, and is then conveyed along the oil groove from the crankshaft to the rolling piston. And radially moved through the gap between the annular end surface of the rolling piston and the bearing cover and into the cylinder interior chamber.

The intrusion of high-temperature lubricating oil into the cylinder has the following effects on the function and performance of the compressor.

In the case of entry into the suction chamber, the hot lubricating oil warms the incoming suction gas, causing an increase in the specific volume of that gas and thus reducing the filling volume of the suction chamber. The mass of the gas filling the suction chamber of the cylinder is thus reduced as a result of the increase in the specific volume of the gas. In addition to this problem, it must be noted that the lubricating oil volume itself entering the suction chamber occupies the gas filling space. However, this effect is of only secondary importance compared to the effect of heating.

The above problems cause a reduction in the pump capacity of the compressor as a result of the penetration of the lubricating oil into the cylinder.

Furthermore, in the case of entry into the cylinder compression chamber, during most of the compression cycle, the lubricating oil is at a temperature higher than the temperature of the gas being compressed, thus causing heating of such gas and reducing the specific volume of that gas. Increase. As a result of this phenomenon, the amount of work required to compress the gas increases, and thus the energy consumption of the compressor increases. This fact can be confirmed in FIG. 2 of the accompanying drawings, which show that the compression pressure rises more rapidly as the lubricant leak into the compression chamber increases. The graph of "pressure and rotation angle" is shown in FIG.

These effects combine to cause a significant decrease in the volumetric and energy efficiency of the compressor.

On the other hand, the presence of the lubricating oil stream fulfills two preferred functions which are fundamentally important for the operation of the compressor:-the most obvious first function is the lubrication of the moving parts contained in the compressor. And the second function is to seal all the gaps between the moving parts and thus prevent the direct leakage of gas from inside the cylinder into the casing, when such leakage occurs, This leakage can even be more harmful with regard to compressor performance degradation than overheating of the gas by the lubricating oil.

The characteristics of lubricating oil that seals the gap between moving parts are:
It is effective against leakage inside the cylinder (from the compressor chamber at low pressure into the suction chamber) and also effective against leakage from the compression chamber into the interior of the casing.

Especially in the case of lubricating oil which penetrates radially into the cylinder through the end face of the rolling piston, this oil will leak gas from the compression chamber into the internal part of the crankshaft and furthermore, Prevents leakage from the part to the inside of the casing.

Thus, the amount of lubricating oil that enters the cylinder must be minimized to an optimum amount, so as to enable sealing of gas leaks while at the same time heating the gas inside the cylinder to a minimum.

One known way to reduce the amount of lubricating oil that enters the cylinder by the gap in the rolling piston end face is to reduce such gap to a minimum size. The minimum size of this gap is
The friction loss between the rolling piston end face and the bearing cover face is sized so that it does not reach a value that completely offsets the gain resulting from the reduction of lubricant flow through the gap. .

It is possible to reduce the gap at the end face of the rolling piston so as to advantageously reduce the amount of lubricating oil entering the cylinder. But the resulting gain is
Regarding the energy efficiency of the compressor, it is always inferior to the gain that can be achieved by reducing the lubricating oil flow alone, due to the friction losses resulting from any reduction of the gap.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to reduce friction between the moving parts of a compressor, more specifically, the friction between the rolling piston end face and the bearing cover and the eccentric portion of the rolling piston and the camshaft. To provide a rotary rolling piston hermetic compressor in which the flow of lubricating oil into the cylinder is significantly reduced as compared to known solutions without significantly increasing the friction between the cylinder and the cylinder.

The rotary rolling piston sealed compressor, which is the object of the present invention, is of the type that includes a sealed casing that receives the condensing pressure of a system such as a refrigerator or air conditioner sent to the casing through a discharge pipe. In this compressor, the casing houses a cylinder block, and a rolling piston assembled around an eccentric portion of a crankshaft supported on a bearing rotates in an inner cylindrical chamber of the cylinder block, The cylindrical chamber is axially closed by an end wall thereof, the interior of the chamber is divided by a rolling piston and a sliding vane into a suction chamber and a compression chamber, and furthermore during the compression cycle For the most part, the internal pressure in the suction chamber is significantly lower than the internal pressure of the casing, and the internal pressure in the compression chamber is significantly lower than the internal pressure of the casing, the shaft for the passage of lubricating oil A directional gap is maintained between the cylindrical chamber end wall and the opposing rolling piston annular surface. There.

In accordance with the present invention, the rolling pistons are sufficient to reduce the lubricant flow entering the discharge and suction chambers by at least 10% without any increase in frictional losses between moving parts. To expand the radial flow path of the lubricating oil flow through opposing axial gaps to the suction and compression chambers, about 1.
A rolling piston is constructed that provides an outer diameter / inner diameter relationship of 63 to about 2.22.

From equations that model the radial flow (viscous flow between parallel disks) of lubricating oil through the rolling piston face, the flow can be determined by the gap (δR) and by the thickness of the rolling piston wall, or More clearly, it can be pointed out that it is controlled by the following relationship.

The nature of these functions can be observed in the graph of FIG. Rolling piston dimensions found in commercial compressors range from 1.40 to defining a thin-walled rolling piston.
An outer diameter (Φext.) / Inner diameter (Φint.) Relationship of 1.55 is given.

In the present invention, generally Is intended to be defined as a thick-walled rolling piston.

From the graph of FIG. 3, the slope of the curve Ln ^-1 . (Φext. / Φint.) Is very remarkable until the relationship of Φext. / Φint. Value = 1.63 is almost reached. It can be pointed out that after reaching 1.6, it gradually becomes calm.

As described above, the property of the curve representing the flow of the lubricating oil toward the inside of the cylinder is proportionally reflected in the performance of the compressor, that is, the function Ln- ¹ (Φext. / Φint.) Can be increased. It must be remembered that the more lubricating oil flows, the worse the volumetric efficiency and energy efficiency of the compressor. Therefore, the relation (from Φext. / Φin) in the commonly used range (from 1.63)
In order to obtain t.), the penetration of lubricating oil into the cylinder
At least 10 by changing the dimensions of the rolling piston
% Reduction is possible, and the rolling piston It is important to point out that they are sized to obtain the relationship Further, a diameter relationship of 1.63 to about 2.22 is fully achievable in the fabrication process commonly used for rotary rolling piston compressors, and using such a relationship presents no obstacles or disadvantages with respect to compressor performance. It is also important to mention that it does not occur.

The only disadvantage, if any, that could be pointed out would be increased friction loss between the piston face and the cylindrical chamber end face due to the increased contact surface. But,
The increase in the contact surface tends to result in a decrease in the angular velocity of the piston on the piston axis, which compensates for the mechanical losses, so that in practice there is no appreciable increase in frictional losses. In addition, such losses due to friction are at least an order of magnitude less than losses caused by hot lubricating oils. Therefore, such losses can be ignored.

Reducing the inner diameter of the piston has yet another beneficial indirect result with respect to the energy efficiency of the compressor when a larger outer / inner diameter relationship is used.
These advantages are as follows.

The reduction of the piston inner diameter naturally also reduces the diameter of the eccentric part of the crankshaft, thus reducing the large viscous drag loss between the contact surface of the piston and said crank eccentric shaft.

-Usually, when the diameter of the eccentric part of the crankshaft is reduced, the diameter of the edge of the short crankshaft can also be reduced, and optionally by adding supports or axial bearings. (See figure for preferred shape), it is even possible to omit the secondary bearing. This solution reduces the friction losses in such bearings.

The angular velocity of the piston on the piston shaft is reduced by reducing the diameter of the eccentric part of the crankshaft and thus by reducing the contact surface between the eccentric part of the crankshaft and the piston, Significantly reduces the friction loss between the blade top and the piston outer diameter, one of the largest friction losses in the compressor.

Thus, it can be concluded that it is more advantageous to obtain an increase in the relationship between roller diameters by reducing the piston inner diameter, rather than by increasing the piston outer diameter. In the compressor of the present invention, the end of the crankshaft constitutes an annular flange housed in a recess formed in the end face of one axial end wall of the cylindrical chamber. This annular flange prevents the crankshaft from moving toward the motor.

Embodiment Referring to FIGS. 1A and 1B, the compressor of the present invention fixes the suction pipe 2 and the discharge pipe 3 and the cylinder block 4.
The inside of the cylinder block 4 has a limited cylindrical chamber for accommodating the rolling piston 5, and the rolling piston 5 is driven by an electric motor including a stator 7 and a rotor 8. It is mounted on the crankshaft 6. The inside of the casing of the compressor is at a high pressure, and the inlet end of the discharge pipe 3 opens to the inside of the casing.

The crankshaft 6 is supported on a main bearing 10 and a sub bearing 20. Each of these bearings is such that it limits the extent of the cylindrical chamber wall in which the rolling piston 5 is moved.
The cylinder block 4 includes plates or flanges 10a, 20a which are pressed and fixed to one axial end surface of the cylinder block 4.

In the embodiment shown, a discharge muffler chamber 13 adjacent to the outer surface of the secondary bearing 20 is provided for receiving the compressed gas inside the cylinder. The secondary bearing plate 20a (or the cylinder block wall 4 in the absence of such bearings) is provided with a discharge orifice 21, the outlet end of which is known inside the discharge muffler chamber 13. The range of the annular valve seat to which the reed valve 30 is attached is limited.

Further according to the basic structure shown in FIGS. 1A and 1B,
The main bearing plate 10a is provided with a radial channel 11, the lower end of which is immersed in the lubricating oil OL stored at the bottom of the casing 1, the upper end of which channel is lubricated with a lubricating oil pump or another oil. Open to the pump means.
In addition, this lubricating oil pump or other pump means is limited in its area around the crankshaft 6 and is adapted to guide the lubricating oil to the bearing and to the axial gap at the end of the rolling piston 5. In fluid communication with a surface groove 14 provided along its length.

As shown in FIG. 1B, the cylinder block 4
The casing has a window 4a for internal pressure equalization and for the passage of lubricating oil and a slot in which the sliding vane 9 is contained. The sliding vane plate 9 divides the cylindrical chamber into a suction chamber and a discharge chamber together with the outer cylindrical surface of the rolling piston 5, and the cylinder block 4
It is supplied through a channel 4b made on its surface and is kept in communication with the inner end of the suction tube 2.

FIG. 4A includes an eccentric part 5a for driving the rolling piston 5 and an end part 6b for being supported inside the auxiliary bearing 20;
1 shows a conventional structure of a crankshaft 6. Usually these two
One particular crankshaft portion has the same diameter as the other portions of the crankshaft body. In this prior art solution, in the arrangement shown in FIG.
Has an annular wall thickness that results in a relationship of Φext. / Φint. <1.60, and therefore a harmful amount of lubricant due to the short radial travel of the lubricant represented by the arrow in FIG. 1B. Can enter the inside of the cylinder.

FIG. 4B shows a crankshaft 60 having an eccentric portion 60a, which drives a rolling piston 50 having an annular wall thickness that results in the relationship Φext. / Φint.> 1.63. The relationship contained within the limits defined in the present invention is the inner diameter of the rolling piston 50 and thus the eccentric part of the crankshaft 60.
It was obtained by reducing the diameter of 60a. By reducing the diameter of the eccentric portion 60a of the crankshaft 60 in this manner, as shown in FIG.4B, the end portion 60b also has a reduced diameter compared to the other portions of the crankshaft main body. It is possible to have.

Yet another advantage resulting from reducing the diameter of portions 60a and 60b of crankshaft 60 as described above is mentioned in the first part of the specification.

FIG.4C shows another possible configuration of the crankshaft 600, which has an eccentric portion 600a of significantly smaller diameter as a result of the larger thickness of the rolling piston wall 500,
Its end portion 600a is completely removed, and thus the secondary bearing 20
Has also been completely removed. In this case, the corresponding axial end wall of the cylinder chamber can consist of a simple closing plate fixed to the adjacent surface of the cylinder block.

In the case of the embodiment shown in FIG.
An axial stop 601 in the form of an annular flange incorporated into the body is provided. In order to limit the movement of the crankshaft 600 in the axial direction toward the motor due to the strength of the magnetic force of the rotor acting on the crankshaft, the stopper is provided on the end face of the plate 10a of the main bearing 10. An eccentric portion 600a is disposed adjacent to the eccentric portion 600a so as to be received in each created recess 10b. The concave portion 10b acts as an axial bearing for the stopper 601 and the axial stopper 60
The depth allows the formation of a large gap between 1 and the adjacent end wall of the rolling piston.

[Brief description of the drawings]

FIG. 1A is a partial longitudinal sectional view of a rotary rolling piston compressor of the type used in the present invention, and FIG. 1B is a line B in FIG. 1A.
FIG. 2 is a graph of the compression pressure generated in relation to the rotation angle of the rolling piston, and FIG. 3 is "the radial flow of lubricating oil passing through the rolling piston surface". Representative graph of the function of "the thickness of the annular wall of the piston", 4A
The figure is a side view of a prior art crankshaft-rolling piston set,
FIG.4B is a side view of a crankshaft-rolling piston set assembled as an embodiment of the present invention, and FIG.4C is a crankshaft-rolling piston set as another embodiment of the present invention. FIG. 5 is a partial enlarged view of the crankshaft-rolling piston set of FIG. 4C when disposed inside a bearing and a cylinder block. DESCRIPTION OF SYMBOLS 1 ... Compressor casing, 2 ... Suction pipe, 3 ... Discharge pipe, 4 ... Cylinder block, 5,50,500 ... Rolling piston, 6,60,600 ... Crankshaft, 10 ... Main bearing, 20 ......
Auxiliary bearing, 10a, 20a: plate or flange, 21: discharge orifice, 30: reed valve, 60, 60a, 600a: crankshaft eccentric part.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F04C 18/356 F04C 29/00

Claims (2)

(57) [Claims] 1. A hermetic compressor having a rotary rolling piston, said compressor comprising a hermetic casing for receiving the condensing pressure of a refrigeration system, said pressure being passed through a discharge pipe to said hermetic casing. The casing accommodates one cylinder block, and a rolling piston mounted around an eccentric portion of a crankshaft supported on bearings rotates in an inner cylindrical chamber of the cylinder block; The cylindrical chamber is axially closed by its axial end wall, and the interior of the chamber is divided into a suction chamber and a compression chamber by the rolling piston and a sliding vane, during the compression cycle. For the most part, the internal pressure in the suction chamber is significantly lower than the internal pressure of the casing, and The internal pressure in the chamber is significantly lower than the internal pressure of the casing, and an axial gap for the passage of lubricating oil is provided between the end wall of the cylindrical chamber and the annular face of the rolling piston opposed thereto. And the rolling piston is about
A bearing having an outer diameter / inner diameter relationship of 1.63 to about 2.22, wherein one axial end wall of the cylindrical chamber facing the body of the crankshaft (600) is fixed to the cylinder block (4); (10) defined by the flange (10a), the crankshaft (600) facing the cylinder block (4) and having an end (601) defining the cylindrical chamber; A hermetic compressor wherein an end (601) of the crankshaft constitutes an annular flange housed in a recess (10b) formed in an end surface of the one axial end wall. 2. The hermetic compression according to claim 1, wherein the outer diameter / inner diameter relationship is obtained as a result of significantly reducing the inner diameter of the rolling piston and the diameter of the eccentric portion of the crankshaft as compared with a normal value. Machine.