KR20020019225A - crankshaft in compressor - Google Patents

Abstract

PURPOSE: A crankshaft of a compressor is provided to maintain pumping amount of refrigeration oil while operating the compressor at lower speed and to actively discharge gas without leakage of the refrigeration oil. CONSTITUTION: A crank shaft for a compressor comprises a shaft unit(130); a drill hole(135) formed on a middle portion of a shaft by being mounted on a lower portion of the shaft; an oil hole(136) extended toward an inner circumference of the shaft; an oil groove(137) forming a slant passage along an inner circumference of the shaft from the oil hole; a balance weight(120) preventing vibration by balancing rotational movement on an upper portion of the shaft unit; and an eccentric pin(110) interlocked with the oil groove by being combined to the connecting rod. Thereby, the crank shaft for the compressor actively discharging gas by preventing leakage of refrigeration oil. Moreover, the crankshaft for the compressor maintains pumping amount of the refrigeration oil.

Description

Crankshaft for compressor {crankshaft in compressor}

The present invention relates to a crankshaft of a compressor, and more particularly, to a crankshaft of a reciprocating compressor in parallel with a low speed operation and a high speed operation.

In general, a compressor serves to compress a working fluid passing through an evaporator and supply it to a condenser in a refrigeration air conditioner such as a refrigerator or an air conditioner.

Hereinafter, with reference to the accompanying drawings, in particular the configuration of the reciprocating compressor, among the general compressor in detail as follows.

As shown in FIG. 1, the reciprocating compressor includes an electric motor 20 for generating a rotational force by applying current in a case 10 enclosed by the upper shell 12 and the lower shell 14, and the electric motor part. It is largely composed of a compression unit for compressing the working fluid by the rotational force of.

The transmission unit 20 is composed of a stator 22 for generating an electromagnetic force by applying a current, and a rotor 24 for generating a rotational force by the electromagnetic force of the stator.

In addition, the compression unit crankshaft 30 that rotates with the rotor 24, a connecting rod 42 for converting the rotational movement of the crankshaft to linear reciprocating motion, and the cylinder block 44 by the connecting rod It consists of a piston 46 for compressing the working fluid in the interior.

One end of the connecting rod 42 is pin-coupled to the eccentric pin 31 formed at the upper end of the crankshaft 30 and the other end is pin-coupled to the piston 46, thereby rotating the crankshaft 30. Can be converted into linear reciprocating motion.

In order to prevent abrasion of various mechanical parts, a lower portion of the case 10 holds a refrigerator oil L, and a lower end of the crankshaft 30 is immersed in the refrigerator oil L. The refrigeration oil (L) is supplied to the eccentric pin (31) along the inside and the circumferential surface of the crankshaft while the crankshaft (30) is rotated, thereby lubricating various mechanical parts in the case and at the same time internal heat Will be released.

On the other hand, one side of the lower shell 14 is provided with a hermetic terminal (hermetic terminal 50) and the cluster 54 to connect the state 22 to an external power source. A plurality of lead wires 56 branched from the stator 22 are fixed to the cluster 54 by terminals, and pins 52 penetrating through the hermetic terminal 50 are coupled to the terminals, thereby providing A PTC (not shown) for supplying external power and an OLP (Over Load Protector, not shown) for shutting off the power when overcurrent is mounted to the outside of the mechanical terminal 50.

Hereinafter, the structure of the crankshaft will be described in detail with reference to the accompanying drawings.

2 is a front view showing a conventional crankshaft structure used in a reciprocating compressor, in which the crankshaft 30 has an eccentric pin 31 which is eccentric with an axial center Y and vibrations when rotating below the eccentric pin. The balance weight 32 to prevent the, and the shaft portion 34 is provided with a plurality of holes in the lower portion of the balance weight and at the same time a piece 33 for pumping the refrigeration oil during rotation at the bottom.

The shaft portion 34 includes a drill hole 35 in which the refrigeration oil pumped by the piece 33 is moved upward, and an oil extending to the circumferential surface of the shaft portion 34 at the end of the drill hole. An oil groove 37 is formed along the circumferential surface of the shaft portion 34 from the oil hole 36 and the oil hole to the eccentric pin 31. At this time, the inner diameter of the drill hole 35 is approximately 50% of the outer diameter of the shaft portion 34, and is formed to be deflected with respect to the axis center Y of the shaft portion.

In addition, a gas hole 38 is formed at one side of the drill hole 35 to extend a distance from a circumferential surface of the shaft portion 34 to discharge the gas.

As the crankshaft configured as described above rotates with the rotor, the coolant oil is pumped by the piece 33 into the drill hole 35 and moved upward by centrifugal force, and then the oil groove 37 through the oil hole 36. Will be moved to). Subsequently, the refrigeration oil travels along the oil groove 37 to the eccentric pin 31 while lubricating the journal bearing portion (not shown) and is scattered to each part of the product. At this time, the gas of the refrigeration oil pumped into the drill hole 35 is discharged to the outside through the gas hole 38.

However, in recent years, a pole conversion motor or a BLDC motor capable of performing both a low speed operation and a high speed operation in order to reduce power consumption of a cold container product has been widely applied as a motor of a compressor.

However, the above-mentioned crankshaft is for high speed operation (approximately 3600 rpm), and a problem arises in that refrigeration oil is not smoothly supplied at low speed operation (approximately 1800 rpm). That is, the refrigeration oil is moved upward by the centrifugal force due to the rotational movement of the crankshaft. When the crankshaft is rotated at a low speed, the centrifugal force decreases rapidly, and thus the refrigeration oil cannot be properly supplied. This results in a fatal effect on the life of the compressor by lowering the lubrication performance to prevent wear of various components and the ability to dissipate internal heat to the outside.

On the other hand, in order to solve the above problems, the drill hole inner diameter of the crankshaft may be increased, but an increase in the drill hole inner diameter without considering the strength of the crankshaft may cause serious damage to the crankshaft. In addition, the increase in the drill hole inner diameter leads to leakage of the refrigeration oil through the gas hole, which causes a problem that gas is impossible to discharge.

The present invention has been made to solve the above problems, an object of the present invention is to provide a compressor for a low speed and high speed operation, the compressor crank that can ensure the smooth supply of refrigeration oil and the discharge of gas even at low speed operation To provide a shaft.

1 is a cross-sectional view showing the configuration of a typical reciprocating compressor

Figure 2 is a front view showing the structure of the crankshaft of the conventional compressor

3 is a front view showing a crankshaft structure for a compressor according to the present invention.

4 is a graph showing the drill hole inner diameter to shaft outer diameter ratio and the amount of refrigeration oil pumping of the crankshaft.

5 is a side view showing the structure of a crankshaft for a compressor according to the present invention;

Explanation of symbols on the main parts of the drawings

110: eccentric pin 120: balance weight

130: shaft 135: drill hole

136: oil hole 137: oil groove

138: gas hole 140: piece

In order to achieve the above object, the crankshaft for the compressor according to the present invention is a drill hole having a predetermined diameter so that the refrigeration oil pumped by the piece inserted in the lower portion moves upward by the centrifugal force and the refrigeration oil pumped in communication with the drill hole. A shaft portion including a gas hole for discharging gas, a balance weight for balancing rotational movement on the upper end of the shaft portion, and an eccentric which is eccentric with a central axis of the shaft portion on an upper side of the balance weight and pin-coupled with a connecting rod A crankshaft for a compressor composed of pins; The drill hole is located on the central axis of the shaft portion, characterized in that the ratio of the drill hole inner diameter to the outer diameter of the shaft portion is 0.8 to 0.85.

The gas hole may extend from the upper portion of the drill hole to the balance weight of the upper end of the shaft portion.

Hereinafter, a compressor crankshaft according to the present invention will be described in detail with reference to the accompanying drawings.

First, Figure 3 is a front view showing a crankshaft structure for a compressor according to the present invention, Figure 4 is a graph showing the drill hole inner diameter to shaft outer diameter ratio and the amount of refrigeration oil pumping of the crankshaft, Figure 5 is a compression according to the present invention Side view of the crankshaft for aircraft.

As shown in FIG. 3, the crankshaft for a compressor according to the present invention is largely composed of an axial part 130, an eccentric pin 110, and a balance weight 120.

The shaft portion 130 is a drill hole 135 having a predetermined diameter in the lower portion of the shaft and formed to the center of the shaft, a gas hole (not shown) in communication with the drill hole to discharge the gas of the refrigeration oil, and the drill hole 135 It consists of an oil hole 136 extending to the circumferential surface of the shaft at the end of, and an oil groove 137 is formed obliquely along the circumferential surface from the oil hole to the top of the shaft.

In addition, a lower portion 140 of the shaft portion 130 is inserted into the drill hole 135 and immersed in the refrigerator oil.

The upper end of the shaft portion 130 balances the rotational movement to prevent vibration, and the upper end of the balance weight is eccentrically located on the central axis Y of the shaft portion 130. The connecting rod is connected to the pin is coupled to the eccentric pin 110 is in communication with the oil groove 137 at the same time.

The crankshaft configured as described above is introduced into the drill hole 135 by the piece 140 while the crankshaft rotates with the rotor, and the freezer oil continues to move upward by centrifugal force through the oil hole 136. The oil groove 137 formed on the circumferential surface of the shaft 130 is supplied to the eccentric pin 110 and scattered to each component.

At this time, the ratio of the inner diameter of the drill hole 135 to the outer diameter of the shaft portion 130 is about 0.8 to 0.85. This is for smooth supply of refrigeration oil during low speed operation in a compressor to which a pole conversion motor or a BLDC motor is applied.

Hereinafter, the selection criteria of the drill hole inner diameter to shaft portion outer diameter ratio will be described in detail.

The source of the force to move the refrigeration oil at the bottom of the shaft up to the eccentric pin is a centrifugal force, the centrifugal force is as follows.

F: centrifugal force

m: mass

r: radius

: Angular velocity

That is, the centrifugal force (F) is proportional to the radius (r), the angular velocity ( Is proportional to the square of. Therefore, in the case of a compressor employing a motor that performs both low speed operation and high speed operation, the centrifugal force at low speed operation (approximately 1800 rpm) is only one quarter under the same radius as the centrifugal force at high speed operation (3600 rpm). This means a drastic reduction in the amount of refrigeration oil pumping.

Therefore, as can be seen from the above equation, even at low speed, the radius of the refrigeration oil must be increased to maintain the pumping amount up to a certain level.

On the other hand, the pumping amount of the refrigeration oil according to the drill hole inner diameter to the shaft outer diameter ratio during the low speed operation through the experimental value as follows.

4 is a graph showing the refrigeration oil firmware pingryang of the drill hole inner diameter for the shaft diameter of the crankshaft ratio, the horizontal axis indicates the drill hole inner diameter for the shaft diameter ratio is N _x and the vertical axis the refrigerator oil pumping amount (Q) cc / It is shown in min. At this time, the experimental value is when the compressor was operated at 1800rpm.

As shown in FIG. 4, the minimum pumping amount Q _{min of} the refrigeration oil, which can smoothly lubricate each component in the compressor and dissipate internal heat to the outside, is about 100 cc / min. It can be seen that the pumping amount Q hardly occurs at the ratio N ₀ . In addition, the pumping amount Q increases gradually as the drill hole inner diameter to shaft outer diameter ratio N _x increases, and the pumping amount Q _min reaches the minimum pumping amount Q _min at N _min . At this time, the value of N _min is approximately 0.8.

Therefore, when the compressor is operated at a low speed of about 1800 rpm, in order to supply the refrigeration oil smoothly, the ratio of the drill hole inner diameter to the outer diameter of the shaft portion should be at least 0.8.

However, the drill hole inner diameter to shaft outer diameter ratio is closely related to the strength of the crankshaft. That is, the shaft portion is subjected to a constant rotational torque. As the inner diameter of the drill hole increases, the thickness thereof becomes thinner, resulting in a breakdown as strength decreases. In this case, when the compressor is operated at a high speed of about 3600 rpm, higher strength is required, and the ratio of the drill hole inner diameter to the shaft outer diameter that can maintain the strength is about 0.85.

Therefore, the ratio of the drill hole inner diameter to the shaft outer diameter of the crankshaft according to the present invention is in the range of 0.8 to 0.85 in consideration of the amount of refrigeration oil pumping at low speed and strength at high speed.

At this time, it is preferable that the drill hole is located in the central axis of the shaft portion without being eccentric.

On the other hand, as shown in Figure 5, the gas hole 138 of the crankshaft for the compressor according to the invention along the axial direction from the upper portion of the drill hole 135 to the balance weight 120 of the upper end of the shaft portion 130 It can be seen that formed.

The gas hole 138 discharges the gas of the freezer oil to the outside of the crankshaft, thereby maintaining a constant internal pressure of the drill hole 135 to facilitate the formation of a path of the freezer oil.

By the way, since the drill hole 135 of the crankshaft according to the present invention has an inner diameter that is closer to that of the circumferential surface of the shaft 130, the gas hole is formed from the side of the drill hole to the circumferential surface of the drill hole as in the prior art. Refrigerator oil leaks easily through the gas hole.

Accordingly, the gas hole 138 of the crankshaft according to the present invention extends from the upper portion of the drill hole 135 to the balance weight 120 of the upper end of the shaft for preventing the leakage of the refrigeration oil and smoothly discharging the gas. This is preferable.

In the compressor crankshaft according to the present invention, by increasing the inner diameter of the drill hole so that the drill hole inner diameter to shaft outer diameter ratio falls within a range of 0.8 to 0.85, pumping of refrigeration oil even during low speed operation in a compressor that performs both low speed operation and high speed operation. The quantity can be kept constant at all times.

Further, by forming a gas hole for discharging the gas of the refrigerator oil introduced into the drill hole along the axial direction from the upper portion of the drill hole to the upper end of the shaft portion, it is possible to smoothly discharge the gas without leakage of the refrigerator oil.

Therefore, it is possible to prevent the wear of various parts due to the insufficient pumping amount of the refrigeration oil, thereby improving the reliability of the product.

Claims (2)

A shaft portion including a drill hole having a predetermined diameter and a gas hole communicating with the drill hole to discharge gas of the pumped refrigerator oil so that the refrigerator oil pumped by the piece inserted at the lower end moves upward by the centrifugal force, and the upper end of the shaft portion. In the crankshaft of the compressor consisting of a balance weight for balancing the rotational movement, and an eccentric pin which is eccentric with the central axis of the shaft portion on the upper side of the balance weight and pinned to the connecting rod, And the drill hole is located at the central axis of the shaft portion, and a ratio of the drill hole inner diameter to the shaft outer diameter is 0.8 to 0.85. The method of claim 1, The gas hole is a crankshaft for a compressor, characterized in that extending from the top of the drill hole to the balance weight of the upper end of the shaft portion.