JP2008280934A - Refrigerant compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that some problems on seizure resistance is left since matrix structure of nodular graphite cast iron is exposed if surface treatment layer peels off at a section where locally load is applied, and that especially run out is large, and an upper end part of a bearing and a sliding part of the crankshaft tend to wear greater than normal part if eccentricity quantity of a crankshaft is high and lamination thickness of a motor is high. <P>SOLUTION: Seizure resistance and wear resistance are improved by using iron sintered alloy for bearings 9, 10, keeping area ratio of ferrite phase 29 constructing matrix structure of nodular graphite cast iron of the crankshaft 8 not greater than 50%, applying induction hardening on a part of the sliding part with bearing material supporting rotation of the crankshaft 8, and converting matrix of the nodular graphite cast iron crankshaft 8 to martensite. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a refrigerant compressor having a crankshaft of spheroidal graphite cast iron and a bearing material for rotation support, which is used for commercial and domestic refrigeration and air conditioning.

As a conventional refrigerant compressor, a material in which an alloy is added to flake graphite cast iron has been used for the crankshaft that transmits the power of the compressor. The use of crankshaft made of spheroidal graphite cast iron with higher rigidity has been increasing. Spheroidal graphite cast iron has a structure in which spheroidal graphite is crystallized, and the base is a dispersion of pearlite and ferrite, but ferrite is soft to the pearlite phase and has seizure resistance and poor sliding resistance. Tended to define the ferrite ratio in the base as small as possible. However, when the ferrite ratio in the base is reduced, that is, when the pearlite ratio is increased, the hardness of the spheroidal graphite cast iron increases, and the workability including rough machining becomes somewhat difficult.
JP-A-11-022686

  However, in the above-described conventional configuration, when the surface treatment layer at the part where the load is applied partially peels, the base structure of the spheroidal graphite cast iron is exposed, which leaves some problems with respect to seizure resistance. In particular, when the eccentric amount of the crankshaft is large and the thickness of the motor is high, the runout is large, and the upper end portion of the bearing and the sliding portion of the crankshaft tend to wear more than usual.

  It is an object of the present invention to improve the seizure resistance of the sliding portion and improve the reliability of the compressor mechanical material.

  In the present invention, in order to improve the sliding seizure resistance between the structure of the spheroidal graphite cast iron crankshaft and the bearing that indicates the structure, only the surface where the most sliding load is applied between the crankshaft and the counterpart bearing material is modified. The quality is improved and the reliability is improved during the operation of the compressor.

  The present invention regulates the ferrite ratio of the base structure of a spheroidal graphite cast iron crankshaft that ensures sliding resistance and seizure resistance under normal compressor operation and usage conditions. The reliability of the mechanical material sliding of the compressor can be improved by limiting the surface.

  In the first invention, the crankshaft is spheroidal graphite cast iron, and the ratio of ferrite and pearlite constituting the base ensures the wear resistance between the crankshaft and the bearing supporting the crankshaft. By setting the ratio to 50% or less, the reliability of mechanical sliding is ensured. The slidability and wear resistance of crankshafts made of spheroidal graphite cast iron are generally better as the ferrite in the base is lower, that is, the higher the pearlite ratio, the higher the hardness proportionally and the lower the workability. Use requires a balance between base organization and processability.

  In the second invention, induction hardening is performed to improve the sliding reliability of the spheroidal graphite cast iron crankshaft. As a result, the base of the spheroidal graphite cast iron becomes martensite and improves the sliding resistance. is there. The induction hardening part of the crankshaft is limited to the part where the uppermost end of the mating bearing is the most severely sliding. The crankshaft subjected to this processing is an optimal processing method for models with particularly high loads, large shaft eccentricity, and motor rotor thickness (high).

  In the third aspect of the invention, in order to carry out surface modification hardening in the same manner as in the second aspect of the invention, shot peening treatment with a steel ball is performed on a spheroidal graphite cast iron crankshaft, and the surface layer of the crankshaft irradiated with the steel ball is formed. It is martensitic and brings about the same effect as the second aspect of the invention, and aims to improve seizure resistance and sliding resistance of the most severe sliding portion with the bearing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a longitudinal sectional view of a mechanism part of a refrigerant compressor according to an embodiment of the present invention, and FIG. 2 is a transverse sectional view showing a main part of the compression mechanism.

  In the figure, reference numeral 1 denotes an airtight container, in which an electric motor unit 2 and a compression mechanism unit 3 are arranged. The electric motor unit 2 includes a rotor 2a and a stator 2b, and a crankshaft 8 rotatably supported by a main bearing 9 and a sub bearing 10 is fixed to the rotor 2a by a method such as press fitting. The compressor unit 3 includes a cylinder 20 having a suction hole 5 and a radial cylinder groove 23, a roller 7 that rotates eccentrically while sliding an outer peripheral surface on the inner peripheral surface of the cylinder 20, and an inner peripheral surface of the roller 7. The eccentric portion of the shaft 8 slidably inserted and the cylinder groove 23 are reciprocally slidably accommodated, and the tip portion is pressed against the roller 7 by the pressing force and back pressure (discharge pressure) by the spring 24. A vane 21 that divides the internal space into a suction chamber 25 and a compression chamber 26, and a main bearing 9 and a sub-bearing 10 that seal both ends of the cylinder are configured.

  Next, the operation of the rotary compressor according to this configuration will be described. When the motor unit 2 is energized from the outside, the rotor rotates and the shaft 8 is rotationally driven. When the shaft 8 rotates, the roller 7 slidably attached to the eccentric portion performs a planetary motion (counterclockwise rotation in FIG. 2) while slidingly contacting the cylinder inner peripheral surface. As a result, refrigerant gas such as HFC is sucked into the suction chamber 25 from the suction pipe 4 through the suction hole 5, and at the same time, the refrigerant gas whose pressure has been increased in the compression chamber 26 passes through the discharge hole 6 from the discharge notch 22 and is sealed. 1 is discharged.

  In FIG. 1, the position of the discharge hole 6 is depicted at a position away from the suction hole for the sake of clarity, but in reality, it is disposed near the suction hole 5 with the vane 21 interposed therebetween as shown in FIG. 2. . At this time, the vane 21 that divides the suction chamber 25 and the compression chamber 26 is pressed against the outer peripheral surface of the roller 7 by the pressure applied to the spring 24 and the back of the vane, and the tip portion is the outer peripheral surface of the roller 7 and the side portion is the cylinder. It will slide with the inner wall surface of the groove 23. The lubrication of the vane 21, the roller 7, and the cylinder groove 23 is performed using the refrigerating machine oil 12 stored in the bottom of the hermetic container in the steady operation state, but there is not enough refrigerating machine oil in the sliding part at the time of starting. Refrigerating machine oil 12 slightly contained in the sucked refrigerant gas (refrigerant oil is slightly discharged from the compressor together with the refrigerant gas, circulates through the refrigeration cycle, and then returns to the compressor from the suction pipe 4 again. Come) will be used.

  As for the crankshaft 8, low alloy cast iron or spheroidal graphite cast iron is generally used, but as described above, the sliding condition at the start of the hermetic rotary compressor is strict so that lubricating oil is not sufficiently supplied, In particular, it can be said that the sliding condition is more severe because the oil film is difficult to be formed between the crankshaft 8 and the main bearing 9 and the sub-bearing 10 because of the rotational motion. In addition, since the HFC refrigerant adopted for environmental measures in recent years has poor lubricity, it can be said that the sliding condition of the rotary compressor using the HFC refrigerant is particularly severe.

  FIG. 3 shows an example of the structure of the spheroidal graphite cast iron crankshaft 8 of the present invention. Spherical graphite 27 is crystallized, and pearlite 28 and ferrite 29 are deposited on the matrix. In the structure of the present invention, the proportion of the area of the ferrite 29 in the entire matrix does not exceed 50%.

  In general, ferrite 29 is soft and inferior in wear resistance and sliding resistance compared to pearlite 28, but it is problematic under normal use conditions by applying appropriate surface treatment (manganese phosphate and molybdenum disulfide). It can be driven without.

  FIG. 4 shows surface modification by partially induction hardening and shot peening of the crankshaft 8 at a portion 30 which is the most severe sliding condition with the main bearing 9 supporting the rotation of the spheroidal graphite crankshaft 8. By hardening it, the seizure resistance and sliding resistance of the crankshaft and the bearing are improved.

  When the part 30 receives a more severe load and becomes a severe sliding condition, when the eccentric amount of the crankshaft 8 is large, in a model in which the thickness of the rotor 2a of the motor is high, the swing in the rotational direction becomes large. The sliding of the part 30 is the most severe.

  The crankshaft of the present invention can ensure supply even in normal operation or in a severe operation situation under a compressor or HFC refrigerant with a heavy design element, with no problem of wear between the crankshaft and the bearing. Become.

The longitudinal cross-sectional view which shows the rotary compressor in embodiment of this invention The cross-sectional view which shows the principal part of the refrigerant compressor in embodiment of this invention Metal structure diagram of crankshaft of the present invention The figure which shows typically the induction hardening and shot-peening site | part of the crankshaft of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Airtight container 2 Electric motor part 3 Compressor part 4 Suction pipe 5 Suction hole 6 Discharge hole 7 Roller 8 Shaft 9 Main bearing 10 Sub bearing 11 Tightening bolt 12 Refrigerating machine oil 20 Cylinder 21 Vane 22 Discharge notch 23 Cylinder groove 24 Spring 25 Suction Chamber 26 Compression chamber 27 Spheroidal graphite 28 Pearlite phase 29 Ferrite phase 30 Surface hardening modification site

Claims (3)

Spheroidal graphite cast iron is used for the crankshaft that gives power, and iron-based sintering is used for the bearing that supports the rotation of the crankshaft, and the area ratio of the ferrite phase constituting the base structure of the spheroidal graphite cast iron of the crankshaft is 50% or less. Refrigerant compressor made up of 2. The refrigerant compressor according to claim 1, wherein a part of a sliding portion between the crankshaft and a bearing material that supports rotation of the crankshaft is subjected to induction hardening to martensite a base of the crankshaft made of spheroidal graphite cast iron. . 2. The refrigerant compressor according to claim 1, wherein a part of a sliding portion between the crankshaft and a bearing material that supports rotation of the crankshaft is subjected to shot peening to harden a base of a crankshaft made of spheroidal graphite cast iron. .

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