JP2004278309A - Gas compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas compressor for improving performance of the compressor, and maintaining high performance over a long period by reducing a width setting value of minimum clearance between a rotor and a cylinder, and improving volumetric efficiency by an improvement in sealability of the minimum clearance without causing seizure and a gall. <P>SOLUTION: This gas compressor is formed as a structure that the inner periphery of the cylinder 4 of a cylinder elliptic short diameter part 4a is composed of a surface refining layer 400 by nitrosulphurizing processing. Thus, even if contact between the cylinder 4 and the rotor 8 is caused in rotor peripheral directional clearance G3 in the vicinity of the cylinder elliptic short diameter part 4a being the minimum clearance between the cylinder 4 and the rotor 8, the seizure and the gall of the cylinder 4 and the rotor 8 are surely prevented by the surface refining layer 400, and the width setting value of the rotor peripheral directional clearance G3 can be arranged further small. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vane rotary type gas compressor used for an air conditioning system such as a car air conditioning system and a GHP system.
[0002]
[Prior art]
In an air conditioning system such as a GHP system, there is a demand for measures to prevent a decrease in efficiency due to a change in refrigerant for preventing ozone layer destruction and power saving for preventing global warming. For this reason, there is an increasing need to improve the performance of a vane rotary type gas compressor used in an air conditioning system.
[0003]
FIG. 9 is a sectional view showing a structural example of a conventional vane rotary type gas compressor. In the gas compressor shown in the figure, a rotor 8 having a perfect circular cross section is rotatably mounted in a cylinder 4 having an inner peripheral substantially elliptical shape, and protrudes and retracts from an outer peripheral surface of the rotor 8 to an inner peripheral surface of the cylinder 4. The structure has a plurality of possible vanes 13. The space inside the cylinder between the cylinder 4 and the rotor 8 is partitioned into a plurality of small chambers by the vanes 13, and the partitioned small chambers function as compression chambers 14. That is, the compression chamber 14 repeats a change in volume by the rotation of the rotor 8 and performs a series of operations of suction, compression, and discharge of the refrigerant gas by the change in volume.
[0004]
As means for improving the performance of the vane rotary type gas compressor having the above-described structure, the following methods (1) to (4) have been proposed and implemented.
[0005]
(1) The minimum value of the minimum gap between the rotor 8 and the cylinder 4, specifically, the minimum gap setting value of the gap G3 between the rotor 8 and the cylinder 4 in the cylinder elliptical minor diameter portion 4 a (hereinafter, referred to as a rotor circumferential gap) ( MTC (Minimum Top Clearance) is reduced, thereby suppressing internal leakage and improving volume efficiency.
[0006]
The internal leak refers to a suction chamber (not shown) from the compression chamber 14-1 (highest pressure portion) containing a refrigerant gas which has been compressed due to a volume decrease and has a high temperature and a high pressure via a rotor circumferential gap G3. And the like, in which high-temperature and high-pressure refrigerant gas leaks to the low-pressure part side.
[0007]
(2) A vane back pressure by oil is supplied to a bottom space of the vane 13, specifically, a clearance space G <b> 1 (hereinafter referred to as a vane bottom clearance space) between the bottom of the vane 13 and the bottom of the vane groove 12. By lowering the vane back pressure, the pressing force of the tip of the vane 13 against the inner peripheral surface of the cylinder 4 is reduced, the sliding resistance of the vane 13 is reduced, and the power is reduced.
[0008]
(3) The volume efficiency is improved and the power is reduced by reducing the resistance in the refrigerant gas suction passage and discharge passage.
[0009]
(4) While reducing the outflow of oil from the gas compressor to the other components of the air conditioning system, the supply amount of oil to the clearance inside the gas compressor, specifically, the rotor circumferential clearance G3 and the like is reduced. In addition, the oil leak suppresses internal leakage through the rotor circumferential gap G3 and the like, and improves volumetric efficiency.
[0010]
In the vane rotary type gas compressor having the structure shown in FIG. 9, in particular, the width set value of the rotor circumferential gap G <b> 3 in (1) greatly affects the performance of the gas compressor. This is because the portion of the rotor circumferential gap G3 is a boundary between the highest pressure portion and the lowest pressure portion, so that an internal leak is likely to occur at the portion of the rotor circumferential gap G3, and the width of the rotor circumferential gap G3 may vary. This is because the amount of internal leak varies depending on the type of the internal leakage. In other words, the smaller the width set value of the rotor circumferential gap G3, the smaller the amount of internal leak through the rotor circumferential gap G3 and the higher the volume efficiency. On the other hand, if the width setting value of the rotor circumferential gap G3 is large, the amount of internal leak through the rotor circumferential gap G3 increases and the volume efficiency decreases.
[0011]
Therefore, from the viewpoint of improving the volume efficiency by improving the sealing performance of the minimum gap (rotor circumferential gap G3) between the rotor 8 and the cylinder 4 and thereby improving the performance of the compressor, the rotor circumferential gap is not considered. It is desirable that G3 be as small as possible.
[0012]
However, when the width set value of the rotor circumferential gap G3 is too small, a problem occurs when the gas compressor is operated at full operation under severe operating conditions of the gas compressor, for example, under the hot summer sun.
[0013]
That is, between the severe operation and the steady operation, particularly during the severe operation, the shaft runout of the rotor shaft 7 provided integrally with the axis of the rotor 8 increases, and the rotor 8 and the cylinder 4 Since the rotor circumferential gap G3 becomes narrower due to radial elastic deformation and thermal deformation of the rotor, the contact between the rotor 8 and the cylinder 4 is more likely to occur at the portion of the rotor circumferential gap G3 during severe operation, There is a problem that burn-in and galling occur due to the contact.
[0014]
Therefore, conventionally, as a means for preventing the seizure or galling as described above, (1) the outer peripheral surface of the rotor 8 is coated with a plating 60 such as copper or lead, as shown in FIG. Although omitted, (2) the outer peripheral surface of the rotor 8 is coated with a chemical conversion film such as a fluororesin. (For an example of the above (1), see Patent Document 1. For an example of the above (2), see Patent Document 2.)
[0015]
However, the coating layer of the plating 60 and the chemical conversion film as described above is basically easily peeled off. In particular, since the fluorine resin coating layer itself is soft, the layer is gradually worn and thinned due to repeated contact with the cylinder during severe operation of the gas compressor. When the coating layer is thin, the effect of preventing seizure and galling by the coating layer is reduced, and the problem that the seizure and galling of the rotor 8 and the cylinder 4 are likely to occur is caused. In addition to this, the rotor circumferential gap G3 is further increased by the thinner coating layer, so that the amount of internal leak through the rotor circumferential gap G3 increases, the volume efficiency decreases, and the performance of the compressor deteriorates. Problems arise.
[0016]
[Patent Document 1]
JP-A-60-34589
[0017]
[Patent Document 2]
JP-A-60-4787
[0018]
[Problems to be solved by the invention]
The present invention has been made in order to solve the above problems, and an object thereof is to reduce the width of the minimum gap between the rotor and the cylinder without causing seizure or galling, and to reduce the minimum gap. It is an object of the present invention to provide a gas compressor capable of improving volumetric efficiency by improving sealing performance and thereby improving the performance of a compressor and maintaining the high performance for a long period of time.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a cast iron cylinder, a steel rotor rotatably suspended in the cylinder, and an inner peripheral surface of the cylinder from an outer peripheral surface of the rotor. The vane is provided so as to be able to protrude and retract, and is composed of a vane that partitions the space inside the cylinder between the cylinder and the rotor into a plurality of small chambers, and small chambers partitioned by the vane. It has a compression chamber that sucks, compresses and discharges refrigerant gas by volume change, and either or both of the inner circumference of the cylinder and the outer circumference of the rotor are reformed by oxynitriding or sulfidation. It is characterized by comprising a surface modified layer comprising:
[0020]
According to the present invention, when the cylinder and the rotor come into contact with each other in the minimum clearance between the cylinder and the rotor, the surface modified layer prevents seizure and galling due to the contact between the cylinder and the rotor.
[0021]
In the present invention, the cylinder may have a structure in which the inner periphery is formed in an elliptical shape, and at least the cylinder inner periphery of the cylinder elliptical minor diameter portion is formed of the surface modified layer in the entire cylinder inner periphery. .
[0022]
Further, in the present invention, the rotor is formed in a perfectly circular cross section, and the cylinder has an inner periphery formed in a substantially elliptical shape. A structure in which the same circular arc surface as that of the above is formed, and of the entire cylinder inner circumference, the cylinder inner circumference of the cylinder elliptical minor diameter portion including at least the true circular arc surface is formed of the surface modified layer. Can also be adopted.
[0023]
The present invention is directed to a cast iron cylinder formed in a substantially elliptical inner circumference, a steel rotor rotatably mounted in the cylinder in a rotatable manner, and an outer circumferential surface of the rotor facing an inner circumferential surface of the cylinder. A vane that is provided so as to be able to protrude and retract, and a vane that partitions the space in the cylinder between the cylinder and the rotor into a plurality of small chambers, and a small chamber that is partitioned by the vane, repeats a large and small change in volume due to rotation of the rotor, A compression chamber for sucking, compressing, and discharging the refrigerant gas by the change in volume, and a surface modification layer formed by modifying the inner periphery of the cylinder or the outer periphery of the rotor by a nitrosulfurization process or a sulfide process. Wherein the minimum value of the clearance set value between the cylinder and the rotor at the elliptical minor diameter portion of the cylinder is smaller than the sum of the following values of A, B, C and D. That.
<A>: A is a value obtained by subtracting the minimum diameter of the rotor shaft from the maximum diameter of a bearing hole that supports the rotor shaft provided integrally with the shaft center of the rotor.
<B>: B is the maximum amount of elastic deformation when the elliptical minor diameter portion of the cylinder elastically deforms in the radial direction during operation of the gas compressor.
<C>: C is the maximum elastic deformation amount when the rotor elastically deforms in the radial direction about the rotor shaft during operation of the gas compressor.
<D>: D represents the maximum amount of thermal deformation when the rotor thermally deforms in the radial direction during the operation of the gas compressor, and indicates that the cylinder elliptical minor diameter portion thermally deforms in the radial direction during the operation of the gas compressor. This is a value obtained by subtracting the maximum thermal deformation amount when performing.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a gas compressor according to the present invention will be described in detail with reference to FIGS.
[0025]
FIG. 1 is a sectional view of a gas compressor according to an embodiment of the present invention. The gas compressor shown in FIG. 1 employs a so-called shell structure in which a compression mechanism 2 is housed in a compressor case 1 having an open end, and a front head 3 is attached to an open end of the compressor case 1.
[0026]
The compression mechanism 2 has a cylinder 4 having a substantially elliptical inner periphery. Side blocks 5 and 6 are attached to the front and rear end surfaces of the cylinder 4, respectively. A rotor 8 having a shape is rotatably suspended via a rotor shaft 7. The cylinder 4 is made of cast iron, and the rotor 8 is made of steel such as carburized and hardened steel.
[0027]
The rotor shaft 7 is provided integrally with the axis of the rotor 8 and is supported via bearings 9 and 10 provided on the front and rear side blocks 5 and 6. The bearings 9, 10 of the side blocks 5, 6 are constituted by bearing holes penetrating the front and back surfaces of the side blocks 5, 6.
[0028]
The front end portion 7F of the rotor shaft 7 has a structure that penetrates through the front head 3 from the bearing 9 of the front side block 5 and projects outside from the center of the boss 3-1 of the front head 3. Note that a seal member 11 is provided on the peripheral surface side of the rotor shaft 7 that penetrates the front head 3, and the seal member 11 blocks the inside and outside of the front head 3.
[0029]
As shown in FIG. 2, the inner peripheral surface of the cylinder 4 in the elliptical minor diameter portion 4 a of the cylinder 4 is a perfect circular arc surface similar to the outer peripheral surface of the rotor 8. A structure in which the cylinder inner periphery of the cylinder elliptical minor diameter portion 4a including the circular arc surface is formed of the surface modified layer 400 is employed.
[0030]
The surface reforming layer 400 is obtained by modifying the inner peripheral surface of the cylinder 4 as a base material by sulphonitriding, and the inner periphery of the cylinder 4 is formed from sulfide of 1 to 5 μm in order from the surface by the reforming. It has a three-layer structure of a layer 400-1, a nitride compound layer 400-2 of 5 to 25 μm, and a nitrogen diffusion layer 400-3 of 30 to 300 μm. The entire part of the three-layer structure is the surface modified layer 400.
[0031]
The uppermost sulfide layer 400-1 is mainly composed of a compound component called FeS, has a solid lubricating action, and contributes to improvement of seizure resistance. In the case of the present embodiment, the sulfide layer 400-1 is on the outermost surface of the inner periphery of the cylinder 4 (the surface to be subjected to the sulfide nitriding treatment) and directly faces the outer periphery of the rotor 8. The intermediate nitride compound layer 400-2 is mainly composed of Fe ₃ Consisting of a compound component of N, it contributes to improvement of abrasion resistance. The lowermost nitrogen diffusion layer 400-3 is a layer in which the nitrogen component is diffused in the cast iron component, which is the base material of the cylinder 4, and contributes to the improvement of the base material strength.
[0032]
The surface modification layer 400 makes it difficult for the cylinder 4 and the rotor 8 to seize. This is because (1) the lubricating action of the sulfide layer 400-1 itself of the surface-modified layer 400, (2) contact of the same kind of metal by the entire surface-modified layer 400 is avoided, and (3) This is considered to be a synergistic effect of improving the balance between the hardness of the inner periphery of the cylinder 4 and the outer periphery of the rotor 8 mainly by the nitrogen diffusion layer 400-3 of the surface modification layer 400.
[0033]
That is, the sulfide layer 400-1 plays a role as an oily agent and an extreme pressure agent in the oil. For example, if the oil film between the cylinder 4 and the rotor 8 breaks for some reason (eg, overload, high temperature, or insufficient oil supply), the sulfide layer 400-1 replaces the oil film.
[0034]
The cast iron, which is the base material of the cylinder 4, and the steel, which is a constituent material of the rotor 8, are considered to be the same kind of metal, but such contact between the same kind of metals is avoided by the surface modified layer 400.
[0035]
In general, when metals come into sliding contact with each other, metals having lower hardness basically wear. The hardness of the cylinder 4 made of cast iron is lower than that of the rotor 8 made of carburized and hardened steel. Looking at some of the actual seizure states of the cylinder 4 and the rotor 8, in most cases, a dug-up phenomenon has occurred in the cylinder 4. In the present embodiment, since the inner periphery of the cylinder 4 is hardened by the nitrosulphurizing process and its hardness is increased, the hardness of the cylinder 4 and the rotor 8 is balanced, and the rate of occurrence of the phenomenon of digging and raising the cylinder 4 is reduced. It is considered that the cylinder 4 and the rotor 8 are hardly seized.
[0036]
The reason why the oxynitriding treatment is performed only on the inner peripheral surface of the cylinder of the cylinder elliptical minor diameter portion 4a as described above is that the distance between the rotor 8 and the cylinder 4 is the shortest near the cylinder elliptical minor diameter portion 4a, Is in contact with the inner peripheral surface of the cylinder 4, and a phenomenon such as seizure or galling tends to occur.
[0037]
Therefore, from the viewpoint of preventing seizure or the like, it is sufficient that at least the cylinder inner peripheral surface of the cylinder elliptical minor diameter portion 4a is subjected to nitrosulphurizing treatment. A nitriding treatment may be performed. In this case, work such as masking a portion other than the inner circumferential surface of the cylinder elliptical minor diameter portion 4a can be omitted, and the work efficiency can be improved.
[0038]
As shown in FIG. 2, five slit-shaped vane grooves 12 are formed in the outer peripheral surface of the rotor 8, and one vane 13 is slidably mounted in each of the vane grooves 12. The gap G1 between the bottom of the vane 13 and the bottom of the vane groove 12 (hereinafter, referred to as a vane bottom clearance space) constitutes a part of a vane back pressure space for supplying a vane back pressure by oil to the bottom of the vane 13. are doing.
[0039]
Each of the vanes 13 is provided so as to be able to protrude and retract from the outer peripheral surface of the rotor 8 toward the inner peripheral surface of the cylinder 4. When the tips of the vanes 13 are pressed against the inner peripheral surface of the cylinder 4, a space in the cylinder between the cylinder 4 and the rotor 8, that is, a crescent-shaped cylinder chamber located at a position facing 180 ° in the circumferential direction of the rotor 8. Divided into multiple compartments. The partitioned small chamber is the compression chamber 14, and the compression chamber 14 repeatedly changes its volume by rotating the rotor 8 in the direction of the arrow R in the drawing. The volume change causes the refrigerant gas to be sucked, compressed and discharged. It is configured to
[0040]
That is, when the volume of the compression chamber 14 changes, the low-pressure refrigerant gas in the suction chamber 15 is sucked into the compression chamber 14 when the volume increases. Such a suction operation to the compression chamber 14 is performed by a suction port (not shown) of the front side block 5 or a suction port dug in the end face of the rear side block 6 so as to communicate with the suction passage 16 of the cylinder 4. (Not shown).
[0041]
Then, when the volume of the compression chamber 14 starts to decrease, the refrigerant gas in the compression chamber 14 starts to be compressed due to the volume reduction effect. Thereafter, when the pressure of the compressed refrigerant gas becomes higher than the pressure on the side of the discharge chamber 18 in the outer space of the cylinder 4, the discharge valve 20 of the cylinder discharge hole 19 located in the vicinity of the elliptical minor diameter portion of the cylinder 4 opens.
[0042]
When the discharge valve 20 is opened as described above, the high-pressure refrigerant gas in the compression chamber 14 flows out of the cylinder discharge hole 19 to the discharge chamber 18 side of the outer space of the cylinder 4. Simultaneously with the passage of the vane 13 through the cylinder discharge hole 19, the pressure difference between the next compression chamber 14 and the discharge chamber 18 sandwiching the discharge valve 20 reverses, and the discharge valve 20 closes.
[0043]
The high-pressure refrigerant gas flowing out to the discharge chamber 18 side passes through the cylinder 4 and the discharge passages 25-1 and 25-2 of the rear side block 6, passes through the oil separator 21 attached to the rear side block 6, and Finally, the liquid is discharged to the discharge chamber 22.
[0044]
The high-pressure refrigerant gas discharged into the discharge chamber 18 contains mist oil for lubricating the sliding portion of the compression mechanism 2 and sealing the gap. The oil component in the high-pressure refrigerant gas is separated and captured by the separation filter 23 of the oil separator 21, and is dropped and stored in the oil sump 24 at the bottom of the discharge chamber 22.
[0045]
The oil reservoir 24 at the bottom of the discharge chamber 22 is acted upon by the high pressure of the discharge chamber 22, that is, the pressure Pd of the high-pressure refrigerant gas discharged from the compression chamber 14 into the discharge chamber 22 (hereinafter, referred to as discharge pressure).
[0046]
The oil in the oil sump 24 is supplied to the sliding portions and gaps of the compression mechanism 2, for example, (1) bearings 9, 10, (2) vane bottom gap space G1, (3) rotor side gap G2, (4) rotor. It is supplied to the circumferential gap G3 and the like. Note that the rotor side gap G2 is a gap between the rotor 8 and the front side block 5 or the rear side block 6.
[0047]
Here, means for supplying oil to the sliding portion and the gap of the compression mechanism 2 will be described.
[0048]
The compression mechanism 2 is provided with a high-pressure oil supply hole 50. The high-pressure oil supply hole 50 has a structure in which one end 50a is open to the oil sump 24 side, and the other end 50b is open to the bearings 9 and 10 of the front and rear side blocks 5 and 6, and A hole 50-1 formed in the side block 6, a hole 50-2 formed in the cylinder 4 so as to communicate therewith, and a hole 50- formed in the front side block 5 so as to communicate therewith. And 3.
[0049]
Therefore, in the gas compressor of the present embodiment, the high-pressure oil supply hole 50 allows high-pressure oil equivalent to the discharge pressure Pd to flow from the oil reservoir 24 to the bearings 9 and 10 of the front and rear side blocks 5 and 6. The bearings 9 and 10 are lubricated by the supplied oil.
[0050]
A sali groove 51 is provided on the inner surface of the rear side block 6 facing the end surface of the rotor 8. The Sarai groove 51 is formed around the bearing 10 of the rear side block 6 and has a structure that opens and communicates with the clearance of the bearing 10. In addition, the bottom of the vane groove 12 is configured to face and communicate with the Sarai groove 51 from its side surface during the period from the suction stroke of the refrigerant gas to the compression stroke. The salary groove 51 having such a structure is similarly provided on the inner surface of the front side block 5.
[0051]
A rear back pressure space 52 is provided on the rear end face 7R side of the rotor shaft 7. The rear back pressure space 52 is formed by a wall surface including the oil separator 21 and a part of the outer wall of the rear side block 6 and the rear end surface 7R of the rotor shaft 7. In addition, the rear back pressure space 52 is configured to communicate with the salary groove 51 of the rear side block 6 through a medium pressure oil supply hole 53 formed in the rear side block 6.
[0052]
Therefore, in the gas compressor of the present embodiment, the oil supplied to the bearing 10 side of the rear side block 6 further passes through the clearance of the bearing 10 and flows out to the saray groove 51 side of the rear side block 6. At the same time, the gas passes through the clearance of the bearing 10, the rear back pressure space 52, and the medium pressure oil supply hole 53 in that order, and flows out to the salary groove 51 to be supplied. On the other hand, the oil supplied to the bearing 9 side of the front side block 5 passes through the clearance of the bearing 9 and flows out to the salary groove 51 side of the front side block 5 to be supplied.
[0053]
At this time, when the bearing 9 or the bearing 10 passes through the clearance, the oil is throttled and the pressure is reduced. As a result, the pressure of the oil supplied to the sali-groove 51 side of the front or rear side blocks 5, 6 is lower than the pressure of the oil supplied to the bearings 9, 10, and the pressure of the discharge pressure Pd and the suction pressure Ps is reduced. Intermediate pressure. Hereinafter, the intermediate pressure oil is referred to as “medium pressure oil”.
[0054]
Then, the medium-pressure oil in the Sarai groove 51 is supplied to the vane bottom gap space G1 as the vane back pressure. The pressure of the medium-pressure oil acts on the bottom of the vane 13 from the vane bottom gap G1. Centrifugal force due to the rotation of the rotor 8 also acts on the vane 13. As described above, the vane 13 pops out from the outer peripheral surface of the rotor 8 toward the inner peripheral surface of the cylinder 4 due to the pressure of the medium-pressure oil and the centrifugal force acting on the vane 13.
[0055]
The oil in the sali- ty groove 51 also flows out and is supplied to the rotor side gap G2. Further, the oil supplied to the vane bottom gap space G1 passes through a sliding gap (not shown) between the side surfaces of the vane groove 12 and the vane 13 and flows out to the outer peripheral surface of the rotor 8, and the rotor circumferential gap G3 And so on.
[0056]
In the gas compressor according to the present embodiment, a crescent-shaped cylinder chamber is provided at a position 180 ° opposite to the center of the rotor shaft 7 by arranging the perfect circle rotor 8 at the center of the substantially elliptical cylinder 4 on the inner circumference. Are formed. Therefore, a series of operations of suction, compression, and discharge of the refrigerant gas can be performed in both of the cylinder chambers. Further, in the gas compressor of the present embodiment, since five vanes 13 are arranged on the rotor 8, the compression chamber partitioned by the vane 13 in one crescent-shaped cylinder chamber during one rotation of the rotor 8. 14 are formed five times. Therefore, during one rotation of the rotor 8, a series of operations of suction, compression and discharge of the refrigerant gas is performed five times in one crescent-shaped cylinder chamber, and is performed ten times in both cylinder chambers. From the relationship with such a structure, two sets of the sali- ble grooves 51 of the rear side block 6 and the front side block 5 are provided at positions 180 ° opposite each other with the rotor shaft 7 as a center. Similarly, two suction passages 16, two discharge chambers 18, two cylinder discharge holes 19, two discharge valves 20, etc. are provided.
[0057]
Next, the operation of the gas compressor according to the present embodiment configured as described above will be described with reference to FIGS.
[0058]
As shown in FIGS. 1 and 2, in the gas compressor according to the present embodiment, when the operation is started, the rotor 8 rotates integrally with the rotor shaft 7 and moves from the compression mechanism 2 to the discharge chamber 22 side. The compressed high-pressure refrigerant gas is discharged to the discharge chamber 22, thereby increasing the pressure in the discharge chamber 22.
[0059]
Then, the oil in the oil sump 24 is filled with: (1) bearings 9, 10, (2) vane bottom gap space G1, (3) rotor side gap G2, (4) rotor circumferential gap G3 near the cylinder elliptical minor diameter portion 4a, etc. Supplied to
[0060]
When oil is supplied to the rotor circumferential gap G3, an oil film of the supplied oil is formed in the rotor circumferential gap G3, and the oil film seals the rotor circumferential gap G3, and the supplied oil allows the rotor 8 and the rotor 8 to be in contact with each other. The cylinder 4 is lubricated.
[0061]
Further, when oil is supplied to the rotor side gap G2, an oil film by the supplied oil is formed in the rotor side gap G2, and the oil film seals the rotor side gap G2, and the rotor 8 and the cylinder 4 by the supplied oil. Lubrication is also performed.
[0062]
Incidentally, in the gas compressor of the present embodiment, the rotor circumferential gap G3 is the minimum gap between the rotor 8 and the cylinder 4. Therefore, contact between the rotor 8 and the cylinder 4 is likely to occur in the portion of the rotor circumferential gap G3. When the rotor 8 and the cylinder 4 come into contact with each other and thereby the oil film in the rotor circumferential gap G3 is broken, the surface modified layer 400 on the inner peripheral surface of the cylinder 4 exhibits its effect.
[0063]
That is, since the uppermost layer of the surface modified layer 400 is the sulfide layer 400-1 contributing to the improvement of seizure resistance, even if the rotor 8 and the cylinder 4 come into contact with each other in the gap G3 in the circumferential direction of the rotor, the contact does not occur. Seizure and galling due to are effectively prevented.
[0064]
Further, since the surface modified layer 400 is obtained by modifying the inner peripheral surface of the cylinder 4 as a base material by sulphonitriding, it is peeled off by contact with the rotor 8 like a conventional fluororesin coating layer or the like. It will not fall.
[0065]
Therefore, the effect of the surface modified layer 400 of preventing seizure and galling due to contact between the rotor 8 and the cylinder 4 is maintained for a long time.
[0066]
From the above, in the gas compressor according to the present embodiment, the configuration that could not be conventionally adopted due to the problem of the seizure and galling of the rotor 8 and the cylinder 4, that is, the minimum value of the gap setting value for the rotor circumferential gap G3 The value can be set smaller than before as follows.
[0067]
That is, in the case of the conventional gas compressor, the minimum value of the gap setting value for the rotor circumferential gap G3 is set to be larger than the sum of the following values A to D (A + B + C + D). This is because the plating and the coating layer of fluororesin described in the related art cannot effectively prevent seizure and galling of the rotor 8 and the cylinder 4 for a long period of time and have low reliability against seizure and galling. This is because it was necessary to actively avoid contact between the rotor 8 and the cylinder 4.
[0068]
On the other hand, in the case of the gas compressor of the present embodiment, the minimum value of the gap setting value for the rotor circumferential gap G3 is set to be smaller than the sum of the following values A to D (A + B + C + D). This is because, in the gas compressor of the present embodiment, the adoption of the above-mentioned surface reforming layer 400 makes it possible to effectively prevent seizure and galling between the rotor 8 and the cylinder 4 for a long period of time. This is because the contact between the rotor 8 and the cylinder 4, which has been conventionally avoided, can be positively allowed due to the improved performance.
<A>:
A is the maximum shaft runout of the rotor shaft 7, that is, a value obtained by subtracting the minimum diameter of the rotor shaft 7 from the maximum diameter of the bearing holes (bearings 9, 10 of the side blocks 5, 6) supporting the rotor shaft 7.
<B>:
B is the maximum amount of elastic deformation when the cylinder elliptical minor diameter portion 4a elastically deforms in the radial direction during operation of the gas compressor.
<C>:
C is the maximum amount of elastic deformation when the rotor 8 elastically deforms in the radial direction with the rotor shaft 7 as a fulcrum during operation of the gas compressor.
<D>:
D is the maximum thermal deformation of the cylinder elliptical minor diameter portion 4a during the operation of the gas compressor from the maximum thermal deformation when the rotor 8 thermally deforms in the radial direction during operation of the gas compressor. This value is obtained by subtracting the thermal deformation.
[0069]
Incidentally, it is inevitable that the surface modified layer 400 employed in the present embodiment is also worn due to contact with the rotor 8. However, the amount of spread of the rotor circumferential gap G3 due to wear of the surface-modified layer 400 is extremely small as compared with the amount of spread of the rotor circumferential gap G3 when the conventional fluororesin coating layer or the like is peeled off. The amount of internal leak through the rotor circumferential gap G3 does not increase extremely, the volume efficiency decreases only slightly, and the performance of the gas compressor does not deteriorate.
[0070]
As described above, according to the gas compressor of the present embodiment, the structure in which the inner periphery of the cylinder 4 of the cylinder elliptical minor diameter portion 4a is made of the surface modified layer 400 by the nitrosulfurization treatment is employed. For this reason, even if contact between the cylinder 4 and the rotor 8 occurs in the minimum gap between the cylinder 4 and the rotor 8 under severe operating conditions, that is, the rotor circumferential gap G3 near the cylinder elliptical minor diameter portion 4a, the surface modification is performed. The layer 400 prevents seizure and galling of the cylinder 4 and the rotor 8. Further, the surface modified layer 400 does not peel off unlike the conventional fluororesin coating layer and the like, and the effect of the surface modified layer 400 of preventing seizure and galling is maintained for a long time. The width set value of G3 can be made smaller than before. Therefore, the width set value of the rotor circumferential gap G3 can be reduced without causing seizure or galling, thereby improving the volumetric efficiency by improving the sealing performance of the rotor circumferential gap G3, and thereby improving the compressor. Can be improved, and the high performance can be maintained for a long period of time.
[0071]
In the above-described embodiment, the structure in which the inner periphery of the cylinder 4 is formed of the surface modified layer 400 is employed. However, the outer periphery of the rotor 8 is modified by a nitrosulphurizing process. However, it is also possible to adopt a structure comprising the above-mentioned surface modified layer. In the case of this structure, it is necessary to reform the entire outer periphery of the rotor 8. This is because any portion of the outer periphery of the rotor 8 may come into contact with the inner periphery of the cylinder 4 at the cylinder elliptical minor diameter portion. Also, an immersion treatment may be performed instead of the above-mentioned sulphonitridation treatment.
[0072]
When the oxynitriding process or the immersion process is performed on the outer periphery of the rotor 8, the difference in hardness between the rotor 8 and the cylinder 4 increases, but the lubricating action of the sulfide layer itself formed on the outer periphery of the rotor 8 by the process increases; The surface modification layer on the outer periphery of the rotor 8 including the sulfide layer avoids direct contact between the rotor 8 and the cylinder 4, thereby preventing seizure between the rotor 8 and the cylinder 4.
[0073]
Further, a structure in which both the inner circumference of the cylinder and the outer circumference of the rotor are formed of the above-described surface modified layer 400 may be employed. Also in the case of this structure, the surface modified layer 400 may be formed by a nitrosulphurizing treatment or by a sulphidizing treatment.
[0074]
The reason why the cast iron cylinder 4 is employed in the above-described embodiment is that the dead volume factor which is the discharge resistance of the refrigerant gas, specifically, the flow path length of the refrigerant gas discharge flow path of the cylinder discharge hole 19 is made as short as possible. That's why.
[0075]
That is, a method using an aluminum alloy cylinder 4 is also conceivable. However, since the strength of the aluminum alloy is lower than that of the cast iron, in the cylinder made of the aluminum alloy, the thickness near the cylinder elliptical minor diameter portion 4a must be increased from the viewpoint of securing the cylinder strength. Then, the flow path length of the cylinder discharge hole 19 penetrating the cylinder elliptical minor diameter portion 4a is necessarily increased by the thickness increase, and as a result, the discharge through the cylinder discharge hole 19 is performed. Therefore, the discharge resistance of the high-pressure refrigerant gas increases, the discharge amount of the high-pressure refrigerant gas per unit time decreases, the volumetric efficiency decreases, and the performance of the gas compressor deteriorates.
[0076]
Therefore, in the gas compressor of the above embodiment, the cylinder 4 made of cast iron is adopted, and the vicinity of the cylinder elliptical minor diameter portion 4a is thinned to the limit of the strength, so that the flow path length is shorter than that of the aluminum alloy cylinder. Is provided to reduce the discharge resistance of the refrigerant gas, thereby improving the volumetric efficiency and the performance of the gas compressor.
[0077]
FIG. 3 shows (1) a cast iron cylinder subjected to a nitrosulfurized treatment (hereinafter referred to as a nitrosulfurized cylinder), and (2) a cast iron cylinder subjected to a sulfided nitriding (hereinafter referred to as a sulfided cylinder). ), (3) Untreated cast iron cylinders (hereinafter referred to as untreated cylinders), and (4) Explanatory diagrams of measurement data when measuring hardness of steel rotors as test objects.
[0078]
According to the hardness measurement data shown in FIG. 3, it is understood that both the oxynitriding cylinder and the oxynitriding cylinder are harder than the untreated cylinder, and harder than the steel rotor. Specifically, the hardness was about 230 HV for the untreated cylinder, about 430 HV for the nitrocarburized cylinder, and about 940 HV for the sulfided cylinder. The hardness of the steel rotor was about 700 HV.
[0079]
4 to 6 are explanatory diagrams of test data when performing a seizure test of the cylinder and the rotor by the Falex test.
[0080]
In the Falex test, the test objects are pressed against each other and rubbed against each other. The test data in FIG. 4 was obtained when the pressing load was set to 150 lbs, the test data in FIG. 5 was used when 170 lbs was set, and the test data in FIG. 7 is test data of FIG.
[0081]
In addition, in this seizure test, (1) a combination of a sulfur-nitrided cylinder and a steel rotor, (2) a combination of a sulfur-treated cylinder and a steel rotor, and (3) a combination of a non-treated cylinder and a steel rotor. The combinations were tested, and a burn-in test was performed for each of them.
[0082]
According to the seizure test data when the load was 150 lbs (FIG. 4), (3) the combination of the untreated cylinder and the steel rotor resulted in seizure in about 2.5 minutes from the start of the test. In the case of a combination of a nitriding cylinder and a steel rotor, or (2) a combination of a sulfiding cylinder and a steel rotor, it does not seize even after more than 50 minutes from the start of the test and is very hard to seize. You can see that.
[0083]
Looking at the seizure test data (FIG. 5 or FIG. 6) of the seizure test data when the load was set to 170 lbs or 200 lbs, it was found that (1) the combination of the oxynitriding cylinder and the steel rotor, and (2) the oxynitriding cylinder It can be seen that the combination of the steel rotor with the steel rotor takes a longer time to seize, and is very difficult to seize.
[0084]
FIG. 7 is an explanatory diagram of experimental data showing a correlation between a rotor circumferential gap and power efficiency and a graph thereof, and FIG. 8 is an experimental data showing a correlation of a rotor circumferential gap and volume efficiency and a graph thereof. FIG. In both cases, the width set value of the rotor circumferential gap G3 of the gas compressor which is the test object machine is expressed by a comparison ratio with the width set value of the rotor circumferential gap G3 of the conventional gas compressor. did. The percentage in the figure is the ratio, and 100% corresponds to the rotor circumferential gap G3 of the conventional gas compressor.
[0085]
As can be seen from the power efficiency graph of FIG. 7 and the volume efficiency graph of FIG. 8, as the width set value of the rotor circumferential gap G3 becomes smaller than before, the power efficiency and the volume efficiency of the gas compressor eventually change. Has also improved. However, there is a peak in the improvement of the power efficiency and the volumetric efficiency, and it is understood that the power efficiency and the volumetric efficiency decrease when the peak is exceeded.
[0086]
For example, at a rotational speed of 1500 rpm, the volume efficiency of the gas compressor becomes maximum in the vicinity P2 where the rotor circumferential gap G3 slightly exceeds 40%. If the width set value of the rotor circumferential gap G3 is further reduced beyond the vicinity P2, the volume efficiency gradually decreases. At a rotational speed of 1500 rpm, the power efficiency of the gas compressor is maximized in the vicinity where the rotor circumferential gap G3 slightly exceeds 50%. If the width set value of the rotor circumferential gap G3 is further reduced beyond that vicinity, the power efficiency gradually decreases. This is considered to be because if the set value of the rotor circumferential gap G3 becomes too small, the influence of the frictional force due to the contact between the rotor 8 and the cylinder 4 becomes significant, and the power loss increases.
[0087]
【The invention's effect】
In the gas compressor according to the present invention, as described above, the inner periphery of the cylinder and / or both the rotor and the rotor are each formed of a surface modified layer modified by a nitrosulfurization treatment or a sulfide treatment. The structure is adopted. Therefore, even if the cylinder and the rotor come into contact at the minimum clearance between the cylinder and the rotor under severe operating conditions of the gas compressor, the cylinder and the rotor are prevented from seizing and galling by the surface modified layer. In addition, the surface modified layer does not peel off unlike the conventional fluororesin coating layer and the like, and the effect of the surface modified layer of preventing seizure and galling lasts for a long period of time. The width setting value of the minimum gap can be made smaller than before. Therefore, without causing seizure or galling, the width setting value of the minimum clearance between the rotor and the cylinder is reduced, and the sealing performance of the minimum clearance is improved to improve the volumetric efficiency and thereby improve the performance of the compressor. A gas compressor suitable for maintaining its high performance for a long period of time can be provided.
[Brief description of the drawings]
FIG. 1 is a sectional view of a gas compressor according to an embodiment of the present invention.
FIG. 2 is a sectional view taken along line AA of FIG. 1;
FIG. 3 is an explanatory diagram of hardness measurement data of a cylinder and a rotor.
FIG. 4 is an explanatory diagram of test data of a seizure test (load: 150 lbs).
FIG. 5 is an explanatory diagram of test data of a burn-in test (load: 170 lbs).
FIG. 6 is an explanatory diagram of test data of a seizure test (load: 200 lbs).
FIG. 7 is an explanatory diagram of a correlation between a rotor circumferential gap and power efficiency.
FIG. 8 is an explanatory diagram of a correlation between a rotor circumferential gap and volumetric efficiency.
FIG. 9 is a cross-sectional view showing a structural example of a conventional vane rotary type gas compressor.
[Explanation of symbols]
1 Compressor case
2 Compression mechanism
3 Front head
3-1 Boss
4 cylinder
4a Cylinder elliptical minor diameter
5 Front side block
6 Rear side block
7 Rotor shaft
7F Front end of rotor shaft
7R Rear end face of rotor shaft
8 rotor
9 Front side block bearings
10. Bearing of rear side block
11 Seal member
12 Vane grooves
13 Vane
14 Compression chamber
15 Inhalation chamber
16 Inhalation passage
18 Discharge chamber
19 Cylinder discharge hole
20 Discharge valve
21 Oil separator
22 Discharge chamber
23 Separation filter
24 oil sump
25-1 Discharge passage of cylinder
25-2 Discharge passage of rear side block
50 High pressure oil supply hole
50-1, 50-2, 50-3 holes
50a One end of high pressure oil supply hole
50b The other end of the high pressure oil supply hole
51 Sarai Groove
52 Rear back pressure space
53 Medium pressure oil supply hole
60 plating
400 Surface modification layer
400-1 sulfide layer
400-2 nitride layer
400-3 nitrogen diffusion layer
G1 Vane bottom clearance space
G2 Rotor side clearance
G3 Rotor circumferential gap
Pd discharge pressure
Ps suction pressure
R Rotor direction

Claims (4)

A cast iron cylinder,
A steel rotor rotatably suspended in the cylinder,
A vane that is provided so as to be able to protrude and retract from the outer peripheral surface of the rotor toward the inner peripheral surface of the cylinder, and that partitions a space in the cylinder between the cylinder and the rotor into a plurality of small chambers;
A compression chamber comprising a small chamber partitioned by the vanes, repeating a change in volume by the rotation of the rotor, and sucking, compressing, and discharging the refrigerant gas by the change in volume,
A gas compressor, wherein at least one of the inner circumference of the cylinder and the outer circumference of the rotor is formed of a surface modified layer formed by nitrosulphurizing or sulphating. The cylinder has an inner periphery formed in an elliptical shape,
A gas compressor characterized in that at least the cylinder inner circumference of the cylinder elliptical minor diameter portion of the entire cylinder inner circumference comprises the surface modified layer. The rotor is formed in a perfect circular cross section,
The inner circumference of the cylinder is formed substantially in an elliptical shape, and a circular arc surface of a perfect circle similar to the outer circumferential surface of the rotor is formed in the inner circumferential portion of the cylinder of the cylinder elliptical minor diameter portion,
A gas compressor, wherein at least the cylinder inner periphery of the cylinder elliptical minor diameter portion including the perfect circular arc surface is made of the surface reforming layer in the entire cylinder inner periphery. A cast iron cylinder formed in a substantially elliptical inner circumference;
A steel rotor rotatably suspended in the cylinder,
A vane that is provided so as to be able to protrude and retract from the outer peripheral surface of the rotor toward the inner peripheral surface of the cylinder, and that partitions a space in the cylinder between the cylinder and the rotor into a plurality of small chambers;
A compression chamber comprising a small chamber partitioned by the vanes, repeating a change in volume by the rotation of the rotor, and sucking, compressing, and discharging the refrigerant gas by the change in volume,
The inner periphery of the cylinder or the outer periphery of the rotor is formed of a surface modified layer formed by a nitrosulphurizing process or a sulphating process,
A gas compressor characterized in that a minimum value of a clearance set value between the cylinder and the rotor at the elliptical minor diameter portion of the cylinder is smaller than the sum of the following values A, B, C, and D.
<A>: A is a value obtained by subtracting the minimum diameter of the rotor shaft from the maximum diameter of a bearing hole that supports the rotor shaft provided integrally with the shaft center of the rotor.
<B>: B is the maximum amount of elastic deformation when the elliptical minor diameter portion of the cylinder elastically deforms in the radial direction during operation of the gas compressor.
<C>: C is the maximum elastic deformation amount when the rotor elastically deforms in the radial direction about the rotor shaft during operation of the gas compressor.
<D>: D represents the maximum amount of thermal deformation when the rotor thermally deforms in the radial direction during the operation of the gas compressor, and indicates that the cylinder elliptical minor diameter portion thermally deforms in the radial direction during the operation of the gas compressor. This is a value obtained by subtracting the maximum thermal deformation amount when performing.

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