JP2579784B2 - Swash plate compressor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a swash plate compressor for compressing a gas such as a refrigerant gas. In particular, the present invention relates to a compressor which is lightweight and has excellent reliability under severe operating conditions for use in vehicle-mounted air conditioning having a large cylinder inner diameter.

(Prior Art and Problems) As shown in FIG. 1, a swash plate compressor is generally mounted on a rotating shaft 2 disposed in a cylinder block 1 and rotates with the rotating shaft. And a piston 5 slid over the swash plate 3 and moored by the shoes 4. The rotational movement of the swash plate that rotates with the rotation shaft is converted by the shoe into reciprocating movement of the piston. With such a structure, the medium to be compressed such as the refrigerant gas circulating through the refrigeration circuit is compressed to a high pressure in the cylinder bore 6 by the piston 5 and sent out to the refrigeration cycle circuit again.

When such a swash plate type compressor is used for vehicle-mounted air conditioning, it is subjected to extremely severe operating conditions. In recent years, vehicles have become lighter, smaller, and front-wheel driven, and compressors mounted inside the hood have also been required to be smaller and lighter.
The oil pump in the compressor is removed and lubricated by circulating oil-containing refrigerant returned from the external refrigeration circuit to the compressor or oil separated from the refrigerant returned to the compressor to each sliding part of the compressor. Has been taken.

In this lubrication method, when the number of rotations of the compressor is high, a relatively large amount of return refrigerant is present, so that there is no problem because the lubrication of each sliding portion is sufficiently performed. However, since the compressor is mounted so as to have substantially the same rotational speed as the engine of the drive source, it is used in a wide range of engine rotational speeds, that is, a wide rotational range of 500 to 6000 rpm. For this reason, when the engine speed is low, the amount of the return refrigerant is small, and the lubrication of each sliding portion is insufficient, so that abrasion proceeds and a seizure phenomenon occurs. Also, since the compressor is mounted inside the bonnet, the temperature inside the bonnet becomes high due to the installation of equipment for exhaust measures and equipment for improving fuel consumption, so the compressor becomes hot and the viscosity of the lubricating oil decreases, and the lubrication effect decreases. However, the above-mentioned problems of wear and seizure are likely to occur.

In the swash plate type compressor used under severe conditions as described above, the most problematic part is the sliding part between the swash plate and the shoe.

The sliding speed between the swash plate and the shoe varies depending on the model, but covers a wide range of approximately 2 to 25 m / sec in order to correspond to the above-mentioned engine speed. It slides at a high speed of approximately 7 to 15 m / sec even during normal running. In addition to such a high sliding speed, a large load is applied to the shoe by applying the compression pressure of the refrigerant to the cross-sectional area of the cylinder bore. The load on the shoe varies depending on the model, but during normal operation it is almost
Is 100 to 200 kg / cm ³ order of surface pressure. Therefore, the PV value is 3000
This is a very large value of kg / cm ² · m / sec. Furthermore, since the shoe and the swash plate are exposed to so-called boundary lubrication, which is in a solid contact state, seizure and wear are likely to occur. In addition, as described above, the oil pump in the compressor is removed for the purpose of weight reduction, and the oil containing oil returned to the compressor from the external refrigeration circuit or the oil returned to the compressor and separated from the refrigerant is removed from the compressor. The lubrication system is designed to circulate through each sliding part, so that the lubricating oil is not supplied to the sliding surface between the swash plate and the shoe for several tens of seconds from the start, and for several minutes when it is long. Then, the shoe and the swash plate slide. In addition, when the refrigerant is used for a long period of time, the operation may be performed in a state where the refrigerant leaks and the refrigerant is insufficient, and the lubricating state becomes extremely severe under such operating conditions. In addition, during the initial operation in an environment where the temperature difference between day and night is large, or at the time of filling the insufficient refrigerant, the refrigerant may be operated in a liquefied state, in which case the lubricating oil is washed with the refrigerant. Not only does it no longer exist on the sliding surface, it also compresses the liquid inside the cylinder bore, and the pressure inside the cylinder bore becomes 100 to 1
Since the load reaches 50 kg / cm ^2, which is 4 to 6 times the load of the normal operation state, seizure easily occurs.

The weight reduction of the swash plate compressor is achieved by the cylinder block 1
The aluminum alloy of the housing 7, the piston 8, the piston 5, and the like are early formed into an aluminum alloy. In order to further reduce the weight, it has been studied to convert the swash plate, which was conventionally made of cast iron or an iron-based sintered alloy, into a high silicon aluminum alloy. It has been practiced in a compressor having a small cylinder inner diameter.

However, when the swash plate is made of a high-silicon aluminum alloy, wear of the shoe is likely to occur due to hard primary crystal silicon dispersed in the aluminum alloy matrix. As a countermeasure against this, it has been proposed to apply various treatments to the sliding surface of the shoe with the swash plate. JP-B-60-54516 proposes to provide a boron-impregnated layer, JP-A-55-128681 proposes a carbide layer, and JP-A-54-67209 proposes an ion nitride layer. However, none of these measures is sufficient, and recently, shoes in which ceramics such as alumina or zirconia are caulked on the bottom surface of steel shoes have been used.

However, even a compressor using a combination of these shoes and a swash plate made of a high silicon aluminum alloy has not yet been able to satisfy the required compressor reliability under severe operating conditions. In particular, in a compressor with a large cylinder inner diameter, the pressure applied to the shoe is high, and seizure and wear are likely to occur.Therefore, the swash plate is cast iron material with excellent lubricity and iron-based sintering with good oil retention due to holes. It was not possible to depart from the combination of using high-silicon aluminum alloy material as the bonding gold and the shoe was delayed in weight reduction.

The present inventor has proposed that in such a compressor, excellent results can be obtained by a combination of a shoe having a hard ion-plated bottom surface and a swash plate made of a high silicon aluminum alloy. No. 62-52981).

However, as a result of further study, the adhesion of the hard ion plating film on the bottom of the shoe was uneven, the ion plating film peeled off from the base, and the film peeled on the sliding part of the compressor became a fine powder. It has been found that there is a case in which the ion plating film may enter and cause abrasion or seizure, and it is necessary to greatly improve the adhesion of the ion plating film.

(Object of the Invention) The present invention provides a lightweight compressor using a material combination which improves the sliding problem of a swash plate type compressor having a large cylinder bore diameter, for which the swash plate cannot be aluminized for the above reasons. It was done with the purpose of obtaining. Further, by using a shoe with an improved adhesion of the ion plating film, the point that the content of the prior application was insufficient was greatly improved.

(Means for Solving the Problems) According to the present invention, a swash plate rotated by a rotating shaft in a cylinder block and a piston moored to the swash plate via a shoe are provided. Accordingly, in the swash plate type compressor in which the piston reciprocates in the cylinder bore, a hard ion plating film having a thickness of 1 to 10 μm is provided on a surface in sliding contact with the swash plate, and the film is formed of a steel shoe. A swash plate type compressor characterized by being composed of a combination which is strongly diffusion bonded. In the present invention, the hard ion plating film provided on the shoe is preferably made of chromium and nitrogen or titanium and nitrogen.

(Operation) In the present invention, the swash plate is made of a high silicon aluminum alloy, and its purpose is to reduce the weight and improve the sliding characteristics by combination with a shoe described later. Materials used as the swash plate include Si: 14 to 20% by weight, Cu: 3 to 8% by weight, Mg: 0.2
A high silicon aluminum alloy consisting essentially of ~ 2.0 wt% and the balance being essentially Al, with additional Pb as required
0.5 to 2% by weight may be contained.

If the content of Si is less than 14% by weight, the number of primary crystal Si particles dispersed in the matrix becomes insufficient, causing wear of the swash plate and seizure with the shoe. On the other hand, if it exceeds 20% by weight, the primary crystal Si becomes coarse and the strength and toughness of the swash plate decrease.

Cu and Mg are indispensable elements for the purpose of securing the strength of the aluminum alloy matrix by heat treatment. If Cu is less than 3% by weight, a satisfactory strength cannot be obtained even by age hardening by heat treatment, while if it exceeds 8%, the crystallized compound is remarkably coarsened, impairing the toughness of the swash plate and deteriorating corrosion resistance. Mg is 0.2
If the amount is less than 20% by weight, satisfactory strength cannot be obtained even by age hardening, and if the amount exceeds 2.0% by weight, toughness is reduced.
Hot forging becomes difficult. If Pb is contained from 0.5% by weight as necessary, Pb precipitates in or near the primary crystal Si particles, so that seizure resistance under operating conditions in which lubricating oil is insufficient increases. In addition, there is a manufacturing effect that extends the life of the tool during machining. If the amount of Pb is less than 0.5% by weight, there is an effect on the machined surface, but there is no effect on seizure resistance. On the other hand, if the amount exceeds 2.0% by weight, it is not possible to produce a continuous cast material having a good structure. Since a minute gap is generated in the portion, when the portion is used as a swash plate, the portion is subjected to stress concentration as an internal defect, and the fatigue strength is significantly reduced.

The manufacture of swash plates involves the use of aluminum alloys of this composition.
A hot-top continuous casting method with a cooling rate faster than DC casting makes a directly connected round bar with a diameter of 50 to 80 mm, and after cutting, forging material close to a swash plate by hot forging, machine after T6 or T7 heat treatment Finished to a predetermined shape by processing. Then press the steel shaft into the central hole and use it. In phototop casting, the cooling rate is high and the primary crystal Si can be made uniform and fine.In addition, the casting material to which lead is added can be cast without coarsening or segregation of the primary silicon as long as it is within the above-mentioned component range. it can. In forging, the toughness of the material is increased by destroying the cast structure, but forging is preferably performed in such a manner that the metal flow by forging is as perpendicular as possible to the direction of the stress applied to the swash plate.

The shoe is made by cutting high carbon steel or high chromium bearing steel, cold forging it into a preliminary shape, and forging it in a sizing mold to increase the dimensional accuracy of the spherical surface. Thereafter, the bottom surface is polished or lap-finished and subjected to ultrasonic cleaning in a Freon liquid, and then a hard film of ion plating is provided in a thickness of 1 to 10 μm on at least a flat portion of the bottom surface which is in sliding contact with the swash plate. afterwards,
Complete adhesion between the base and the ion plating film. If the thickness of the ion plating film is less than 1 μm, the ion plating film will be worn by prolonged use. On the other hand, when the thickness exceeds 10 μm, the coating is apt to peel off during quenching or use of the ion plating. As the ion plating film, good results are obtained when a film composed of titanium and nitrogen or chromium and nitrogen is combined with the swash plate.
In particular, when a film made of chromium and nitrogen is combined with the swash plate made of aluminum alloy, the result is extremely excellent in seizure resistance and wear resistance.

In the ion plating, the shoe is set on a jig, the surface is ultrasonically cleaned in that state, then degreased, and then mounted in a vacuum vessel of an arc ion plating apparatus. 10 inside the container
After a high vacuum of about ^-5 Torr, the shoe was heated to 400 to 600 ° C with a built-in heater, and an arc was blown on the surface of the target made of titanium or chromium, and most of these metal elements were ionized. Make it fly out of the target surface. At this time, a bias voltage of 700 to 800 V is applied to the shoe and the jig to attract the ionized titanium or chromium that has jumped out to the shoe and the jig surface.
The surface is activated by so-called bombarding. Thereafter, nitrogen gas was introduced into the vacuum vessel to reduce the degree of vacuum to 0.02 To.
rr and a bias voltage of 30 to 120 V to form an ion plating film on the shoe surface. The temperature of the shoe surface is measured by a radiation thermometer during the time until the film thickness reaches the specified value, and the temperature of the shoe is controlled to maintain the specified temperature between 400 and 500 ° C by raising and lowering the bias voltage and arc current. . After a lapse of time necessary for obtaining a predetermined film thickness, ion plating is stopped, and after cooling in the container, the shoe is taken out of the container. In this state, the adhesion between the ion plating film and the matrix is insufficient, so that the substrate is heated and held at a temperature of 500 ° C. or more in a vacuum furnace or an atmosphere furnace. Particularly preferably, the temperature is 700 ° C. or higher. Diffusion occurs between the ion plating film and the matrix by the heating and holding, and the adhesion can be completed.
Further, the internal strain of the ion plating film is released by the heating, so that the hardness is reduced, so that there is no tendency to damage the partner swash plate. In addition, since the base of the shoe is lowered by heating, wear of the ball portion occurs and the proof strength of the ion plating film base is reduced, so that local deformation and dents due to surface pressure during handling and use are reduced. Disadvantages. Therefore, the above-mentioned problem can be solved by setting the heating temperature of the ion plating to the quenching temperature, forcibly cooling after holding, and further performing tempering. After that, the surface roughness of the ion plating film was reduced to 0.
If it is not more than 4 μm, the swash plate of the other party will be worn. Therefore, lapping is performed so that the surface roughness becomes less than 0.4 μm. Furthermore, in order to improve the roughness of the ball part of the shoe, barrel finishing is performed, and after confirming the dimensions, it is incorporated into a compressor.

(Example-1) First, an evaluation test for seizure resistance was performed with various material combinations using a shoe body friction and wear tester shown in a top view in FIG. 2 and a side view in FIG. In the figure, reference numeral 10 denotes a shaft which is rotated by a rotary power transmission mechanism (not shown), which is supported by a bearing 9 and to which a disk-shaped test piece 11 of a swash plate material is attached.
A hydraulic cylinder 14 is provided on a holder 13 provided in parallel with the shaft 10 and mounted on a shaft 12 fixed by an indicator (not shown) so as to be able to move straight and rotate freely. 16 has a structure in which a disc-shaped test piece 11 made of a swash plate material is sandwiched from both sides. The shoe is mounted so that it can rotate. The holder 13 is provided with a weight balancer 17 for adjusting the balance with the shaft 12 as a fulcrum. The frictional force between the disc-shaped test piece 11 and the shoe 16 is transmitted to the tension-type load cell 19 via the piano wire 18. From the load cell, it is amplified by a strain amplifier (not shown) and recorded on a recorder. A predetermined pressure is applied to the hydraulic pressure to the hydraulic cylinder from a hydraulic unit (not shown) via a servo valve.

As a disc-shaped test piece material, a T7-treated high silicon aluminum alloy shown in Table 1 was used.

The shoe was made into a semi-hemispherical preform by cold forging of SUJ-2 material using a parts former, and after annealing, it was further forged in a sizing mold to improve the dimensional accuracy of the ball. Thereafter, the bottom surface is polished, and a hard film by ion plating is provided with a thickness of 3 to 8 μm on at least a flat portion of the bottom surface which is in sliding contact with the swash plate. The ion plating method is as described above. After ion plating, 82 in a vacuum quenching furnace
After holding at 0 ° C. for 30 minutes, it was oil-cooled and quenched, and then tempered at 180 ° C. in a nitrogen atmosphere furnace. The type of ion plating film of the shoe subjected to the test, the measurement result of the film thickness and hardness, and the crystal structure of the film by X-ray diffraction were as shown in Table 2. In addition, 99.5
% Al ₂ O ₃ (test piece No. A) and partially stabilized zirconia shoe (test piece No. Z) each having a bottom surface roughness of 0.3 μm with Ra were used. The shape was exactly the same as the ion-plated product.

Test conditions Circumferential speed: 2.5m / sec Lubricating oil: Compressor oil (Sniso 5GS) Lubricating method: Oil spraying method (0.6cc / min) Load: Starting from 40kg, step up in steps of 10kg, hold for 3 minutes at each load stage Test Piece surface roughness Disc-shaped test piece: 0.8 to 1.0 S Shoe: 0.3 to 0.4 S For the evaluation of seizure, the load point at which the friction coefficient becomes 0.05 is defined as the seizure load.

Table 3 shows the combinations of the disc-shaped test piece and the shoe material and the seizure load based on the test results.

All were superior to ceramics (Al ₂ O ₃ , partially stabilized zirconia), but especially when the composition of the coating was Cr,
S-2 of S-1, Cr ₂ N composition is Cr ₂ N is good.

(Example-2) A compressor was assembled using a swash plate and a shoe as a material combination of Example-1, and an actual machine test was performed on a bench under the following conditions.

Compressor: 6-cylinder swash plate compressor (cylinder bore diameter: 36 mm,
Cylinder bore PCD: 66mm, total displacement: 150cc) Revolution: 4000rpm Exhaust gas pressure: 5-5.5kg / cm ² Intake side gas pressure: about 50mmHg Operating time: Up to 20 hours Lubricating oil: Compressor oil (Sniso 5GS) 100cc Enclosed refrigerant amount: 240g (20% of the normal amount) During operation, the torque of the torque meter is automatically monitored, and when it increases by 5% from the steady torque, it is automatically stopped.
In the combination of the shoe and the swash plate of the present invention, there is no abnormality
Endured driving for hours. No seizure was observed in the results of the disassembly after the test. However, the combination No. 6 for comparison was stopped in 5 hours for No. 6 and 8 hours for No. 7 due to the increase in torque, and as a result of disassembly investigation, it was confirmed that seizure occurred between the shoe and the swash plate. .

(Example-3) Adhesion by the presence or absence of diffusion treatment was evaluated by the following method using a shoe which had been subjected to ion plating of the same lot as in Example-1 and was not subjected to quenching treatment after ion plating. did.

Evaluation method The grindstone and the shoe were each placed in a pot of a centrifugal barrel machine, 30 pieces each, and after operating the barrel machine for 90 minutes, the ion plating surface was investigated. The results are shown in Table 4.

As described above, it was confirmed that by performing the heating and holding after the ion plating, the diffusion occurred between the ion plating film and the matrix, and the adhesion was improved.

Incidentally, the hardness is reduced by about 400 to 800 in HmV by this heat treatment. From the observation of the X-ray diffraction peak, it is confirmed that the cause is that the internal strain is released by heating and holding at a high temperature. No change is observed in the crystal orientation even by heating and holding.

(Effect of the Invention) As described above, according to the present invention, in a model having a large cylinder bore, that is, a large load applied to a shoe, which has conventionally been difficult to aluminize a swash plate, a swash plate formed of a high silicon aluminum alloy is used. By using a combination of a plate and a shoe in which a hard ion plating film is diffusion-bonded to a steel base at least on the sliding contact surface with the swash plate, the sliding characteristics are greatly improved, and the weight of the compressor is reduced. It becomes possible. Further, since the shoe is a small-sized component, a large amount of processing can be performed at a time by the ion plating apparatus, so that the economy is excellent.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the configuration of a swash plate type compressor according to the present invention, FIG. 2 is a top view of a shoe actual friction and wear tester used in a comparative test, FIG. 3 is a side view thereof, and FIGS. 4C and 4D are cross-sectional views each showing an embodiment of the shoe of the present invention. In the figure: 3 ... swash plate, 4 ... shoes, 4a ... ion plating film layer.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Katsumi Takiguchi 1-37 Hokutocho, Kashiwazaki-shi, Niigata Examiner Kazuo Ishibashi, RIKEN Kashiwazaki Works

Claims (3)

(57) [Claims] 1. A swash plate rotated by a rotation shaft in a cylinder block, and a piston moored to the swash plate via a shoe, wherein the piston reciprocates in a cylinder bore according to rotation of the swash plate. In the swash plate type compressor to be moved, the swash plate formed of a high silicon aluminum alloy, and at least a sliding contact surface with the swash plate, a hard ion plating film having a thickness of 1 to 10 μm and a steel base. A swash plate compressor characterized by being combined with a diffusion bonded shoe. 2. The swash plate compressor according to claim 1, wherein said hard ion plating film of said shoe comprises chromium and nitrogen. 3. The swash plate compressor according to claim 1, wherein said hard ion plating film of said shoe comprises titanium and nitrogen.