JP2002089436A - Variable displacement swash plate compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable displacement swash plate compressor reducing the cost of manufacture while having seizure resistance and a low friction coefficient equal to, or better than, those of a flame spraying membrane. SOLUTION: In this variable displacement swash plate compressor, provided with a cylinder block 1 having a plurality of cylinder bores 6, a swash plate 10 rotated by a shaft 5 in this cylinder block 1, a piston 7 received slidably to the cylinder bore 6, and shoes 60, 61 interposed between these piston 7 and swash plate 10 to coat planes 60b, 61b thereof with an amorphous hard carbon film, to make the piston 7 perform a reciprocating motion in the cylinder bore 6 in accordance with rotation of the swash plate 10, the swash plate 10 is constituted by cast iron.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a variable displacement swash plate type compressor.

[0002]

2. Description of the Related Art A conventional variable displacement swash plate type compressor includes a cylinder block having a plurality of cylinder bores, a swash plate rotated by a shaft in the cylinder block, and a piston slidably received in the cylinder bore. A shoe is provided between the piston and the swash plate and has a sliding surface coated with an amorphous hard carbon film.

The swash plate changes the inclination angle in accordance with the change in the pressure of the crank chamber in which the swash plate is housed, and the stroke of the piston changes.

[0004] Cylinder bores are formed at regular intervals on a circumference around a shaft in a cylinder block.

[0005] The rotation of the swash plate causes the shoe to relatively rotate on the sliding surface of the swash plate, so that the rotational force of the swash plate is converted into a linear reciprocating motion of the piston.

As a result of the reciprocating motion of the piston in the cylinder bore, the volume of the compression chamber in the cylinder bore changes, and the suction, compression and discharge of the refrigerant gas are sequentially performed by this volume change, and the capacity according to the inclination angle of the swash plate. Is discharged.

[0007]

By the way, in recent years, the weight of automobile parts has been reduced, and the material of refrigerant compressors has been changed from iron-based materials to aluminum alloys.

When an aluminum alloy is used for the swash plate, an iron-based material is used for the swash plate because it is not possible to take a large moment to stand up the swash plate by overcoming the inertial force generated by the reciprocating motion of the piston.

For the shoe, bearing steel (SUJ2) is used in order to secure sliding characteristics such as seizure resistance and wear resistance with a piston formed of an aluminum alloy material.

Since the sliding portion between the swash plate and the shoe is made of the same material, the sliding characteristics such as seizure are reduced. Japanese Patent Application Laid-Open No. 9-209926 and the like disclose a technique of applying a copper-based thermal spray coating to secure the sliding characteristics on the flat portion of the swash plate and the flat portion of the shoe, which are the sliding portions, in order to secure the sliding characteristics. ing.

However, the formation of the thermal spray coating requires the steps of machining the swash plate material, undercoating treatment, thermal spraying, machining such as polishing, and coating molybdenum disulfide, which greatly increases the production cost. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a variable-capacity swash plate type compression system which has sliding characteristics equal to or higher than that of a thermal sprayed coating and can reduce manufacturing costs. Is to provide a machine.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 is a cylinder block having a plurality of cylinder bores, a swash plate rotated by a shaft in the cylinder block, and a slidable cylinder bore. And a shoe interposed between the piston and the swash plate and having a sliding surface coated with a hard film,
A variable displacement swash plate compressor in which a piston reciprocates in a cylinder bore in accordance with rotation of a swash plate, wherein the swash plate is made of an iron-based material.

Since the swash plate is made of an iron-based material as described above, the swash plate and the shoe are made of the same material. However, since the sliding surface of the shoe is coated with a hard coating, the swash plate and the shoe slide. Heat generation due to movement can be suppressed low, and the coefficient of friction between the swash plate and the shoe can be reduced.

According to a second aspect of the present invention, in the variable displacement swash plate type compressor according to the first aspect of the present invention, the iron-based material is cast iron.

Since the iron-based material is cast iron as described above,
The wear resistance is improved.

According to a third aspect of the present invention, in the variable displacement swash plate type compressor according to the first or second aspect, a heat hardening treatment is applied to a surface of the swash plate.

Since the surface of the swash plate is subjected to the heat curing treatment, the hardness of the surface of the swash plate is further increased.

According to a fourth aspect of the present invention, in the variable displacement swash plate type compressor according to any one of the first to third aspects, the surface of the swash plate is coated with a solid lubricant. I do.

Since the surface of the swash plate is coated with a solid lubricant, sliding without lubricant can be prevented.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing a variable displacement type swash plate type compressor according to one embodiment of the present invention.

A rear head 3 is disposed on one end of a cylinder block 1 of the variable displacement type swash plate type compressor via a valve plate 2, and a front head 4 is disposed on the other end. The front head 4, the cylinder block 1, the valve plate 2 and the rear head 3 are integrally connected in the axial direction by through bolts 31.

In the cylinder block 1, cylinder bores 6 are formed at regular intervals along a circumference centered on the shaft 5.

A piston 7 is slidably inserted into each cylinder bore 6. At one end of the piston 7, concave portions 51a and 51b that rotatably support a pair of shoes 60 and 61 described later are formed.

The front head 4 has a swash plate 10 to be described later.
And a crank chamber 8 for accommodating the thrust flange 40 and the like. In addition, a suction chamber 13 and a discharge chamber 12 are formed in the rear head 3.

The suction chamber 13 contains a low-pressure refrigerant gas to be supplied to the compression chamber 6a. The discharge chamber 12 is located around the suction chamber 13. The discharge chamber 12 contains the high-pressure refrigerant gas discharged from the compression chamber 6a.

One end of the shaft 5 is rotatably supported by the front head 4 via a radial bearing 26, and the other end of the shaft 5 is a radial bearing 25 and a thrust bearing 24.
And is rotatably supported by the cylinder block 1 via the.

The thrust flange 40 is fixed to the shaft 5 and rotates integrally with the shaft 5.

The swash plate 10 is attached to the shaft 5 via a hinge ball 9 so as to be inclined and slidable. The swash plate 10 is made of ductile cast iron (FCD) (iron-based material).

Although the surface of the swash plate 10 may be left as it is, it is preferable that the surface of the swash plate 10 be subjected to a thermosetting treatment such as soft nitriding or induction hardening. By this heat curing treatment, the swash plate 10
Can have a Vickers hardness of 500 Hv or more.

On the surface of the swash plate 10, graphite, tungsten disulfide (WS ₂ ), fluororesin (PT
FE) and a solid lubricant such as molybdenum disulfide (MoS ₂ ). At this time, it is desirable that the surface roughness (ten-point average roughness) of the swash plate 10 be RZ 1.6 or less.

The swash plate 10 is connected to a thrust flange 40 via a link mechanism 41, and rotates together with the rotation of the thrust flange 40.

The periphery of the swash plate 10 and one end of the piston 7 are connected via shoes 60 and 61.

The shoes 60 and 61 are formed of bearing steel (SUJ2). These shoes 60, 61 are spherical surfaces 60a,
61a and flat surfaces (sliding surfaces) 60b, 61b.

The spherical surfaces 60a and 61a come into contact with the concave surfaces 51a and 51b at one end of the piston 7, and the flat surfaces 60b and 61b
Are in contact with the sliding surfaces 10a and 10b of the swash plate 10.

On the planes 60b and 61b, titanium nitride (Ti
N), chromium nitride (Crn), tungsten carbide (W
C) or a hard coating such as amorphous hard carbon (DLC (diamond-like carbon)) to prevent seizure due to sliding of the same material. The surface roughness of the planes 60b and 61b is RZ 1.6 or less.

The above film is formed by a PVD method or a CVD method.

If the thickness of the amorphous hard carbon film is less than 2 μm, sufficient abrasion resistance cannot be obtained.
μm or more, for example, 7 μm. The thickness of the chromium nitride film is, for example, about 5 μm.

According to the wear test, the amorphous hard carbon film has better seizure resistance and wear resistance than titanium nitride and chromium nitride films. Further, the chromium nitride film has better seizure resistance than the titanium nitride film.

A pair of shoes 60 and 61 are arranged for each piston 7 so as to sandwich the swash plate 10, and the shoes 60 and 61 move on the sliding surfaces 10 a and 10 b of the swash plate 10 as the shaft 5 rotates. Relative rotation.

The rotation of the swash plate 10 causes the piston 7 to reciprocate in the cylinder bore 6.

The valve plate 2 has a discharge port 15 for communicating the compression chamber 6a and the discharge chamber 12, and a suction port 16 for communicating the compression chamber 6a and the suction chamber 13, each having a predetermined interval along the circumferential direction. It is provided every other.

The discharge port 15 is opened and closed by a discharge valve 21, and the suction port 16 is opened and closed by a suction valve 17.

A thrust flange 40 fixed to the front end of the shaft 5 is rotatably supported on the inner wall surface of the front head 30 via a thrust bearing 33.

The swash plate 10 connected to the thrust flange 40 via the link mechanism 41 can be inclined with respect to a plane perpendicular to the shaft 5.

Next, the operation of the variable displacement type swash plate type compressor will be described.

When the rotational power of the vehicle-mounted engine (not shown) is transmitted to the shaft 5, the rotational force of the shaft 5 is transmitted to the swash plate 10 via the thrust flange 40 and the link mechanism 41, and the swash plate 10 rotates.

The rotation of the swash plate 10 causes the shoes 60 and 61 to relatively rotate on the sliding surfaces 10a and 10b of the swash plate 10, and the rotational force from the swash plate 10 is converted into a linear reciprocating motion of the piston 7.

When the piston 7 reciprocates in the cylinder bore 6, the volume of the compression chamber 6 a in the cylinder bore 6 changes, and the suction, compression and discharge of the refrigerant gas are sequentially performed by this volume change, and the inclination angle of the swash plate 10 is changed. The high-pressure refrigerant gas having a capacity corresponding to the pressure is discharged.

At the time of suction, the suction valve 17 is opened, low-pressure refrigerant is sucked from the suction chamber 13 into the compression chamber 6a in the cylinder bore 6, and at the time of discharge, the discharge valve 21 is opened and the high-pressure refrigerant is discharged from the compression chamber 6a to the discharge chamber 12. Refrigerant gas is discharged. The high-pressure refrigerant gas in the discharge chamber 12 is discharged from the discharge port 3a to a cooler (not shown).

At the time of compression, the compression reaction force of the piston 7 is
And the thrust bearing 33 via the thrust flange 40.

When the heat load decreases and the pressure in the crank chamber 8 increases, the inclination angle of the swash plate 10 decreases, so that the stroke amount of the piston 7 decreases and the discharge capacity decreases.

On the other hand, when the heat load increases and the pressure in the crank chamber 8 decreases, the inclination angle of the swash plate 10 increases, so that the stroke amount of the piston 7 increases and the discharge capacity increases.

According to this embodiment, the following effects can be obtained.

The case where the amorphous hard carbon film is applied and the case where the thermal spray coating is applied are shown as examples.

FIG. 2 is a diagram showing the results of a seizure test of the compressor.

In FIG. 2, the vertical axis represents the crank temperature (° C.).
, And the horizontal axis indicates the rotation speed (r / min) of the compressor.

Note that a is a plane 60 of the shoes 60 and 61.
When a copper-based thermal spray coating (0.1 mm in film thickness) is formed on b, 61b, b is the flat surfaces 60b, 61b of the shoes 60, 61.
When an amorphous hard carbon film (1 μm thick) is formed on
Indicates a case where an amorphous hard carbon film (thickness: 7 μm) was formed on the planes 60b and 61b of the shoes 60 and 61, and Δ indicates occurrence of seizure.

Test conditions: Full stroke fixed, refrigerating machine oil 30 g, Freon usage 700 g, discharge pressure 2.4 MPa,
Evaporator loading dry bulb 40 ° C, humidity 50%, air volume 480
m ³ / h, 800 rpm, 1300 rpm, 1800 r
pm, 2300 rpm, 2700 rpm, 3000 rpm
m, 3200 rpm, and 3400 rpm for 10 minutes, and the surface of the swash plate 10 was covered with molybdenum disulfide after nitriding.

When an amorphous hard carbon film having a thickness of 7 μm is formed on the planes 60 b and 61 b of the shoes 60 and 61, the swash plate 1
Since the predetermined sliding characteristics can be ensured even though 0 and the shoes 60 and 61 are made of the same material, the crank temperature is kept low, and excellent seizure resistance and wear resistance are maintained over a long period of time. be able to.

Since the crank temperature can be kept low, a shaft seal assembled around the crank chamber,
Gaskets and bearings provided in the crank chamber are less likely to be damaged, and durability is improved.

Since the film forming temperature is as low as about 160 ° C., the mechanical processing performed in the step of forming the thermal sprayed film becomes unnecessary.
The number of working steps can be reduced as compared with the case where a thermal spray coating is formed, and the manufacturing cost can be reduced. In addition, there is no risk of environmental pollution because it does not contain a lead component unlike the formation of a copper-based thermal spray coating.

The friction coefficient between the swash plate 10 and the shoes 60 and 61 can be reduced to be equal to or higher than that of the thermal spray coating, and the rotational torque of the compressor can be reduced to improve the fuel efficiency of the vehicle.

In the above embodiment, the coating was applied to the flat surfaces 60b and 61b of the shoes 60 and 61.
b, 61b, the sliding surface 10 of the swash plate 10
a, 10b, the spherical surfaces 60a, 61a of the shoes 60, 61 and the concave portions 51a, 51b at one end of the piston 7 may be coated with a coating.

In the above embodiment, the shoes 60,
The present invention is applied to a variable displacement type swash plate type compressor having a structure in which 61 is directly supported by one end of a piston 7. However, the present invention is applied to a structure in which a connecting rod is interposed between the shoes 60, 61 and the piston 7. The invention can also be applied.

[0067]

As described above, according to the variable displacement type swash plate type compressor of the first aspect of the present invention, the sliding characteristic is equal to or higher than that of the thermal sprayed coating, and the manufacturing cost is reduced by reducing the number of working steps. Can be achieved.

According to the variable displacement type swash plate type compressor of the second aspect of the present invention, the wear resistance of the swash plate is improved.

According to the variable displacement type swash plate type compressor of the third aspect of the present invention, the wear resistance is further improved.

According to the variable displacement type swash plate type compressor according to the fourth aspect of the present invention, seizure resistance is further improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a variable displacement swash plate type compressor according to one embodiment of the present invention.

FIG. 2 is a view showing a result of a seizure test of a compressor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 5 Shaft 6 Cylinder bore 7 Piston 8 Crank chamber 10 Swash plate 10a, 10b Sliding surface of swash plate 60, 61 Shoe 60b, 61b Flat surface (sliding surface)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshiyuki Ishida 39, Higashihara, Chiyo-ji, Odai-gun, Osato-gun, Saitama Prefecture Inside of Xexel Valeo Climate Control (72) Inventor Kentaro Sho 13 3-13 Yayumicho, Higashimatsuyama City, Saitama Prefecture No. 26 Bosch Automotive System Co., Ltd. (72) Inventor Nobuhiro Tomita 3-13-26 Yayumicho, Higashimatsuyama-shi, Saitama F-term in Bosch Automotive System Co., Ltd. 3H076 AA06 BB26 CC20

Claims (4)

[Claims] 1. A cylinder block having a plurality of cylinder bores, a swash plate rotated by a shaft in the cylinder block, a piston slidably received in the cylinder bore, and a gap between the piston and the swash plate. A variable capacity swash plate compressor in which the piston is reciprocated in the cylinder bore in response to the rotation of the swash plate. A variable displacement type swash plate type compressor characterized by comprising a system material. 2. The variable displacement swash plate compressor according to claim 1, wherein said iron-based material is cast iron. 3. The variable displacement type swash plate type compressor according to claim 1, wherein a heat hardening treatment is applied to a surface of the swash plate. 4. The variable displacement type swash plate type compressor according to claim 1, wherein a solid lubricant is coated on a surface of said swash plate.