JPH05551B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a variable displacement swash plate compressor equipped with a double-ended piston.

(Prior Art) In a double-headed piston type compressor disclosed in Japanese Patent Application Laid-Open No. 58-162782, a swash plate is supported so as to be rotatable integrally with the rotating shaft and swingable back and forth. The inclination angle of the air conditioner is controlled based on suction pressure information that reflects the cooling load. However, since the center of oscillation of the swash plate is set at a fixed position on the rotation axis, the top dead center of the compression stroke of the double-headed piston fluctuates depending on the inclination angle of the swash plate in both the front and rear compression chambers. Substantial compression and discharge cannot be performed in the compression action area on the small volume side where the inclination angle is close to zero.

The applicant of the present application has filed Japanese Patent Application No. 62-298630 for a compressor that improves this drawback. The center of oscillation of the swash plate in this compressor is set at the radial position of the rotating shaft that corresponds to the cylinder bore of the cylinder block that houses the double-headed piston. is defined at a fixed position, and substantial compression and discharge are performed even in the compression action area on the small capacity side where the swash plate inclination angle is close to zero.

(Problem to be Solved by the Invention) The swash plate inclination is determined by the pressure in both the front and rear cylinder bores through the sliding control body and the swash plate that change the volume of the control pressure chamber that is switchably connected to the discharge pressure region or the suction pressure region. It is controlled by the opposition between the plate rocking force and the pressure in the control pressure chamber, and the sliding control body is slidably supported on the rotating shaft. The force exerted by the swash plate, which swings due to this pressure opposition, on the rotating shaft is received by the cylinder block via the thrust bearing interposed between the rotating shaft and the cylinder block. If an excessive load is applied to the thrust bearing, early functional deterioration of the thrust bearing is inevitable.

The present invention aims to avoid a decrease in the reliability of the thrust bearing that receives the acting force of the swash plate on the rotating shaft of a variable capacity compressor whose fixed position is the top dead center of the compression stroke in one cylinder bore that accommodates the double-ended piston. The purpose is to

(Means for Solving the Problems) To achieve this, in the present invention, the swash plate rocking force generated by refrigerant gas compression and the pressure in the control pressure chamber are opposed to each other via the swash plate and the sliding control body, and this opposition causes the rocking A guide pin was attached to the swash plate side, and a guide hole having a guiding relationship with the guide pin was provided on the rotating shaft side, and the guide hole was set at a position crossing the axial center of the rotating shaft.

(Function) The acting force of the swash plate on the rotating shaft is transmitted to the thrust bearing through the engagement relationship between the guide pin on the swash plate side and the guide hole on the rotating shaft side, and the position of action on the thrust bearing is between the guide pin and the guide hole. defined in the engaged position. When this engagement position moves away from the axial center of the rotating shaft, the force acting on the swash plate acts as an unbalanced load on the thrust bearing, and the force acting on the swash plate is evenly received by the multiple thrust bearings around the rotating shaft. become unable to do so. Therefore, as the engagement position moves away from the center of the rotating shaft, the unbalanced load increases and the load on the thrust bearing becomes excessive.However, in a configuration in which the guide groove crosses the center of the rotating shaft, The distance between the engagement position and the engagement position can be reduced.
Therefore, the load on the thrust bearing can be suppressed as much as possible, and the reliability of the thrust bearing can be improved.

(Example) Hereinafter, an example embodying the present invention will be described based on the drawings.

A front housing 2 and a rear housing 3 are fixedly connected to both front and rear end surfaces of the cylinder block 1, and a rotating shaft 4 is supported as possible by the front housing 2 and the cylinder block 1 via a front shaft portion 4a. . Front shaft portion 4a
The rear shaft portion 4b is attached to the bearing receiving plate 3 on the inner end side of the rear shaft portion 4b.
1 and connecting bodies 5 and 6, guide holes 5a and 6a are formed in the connecting bodies 5 and 6, and between the bearing receiving plate 31 and the inner end surface of the cylinder block 1, A thrust bearing 32 is interposed therebetween.

A guide bush 7 is slidably fitted into the rear shaft portion 4b, and a pressure spring 8 is interposed between the tip of the rear shaft portion 4b and the inner end of the guide bush 7. Base end 7a of guide bush 7
is formed into a spherical shape, and a swash plate 9 is rotatably fitted into this spherical portion 7a. A bridge 9a is formed on the front surface of the swash plate 9, and a guide pin 9b is fitted in the middle of the bridge so as to protrude to both sides, and a rotor 9c is attached to both ends of the guide pin 9b. installed. Bridge 9
a is sandwiched between both connecting bodies 5 and 6, and
Both rotors 9c are connected to the guide holes 5a, 6 of the connecting bodies 5, 6.
a, thereby causing the swash plate 9 to rotate together with the rotating shaft 4 within the swash plate chamber 1a.

The rotating shaft 4, the swash plate 9, and the guide bush 7 are connected to each other through a guiding relationship between the guide pin 9b and the guide holes 5a, 6a, and a rotatable relationship between the swash plate 9 and the guide bush 7, which is slidable back and forth. , this causes the swash plate 9 to move toward the guide bush 7.
The swash plate 9 can be oscillated as the swash plate 9 slides, and the oscillation center C is set on the periphery side of the swash plate 9. Swash plate 9
A double-headed piston 10 is accommodated in a front cylinder bore 1b and a rear cylinder bore 1c which are formed correspondingly on the rotation locus of the shaft 1.
1 and 12, and the double-ended piston 1
0 reciprocates back and forth as the swash plate 9 rotates.

Cylinder block 1 and both front and rear housings 2, 3
A partitioning plate 13, 14 and a valve forming plate 15, 16 are interposed between the two housings, and suction chambers 17, 18 and discharge chambers 19, 20 are defined in both the front and rear housings 2, 3. The refrigerant gas in the suction pipe 21 constituting the external refrigerant gas circuit enters the swash plate chamber 1a from the inlet 22 as the double-headed piston 10 reciprocates, and passes through the front suction passage 1d, the rear suction passage 1e, and the front suction chamber. 17, rear side suction chamber 18, and suction ports 13a, 14a which are opened and closed by suction valves 15a, 16a, and are sucked into front side compression chamber Pf and rear side compression chamber Pr, where they are subjected to compression action. A discharge port 1 is opened and closed by discharge valves 29 and 30 from both compression chambers Pf and Pr.
The refrigerant gas discharged to both discharge chambers 19 and 20 via 3b and 14b flows out to the discharge passage 1f, and
It is discharged from the outlet 23 via the discharge passage 1f.

The swing center C of the swash plate 9 is set on the peripheral edge side of the swash plate 9, and is also set closer to the rear cylinder bore 1c, so that the front compression chamber
The compression stroke top dead center of the double-headed piston 10 at Pf varies depending on the inclination angle of the swash plate 9, but the compression stroke top dead center of the double-headed piston 10 in the rear side compression chamber Pr is at the fixed position shown in FIGS. stipulated. Therefore, in the front side compression chamber Pf, when the swash plate inclination angle is small, only compression and expansion are performed without substantial suction and discharge, but in the rear side compression chamber Pr, where the top dead center of the compression stroke is constant. Substantial compression with suction and discharge takes place regardless of the inclination angle of the swash plate 9.

A spool-shaped sliding control body 24 is fitted into the rear suction chamber 18 so as to be slidable in the longitudinal direction, and a part of the rear suction chamber 18 is divided into a control pressure chamber 18a by a flange portion 24a. At the same time, the cylindrical portion 18b is attached to the thrust bearing 25.
and is supported by the guide bush 7 via a radial bearing 26 so as to be relatively rotatable. As a result, the pressure in the control pressure chamber 18a is reduced by the sliding control body 24,
Via the guide bush 7 and the swash plate 9, the swash plate rocking force generated by the pressure in the front side compression chamber Pf and the pressure in the rear side compression chamber Pf and the spring force of the pressure spring 8 are opposed.

The control pressure chamber 18a is the rear side discharge chamber 2 in the discharge pressure region.
0, and is connected to the swash plate chamber 1a in the suction pressure region via the capacity control valve mechanism 27.
By opening and closing the valve body 28 based on the suction pressure in the suction pipe line 21, the control pressure chamber 18a is controlled to switch to a high pressure equivalent to the discharge pressure or a low pressure equivalent to the suction pressure, and the swash plate 9 is moved to the maximum inclination position shown in FIG. It is oscillated to the minimum inclination angle position shown in FIG.

This swinging motion is guided through the engagement between the guide holes 5a, 6a on the rotating shaft 4 side and the rotor 9c on the swash plate 9 side, and the guide holes 5a, 6a bring about this guiding action.
is oblique to the axial center l of the rotating shaft 4. Furthermore, a guide hole 5 that engages when the tilt angle of the swash plate 9 increases.
The engagement part K between a, 6a and the rotor 9c is the axis center l.
The positions of the guide holes 5a, 6a are set so as to cross the swash plate 9 from the inclined position shown in FIG.
When swinging to the tilted position shown in the figure, the engagement portion K crosses the axis center l.

Force F acting on the rotating shaft 4 side via the engagement part K
is expressed as the following equation (1).

F=ΣFk+Fg...(1) Fg=[{ΣFk(Xy-r・cos α/cosβ) /cos β}+M ₁ −M ₂ ]/Xy However, Fk (k=1 to 5) is each double-ended piston 10
gas pressure, Xy is the instantaneous center X of the engagement part K
The distance from to the shaft center l, r is the distance from the swing center C to the shaft center l, α is the angle formed by the line connecting the engagement part K and the instantaneous center X of the guide pin 9b and the shaft center l, β represents the inclination angle of the swash plate 9, M ₁ represents the unbalance moment due to the inertia of the swash plate 9, and M ₂ represents the unbalance moment due to the inertia of the double-headed piston 10.

The force F expressed by equation (1) is applied to the engagement portion K, the connecting body 5,
6 and the thrust bearing 32 via the bearing receiving plate 31. Engagement part K is axis center l
When the force F moves away from the thrust bearing 32, the force F acts as an unbalanced load on the thrust bearing 32, and the way the force F is received by the plurality of thrust bearings 32 becomes uneven. Therefore, if the distance of the engagement portion K from the axis center l is large, the load on the thrust bearing 32 becomes excessive, and early deterioration of the function of the thrust bearing 32 is unavoidable.

As a standard for expressing the unbalanced load on the thrust bearing 32, a load F' expressed by the following equation (2) is usually used.

F'=F(1+ρr ₁ /r ₂ )...(2) However, ρ is a constant, and r ₁ is the axis center l from the engagement part K.
The distance r ₂ represents the distance from the inside of the thrust bearing 32 to the shaft center l. Note that the value of the constant ρ is determined empirically. Load expressed by equation (2)
F' is considered to be the actual load on the thrust bearing 32 when the force F acts on the engagement part K, and is different from the case where the force F acts on the engagement part K located at a distance r ₁ from the shaft center l. , is equivalent to the case where the force F' acts on the engagement portion K on the axis center l. Therefore, the larger the distance r ₁ is, the more the thrust bearing 32
However, in this embodiment in which the guide holes 5a and 6a are positioned so as to cross the axis center l, the distance _r1 is small on average, and the load on the thrust bearing 32 does not become excessive. As a result, early functional deterioration of the thrust bearing 32 is avoided, and the reliability of the thrust bearing 32 is high.

According to equation (1), the force F acting on the rotating shaft 4 side via the engagement portion K increases as the swash plate inclination angle β increases. Therefore, as shown in FIG. 1, by bringing the engagement portion K where the inclination angle β is maximum as close as possible to the shaft center l, the maximum unbalanced load can be made as small as possible, and the thrust bearing 32 The load is minimized and the reliability of the thrust bearing 32 is further increased.

(Effects of the Invention) As detailed above, in the present invention, the guide hole is set at a position that crosses the axis center of the rotating shaft, so that it is possible to reduce the unbalanced load on the thrust bearing that receives the load in the thrust direction of the rotating shaft. I can,
This has the excellent effect of increasing the reliability of this thrust bearing.

[Brief explanation of the drawing]

The drawings show an embodiment embodying the present invention; FIG. 1 is a side sectional view of a compressor and a capacity control valve mechanism, FIG. 2 is a sectional view taken along line A-A in FIG. FIG. 3 is a side sectional view showing a minimum plate inclination state. Cylinder block...1, Rotating shaft...4, Guide hole...5a, 6a, Swash plate...9, Guide pin...
...9b, rotor...9c, control pressure chamber...18a,
Sliding control body...24, thrust bearing...3
2. Axis center...l.

Claims (1)

[Claims] 1. A rotary shaft is rotatably housed and supported in a cylinder block that reciprocably accommodates a double-headed piston, and a swash plate for reciprocating the double-headed piston is fixed to the rotary shaft and is movable back and forth around its periphery. The pivot center position is set near the rear cylinder bore, and the reciprocating region of the double-headed piston is set above the rotation region of the pivot center due to rotation of the rotating shaft. In a swash plate compressor in which the top dead center of the compression stroke in the cylinder bore is a fixed position, a sliding control body that changes the volume of a control pressure chamber for capacity control that is switched to a pressure equivalent to discharge pressure or suction pressure is attached to the rotating shaft. The swash plate is slidably supported, and the swash plate rocking force generated by refrigerant gas compression and the pressure in the control pressure chamber are opposed to each other via the swash plate and the sliding control body, and a guide is provided on the swash plate side that is swung by this opposition. A variable capacity swash plate compressor, in which a pin is attached, a guide hole is provided on the rotating shaft side in a guiding relationship with the guide pin, and the guide hole is set at a position crossing the center of the rotating shaft.