JPH0237177A - Variable displacement swash plate type compressor - Google Patents

Abstract

PURPOSE:To make improvements in displacement variable controllability at the whole area of a compression ratio by specifying a guide curve of a guide hole in making a displacement position of a guide pin in the axial direction of a turning shaft of its variable, while installing a compensating spring for energizing it in the swash plate angle decrement direction. CONSTITUTION:As a guide curve S of a guide hole 5a making a displacement position of a guide pin 9b on the axial direction of a turning shaft of its variable, it is monotonically increased to displacement of the guide pin in the swash plate angle increment direction, and it has an inflection point changing from negative to positive in the midway, while such a curve as reducing control pressure linearly to a circular arc in a negative monotonic area and the displacement of the guide pin in the swash plate angle increment direction at a specified compression ratio is made so as to have it in the monotonic increment area. In addition, there is provided with a compensating spring 30 for energizing a sliding control body in the swash plate inclination decrement direction and pulling up the control pressure and compensating it.

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 a 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-ended 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 filed a patent application in 1983 for a compressor that improved this drawback.
It has been filed under No. 298630. The center of swing 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, so that the top dead center of the compression stroke in the cylinder bore on one side of 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.

The swash plate inclination is determined by the swash plate rocking force due to the pressure in the front and rear cylinder bores and the pressure in the control pressure chamber via the sliding control body that changes the volume of the control chamber connected to the discharge pressure area or the suction pressure area and the swash plate. It is controlled by the opposition of
The sliding control body is slidably supported on the rotating shaft. The force exerted on the rotating shaft by the swash plate, which oscillates due to this pressure opposition, is received by the linear guide hole on the rotating shaft side via the guide pin on the swash plate side, and the guide relationship between the guide pin and the guide hole is The swash plate inclination angle is controlled by.

[Problems to be Solved by the Invention] The linear guide hole disclosed in Japanese Patent Application No. 62-298630 cannot monotonically increase the control pressure on the maximum capacity side, and a correction spring is used in this region. Therefore, it is necessary to correct the control pressure in the upward direction. Moreover,
At a specific compression ratio expressed as the ratio of discharge pressure to suction pressure, the control pressure on the minimum capacity side is lower than the suction pressure, and the control performed using the refrigerant gas pressure, which cannot be lower than the suction pressure, is on the minimum capacity side. Since this becomes impossible, it is also necessary to raise the control pressure on the minimum capacity side. If a correction spring is used to correct the increase in the control pressure on the minimum capacity side, the amount of increase in the control pressure on the maximum capacity side will increase, and there is a risk that the control pressure on the maximum capacity side will exceed the discharge pressure.

If the control pressure exceeds the discharge pressure, the control performed using the refrigerant gas pressure, which cannot exceed the discharge pressure, becomes uncontrollable on the maximum discharge side.

An object of the present invention is to improve the capacity variable controllability of a variable capacity compressor in which the compression stroke top dead center of one cylinder bore housing a double-ended piston is set at a fixed position.

[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 is attached to the swash plate side, and a guide hole is provided on the rotating shaft side to have a guiding relationship with the guide pin, and the guide hole is provided with a displacement position of the guide pin in the axial direction of the rotating shaft as a variable. The guide curve monotonically increases with respect to the displacement of the guide pin in the direction of increasing swash plate inclination angle, has an inflection point that changes from negative to positive along the way, and has a circular arc in the negative monotonically increasing region.
At a specific compression ratio, a curve that linearly decreases the control pressure with respect to the displacement of the guide pin in the direction of increasing the swash plate inclination is a curve that has a positive monotonically increasing region, and a curve that decreases the control pressure linearly in the direction of decreasing the swash plate inclination. A correction spring is provided to bias the control pressure and correct it.

[Operation] The acting force of the swash plate on the rotating shaft is stopped by the engagement relationship between the guide pin on the swash plate side and the guide hole on the rotating shaft side.
The swash plate inclination angle is controlled by the guide relationship between the guide hole and the guide pin. In the case of a low compression ratio, the control pressure decreases linearly on the maximum capacity side in response to the displacement of the guide pin in the direction of increasing the swash plate inclination angle, but this decrease is compensated for in the direction of increasing movement by pulling up the compensation spring. Ru. In the case of a high compression ratio, the control pressure increases linearly on the maximum displacement side with respect to the displacement of the guide pin in the direction of increasing the swash plate elevation angle, and does not exceed the discharge pressure. On the other hand, on the minimum capacity side, the control pressure increases monotonically at all compression ratios in response to the displacement of the guide pin in the direction of increasing the swash plate inclination due to the guiding action of the circular guide hole, and can be set higher than the suction pressure. be. Therefore, smooth capacity variable control is possible regardless of the compression ratio.

[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 rotation shaft 4 is attached to the front housing 2 and the cylinder block 1.
is rotatably supported via the front shaft portion 4a. The rear shaft portion 4b is attached to the inner end of the front shaft portion 4a, and the flange holder is connected and fixed via the plate 8 skinned connecting bodies 5, 6, and the connecting bodies 5, 6 are provided with guide holes 5a, 6a is formed, and a thrust bearing 27 is interposed between the plate 8 and the inner end surface of the cylinder block 1.

A guide bushing 7 is slidably fitted into the rear shaft portion 4b, and shaft pins 7a (only one shown) are provided protruding from the left and right sides of the base end of the guide bushing 7. A swash plate 9 is rotatably supported on 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 9 is attached to both ends of the guide pin 9b.
C is installed. The bridge 9a has both connecting bodies 5゜6
Both rotors 9C are sandwiched between the connecting body 5.
The swash plate 9 is fitted into the guide holes 5a, 6a of the swash plate 6, and thereby the swash plate 9 rotates together with the rotating shaft 4 within the swash plate chamber la.

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, and a rotatable relationship between the swash plate 9 and the guide bush 7, which is slidable back and forth. As a result, the swash plate 9
is swingable as the guide bushing 7 slides, and the swinging center C is set on the peripheral edge side of the swash plate 9.

A double-headed piston 10 is accommodated in a front cylinder bore 1b and a rear cylinder bore IC that are formed correspondingly on the rotational trajectory of the swash plate 9. These double-headed pistons 10 and the swash plate 9 are connected to a shoe 11. The double-headed piston 10 reciprocates back and forth as the swash plate 9 rotates.

Between the cylinder block 1 and both the front and rear housings 2 and 3 there is a partition play) 13.14 and a valvuloplasty play) 15.1
A suction chamber 17.18 and a discharge chamber 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 boats 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. Then, from both the compression chambers Pf and Pr, the discharge chamber 19.
The refrigerant gas discharged to 20 flows out to the discharge passage lf and is discharged from the outlet 23 via the discharge passage 1rfc.

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 pore IC, so that the top dead center of the compression stroke of the double-ended piston 10 in the front compression chamber Pf varies depending on the inclination angle of the swash plate 9, but the compression stroke top dead center of the double-headed piston 0 in the rear side compression chamber Pr is defined at the fixed position shown in FIG. 1.4.

Therefore, in the front side compression chamber Pf, when the swash plate inclination is small, compression and expansion without substantial suction and discharge are performed, 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.

Inside the rear suction chamber 18 is a spool-shaped sliding control body 24.
is fitted so as to be slidable in the front-rear direction, and a part of the rear (!
b is the thrust bearing 25 and the radial flange 2
It is supported by a guide bush 7 via a guide bush 7 so as to be relatively rotatable. As a result, the pressure in the control pressure chamber 18a is transmitted through the sliding control body 24, the guide bush 7, and the swash plate 9 to the swash plate rocking force generated by the pressure in the front compression chamber Pr and the pressure in the rear compression chamber Pr. to counter.

The control pressure chamber 18a, the rear discharge chamber 20 in the discharge pressure region, the swash plate chamber la in the suction pressure region, and the suction pipe line 21 are connected to a capacity control valve mechanism (not shown), and the longitudinal displacement of the sliding control body 24 is controlled by the control pressure chamber 18a. It is controlled by fluctuations in the suction pressure within the suction pipe 21. That is, the control pressure chamber 18 is opened and closed by opening and closing the valve body in the capacity control valve mechanism based on the suction pressure in the suction pipe 21.
a is controlled to be switched to a high pressure equivalent to the discharge pressure or a low pressure equivalent to the suction pressure, and the swash plate 9 is swingably arranged between the maximum inclination position shown in FIG. 1 and the minimum inclination position shown in FIG.

A correction spring 30 is interposed between the inner surface of the tip of the guide bush 7 and the tip of the rotary shaft 4, and the slide control body 24 moves in the direction of increasing the swash plate inclination angle to the correction spring 30 as shown in FIG. A spring characteristic is set such that the correction spring 30 comes into contact with the inner end surface of the bushing 7 when the correction spring 30 is disposed at the solid line position.

Swinging of the swash plate 9 is guided through 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 that provide this guiding action are connected to the rotating shaft 4. axis l
It is oblique to . As shown in FIG. 4, the displacement curve of the guide pin 9b, that is, the guide curve S of the guide holes 5a and 6a, has an inflection point SQ at the displacement position XQ with the displacement position X of the guide pin 9b as a variable, and O≦X< X(1 is a negative monotonically increasing section where the slope α of the tangent to the guide curve S decreases as the variable X increases, and X(1<X≦x1 is a positive monotonically increasing section where the slope α increases as the variable X increases. It becomes.And,
A circular arc Sc centered at point Q is used as a guide curve for the monotonically increasing section O≦X<Xo, and its angular range is θ
It becomes.

The displacement position x1 of the guide pin 9b corresponds to the position of the shaft pin 7a shown by the solid line in FIG. 4, that is, when the swash plate inclination angle β is maximum, and the discharge capacity is maximum. Displacement position X of guide pin 9b
=O corresponds to the position of the shaft pin 7a shown by the chain line on the right side, that is, the case where the swash plate inclination angle β is the minimum, and the discharge capacity is the minimum.

The horizontal axis 2 of the graph shown in FIG. 7 represents the displacement position of the sliding control body 24, and the vertical axis P represents the control pressure in the control pressure chamber 18a.
The horizontal axis V of the graph shown in FIG. 6 represents the discharge capacity, and Vma
x represents the maximum discharge volume, and Vmin represents the minimum discharge volume. The curve D1 shown by the chain line in FIG. 6 is a positive monotonically increasing section X (1<
Guide curve S at X≦x1 (hereinafter referred to as section X Q ”
< The guide curve S at X≦x1 is expressed as S').
The minimum control pressure P1min corresponding to in is equal to or higher than the suction pressure Ps, and the maximum control pressure P1ma corresponding to the maximum discharge volume Vmax
x is set to be less than or equal to the discharge pressure Pdl.

The control pressure P is expressed by the following equation (1).

However, Fj is each compression chamber Pf.

Gas pressure, M is each compression chamber Pf, P Moment caused by the pressure Fj The distance shown, B is each compression chamber Pf.

Represents area.

The discharge capacity ■ is 1:1 with the displacement 2 of the sliding control body 24 P = CM-sin a/L-ΣFj)/B+
Ps ・ ・ ・ (1) The refrigerant gap and L in the refrigerant r in Pr correspond to the pressure received in Pr in FIG. 4, and are expressed by the following equation (2).

v=B ・ 2z+■min ・ ・ ・
(2) That is, the control pressure P, which is a function of the discharge volume V, corresponds to the displacement 2 of the sliding control body 24 in a ratio of 1:1, and if the control pressure P is differentiated by the displacement 2, it is expressed by the following equation (3). Ru.

dP/dz=dP/dV ・dV/dz=dP/dV
・ 2B ・ ・ ・ (3) The differential d P/d V in equation (3) represents the slope of the tangent to the basic curve D1 in Figure 6, and the discharge volume ■ is the slope from the minimum discharge volume V win to around ■ 1 ρ is negative, the slope σ from the vicinity of vl of the discharge capacity ■ to the maximum discharge capacity Vmax is positive, and the slope σ is set to be a constant. That is, to express formula (3) more accurately, the following formula (3-a),
(3-b).

dP/dz=ρ ・2B<OVl>V≧Vmin
・ ・ ・ (3-a) dP/dz=-y l 2B>OVmax>V≧v
1. . . (3-b) Also, the guide curve S (x) and displacement 2 are the following formula (4)% formula % However, t and o are the distances between the guide pin 9b and the shaft pin 7a (
(constant), and Ll is the distance between the shaft pin 7a and the guide pin 9b on the rotation axis β when the displacement 2 of the sliding control body 24 is 0.

Differentiating equation (4) with respect to displacement X yields the following equation (5).

2(x+L1-z)(1-dz/dx)+23-dS
/dx=2(x+L1-z)(1-dz/dx)+2
3cr-〇・
・ ・ (5) Furthermore, the distance shown in FIG. 4 is specified by the straight lines 11 and 122 determined by the guide curve 5(x), and the distance fiL specified by the guide curve S, which is a function of the displacement 2 and the slope α, is It is a function of displacement 2 and slope α. Note that the straight line /l is the guide pin 9 from the guide holes 5a and 6a.
It represents the direction line of the reaction force against b, and this reaction force is in the direction of arrow p in FIG. Therefore, the guide curve S is calculated using equation (1) expressing the control pressure P, equations (3-a) and equation (3-b) expressing the slope of the control pressure P differentiated by the displacement 2, and the equation (3-a) and equation (3-b) expressing the slope of the control pressure P differentiated by the displacement 2. It is determined from equation (4) expressing the relationship and equation (5) expressing the relationship between displacement 2, displacement is set as a monotonically increasing curve with .

In a positive monotonically increasing section XO<X≦XI where the slope α of the tangent to the guide curve S increases as the variable In the negative monotonically increasing section O≦X<XO that decreases as the curve increases, the circular arc Sc is used as the guide curve. Due to the guiding action of the arc Sc, the slope σ is positive, that is, the control pressure increases monotonically with respect to the displacement of the guide pin 9b in the direction of increasing the swash plate inclination angle.

Curve D2. shown by a chain line in FIG. D3. D4. D5゜D6
is each discharge pressure Pd2. when the action of the correction spring 30 is excluded.
Pd3. Pd4. Pd5. The control pressure curves corresponding to pcta are shown, and each control pressure curve D2. D3゜D4. D5. D6
is greater than or equal to the suction pressure Ps and each discharge pressure Pd2. Pd3. Pd4
．． Pd5. pa6 or less, but the control pressure curves DI, D2
．． At D3, the maximum capacity side monotonically decreases or becomes a substantially constant value with respect to the displacement of the guide pin 9b in the increasing direction of the swash plate inclination, and an uncontrollable region occurs on the maximum capacity side. The straight line EO represents the spring characteristics of the correction spring 30. The spring action of the correction spring 30 that provides this spring characteristic EO is expressed by each curve D2°D3. D4.
D5. D6 and basic curve D! , each curve D2
．． D3. D4. D5. D6 and the basic straight line D1 are corrected as shown by solid lines.

The guide song gs' set based on the basic curve D1 is the seventh
As shown in the figure, each discharge pressure pa1. Pd2゜Pd3. Pd
4. Control pressure curve C1 shown by a chain line for Pds and Pda
, C2, C3, C4, C5°C6. The control pressure curves C1 and C2C5 shown by chain lines are curves that monotonically decrease or are substantially constant on the maximum capacity side, and have an uncontrollable region on the maximum capacity side.

However, due to the spring characteristic EO of the correction spring 30, each control pressure curve Cm, c2. c3. c4. , cS.

C6 is corrected as shown by the solid line on the maximum capacity side, and the corrected control pressure curves Cm, C2, C3 are monotonically increasing curves and the discharge pressures Pd, , Pd2 . Pd3 or less. Therefore, at any compression ratio, the displacement position 2 of the sliding control body 24 =
Smooth tilting motion of the swash plate 9 can be obtained in the entire range from 0 to the maximum displacement position z max, and smooth capacity variable controllability can be achieved.

The present invention is, of course, not limited to the above-mentioned embodiments. For example, in order to obtain a control pressure curve that monotonically increases as the displacement 2 of the sliding control body 24 increases, an arcuate curve close to the straight part of the basic curve Dl is required. , it is also possible to adopt a smooth curve such as an elliptic arc curve, and a guide curve substantially similar to that of the above embodiment can be obtained.

Furthermore, the embodiment shown in FIG. 8 is also possible as a construction in which the correction spring is incorporated. In this embodiment, a pair of correction springs 31 and 32 are interposed in series between the rotating shaft 4 and the inner end surface of the guide bush 7, and a support bolt 3 is provided at the tip of the rotating shaft 4.
3 is screwed on.

A spring holder 34 is supported by the support bolt 33, and a correction spring 31 is interposed between the rotating shaft 4 and the spring holder 34. The correction spring 31 has a preload G
is applied, and the spring holder 34 moves to the left only when a load greater than the preload G is applied to the spring holder 34 from the head 33a side. The correction spring 32 is set to have spring characteristics such that the guide bush 7 comes into contact with the spring holder 34 when the guide bush 7 comes to the position indicated by the chain line in FIG.

The spring characteristics of the combination of both correction springs 31 and 32 are shown in FIG. 9, where the straight line vAEt represents the action of only the correction spring 32, and the straight line E2 represents the superimposed action of the correction springs 31 and 32 in series. . To be more precise, the spring constant of the correction spring 31 is kl, and the spring constant of the correction spring 32 is 2.
Then, the acting force represented by each straight line El, E2 is 1. 2 is the following formula % Formula % Also, the preload G is expressed by the following formula (8).

G=kl (z2 zl) ・ ・
(8) By using such a spring characteristic due to the combination of the correction springs 31 and 32, it becomes easy to appropriately correct the control pressure in a wide range from the maximum capacity to the minimum capacity side,
Further improvement in capacity variable controllability becomes possible.

[Effects of the Invention] As described in detail above, the present invention provides a guide curve for the guide hole in which the displacement position of the guide pin in the axial direction of the rotating shaft is used as a variable, so that the displacement of the guide pin in the direction of increasing the swash plate inclination angle is It increases monotonically with respect to the swash plate, and has an inflection point that changes from negative to positive in the middle, and has a circular arc in the negative monotonically increasing region, and at a certain compression ratio, it is linear with respect to the displacement of the guide pin in the direction of increasing swash plate inclination. Since the curve that decreases the control pressure in a positive monotonically increasing region is used, and a correction spring is provided to bias the sliding control body in the direction of decreasing the swash plate inclination, the swash plate inclination will be constant regardless of the compression ratio. The control pressure monotonically increases as the pressure increases, which has the excellent effect of improving capacity variable control over the entire compression ratio range.

[Brief explanation of the drawing]

1 to 7 show an embodiment embodying the present invention.
The figure is a side cross-sectional view of the compressor, Figure 2 is a cross-sectional view taken along the line A-A in Figure 1, Figure 3 is a side view of a main part broken away, Figure 4 is a graph for explaining the guide curve, and Figure 5 is a graph for explaining the guide curve. 6 is a graph showing the relationship between discharge capacity and control pressure. FIG. 7 is a graph showing the relationship between displacement of the sliding control body and control pressure. The figure is a cutaway side view of the main parts separately showing the present invention, and FIG. 9 is a graph showing the spring characteristics of the combined correction spring. Guide holes 5a, 6a, swash plate 9, guide pin 9b, rotor 9C1 control pressure chamber 18a, sliding control body 24, correction spring 30
, 31, 32, basic curve Di, spring characteristic EO1 control pressure curve CI, C2, C3, C4 ° cs, c6, guide curve s
, s', arc Sc, inflection point sg.

Claims (1)

[Claims] 1. A rotary shaft is rotatably housed and supported in a cylinder block that reciprocably accommodates the double-headed piston, and a swash plate that drives the double-headed piston to reciprocate is attached to the rotary shaft so that the swash plate is not relatively rotatable and moves back and forth around its periphery. The pivoting center position is set close to the rear cylinder bore, and the reciprocating region of the double-headed piston is set above the rotational region of the pivoting center caused by the rotation of the rotating shaft. In a swash plate compressor with the compression stroke top dead center at 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 slid on the rotating shaft. The swash plate is movably 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 pin is provided on the swash plate side that is swung by this opposition. At the same time, a guide hole having a guiding relationship with the guide pin is provided on the rotating shaft side, and a guide curve of the guide hole with the displacement position of the guide pin in the axial direction of the rotating shaft as a variable is set in the direction of increasing swash plate inclination. It increases monotonically with respect to the displacement of the guide pin, and has an inflection point that changes from negative to positive along the way, and has a circular arc in the negative monotonically increasing region, and at a certain compression ratio, the guide in the direction of increasing swash plate inclination. The variable capacity has a curve in which the control pressure linearly decreases with respect to the displacement of the pin in a positive monotonically increasing region, and is further provided with a correction spring to bias the sliding control body in the direction of decreasing the swash plate inclination. Type swash plate compressor.