JP2009127470A - Variable displacement swash plate type compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively provide a variable displacement swash plate type compressor for preventing a piston top position from being changed according to an inclination change in a wash plate by simple structural improvement. <P>SOLUTION: This compressor has a driving shaft, a rotor integrally rotated integrally with the driving shaft, a swash plate connected to the rotor via a hinge mechanism, integrally rotated with the driving shaft, having a sliding contact point slidingly contacting in the axial direction on an outside surface of the driving shaft with a central boss and displaced so as to change an inclination to the driving shaft while coming into sliding contact by the sliding contact point, a shoe slidingly contacting with both side surfaces of the outer periphery of the swash plate, and a piston for converting the rotary motion of the swash plate into reciprocating motion via a shoe. The variable displacement swash plate type compressor is characterized by forming the outside surface of the driving shaft in a sliding contact area of the sliding contact point as a freely bending surface extending in the axial direction so that the piston top position becomes a constant position when the inclination of the swash plate is changed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a variable displacement swash plate compressor, and more particularly to a variable displacement swash plate compressor capable of suppressing fluctuations in piston top position even when the inclination angle of the swash plate changes.

  Conventionally, for example, as shown in FIG. 4, a drive shaft 101 that is rotationally driven, a rotor 102 that is rotated integrally with the drive shaft 101, and a rotor mechanism 102 that is connected to the rotor 102 via a hinge mechanism 103 to be integrated with the drive shaft 101. The center boss 104 has a sliding contact 105 (hereinafter also referred to as a K point) that is slidably contacted on the outer surface of the drive shaft 101 in the axial direction XX. The swash plate 106 is displaced so as to change the inclination angle θ with respect to the drive shaft 101, a pair of shoes 107 slidably in contact with both outer peripheral side surfaces of the swash plate 106, and the shoes 107 There is known a variable displacement swash plate compressor 109 having a piston 108 through which the rotational movement of the swash plate 106 is converted into a reciprocating motion in the axial direction XX. The K point 105 moves linearly in the axial direction XX on the outer surface of the drive shaft 101, and the reciprocating stroke of the piston 108 is adjusted by changing the inclination angle θ of the swash plate 106. As a result, the discharge capacity of the compressor 109 can be varied.

  In the conventional structure as described above, the K point 105 of the swash plate boss 104 has a fixed position on the outer surface of the drive shaft 101 on the outer surface of the drive shaft 101 as shown in FIG. Although it is linearly moved in the axial direction XX while sliding, the piston top position (the top dead center of the piston 108 in the reciprocating motion of the piston 108) is accompanied by the change in the inclination angle θ of the swash plate 106. For example, the point position changes as shown in FIG. That is, when the piston top position when the inclination angle θ of the swash plate 106 is either the maximum (Max) or the minimum (Min) is used as a reference, δ is between the maximum position at the Max angle and the top position at the Min angle. A position change occurs. When the piston top position changes in this way, a dead volume corresponding to at least δ is generated, which limits the improvement of the volume efficiency of the compressor 109.

Paying attention to such problems, Patent Document 1 proposes a structure in which the cam surface in the hinge mechanism is processed to have a special profile, thereby suppressing the change in the piston top position.
JP 2003-254231 A

  However, in the proposal by the above-mentioned patent document 1, the hinge mechanism having a complicated structure is originally processed (that is, a part that is difficult to process) is processed, and the processing cost is increased and high-precision processing is performed. Since it is difficult, the problem that the effect of suppressing the change in the target piston top position cannot be obtained efficiently remains.

  Therefore, the object of the present invention is to reduce the dead volume caused by the change in the piston top position by reducing the piston top position in accordance with the change in the inclination angle of the swash plate at a low cost and with high accuracy by a simple structure improvement. An object of the present invention is to provide a variable capacity swash plate compressor that can improve the volumetric efficiency of the compressor.

  In order to solve the above-described problems, a variable displacement swash plate compressor according to the present invention includes a drive shaft, a rotor that is rotated integrally with the drive shaft, and the drive shaft coupled to the rotor via a hinge mechanism. And a slidable contact (point K) slidably contacting the outer surface of the drive shaft in the axial direction at the central boss, and the tilt angle with respect to the drive shaft changes while performing slidable contact with the slidable contact And a pair of shoes slidably in contact with both sides of the outer periphery of the swash plate and rotatably supported by the swash plate, and the rotational movement of the swash plate is converted into a reciprocating motion via the shoe. In a variable displacement swash plate compressor having a piston, the piston top position when the inclination angle of the swash plate changes is fixed on the outer surface of the drive shaft in the sliding contact area of the sliding contact. A free curved surface extending in the axial direction Consisting of.

  In such a variable capacity swash plate compressor according to the present invention, the outer surface of the drive shaft that is easy to process is not the hinge mechanism that is difficult to process as in Patent Document 1, but more accurately the outer surface of the drive shaft. The sliding contact area of the sliding contact is processed into a free-form surface extending in the axial direction so that the piston top position is a constant position. Since it is easy to machine, the desired free-form surface can be machined with high accuracy, and the locus of the sliding contact sliding along the free-form surface is accurately controlled to the desired desired locus. Therefore, even if the inclination angle of the swash plate changes, the piston top position does not change. By setting the piston top position to a fixed position, it is not necessary to anticipate the dead volume due to the change in the piston top position, or it can be minimized, and the volumetric efficiency of the compressor is improved.

  For example, the free-form surface calculates the position of the sliding contact when the inclination angle of the swash plate is changed under the condition that the piston top position is a fixed position, and calculates each calculated By connecting the positions of the sliding contacts, it can be specified as a curved surface according to the model. The step amount for the calculation can be arbitrarily set, and the smaller the step amount, the smoother the line (line on the cross section) or the surface connecting the calculated positions of the sliding contacts. The calculation formula can be geometrically set according to the model, and if a numerical value to be substituted is set in small increments, it is possible to easily obtain a desired free-form surface using general-purpose spreadsheet software.

  The free-form surface can be formed as a surface that extends in a curved line in the axial direction and linearly extends in a direction orthogonal to the axial direction, that is, a flat surface that changes in a curved line in the axial direction. If such a surface is set, a desired free-form surface can be easily machined with an ordinary machine capable of program control or numerical control.

  If the center of rotation of the pair of shoes is located on the neutral plane of the swash plate, the locus of the sliding contact with the change in the inclination angle of the swash plate can be easily calculated. By setting a free-form surface on the drive shaft so that the piston top position is a constant position, the piston top position will not change even if the inclination angle of the swash plate changes. Structure can be achieved.

  As the hinge mechanism, a mechanism including a pin and a link rotated around the pin can be employed. However, it is also possible to employ a mechanism in which the link is rotated around the pin while the pin slides through a long hole formed in the link.

  According to the variable displacement swash plate compressor according to the present invention, the piston top position when the inclination angle of the swash plate changes can be ensured by processing the outer surface of the drive shaft into a free-form surface that can be implemented easily and inexpensively. The piston top position can be minimized or the amount of change in the piston top position can be minimized, thereby minimizing the dead volume at the piston top position in the entire swash plate inclination angle region and improving the volume efficiency of the compressor. it can.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
1 to 3 show a variable displacement swash plate compressor according to an embodiment of the present invention. As shown in FIG. 1, the variable capacity swash plate compressor 1 includes a drive shaft 2 that is rotated by a drive force from a drive source (not shown), and is fixed to the drive shaft 2 and rotates integrally with the drive shaft 2. The rotor 3 is connected to the rotor 3 via a hinge mechanism 6 having a pin 4 and a link 5 rotated around the pin 4, and is arranged so as to be rotated integrally with the drive shaft 2. The swash plate 7 is provided, and the swash plate 7 is connected to the hinge mechanism 6 through the cam portion 8. As shown in FIG. 2, the swash plate 7 has a slidable contact 10 (point K) that slidably contacts the outer surface of the drive shaft 2 in the axial direction XX on the boss portion 9 at the center. The swash plate 7 is displaced so that the inclination angle θ with respect to the drive shaft 2 changes while performing sliding contact with the sliding contact 10. A pair of shoes 12 rotatably held at the rear end of the piston 11 are slidably contacted on both outer peripheral side surfaces of the swash plate 7, and the rotational movement of the swash plate 7 is caused by the sliding contact of the shoes 12. 11 is converted into a reciprocating motion in the axial direction XX, and the stroke of the reciprocating motion of the piston 11 is adjusted in accordance with the inclination angle θ of the swash plate 7. The discharge capacity of the variable displacement swash plate compressor 1 is varied according to the stroke of the piston 11.

  The sliding contact area of the sliding contact 10 (point K) is a specific range in the axial direction X-X at a specific position in the circumferential direction of the outer surface of the drive shaft 2 (position on the lower surface side of the drive shaft 2 in the figure). The specific range corresponding to the range of the maximum value to the minimum value of the inclination angle θ of the swash plate 7). The outer surface of the drive shaft 2 in the sliding contact area of the sliding contact 10 is such that the piston top position 13 becomes a constant position when the inclination angle θ of the swash plate 7 changes (or the change amount of the piston top position 13 is changed). It is formed on a free curved surface 14 extending in the axial direction XX so as to be minimized. For example, as shown in FIG. 3, the free-form surface 14 extends in a curved line in the axial direction XX, and extends linearly in a direction perpendicular to the axial direction XX (direction perpendicular to the paper surface in FIG. 3). The surface, that is, a flat surface is formed as a surface that changes in a curved shape in the axial direction. Such a free-form surface 14 prevents the piston top position 13 from changing even when the inclination angle θ of the swash plate 7 changes (that is, the piston top position change curve as shown in FIG. In order to achieve a linear characteristic that does not occur), it is formed on the outer surface of the drive shaft 2 over at least a range 15 (axial range) corresponding to the maximum inclination angle θmax and the minimum inclination angle θmin of the swash plate 7.

  The free curved surface 14 to be formed on the outer surface of the drive shaft 2 as described above can be set by calculation as follows, for example, along the curve (curved surface) obtained by the calculation, for example, program control or numerical control. It is reliably processed into a predetermined shape by a possible processing machine. That is, the free curved surface 14 is the position of the sliding contact 10 when the inclination angle θ of the swash plate 7 is changed under the condition that the piston top position 13 is a fixed position. Specified as a continuous curved surface according to the model (size of each part for each model) by calculating geometrically in small increments for each preset increment and connecting the calculated positions of each sliding contact 10 can do. The smaller the step for calculation, the smoother the resulting surface. The calculation can be performed using general-purpose spreadsheet software.

  The free curved surface 14 as described above is formed on the outer surface of the drive shaft 2, and the sliding contact 10 is moved along the free curved surface 14 in the axial direction XX when the inclination angle θ of the swash plate 7 changes. By sliding and moving, the piston top position 13 is maintained at a constant position even if the swash plate inclination angle θ changes. Since the piston top position 13 does not change, it is not necessary to anticipate the dead volume (FIG. 4) at the piston top position, and the occurrence of this dead volume can be minimized. As a result, the volumetric efficiency of the compressor 1 can be greatly improved. Further, since the free-form surface 14 can be easily and accurately processed using a normal processing machine, a desired effect can be easily obtained at low cost.

  The structure of the variable displacement swash plate compressor according to the present invention is applicable to any type of variable displacement swash plate compressor having a swash plate boss portion having a sliding contact with the drive shaft side.

It is a schematic longitudinal cross-sectional view which shows the principal part of the capacity | capacitance variable swash plate type compressor which concerns on one embodiment of this invention. It is a partial expanded longitudinal cross-sectional view of the compressor of FIG. It is a fragmentary sectional view of the drive shaft which shows the free-form surface in the compressor of FIG. It is a schematic longitudinal cross-sectional view which shows the principal part of the conventional capacity | capacitance variable swash plate type compressor. It is a partial expanded longitudinal cross-sectional view of the compressor of FIG. FIG. 5 is a relationship diagram between a swash plate inclination angle and a piston top position showing an example of a change in piston top position in the compressor of FIG. 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Variable capacity | capacitance type swash plate type compressor 2 Drive shaft 3 Rotor 4 Pin 5 Link 6 Hinge mechanism 7 Swash plate 8 Cam part 9 Boss part 10 Sliding contact 11 Piston 12 Shoe 13 Piston top position 14 Free curved surface 15 Axial range of free curved surface θ Swash plate inclination angle

Claims (5)

  A drive shaft, a rotor that is rotated integrally with the drive shaft, and a rotor mechanism that is coupled to the rotor via a hinge mechanism and rotated integrally with the drive shaft. A central boss portion extends axially on the outer surface of the drive shaft. A swash plate that has a sliding contact that is in sliding contact, and is displaced so that an inclination angle with respect to the drive shaft changes while performing sliding contact with the sliding contact, and is slidably contacted with both side surfaces of the outer periphery of the swash plate and is rotatable. In the variable displacement swash plate compressor having a pair of held shoes and a piston through which the rotational movement of the swash plate is converted into reciprocating motion, the drive shaft in the sliding contact region of the sliding contact The variable capacity swash plate compressor is characterized in that the outer surface is formed as a free-form surface extending in the axial direction so that the piston top position when the inclination angle of the swash plate changes becomes a constant position.   The free-form surface calculates the position of the sliding contact when the inclination angle of the swash plate is changed under the condition that the piston top position is a fixed position, and calculates each calculated The variable capacity swash plate compressor according to claim 1, wherein the variable displacement swash plate compressor is specified as a curved surface corresponding to a model by connecting positions of sliding contacts.   3. The variable displacement swash plate compressor according to claim 1, wherein the free-form surface is formed on a surface that extends in a curved line in the axial direction and linearly extends in a direction orthogonal to the axial direction.   The variable displacement swash plate compressor according to any one of claims 1 to 3, wherein a center of rotation of the shoe is located on a neutral surface of the swash plate.   The variable capacity swash plate compressor according to any one of claims 1 to 4, wherein the hinge mechanism includes a mechanism including a pin and a link rotated around the pin.

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