Patent Application
20080063550
The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:
The following will describe a preferred embodiment according to the present invention with reference to
Referring to
The cylinder block 11 and the front housing 12 cooperate to define therebetween a crank chamber 20, and a drive shaft 21 extends in the crank chamber 20. The drive shaft 21 is rotatably supported by the cylinder block 11 and the front housing 12 through radial bearings 21a and 21b, and connected to an engine as the drive source of a vehicle.
In the crank chamber 20, a disc-shaped lug plate 22 is secured on the drive shaft 21 for rotation therewith. A disc-shaped swash plate 23 as a cam plate is provided in the crank chamber 20. The swash plate 23 has a center hole 23b through which the drive shaft 21 is inserted so that the swash plate 23 is rotatably and inclinably supported by the drive shaft 21 through the hole 23b. A hinge mechanism 24 is interposed between the swash plate 23 and the lug plate 22, and the swash plate 23 is connected to the lug plate 22 through the hinge mechanism 24. Such arrangement permits the swash plate 23 to rotate synchronously with the lug plate 22 and the drive shaft 21 and to incline with respect to the drive shaft 21 while sliding in the direction of the axis T of the drive shaft 21.
The cylinder block 11 has formed therethrough a plurality of cylinder bores 25 (five cylinder bores in the preferred embodiment) which are arranged around the drive shaft 21 at equiangular intervals and extend in the direction of the axis T of the drive shaft 21. Each cylinder bore 25 receives therein a single-headed piston 26 for reciprocation. The front and rear openings of the cylinder bore 25 are closed by the piston 26 and the valve-port assembly 13, respectively, so that a compression chamber 27 is defined in the cylinder bore 25. The volume of the compression chamber 27 is variable in accordance with the reciprocation of the piston 26.
The working stroke of the piston 26 is determined by the differential pressure between the pressure acting on the rear surface of the piston 26 (or the surface facing the compression chamber 27 in
Each piston 26 engages with the outer peripheral portion of the swash plate 23 through a pair of shoes 23a. As the swash plate 23 is rotated with the drive shaft 21, the swash plate 23 makes a wobbling motion in the direction of the axis T of the drive shaft 21, thereby causing the piston 26 to move reciprocally in its cylinder bore 25 in the direction of the axis T of the drive shaft 21. In the compressor 10 of the preferred embodiment, the crank chamber 20, the drive shaft 21, the swash plate 23, the piston 26, and the like constitute a compression mechanism.
A suction chamber 28 as a suction-pressure region and a discharge chamber 29 as a discharge-pressure region are defined in the rear housing 16. More specifically, the suction chamber 28 is provided radially outward of the discharge chamber 29 so as to surround the discharge chamber 29. The rear housing 16 has an inlet 28a through which refrigerant gas is introduced into the suction chamber 28. The rear housing 16 has an outlet 29a through which refrigerant gas in the discharge chamber 29 is delivered out of the compressor 10.
The valve plate 17 of the valve-port assembly 13 has suction ports 30 which are located in radially outward region of the valve plate 17 in facing relation to the respective cylinder bores 25. The valve plate 17 has discharge ports 31 which are located radially inward of the suction ports 30 in facing relation to the respective cylinder bores 25. The suction valve plate 18 of the valve-port assembly 13 has suction valves 32 for opening and closing the respective suction ports 32. The suction valve plate 18 has discharge holes 33 which are located at positions corresponding to the respective discharge ports 31. The discharge valve plate 19 has discharge valves 34 for opening and closing the respective discharge ports 31. The opening degree of the discharge valve 34 is restricted by a retainer 35. The gasket 14, the suction valve plate 18, the valve plate 17, the discharge valve plate 19, the gasket 15 and the retainer 35 are arranged between the cylinder block 11 and the rear housing 16 in this order as seen from the cylinder block 11 and these are fastened together by a bolt B2. A hole BT2 is formed in the gaskets 14 and 15, the suction valve plate 18, the valve plate 17, the discharge valve plate 19, and the retainer 35 for receiving therethrough the bolt B2. The suction valve plate 18 is fixed so that the suction valves 32 are located at positions corresponding to the respective suction ports 30, and the discharge valve plate 19 is fixed so that the discharge valves 34 are located at positions corresponding to the respective discharge ports 31.
The compressor 10 is provided with a bleed passage 36, a supply passage 37 and a known electromagnetically operated control valve 38. The bleed passage 36 connects the crank chamber 20 to the suction chamber 28, and the supply passage 37 connects the discharge chamber 29 to the crank chamber 20. The control valve 38 is arranged in the supply passage 37.
The compressor 10 is connected to an external refrigerant circuit 40. More specifically, the inlet 28a and the outlet 29a in the rear housing 16 are connected through the external refrigerant circuit 40. The external refrigerant circuit 40 includes a condenser 40a, an expansion valve 40b, and an evaporator 40c. The refrigerant gas is introduced from the evaporator 40c in the external refrigerant circuit 40 to the suction chamber 28 through the inlet 28a. During the suction stroke when the piston 26 moves from its top dead center toward its bottom dead center, the refrigerant gas in the suction chamber 28 is drawn into the compression chamber 27 through the suction port 30 while pushing open the suction valve 32. During the discharge stroke when the piston 26 moves from its bottom dead center toward its top dead center, the refrigerant gas in the compression chamber 27 is compressed to a predetermined pressure and then discharged into the discharge chamber 29 through the discharge port 31 while pushing open the discharge valve 34. The refrigerant gas in the discharge chamber 29 is delivered out of the compressor 10 to the external refrigerant circuit 40 through the outlet 29a of the discharge chamber 29. In the compressor 10 of the present preferred embodiment, a refrigerant passage is provided by the compression chamber 27, the suction chamber 28, the discharge chamber 29, the suction port 30, and the discharge chamber 31. It is noted that the refrigerant passage is provided for each of the compression chambers 27.
In operation of the compressor 10, the opening degree of the control valve 38 is adjusted to control the balance between the amount of the high-pressure refrigerant gas supplied to the crank chamber 20 through the supply passage 37 and the amount of the refrigerant gas drawn from the crank chamber 20 through the bleed passage 36. Thus, the pressure in the crank chamber 20 is adjusted and the inclination angle of the swash plate 23 is changed, accordingly, thereby variably controlling the stroke length of the piston 26 and hence the displacement of the compressor 10. As the opening degree of the control valve 38 is decreased, the pressure in the crank chamber 20 is decreased and the inclination angle of the swash plate 23 is increased thereby to increase the stroke length of the piston 26 and hence the displacement of the compressor 10. On the other hand, as the opening degree of the control valve 38 is increased, the pressure in the crank chamber 20 is increased and the inclination angle of the swash plate 23 is decreased thereby to decrease the stroke length of the piston 26 and hence the displacement of the compressor 10.
The following will describe in detail the structures of the gaskets 14 and 15 which are used in the compressor 10 of the preferred embodiment with reference to
The following will describe the structure of the gasket 14 as a first seal member which is located adjacent to the cylinder block 11. The gasket 14 is disc-shaped as shown in
The gasket 14 has formed adjacent to the outer periphery thereof a projecting outer bead 44 as a first seal portion. As shown in
The outer and inner beads 44 and 45 are formed as full beads so as to project in the same direction, or toward the cylinder block 11 as shown in
The gasket 14 is provided with rubber coatings 42a, 42b on both surfaces of the metal plate 41 which is formed into a shape having the outer and inner beads 44 and 45. Thus, the gasket 14 has on its surfaces beaded portions (or beaded surface) forming the outer and inner beads 44 and 45 and non-beaded portions (or non-beaded surface) where no bead is formed. The non-beaded portions are planar.
The outer bead 44 is formed with a projection having a uniform height h1 (
h2<h1.
The following will describe the structure of the gasket 15 as a second seal member which is located adjacent to the rear housing 16. The gasket 15 which is disc-shaped as shown in
The gasket 15 has formed adjacent to the outer periphery thereof a projecting outer bead 48 as a first seal portion. As shown in
The outer and inner beads 48 and 49 are formed as full beads so as to project in the same direction, or toward the rear housing 16 as shown in
The gasket 15 is provided with rubber coatings 47a and 47b on both surfaces of the metal plate 46 which is formed into a shape having the outer and inner beads 48 and 49. Thus, the gasket 15 has on its surfaces beaded portions (or beaded surface) forming the outer and inner beads 48 and 49 and non-beaded portions (or non-beaded surface) where no bead is formed. The non-beaded portions are planar.
The outer bead 48 is formed with a projection having a uniform height h3 along the entire outer periphery of the gasket 15. The height h3 of the outer bead 48 is a dimension as measured from the non-beaded portion of the gasket 15 to the top of the outer bead 48 as shown in
h4<h3.
The above-described gasket 14 is disposed between the cylinder block 11 and the valve-port assembly 13 so that the outer and inner beads 44 and 45 are in contact with the rear surface of the cylinder block 11 as shown in
Since the shapes, more specifically, the heights h1 and h2 of the outer and inner beads 44 and 45 of the gasket 14 are different from each other, the contact pressures of the outer and inner beads 44 and 45 are different from each other. Since the height h1 of the outer bead 44 is larger than the height h2 of the inner beads 45, the contact pressure of the outer bead 44 is larger than that of the inner beads 45. Similarly, since the shapes, more specifically, the heights h3 and h4 of the outer and inner beads 48 and 49 of the gasket 15 are different from each other, the contact pressures of the outer and inner beads 48 and 49 are different from each other. Since the height h3 of the outer bead 48 is larger than the height h4 of the inner bead 49, the contact pressure of the outer bead 48 is larger than that of the inner bead 49.
The seal structure of the compressor 10 of the preferred embodiment is provided in such a way that the contact pressures of the gaskets 14 and 15 increase toward the radially outer side of the compressor. Further, the bolts B1 of the compressor 10 are located adjacent to the outer periphery of each housing component. Thus, in the seal structure of the preferred embodiment, the beads adjacent to the bolts B1 (or the outer beads 44 and 48) have larger height and hence greater contact pressure. Each of the heights h1 through h4 of the beads 44, 45, 48 and 49 is set so as to produce a contact pressure that is required for preventing leak of the refrigerant gas. The contact pressure to be produced depends on the fastening force of the bolts B1 and the kind of refrigerant to be used. When carbon dioxide is used as refrigerant in the compressor 10 of the preferred embodiment, the required contact pressure is larger than that in case of using chlorofluorocarbon as refrigerant.
The following will describe the operation of the compressor 10 of the preferred embodiment. In the compressor 10, the refrigerant gas in the suction chamber 28 is drawn into the compression chamber 27, compressed in the compression chamber 28 and discharged into the discharge chamber 29, as described earlier herein. Thus, the pressures in the compression chamber 27, the suction chamber 28 and the discharge chamber 29 vary during suction and discharge strokes, thereby generating pressure differential among the compression chamber 27, the suction chamber 28 and the discharge chamber 29. For example, during the suction stroke, there is no pressure differential between the compression chamber 27 and the suction chamber 28 but a pressure differential is generated between the compression chamber 27 and the discharge chamber 29. On the other hand, during the discharge stroke, there is no pressure differential between the compression camber 27 and the discharge chamber 29 but the pressure differential is generated between the compression chamber 27 and the suction chamber 28.
The valve plate 17 is bent under the influence of the above pressure variation, thus the contact pressures of the gaskets 14 and 15 being changed, accordingly. More specifically, during the suction stroke, the gaskets 14 and 15 receive a force which presses the gaskets 14 and 15 against the cylinder block 11 and, during the discharge stroke, the gaskets 14 and 15 are subjected to a force which presses the gaskets 14 and 15 against the rear housing 16. The contact pressure of the gaskets 14 and 15 varies significantly specifically at the beads which are located adjacent to the refrigerant passage which are more susceptible to the influence of the pressure of the refrigerant gas drawn or discharged during the suction or discharge stroke (or the inner beads 45 and 49 in the preferred embodiment).
In the compressor 10 of the preferred embodiment, the heights h1 and h3 of the outer beads 44 and 48 are set larger than the heights h2 and h4 of the inner beads 45 and 49. That is, the heights of the beads located adjacent to the refrigerant passage are lower. Therefore, the degree of change in shape of the beads 45 and 49 when they undergo repeatedly alternate deformation by being pressed against contact surface by variable pressure and the subsequent restoration to their original shape is reduced. As a result, the gaskets 14 and 15 are less susceptible to damage due to pressure variation during the suction and discharge strokes which causes the repeated deformation and restoration of the gaskets 14 and 15.
It is noted that since leakage of the refrigerant gas from the refrigerant passage is permissible within the range in which the compressor 10 can maintain its intended performance, priority may be attached to successful prevention of damage to the inner beads 45 and 49 in setting the heights h2 and h4 of the inner beads 45 and 49 which are more susceptible to the pressure variation. Meanwhile, since the airtightness of the compressor 10 need to be ensured for preventing the refrigerant gas from leaking out of the compressor 10, priority may be attached to the airtightness of the compressor 10 in setting the heights h1 and h3 of the outer beads 44 and 48.
According to the preferred embodiment described above, the following advantageous effects are obtained.
(1) The heights h2 and h4 of the inner beads 45 and 49 adjacent to the refrigerant passage are set smaller than the heights h1 and h3 of the outer beads 44 and 48 which are located more distant from the refrigerant passage than the inner beads 45 and 49, so that the degree of deformation and restoration of the beads 45 and 49 which is caused by variation of the contact pressure of the beads due to the pressure variation in the compressor 10 is reduced, with the result that the degree of deformation of the beads 45 and 49 is reduced and, therefore, the gaskets 45 and 45 are successfully prevented from being damaged.
(2) The heights h1 and h3 of the beads 44 and 48 may be set at a level which produces a contact pressures thereof that is enough to ensure the airtightness of the compressor 10.
(3) The outer beads 44 and 48 are located at positions adjacent to the fastening bolts B1 where the beads 44 and 48 are less susceptible to the influence of pressure variation in the compressor 10 and, therefore, the beads 44 and 48 are pressed against the contact surfaces of the cylinder block 11 and the rear housing 16 with a contact pressures by the fastening force of the bolts B1 that is enough to ensure the airtightness of the compressor 10.
(4) When carbon dioxide is used as refrigerant, the working pressure in the compressor 10 is much higher than that in the case of using chlorofluorocarbon as refrigerant and the pressure differential between high-pressure region and low-pressure region in the compressor 10 is large, thus making the refrigerant gas easy to leak. Thus, when carbon dioxide is used as refrigerant, the gaskets 14 and 15 are required to provide higher airtightness of the compressor 10 than the case of using chlorofluorocarbon as refrigerant. In the refrigeration cycle using carbon dioxide as refrigerant in the preferred embodiment, the outer beads 44 and 48 maintains the airtightness of the compressor 10 while the inner beads 45 and 49 is prevented from being damages by varying contact pressures due to the pressure variation within the compressor 10.
The above preferred embodiment may be modified in various ways as exemplified below.
In an alternative embodiment, the beads 44, 45, 48 and 49 may be formed as half beads. In any one of the gaskets 14 and 15, either of the outer and inner beads may be formed as a full bead, while the other may be formed as a half bead.
In an alternative embodiment, each of the gaskets 14 and 15 may be provided by a flat metal plate which is clad on both surfaces with rubber coatings having raised portions serving as beads.
In an alternative embodiment, the present invention may be applied to a double-headed piston type compressor instead of the single-headed piston type compressor as shown in
In an alternative embodiment, the compressor 10 may be used in a refrigeration cycle of a vehicle air-conditioner in which refrigerant such as chlorofluorocarbon other than carbon dioxide is used.
In the preferred embodiment, the compressor 10 is of a five-cylinder type. However, the compressor may have cylinder bores the number of which is other than five.
The inner beads 45 and 49 of the gaskets 14 and 15 are formed with the heights h2 and h4 which are of substantially the same dimension in the above-described preferred embodiment. In an alternative embodiment, however, the inner beads 45 and 49 may be formed with heights which are different from each other. In this case, it is preferable that the inner beads for the gasket 14 should be lower than that for the gasket 15. In the compressor 10 of the preferred embodiment, the length of the beads of the gasket 14 adjacent to the cylinder block 11 is longer than that of the gasket 15, so that contact pressure of the gasket 14 is dispersed relatively easily. Thus, the contact pressure of one of the inner beads 45 of the gasket 14 is smaller than that of the inner bead 49 of the gasket 15 and, therefore, the inner beads 45 of the gasket 14 are more susceptible to the pressure variation in the compressor. For that reason, the beads 45 are formed with a height that is smaller than that of the bead 49.
In an alternative embodiment, the bolts for fastening the housing member of the compressor such as bolts B1 may be disposed adjacent to the center of the compressor.
In an alternative embodiment, the positions of the suction chamber 28 and the discharge chamber 29 in the rear housing 16 may be reversed. In other words, the discharge chamber 29 may be formed so as to surround the suction chamber 28.
Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein but may be modified within the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| P2006-243070 | Sep 2006 | JP | national |
