Patent Grant
7699585
The present invention relates to a swash plate type compressor and more particularly to a structure for cooling heat-generating sliding portions of the swash plate type compressor.
A conventional swash plate type compressor is disclosed, for example, in the unexamined Japanese patent application publication No. 8-284816.
The front housing 55 of the compressor 50 has a passage 56 formed therein. A drive shaft 58 has a communication passage 59 formed therein. The crank chamber 51 is sealed by a lip seal 57 which is provided between the front housing 55 and the outer peripheral surface of the drive shaft 58.
To control the crank chamber pressure Pc, part of refrigerant in the discharge chamber 54 is introduced into the crank chamber 51 with its flow rate being adjusted by the control valve 53. Refrigerant introduced into the crank chamber 51 is used to create the crank chamber pressure Pc and then flows through the passage 56 in the front housing 55, the communication passage 59 in the drive shaft 58 and other passages formed in the compressor 50 finally into the suction chamber 60, as indicated by arrows.
The refrigerant contains lubricating oil which is supplied into the crank chamber 51 and then guided through the oil supply passage 63 and the passage 56 to the lip seal 57 together with refrigerant for lubricating the lip seal 57. The lubricating oil is finally drawn to the suction chamber 60 through the communication passage 59.
However, refrigerant introduced into the crank chamber 51 increases in temperature while it flows in the crank chamber 51, which impedes cooling of the heat-generating sliding portions of the compressor 50, such as the lip seal 57, a thrust bearing 61 and a link 62, requiring cooling during operation of the compressor 50.
The present invention is directed to providing a swash plate type compressor that can sufficiently cool the heat-generating sliding portions of the compressor.
In accordance with the present invention, a swash plate type compressor has a housing, a drive shaft, a lug plate, a swash plate, a piston and a heat-generating sliding portion. The housing has a cylinder bore, a suction pressure region, a discharge pressure region and a crank chamber. The drive shaft is rotatably supported by the housing. The lug plate is secured to the drive shaft. The swash plate is tiltably coupled to the lug plate. The piston is coupled to the swash plate and reciprocally accommodated in the cylinder bore. Refrigerant in the discharge pressure region is introduced into the crank chamber through a supply passage while the refrigerant in the crank chamber is drawn out to the suction pressure region through a bleed passage for controlling pressure in the crank chamber, whereby inclination angle of the swash plate is changed. The heat-generating sliding portion is provided in the crank chamber. The supply passage includes a communication port that communicates with the crank chamber and a first throttle portion for throttling the refrigerant. At least parts of the supply passage and the bleed passage are formed in the drive shaft. A part of the bleed passage formed in the drive shaft is located between a part of the supply passage formed in the drive shaft and an outer peripheral surface of the drive shaft.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
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 first preferred embodiment of a swash plate type compressor 1 with reference to
Referring to
In the crank chamber 6, a drive shaft 7 is rotatably supported by the front housing 3 and the cylinder block 2. The drive shaft 7 includes a cylindrical hollow first shaft portion 7a having an opening at one end thereof and a cylindrical hollow second shaft portion 7b having openings at the opposite ends thereof and press-fitted in the opening of the first shaft portion 7a. An O-ring 42 is held between the inner peripheral surface of the first shaft portion 7a and the outer peripheral surface of the second shaft portion 7b adjacent to the front end of the second shaft portion 7b. The first shaft portion 7a is supported at the front and rear ends thereof by radial bearings 39 and 40, respectively.
A lip seal 8, which is one of the heat-generating sliding portions of the compressor 1, is provided between the outer peripheral surface of the front end portion of the drive shaft 7 and the front housing 3 for sealing of the crank chamber 6. In the crank chamber 6, a lug plate 9 is secured to the drive shaft 7 for rotation therewith. A thrust bearing 10 is provided between the lug plate 9 and the inner wall surface of the front housing 3.
A substantially disc-shaped swash plate 11 is tiltably fitted around the drive shaft 7 in the crank chamber 6 and tiltably coupled to the lug plate 9 through a link 12. A plurality of pistons 13 is arranged around the drive shaft 7 and coupled to the outer periphery of the swash plate 11 through a pair of shoes 14. Each of the pistons 13 is reciprocally accommodated in an associated cylinder bore 16, which is formed in the cylinder block 2. As the swash plate 11 is rotated, the pistons 13 are reciprocated in their associated cylinder bores 16.
A discharge chamber 17, which is a part of the discharge pressure region of the compressor 1, is formed at the center of the rear housing 5 and connected to an external refrigerant circuit through an outlet (not shown). On the other hand, a suction chamber 18, which is a part of the suction pressure region of the compressor 1, is formed around the discharge chamber 17 in the rear housing 5 and connected to the external refrigerant circuit through an inlet (not shown).
The valve port assembly 4 has suction ports 19, suction valves (not shown), discharge ports 20 and discharge valves (not shown). Each of the cylinder bores 16 is communicable with the suction chamber 18 through the respective suction port 19 and with the discharge chamber 17 through the respective discharge port 20. A retainer is provided on the rear side of the discharge ports 20.
A control valve 21 is provided in the rear housing 5 for adjusting the flow rate of refrigerant introduced into the crank chamber 6 thereby to control pressure in the crank chamber (crank chamber pressure Pc). The control valve 21 functions as a first throttle portion. The control valve 21 is in communication with the discharge chamber 17 through a passage on one hand and with one end of a passage 22 formed in the rear housing 5 on the other. The passage 22 extends from the control valve 21 toward the valve port assembly 4 and communicates with one end of a passage 23 formed in the valve port assembly 4. The other end of the passage 23 is in communication with one end of a passage 24 formed in the cylinder block 2 and the other end of the passage 24 is in communication with one end of a passage 25 formed axially in the drive shaft 7. The other end of the passage 25 is in communication with a passage 26 that communicates with the crank chamber 6. The passage 26 has a communication-port 26a which is radially opened to the crank chamber 6 and in communication with the lip seal 8. The control valve 21 and the passages 22, 23, 24, 25, 26 cooperate to form a supply passage for supplying refrigerant in the discharge pressure region into the crank chamber 6.
The drive shaft 7 has a passage 35 formed between the swash plate 11 and the lug plate 9 and having a communication port for drawing refrigerant and lubricating oil from the crank chamber 6 toward the suction chamber 18. The passage 35 is in communication with one end of a passage 36, the other end of which is in communication with one end of a passage 37 formed in the cylinder block 2. It is noted that a lip seal 38 is provided between the passage 36 and the passage 24. The passage 37 is in communication with one end of a passage 28 which is formed in the valve port assembly 4 and the other end of which communicates with the suction chamber 18. The passages 35, 36, 37, 28 cooperate to form a bleed passage for drawing refrigerant in the crank chamber 6 into the suction pressure region. The lip seal 38 is located at the rear end of the drive shaft 7 for sealing the bleed passage from the supply passage, that is, for sealing the inside of the second shaft portion 7b from the outside thereof. The lip seal 38 defines the supply passage in the drive shaft 7 together with the inner peripheral surface of the second shaft portion 7b and also defines the bleed passage in the drive shaft 7 together with the inner peripheral surface of the first shaft portion 7a and the outer peripheral surface of the second shaft portion 7b. It is noted that the supply passage and the bleed passage are so formed that the cross-sectional areas at any portion thereof are larger than that of the throttle of the control valve 21, so that the flow of refrigerant in such passages is not prevented.
The following will describe the operation of the compressor 1 according to the first preferred embodiment.
As the drive shaft 7 is driven by a drive source (not shown), the swash plate 11 rotates, with the result that each of the pistons 13 reciprocates in the associated cylinder bore 16. Refrigerant in the external refrigerant circuit is introduced into the suction chamber 18 and then drawn through the respective suction ports 19 into the cylinder bores 16, in which the refrigerant is compressed by the pistons 13. The compressed refrigerant is forced into the discharge chamber 17 through the discharge ports 20 and then discharged out thereof into the external refrigerant circuit.
Part of refrigerant in the discharge chamber 17 is introduced into the crank chamber 6 for controlling the inclination angle of the swash plate 11. The flow rate of refrigerant introduced into the crank chamber 6 is controlled by adjusting the degree of opening of the control valve 21. When refrigerant passes through the control valve 21, the valve portion of the control valve 21 throttles or regulates the flow of refrigerant thereby to reduce its pressure and hence its temperature. For example, refrigerant in the discharge pressure region subjected to a high pressure and has a temperature of about 150 degrees C. The refrigerant is lowered in pressure by passing through the control valve 21 and its temperature is dropped to approximately 100 degrees C. Refrigerant that has thus decreased in temperature passes through the passages 22, 23, 24, 25, 26 in this order and is introduced into the crank chamber 6 through the communication port 26a. Since refrigerant that has decreased in temperature and flows past the communication port 26a directly blows onto the lip seal 8 just after being introduced into the crank chamber 6, the lip seal 8 which generates heat during operation of the compressor 1 is cooled by refrigerant.
Refrigerant thus introduced into the crank chamber 6 serves to adjust the crank chamber pressure Pc in accordance with the degree of opening of the control valve 21, and the inclination angle of the swash plate 11 is controlled by the pressure difference between the crank chamber pressure Pc and the pressure in the cylinder bores 16, thus controlling the displacement of the compressor 1. That is, the inclination angle of the swash plate 11 may be changed by adjusting the crank chamber pressure Pc in the crank chamber 6. Refrigerant in the crank chamber 6 is drawn out to the suction chamber 18 through the passages 35, 36, 37, 28 in this order.
It is noted that lubricating oil contained in refrigerant in the crank chamber 6 is not uniformly distributed, but the oil content is less in the region between the swash plate 11 and the lug plate 9. One reason is that refrigerant containing lubricating oil is compelled away from the drive shaft 7 between the swash plate 11 and the lug plate 9 due to the rotating action and centrifugal force of the swash plate 11. Another reason is that refrigerant compelled away from the drive shaft 7 due to the operation of the swash plate 11 or other reasons attaches on the inner wall of the front housing 3 or other parts, and some lubricating oil may adhere thereto. Thus, there is less lubricating oil between the swash plate 11 and the lug plate 9. On the contrary, more lubricating oil is present in the parts other than between the swash plate 11 and the lug plate 9, namely, near the inner wall surface of the front housing 3 and between the swash plate 11 and the cylinder block 2.
Refrigerant that flows through the bleed passage, particularly through the passage 35, after cooling the lip seal 8, increases in temperature to a level that is still lower than the temperature of peripheral parts of the drive shaft 7, particularly the outer peripheral portion of the drive shaft 7.
Thus, the refrigerant which is decreased in temperature due to throttling by the valve portion of the control valve 21 when refrigerant is introduced into the crank chamber 6 is directly blown onto the lip seal 8. Therefore, the lip seal 8 which is heated during operation of the compressor 1 is cooled down by the refrigerant.
This cooling effect is synergistically improved by forming the passages 25, 36 in the drive shaft 7 with the passage 36 provided between the passage 25 in the drive shaft 7 and the outer peripheral surface of the first shaft portion 7a. That is, the passage 36, which is a part of the bleed passage, is formed to surround the passage 25, so that the passage 36 and refrigerant flowing therein prevent the heat on the outer peripheral side of the drive shaft 7 from being conducted to the passage 25. Therefore, the temperature of refrigerant in the passage 25 is kept at a lower level. Thus, refrigerant with lower temperature is directly blown onto the lip seal 8, so that the lip seal 8 is further effectively cooled.
Additionally, the bleed passage having a communication port 35 for drawing therethrough refrigerant and lubricating oil from the crank chamber 6 into the suction chamber 18 is provided at a position where the refrigerant contains less lubricating oil, rather than at a position near the lip seal 8 where the refrigerant contains more lubricating oil. Therefore, the amount of lubricating oil discharged out of the compressor 1 is reduced and a relatively large amount of lubricating oil is accumulated in the crank chamber 6, so that the compressor 1 is desirably operated during its off state where substantially no refrigerant is introduced, compressed and discharged, but the swash plate 11 is being rotated. Furthermore, the drive shaft 7 which has two passages in the form of cavities can be made advantageously light in weight.
In the first preferred embodiment, the first shaft portion 7a and the second shaft portion 7b are made of metal. In an alternative embodiment, the second shaft portion 7b is made of heat insulation material such as resin. In another alternative embodiment, the drive shaft 7 is provided with heat insulation treatment, for example, by coating the first shaft portion 7a and/or the second shaft portion 7b with heat insulation material or by fitting a hollow cylindrical heat insulation member on the inner or outer periphery of at least one of the first and second shaft portions 7a, 7b as a part of the drive shaft 7. The second shaft portion 7b, whose rigidity may be lower than that of the first shaft portion 7a, may be made of a heat insulation material with a lower rigidity.
Thus making part of the drive shaft 7 using a heat insulation material, the conduction of heat generated on the outer periphery of the drive shaft 7 to the passage 25 is prevented more effectively than without using the heat insulation material for the drive shaft 7. Thus, the cooling of the lip seal 8 is further improved.
The position where the O-ring 42 is provided is not limited to a position between the inner peripheral surface of the first shaft portion 7a and the outer peripheral surface of the second shaft portion 7b. For example, the O-ring 42 may be provided between the front end 7x of the second shaft portion 7b and a step 7y which is formed on the inner peripheral surface of the first shaft portion 7a that is engaged with the front end 7x, as shown in
The shape of cross-section of the drive shaft 7 is not limited to that of
In
In
In
Furthermore, the position of the passage 35 in the drive shaft 7 is not limited to that between the swash plate 11 and the lug plate 9, but the passage 35 may be located closer to the lip seal 8 or near the front end of the crank chamber 6, that is, near the position where the drive shaft 7 contacts with the lug plate 9.
In such a case, the passage 36 becomes longer and, accordingly, the second shaft portion 7b is formed longer. Thus, the portion of the passage 25 where refrigerant flowing therein is thermally insulated by the passage 36 becomes longer, so that the heat on the outer peripheral side of the drive shaft 7 is effectively insulated and the lip seal 8 is further effectively cooled.
The target component of the compressor 1 to be cooled by refrigerant is the lip seal 8 in this embodiment of
The O-ring 42 which is held between the inner peripheral surface of the first shaft portion 7a and the outer peripheral surface of the second shaft portion 7b near the front end of the second shaft portion 7b may be omitted. That is, the inner peripheral surface of the first shaft portion 7a closely contacts with the outer peripheral surface of the second shaft portion 7b by press-fitting, thereby having a seal structure.
The following will describe a second preferred embodiment of a swash plate type compressor 1′ according to the present invention with reference to
As shown in
Refrigerant passing through the passages 22, 23, 24 in
According to the compressor 1′, of the second preferred embodiment having the second throttle portion 7′h in the supply passage between the control valve 21 and the communication port 26a, the temperature of refrigerant that reaches the communication port 26ais reduced by the second throttle portion 7′h, with the result that the lip seal 8 is effectively cooled.
The position where the second throttle portion 7′h is provided is not limited to the front end of the second shaft portion 7′b, but the second throttle portion may be formed as a part of the supply passage in the drive shaft 7 in an alternative embodiment to the second preferred embodiment. For example, the second throttle portion may be provided at the rear end or halfway of the second passage part 25′b. Alternatively, it may be provided at the front end, rear end or halfway of the first passage part 25′a. Particularly, providing the second throttle portion near the front end of the first passage part 25′a, that is, near the passage 26 of
The second throttle portion may be formed separately from the second shaft portion 7′b unlike the one 7′h which is formed integrally with the second shaft portion 7′b as shown in
The following will describe a third preferred embodiment of a swash plate type compressor 101 according to the present invention with reference to
The third preferred embodiment differs from the first preferred embodiment in that the structure around the rear end of the drive shaft 7 is modified as shown in
In the third preferred embodiment, the lip seal 38 of the first preferred embodiment is not provided. Instead, the second bearing 140 is provided for sealing the passage 24 which is a part of the supply passage, from the passage 36 which is a part of the bleed passage. It is noted that the pressure differential between the supply passage and the bleed passage is small enough for the plain bearing 140 to seal the supply passage from the bleed passage.
According to the third preferred embodiment, the lip seal 38 is replaced by the plain bearing 140 having a higher durability, with the result that durability of the compressor 101 is improved.
The following will describe a fourth preferred embodiment of a swash plate type compressor 201 according to the present invention with reference to
Referring to
According to the fourth preferred embodiment wherein the drive shaft 207 is so formed that the small diameter portion 207d of the first shaft portion 207a is directly fitted around the rear end of the second shaft portion 207b, the strength of the drive shaft 207 is improved.
An O-ring may be provided at a position where the small diameter portion 207d of the first shaft portion 207a is fitted around the second shaft portion 207b for ensuring the seal between the supply passage and the bleed passage.
The following will describe a fifth preferred embodiment of a swash plate type compressor 301 according to the present invention with reference to
The drive shaft 307 includes a first shaft portion 307a and a second shaft portion 307b. The first shaft portion 307a has a small diameter portion 307f whose inner diameter is small and a large diameter portion 307g that has an inside diameter larger than the small diameter portion 307f. The second shaft portion 307b is press-fitted into the large diameter portion 307g of the first shaft portion 307a.
Referring to
A passage 335 is formed in the first shaft portion 307a at a position between the swash plate 11 and the lug plate 9 for drawing refrigerant from the crank chamber 9 into the suction chamber 18. The passage 335 is in communication with one end of a passage 336 which is formed between the inner peripheral surface of the large diameter portion 307g of the first shaft portion 307a and the outer peripheral surface of the second shaft portion 307b. The other end of the passage 336 is in communication with one end of a passage 337. The first shaft portion 307a has a communication hole 307c that connects the passage 336 to the passage 337. A lip seal 338 is provided around the first shaft portion 307a at the rear end thereof for sealing the supply passage from the bleed passage.
The following will describe a sixth preferred embodiment of a swash plate type compressor 401 according to the present invention with reference to
Referring to
The plain bearing 439 has an inner annular groove 439a and an outer annular groove 439b on the inner peripheral surface and the outer peripheral surface thereof, respectively. The inner annular groove 439a and the outer annular groove 439b are located, for example, at the axial center of the plain bearing 439. Each of the inner annular groove 439a and the outer annular groove 439b has tapered surfaces 439d on its front and rear ends, respectively. The inner annular groove 439a is in communication with the outer annular groove 439b through a bearing communication hole 439c that extends through the plain bearing 439.
The plain bearing 439 is fixed to the cylinder block 402, so that relative position between the communication hole 407c and the bearing communication hole 439c varies with rotation of the drive shaft 407, but the inner annular groove 439a is maintained in constant communication with the communication hole 407c and the passage 437, irrespective of the position of the bearing communication hole 439c. Therefore, the passage 436 is constantly in communication with the passage 437.
The passage 35 (shown in
The pressure differential between the passages 24, 425 that are part of the supply passage and the inner annular groove 439a, the outer annular groove 439b and the bearing communication hole 439c that are part of the bleed passage is small enough for the plain bearing 439 to seal successfully the supply passage from the bleed passage.
According to the sixth preferred embodiment wherein the plain bearing 439 which is provided at the rear end of the drive shaft 407 functions not only as a support for the drive shaft 407 but also as a seal for the supply passage and the bleed passage, there is no need for providing an additional member such as partition wall for sealing the supply passage from the bleed passage and, therefore, the structure of the compressor becomes simple. At the rear end of the drive shaft 407, the bleed passage is not formed outside or at the end of the plain bearing 439 supporting the drive shaft 407, but formed inside thereof (or halfway the plain bearing 439 as seen in the axial direction thereof). Therefore, lubricating oil contained in refrigerant that flows through the bleed passage flows through the entire plain bearing 439, thereby further efficiently lubricating the plain bearing 439.
In the sixth preferred embodiment, the inner annular groove 439a, the outer annular groove 439b and the bearing communication hole 439c are provided at the axial center of the plain bearing 439. It is noted, however, that the position of the inner and outer annular grooves 439a, 439b may be changed to halfway the plain bearing 439 as viewed in its axial direction. The position may be changed so as to achieve efficient sealing effect, for example, in view of the above pressure differential.
Additionally, the inner annular groove 439a may be formed not on the inner peripheral surface of the plain bearing 439 but on the outer peripheral surface of the first shaft portion 407a. Similarly, the annular groove 439b does not have to be formed necessarily on the outer peripheral surface of the plain bearing 439, but it may be formed in the inner peripheral surface of the cylinder block 402. By so providing the annular grooves 439a, 439b, the plain bearing 439 is improved in strength.
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 |
|---|---|---|---|
| 2005-020290 | Jan 2005 | JP | national |
| 2005-149679 | May 2005 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4685866 | Takenaka et al. | Aug 1987 | A |
| 7377754 | Saiki et al. | May 2008 | B2 |
| 20020041809 | Yokomachi et al. | Apr 2002 | A1 |
| 20040118149 | Tsunoda | Jun 2004 | A1 |
| 20040197202 | Saiki et al. | Oct 2004 | A1 |
| Number | Date | Country |
|---|---|---|
| 1 447 562 | Aug 2004 | EP |
| 1 493 923 | Jan 2005 | EP |
| 4-179874 | Jun 1992 | JP |
| 5-018355 | Jan 1993 | JP |
| 7-004353 | Jan 1995 | JP |
| 08-284816 | Oct 1996 | JP |
| 8-284816 | Oct 1996 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20060165536 A1 | Jul 2006 | US |
