VARIABLE DISPLACEMENT TYPE SWASH PLATE COMPRESSOR

BACKGROUND OF THE INVENTION

The present invention relates to a variable displacement swash plate type compressor.

Japanese Unexamined Patent Application Publication No. 2006-132446 discloses a variable displacement swash plate type compressor (hereinafter simply referred to as compressor). The compressor includes a housing, a drive shaft, a swash plate, a piston, and a control mechanism. The housing includes a cylinder block having therethrough a cylinder bore, a first housing member cooperating with the cylinder block to define a crank chamber between the first housing member and the cylinder block, and a second housing member having therein a discharge chamber and a suction chamber. The drive shaft is rotatably supported in the housing, and has thereon a lug member which is disposed in the crank chamber.

The swash plate is rotatably supported on the drive shaft for rotation with the drive shaft and faces the lug member in the crank chamber. The piston is reciprocally movable in the cylinder bore with a stroke length depending on the inclination angle of the swash plate, thereby forming a compression chamber in the cylinder bore. The compressor further has a shaft hole, a sealing member, and a communication passage formed in the first housing member. The shaft hole for receiving the drive shaft is connected to the crank chamber. The sealing member is disposed outward of the crank chamber and the shaft hole in the compressor in the axial direction of the drive shaft. The sealing member supports the drive shaft to be rotatable and creates a tight seal between crank chamber and outside of the housing. The communication passage extends so as to intersect with the drive shaft. The communication passage opens to the crank chamber at one end thereof and opens at another end thereof between the shaft hole and the sealing member.

The control mechanism has a feeding passage connecting the discharge chamber and the crank chamber, a bleeding passage connecting the crank chamber and the suction chamber, and a displacement control valve. The control mechanism is configured to control the inclination angle of the swash plate with the pressure in the crank chamber. The displacement control valve is configured to adjust the opening degree of the feeding passage. The bleeding passage includes an axial passage, first radial passages, and second radial passages. The axial passage extends in the drive shaft in the axial direction of the drive shaft. The first and the second radial passages communicate with the axial passage in the drive shaft and extend from the axial passage in the radial direction of the drive shaft to open on an outer peripheral surface of the drive shaft. Specifically, the first radial passages are located outward of the crank chamber and open on the outer peripheral surface of the drive shaft between the lug member and the sealing member. The first radial passages are in constant communication with the crank chamber through the communication passage. The second radial passages open on the outer peripheral surface of the drive shaft at positions near the swash plate, where a refrigerant gas contains smaller amount of lubricant compared to the refrigerant gas exists in other locations in the crank chamber. The compressor further includes a valve member that is axially movable on the drive shaft along with the swash plate.

In this compressor, the inclination angle of the swash plate decreases as the pressure within the crank chamber is increased by the control mechanism, with the result that the discharge volume per rotation of the drive shaft decreases.

While on the other hand, the inclination angle of the swash plate increases as the pressure within the crank chamber is decreased by the control mechanism, with the result that the discharge volume per rotation of the drive shaft increases. When the inclination angle of the swash plate is the maximum or the minimum inclination angles, the valve member axially moves on the drive shaft to close the openings of the second radial passages on the drive shaft, therefore, the second radial passages are disconnected from the crank chamber by the valve member, which prevents the refrigerant gas in the crank chamber from being introduced from the second radial passages into the suction chamber through the axial passage. While the inclination angle of the swash plate is an intermediate inclination angle, which is smaller than the maximum inclination angle and greater than the minimum inclination angle, the valve member allows the second radial passages to connect to the crank chamber. As a result, the refrigerant gas in the crank chamber is introduced from each of the first and the second radial passages into the suction chamber through the axial passage. Since the refrigerant gas existing near the swash plate contains small amount of lubricant as described above, the refrigerant gas introduced from the crank chamber into the suction chamber through the second radial passages and the axial passage contains smaller amount of lubricant than the refrigerant gas introduced from the crank chamber into the suction chamber through the first radial passages and the axial passage. In this compressor, the second radial passages are connected to the crank chamber. This configuration enables the reduction of the flow rate of the refrigerant gas introduced from the crank chamber into the suction chamber through the first radial passages and the axial passage, while lubricant does not flow excessively from the crank chamber into the suction chamber.

In the adjustment of the pressure within the crank chamber, this configuration of the compressor enables to secure the flow rate of the refrigerant gas introduced from the crank chamber into the suction chamber through the first and the second radial passages and the axial passage, while controlling the amount of the lubricant introduced with the refrigerant gas from the crank chamber to the suction chamber. Accordingly, this compressor is capable of securing the lubricant in the crank chamber to lubricate inside the crank chamber while exhibiting high pressure controllability, which leads to high durability of the compressor.

However, a compressor having higher durability while having higher controllability is requested. In this compressor, the crank chamber and the second radial passages do not communicate with each other when the inclination angle of the swash plate is the minimum inclination angle, so that flow rate of the refrigerant gas with the lubricant introduced from the crank chamber into the suction chamber through the first radial passages and the axial passage increases. There is a case in that the refrigerant gas with the lubricant introduced from the crank chamber into the suction chamber is introduced into the compression chamber, and then discharged through the discharge chamber to a condenser outside the compressor, even at the minimum inclination angle of the swash plate and minimum discharge volume. Also, at the minimum inclination angle of the swash plate, the lubricant introduced with the refrigerant gas into the crank chamber decreases because the flow rate of the refrigerant gas introduced from an evaporator outside the compressor into the suction chamber decreases. Therefore, this compressor may cause the shortage of the lubricant in the crank chamber and is difficult to further improve its durability.

The present invention, which has been made in light of the above described problems, is directed to providing a variable displacement swash plate type compressor that has higher durability and controllability.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there is provided a variable displacement swash plate type compressor including a housing, a drive shaft, a swash plate, a piston, and a control mechanism. The housing has a discharge chamber, a suction chamber, a crank chamber, and a cylinder bore. The drive shaft is rotatably supported in the crank chamber. The swash plate is disposed in the crank chamber and supported on the drive shaft for rotation with the drive shaft. The piston is reciprocally movable in the cylinder bore with a stroke length depending on an inclination angle of the swash plate. The piston forms a compression chamber in the cylinder bore. The control mechanism is configured to change the inclination angle of the swash plate between a maximum inclination angle and a minimum inclination angle by a pressure within the crank chamber. The control mechanism has a feeding passage connecting the discharge chamber and the crank chamber, a bleeding passage connecting the crank chamber and the suction chamber, and a displacement control valve. The displacement control valve is configured to adjust at least one of an opening degree of the feeding passage and the bleeding passage. The bleeding passage has an axial passage, a first radial passages, and at least one second radial passage. The axial passage is formed in the drive shaft in an axial direction of the drive shaft. The first radial passage is formed in the drive shaft, communicates with the axial passage and extends in a radial direction of the drive shaft to open on an outer peripheral surface of the drive shaft in the crank chamber. The second radial passage is formed in the drive shaft, communicates with the axial passage and extends in the radial direction of the drive shaft to open on the outer peripheral surface of the drive shaft at a position that is closer to the swash plate than the first radial passage is to the swash plate. A valve member is disposed on the drive shaft. The valve member is movable in the axial direction of the drive shaft with the swash plate. The first radial passage is in constant communication with the crank chamber. The valve member is configured to connect the second radial passage to the crank chamber when the swash plate is at the maximum inclination angle or the minimum inclination angle and to disconnect the second radial passage from the crank chamber when the swash plate is at an intermediate inclination angle that is smaller than the maximum inclination angle and greater than the minimum inclination angle.

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.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention together with objects and advantages thereof, may best be understood by reference to the following description of the embodiments together with the accompanying drawings in which:

FIG. 1 is a longitudinal cross-sectional view of a compressor according to a first embodiment of the present invention, showing a state of a swash plate in its maximum inclination;

FIG. 2 is a longitudinal cross-sectional view of the compressor of FIG. 1, showing a state of the swash plate in its intermediate inclination;

FIG. 3 is a longitudinal cross-sectional view of the compressor of FIG. 1, showing a state of the swash plate in its minimum inclination;

FIG. 4 is a fragmentary cross-sectional view of first radial passages and an axial passage taken along line IV-IV in FIG. 1;

FIG. 5 is a fragmentary cross-sectional view of second radial passages and the axial passage taken along line V-V in FIG. 1;

FIG. 6 is a graph showing a relationship between the inclination angle of the swash plate and the sum of the opening areas of the first and the second radial passages, according to the first embodiment of the present invention; and

FIG. 7 is a schematic enlarged plan view showing second radial passages in a compressor according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following will describe a variable displacement single-head swash plate type compressor (hereinafter simply referred to as the compressor) according to two embodiments of the present invention with reference to the accompanying drawings. The compressor according to the embodiments is mounted on a vehicle and forms a part of a refrigeration circuit of an air conditioner of the vehicle.

First Embodiment

Referring to FIGS. 1 to 3, there is shown a compressor according to a first embodiment. The compressor includes a housing 1, a drive shaft 3, a swash plate 5, a plurality of pistons 7, and a control mechanism 9.

In FIG. 1, the left side and the right side of the figure will be referred to as the front and the rear of the compressor. The upper side and the lower side of FIG. 1 will be referred to as the upper and the lower of the compressor. Directions indicated in FIGS. 2 to 7 excluding FIG. 6 correspond to the directions indicated in FIG. 1. The directions described in two embodiments are merely exemplary and the compressor of the present invention may be mounted appropriately in various postures depending on the vehicle on which the compressor is mounted.

The housing 1 includes a first housing member 13, a second housing member 15, a cylinder block 17, and a valve forming plate unit 19. The first housing member 13 forms a front part of the compressor. The second housing member 15 forms a rear part of the compressor. The cylinder block 17 is disposed between the first housing member 13 and the second housing member 15.

The first housing member 13 includes a front wall 13a and a peripheral wall 13b. The front wall 13a extends in the vertical direction of the compressor on a front side of the compressor. The peripheral wall 13b is integrally formed with and extends backward from the front wall 13a, so that the first housing member 13 is formed in an approximately cylindrical-bottomed shape by the front wall 13a and the peripheral wall 13b. The front wall 13a and the peripheral wall 13b of the first housing member 13 and the cylinder block 17 cooperate to define a crank chamber 21 in the first housing member 13.

The first housing member 13 further has a boss 13c, a first shaft hole 13d, and a communication passage 13e. The boss 13c projects forward from the front wall 13a, and has therein a first accommodation space 130. The first accommodation space 130 spatially extends backward from the front end of the boss 11c. The boss 13c accommodates a sealing member 23 in the first accommodation space 130. The first shaft hole 13d extends in the longitudinal direction of the compressor and connects the first accommodation space 130 and the crank chamber 21. The first housing member 13 has a first slide bearing 25a in the first shaft hole 13d.

The communication passage 13e extends obliquely in the longitudinal direction of the compressor and connects the first accommodation space 130 and the crank chamber 21. Specifically, the front end of the communication passage 13e opens to the first accommodation space 130 at a position behind the sealing member 23. The rear end of the communication passage 13e opens to the crank chamber 21 at a position in front of a lug member 41. Accordingly, the first accommodation space 130 communicates with the crank chamber 21 through the communication passage 13e. Details of the lug member 41 will be described later.

The second housing member 15 has a suction chamber 15a, a discharge chamber 15b, an annular wall 15c, an outer peripheral wall 15d, a suction port 15e, a second accommodation space 15f, and a discharge port 15g. The suction chamber 15a is defined by the annular wall 15c and located in the radial center of the second housing member 15. The discharge chamber 15b is defined by the annular wall 15c and the outer peripheral wall 15d and is located radially outward of the suction chamber 15a, so that the discharge chamber 15b has an annular shape and surrounds the suction chamber 15a.

The suction port 15e extends in the second housing member 15 in the longitudinal direction of the compressor and opens to suction chamber 15a at the front end of the suction port 15e. The suction port 15e opens on the rear surface of the second housing member 15 at the rear end of the suction port 15e. Accordingly, the suction port 15e connects the suction chamber 15a and the outside of the compressor. The second accommodation space 15f communicates with the discharge chamber 15b and extends in the second housing member 15 in the longitudinal direction of the compressor. The discharge port 15g extends vertically in the second housing member 15 and the upper end of the discharge port 15g opens on the upper surface of the second housing member 15. The discharge port 15g communicates with the discharge chamber 15b through the second accommodation space 15f.

The second housing member 15 includes a discharge check valve mechanism 27 disposed in the second accommodation space 15f. The discharge check valve mechanism 27 includes a valve case 27a, a check valve body 27b, and a first coil spring 27c. The discharge check valve mechanism 27 is configured to connect or disconnect the discharge chamber 15b to the outside of the compressor.

The valve case 27a is fixed inside the second accommodation space 15f of the second housing member 15 by a circlip 29. The valve case 27a has a first communication hole 271 and a second communication hole 272. The first communication hole 271 connects inside of the valve case 27a and the discharge chamber 15b of the second housing member 15. The second communication hole 272 connects inside of the valve case 27a and the discharge port 15g. The check valve body 27b is movably accommodated in the valve case 27a. The first coil spring 27c is disposed in the valve case 27a and urges the check valve body 27b forward.

The second housing member 15 has a first feeding passage 31a, a second feeding passage 31b, and a displacement control valve 33. The first feeding passage 31a connects the discharge chamber 15b and the displacement control valve 33. The second feeding passage 31b is connected to the displacement control valve 33 at the rear end of the second feeding passage 31b and opens on the front surface of the second housing member 15 at the front end of the second feeding passage 31b. The displacement control valve 33 is configured to adjust the opening degree of the first and the second feeding passages 31a, 31b for adjusting the pressure within the crank chamber 21 in response to the external control of supplying electric power. Details of the displacement control valve 33 will be described later.

The cylinder block 17 has therein a plurality of cylinder bores 17a. The cylinder bores 17a are arranged circumferentially and equiangularly. Each of the cylinder bores 17a communicates with the crank chamber 21 at the front end thereof. The cylinder block 17 further has a retainer groove 17b that determines the maximum opening degree of a suction reed valve 191a. Details of the suction reed valve 191a will be described later.

The cylinder block 17 further has therein a spring chamber 17c, a communication space 17d, a second shaft hole 17e, and a third feeding passage 31c. The spring chamber 17c extends backward from the front surface of the cylinder block 17 and communicates with the crank chamber 21, so that the spring chamber 17c forms a part of the crank chamber 21. The cylinder block 17 includes a return spring 35 disposed in the spring chamber 17c. The return spring 35 urges the swash plate 5 toward the front side of the crank chamber 21 when the inclination angle of the swash plate 5 is at the minimum.

The communication space 17d of the cylinder block 17 extends forward from the rear surface of the cylinder block 17. The cylinder block 17 further has a first thrust bearing 37a and a second coil spring 39 disposed in the communication space 17d. The second coil spring 39 is interposed between the first thrust bearing 37a and the valve forming plate unit 19 to support and urge the first thrust bearing 37a forward. The second shaft hole 17e longitudinally extends to connect the spring chamber 17c and the communication space 17d. The cylinder block 17 further has a second slide bearing 25b disposed in the second shaft hole 17e. The first and the second slide bearings 25a, 25b may be replaced by rolling bearings.

The third feeding passage 31c longitudinally extends in the cylinder block 17. The third feeding passage 31c opens to the crank chamber 21 at the front end of the third feeding passage 31c and opens on the rear surface of the cylinder block 17 at the rear end of the third feeding passage 31c.

The valve forming plate unit 19 is disposed between the cylinder block 17 and the second housing member 15, and includes a valve plate 190, a suction valve plate 191, a discharge valve plate 192, and a retainer plate 193.

The valve forming plate unit 19 has the same number of suction holes 190a and discharge holes 190b as the cylinder bores 17a. The suction holes 190a are formed through the valve plate 190, the discharge valve plate 192, and the retainer plate 193. The discharge holes 190b are formed through the valve plate 190 and the suction valve plate 191. The valve forming plate unit 19 further has a throttle passage 190c and a third communication hole 190d. The throttle passage 190c and the third communication hole 190d are formed through the valve plate 190, the suction valve plate 191, the discharge valve plate 192, and the retainer plate 193.

Each cylinder bore 17a communicates with the suction chamber 15a through the suction hole 190a, and also communicates with the discharge chamber 15b through the discharge hole 190b. The throttle passage 190c connects the communication space 17d and the suction chamber 15a. The third communication hole 190d connects the second feeding passage 31b and the third feeding passage 31c.

The suction valve plate 191 is disposed on the front surface of the valve plate 190, and includes the suction reed valves 191a, which are elastically deformable so as to open or close the suction holes 190a. The discharge valve plate 192 is disposed on the rear surface of the valve plate 190, and has discharge reed valves 192a, which are elastically deformable so as to open or close the discharge holes 190b. The retainer plate 193 is disposed on the rear surface of the discharge valve plate 192 to determine the maximum opening degree of each discharge reed valve 192a.

In this compressor, the first to the third feeding passages 31a to 31c and the third communication hole 190d cooperate to form a feeding passage 31. The second and the third feeding passages 31b, 31c and the third communication hole 190d cooperate to connect the crank chamber 21 and the displacement control valve 33. Accordingly, the feeding passage 31 and the displacement control valve 33 cooperate to connect the crank chamber 21 and the discharge chamber 15b.

The drive shaft 3 has an outer peripheral surface 30 and extends longitudinally through the first housing member 13 and the cylinder block 17. Specifically, the drive shaft 3 is inserted in the boss 13c and extends backward longitudinally through the crank chamber 21 to be inserted in the cylinder block 17. More specifically, the drive shaft 3 is inserted into the sealing member 23 in the first accommodation space 130 at the front end of the drive shaft 3. The drive shaft 3 is supported by the first slide bearing 25a in the first shaft hole 13d and by the second slide bearing 25b in the second shaft hole 17e. The drive shaft 3 is also supported by the first thrust bearing 37a in the communication space 17d at the rear end of the drive shaft 3. Accordingly, the drive shaft 3 is supported in the crank chamber 21 so as to rotate about the axis O of the drive shaft 3 that is parallel to the longitudinal direction of the compressor. The sealing member 23 holds the drive shaft 3 to be rotatable and seals off the crank chamber 21 from outside of the first housing member 13.

The drive shaft 3 has a threaded portion 3a at the front end thereof and is connected to a pulley or an electromagnetic clutch (not shown) at the threaded portion 3a.

The drive shaft 3 has thereon the lug member 41, the swash plate 5, a valve member 43, and a third coil spring 45. The lug member 41 is press-fit to the drive shaft 3, so that the lug member 41 is rotatable with the drive shaft 3 in the crank chamber 21. The lug member 41 has a second thrust bearing 37b disposed between the front wall 13a of the first housing member 13 and the lug c member 41.

The lug member 41 includes a pair of lug arms 41a. The lug arms 41a are disposed adjacent to each other and extends backward from the lug member 41. The lug member 41 further includes a pair of guide faces 41b disposed between the lug arms 41a. The guide faces 41b extend obliquely backward from the outer periphery side of the lug member 41 toward the axis O of the drive shaft 3. The drawings such as FIG. 1 show one lug arm 41a and one guide face 41b.

The swash plate 5 is disposed behind the lug member 41 in the crank chamber 21 such that the lug member 41 faces the swash plate 5. The swash plate 5 is formed in an approximate disc shape and has a front surface 5a and a rear surface 5b that face frontward and rearward, respectively. The swash plate 5 further has an insertion hole 5c, an abutment portion 5d, and a weight portion 5e.

The insertion hole 5c passes through the swash plate 5 from the front surface 5a to the rear surface 5b for receiving the drive shaft 3, so that the swash plate 5 is supported on the drive shaft 3 for rotation with the drive shaft 3. The abutment portion 5d projects toward the drive shaft 3 in the insertion hole 5c to abut on the outer peripheral surface 30 of the drive shaft 3 in the insertion hole 5c. The weight portion 5e of the swash plate 5 is formed in an approximate semi-cylindrical shape and extends forward from the front surface 5a of the swash plate 5. The weight portion 5e includes a pressing surface 500. The pressing surface 500 extends obliquely toward the axis O of the drive shaft 3 and is formed continuously from the abutment portion 5d in the insertion hole 5c of the swash plate 5.

The swash plate 5 further includes a pair of swash plate arms 5f. The swash plate arms 5f are disposed adjacent to each other and extend forward from the front surface 5a of the swash plate 5. The swash plate arms 5f are located opposite to the abutment portion 5d and the weight portion 5e across the axis O of the drive shaft 3. The drawings such as FIG. 1 show one of the swash plate arms 5f.

In this compressor, the swash plate 5 is mounted on the drive shaft 3 such that the swash plate arms 5f are located between the lug arms 41a. The lug member 41 and the swash plate 5 are coupled to each other such that the swash plate arms 5f are located between the lug arms 41a. This configuration enables the swash plate 5 to rotate with the lug member 41 in the crank chamber 21 by the rotary movement of the drive shaft 3 transmitted through the lug arms 41a to the swash plate arms 5f.

The swash plate arms 5f are located between the lug arms 41a, so that the swash plate arms 5f abut and slide on the guide faces 41b at the front ends of the swash plate arms 5f. This configuration enables the swash plate 5 to change its inclination angle to the maximum inclination angle shown in FIG. 1, the intermediate inclination angle in FIG. 2, or the minimum inclination angle in FIG. 3 with respect to an imaginary plane perpendicular to the axis O of the drive shaft 3. The intermediate inclination angle of the swash plate 5 is an angle that is smaller than the maximum inclination angle and is greater than the minimum inclination angle. In this compressor, the intermediate inclination angle of the swash plate 5 has a certain definite range between the maximum inclination angle and the minimum inclination angle, more specifically, the intermediate inclination angle is an angle of the swash plate 5 while the valve member 43 is covering whole the openings of the second radial passages 55a to 55c on the outer peripheral surface 30 of the drive shaft 3. Details of the valve member 43 will be described later.

The valve member 43 is formed in a ring shape and has a front end face 43a, a rear end face 43b, and a tapered surface 43c formed continuously from the front end face 43a to the rear end face 43b to decrease the diameter. The valve member 43 is tapered from the front end face 43a to the rear end face 43b. The valve member 43 is disposed between the lug member 41 and the swash plate 5. The third coil spring 45 is disposed between the lug member 41 and the front end face 43a of the valve member 43. The drive shaft 3 is inserted into the valve member 43 and the third coil spring 45. The third coil spring 45 urges the valve member 43 backward in the crank chamber 21. In this compressor, as shown in FIGS. 1 to 3, the tapered surface 43c of the valve member 43 constantly abuts on the pressing surface 500 of the swash plate 5 regardless of the inclination angle of the swash plate 5. This configuration enables the valve member 43 to axially slide on the outer peripheral surface 30 of the drive shaft 3 between the lug member 41 and the swash plate 5 in conjunction with the inclination of the swash plate 5.

The pistons 7 are reciprocally movable in the respective cylinder bores 17a, respectively. Each piston 7 and the valve forming plate unit 19 cooperate to define a compression chamber 47 in the cylinder bore 17a.

The pistons 7 each have a recess 7a for engagement. The recess 7a has therein semi-spherical shoes 49a, 49b. The shoes 49a, 49b serve as a conversion mechanism that is configured to convert the rotary movement of the swash plate 5 to the reciprocating movement of the piston 7. This configuration enables the piston 7 to be reciprocally movable in the cylinder bore 17a with a stroke length depending on the inclination angle of the swash plate 5. The shoes 49a, 49b may be replaced by a wobble type conversion mechanism including a thrust bearing for supporting a wobble plate on the rear surface 5b of the swash plate 5 and connecting rods for connecting the wobble plate and the pistons 7.

The drive shaft 3 has therein an axial passage 51, first radial passages 53a to 53c (FIG. 4), the second radial passages 55a to 55c (FIG. 5), and a third radial passage 57 (FIGS. 1 to 3).

The axial passage 51 extends in the drive shaft 3 in the axial direction of the drive shaft 3 and communicates with the communication space 17d at the rear end of the axial passage 51. The axial passage 51 has a larger diameter than that of the throttle passage 190c.

The first radial passages 53a to 53c are located in the rear part of the drive shaft 3. As shown in FIG. 4, each of the first radial passages 53a to 53c communicates with the axial passage 51and extends from the axial passage 51 in the radial direction of the drive shaft 3 to open on the outer peripheral surface 30 of the drive shaft 3 at intervals in the circumferential direction of the drive shaft 3. Specifically, the first radial passages 53b, 53c extend in opposite directions, which are perpendicular to the first radial passage 53a, with respect to the axis O of the drive shaft 3 and open on the outer peripheral surface 30 of the drive shaft 3. Each of the first radial passages 53a to 53c has a larger diameter than that of the throttle passage 190c shown in FIGS. 1 to 3.

The second radial passages 55a to 55c are formed at the approximate longitudinal center of the drive shaft 3, that is, disposed in front of the first radial passages 53a to 53c. As shown in FIG. 5, each of the second radial passages 55a to 55c communicates with the axial passage 51 and extends from the axial passage 51 in the radial direction of the drive shaft 3 to open on the outer peripheral surface 30 of the drive shaft 3 at intervals in the circumferential direction of the drive shaft 3 as well as the first radial passages 53a to 53c. Specifically, the second radial passages 55b, 55c extend in opposite directions, which are perpendicular to the second radial passage 55a, with respect to the axis O of the drive shaft 3 and open on the outer peripheral surface 30 of the drive shaft 3. The second radial passages 55a to 55c each have the same diameter as the first radial passages 53a to 53c, that is, each of the second radial passages 55a to 55c has a larger diameter than that of the throttle passage 190c shown in FIGS. 1 to 3.

As shown in FIG. 1, the third radial passage 57 is formed in the front part of the drive shaft 3 in front of the first and second radial passages 53a to 53c, 55a to 55c. The third radial passage 57 communicates with the axial passage 51 and extends from the axial passage 51 in the radial direction of the drive shaft 3 to open on the outer peripheral surface 30 of the drive shaft 3. The third radial passage 57 has the same diameter as each of the first and second radial passages 53a to 53c, 55a to 55c, that is, the third radial passage 57 has a larger diameter than that of the throttle passage 190c.

In this compressor, the drive shaft 3 is inserted into the first housing member 13 and the cylinder block 17, so that the first radial passages 53a to 53c are positioned in the spring chamber 17c, that is, positioned on the rear side of the crank chamber 21. The first radial passages 53a to 53c are in constant communication with the crank chamber 21.

When the swash plate 5 is at the maximum inclination angle, the second radial passages 55a to 55c are positioned in the insertion hole 5c of the swash plate 5 at the approximate longitudinal center of the crank chamber 21, in other words, the second radial passages 55a to 55c open on the outer peripheral surface 30 of the drive shaft 3 in the crank chamber 21 at positions that are closer to the swash plate 5 than the first radial passages 53a to 53c are to the swash plate 5. The first radial passages 53a to 53c open on the outer peripheral surface 30 of the drive shaft 3 in the crank chamber 21 at positions that are closer to the cylinder bores 17a than the second radial passages 55a to 55c are to the cylinder bores 17a.

The drive shaft 3 and the swash plate 5 are positioned such that the second radial passages 55a to 55c and the abutment portion 5d do not face each other in the insertion hole 5c of the swash plate 5. That is, the second radial passages 55a to 55c open on the outer peripheral surface 30 of the drive shaft 3 at positions that are spaced from the abutment portion 5d in the circumferential direction of the drive shaft 3. In this compressor, the second radial passages 55a to 55c are connected to or disconnected from the crank chamber 21 by the axial movement of the valve member 43 on the drive shaft 3. This connecting system between the second radial passages 55a to 55c and the crank chamber 21 will be described later.

The third radial passage 57 is positioned in the first accommodation space 130, specifically, positioned between the sealing member 23 and the lug member 41. The first accommodation space 130 communicates with the crank chamber 21 through the communication passage 13e, so that the third radial passage 57 in the first accommodation space 130 is in constant communication with the crank chamber 21.

In this compressor, the axial passage 51, the first radial passages 53a to 53c, the second radial passages 55a to 55c, the third radial passage 57, the communication space 17d, and the throttle passage 190c cooperate to form a bleeding passage 59, so that the crank chamber 21 communicates with the suction chamber 15a through the bleeding passage 59. The feeding passage 31, the bleeding passage 59 and the displacement control valve 33 cooperate to form the control mechanism 9.

In this compressor, the suction port 15e is connected to an evaporator through a pipe. The discharge port 15g is connected to a condenser through a pipe. The evaporator and the condenser are connected through the pipes and an expansion valve. The evaporator, the expansion valve, the condenser, and the compressor cooperate to form a refrigeration circuit of a vehicle air conditioner. The evaporator, the expansion valve, the condenser, and the pipes are not shown in the drawings.

In this compressor, each piston 7 makes a reciprocating movement in the cylinder bore 17a in response to the rotation of the swash plate 5 caused by the rotary movement of the drive shaft 3. The compression chamber 47 changes its volume depending on the stroke length of the piston 7. The refrigerant gas, which flows from the evaporator into the suction chamber 15a through the suction port 15e, is introduced from the suction chamber 15a into the compression chamber 47 to be compressed. The compressed refrigerant gas is discharged from the compression chamber 47 to the discharge chamber 15b, and then discharged to the condenser through the discharge port 15g. When the pressure within the discharge chamber 15b is below a predetermined pressure value, as shown in FIG. 3, the first coil spring 27c urges the check valve body 27b to close the first and the second communication holes 271, 272 so as to prevent the back-flow of the refrigerant gas from the condenser to the discharge chamber 15b. However, the check valve body 27b may not completely close the first and the second communication holes 271, 272 so as to discharge a small flow rate of refrigerant gas, which is discharged from the compression chamber 47 to the discharge chamber 15b, to the condenser.

In this compressor, the control mechanism 9 is configured to adjust the pressure within the crank chamber 21 so as to adjust the discharge volume of the compressor.

Specifically, the displacement control valve 33 of the control mechanism 9 adjusts the opening degree of the feeding passage 31, which is formed by the first to the third feeding passages 31a to 31c and the third communication hole 190d. The refrigerant gas at high pressure is introduced from the discharge chamber 15b into the crank chamber 21 through the feeding passage 31. Then, the refrigerant gas in the crank chamber 21 is introduced into the suction chamber 15a through the bleeding passage 59, which is formed by the axial passage 51, the first radial passages 53a to 53c, the second radial passages 55a to 55c, the third radial passage 57, the communication space 17d and the throttle passage 190c. The adjustment of the opening degree by the displacement control valve 33 of the control mechanism 9 controls the balance between the flow rate of the high pressure refrigerant gas introduced from the discharge chamber 15b into the crank chamber 21 through the feeding passage 31 and the flow rate of the refrigerant gas introduced from the crank chamber 21 into the suction chamber 15a through the bleeding passage 59. The balance between these two flow rates determines the pressure within the crank chamber 21. The change in the pressure within the crank chamber 21 varies the differential pressure between the crank chamber 21 and the compression chambers 47, thereby changing the inclination angle of the swash plate 5. The inclination angle of the swash plate 5 determines the stroke length of each piston 7 to adjust the discharge volume of the compressor.

Accordingly, in this compressor, the pressure within the crank chamber 21 increases as the displacement control valve 33 increases the opening degree of the feeding passage 31, so that the swash plate 5 decreases its inclination angle with the abutment portion 5d abutting on the outer peripheral surface 30 of the drive shaft 3. The decreasing inclination angle of the swash plate 5 decreases the stroke length of each piston 7, thereby decreasing the discharge volume per rotation of the drive shaft 3. Conversely, the pressure within the crank chamber 21 decreases as the displacement control valve 33 decreases the opening degree of the feeding passage 31, so that the swash plate 5 increases its inclination angle with the abutment portion 5d abutting on the outer peripheral surface 30 of the drive shaft 3. The increasing inclination angle of the swash plate 5 increases the stroke length of each piston 7, thereby increasing the discharge volume per rotation of the drive shaft 3.

In this compressor, the drive shaft 3 has therein the first radial passages 53a to 53c, the second radial passages 55a to 55c, and the third radial passage 57 that communicate with the axial passage 51, and the refrigerant gas in the crank chamber 21 is introduced into the suction chamber 15a through the first radial passages 53a to 53c and the second radial passages 55a to 55c. This configuration enables the flow rate control of the refrigerant gas introduced from the third radial passage 57 to the axial passage 51. The throttle passage 190c has a smaller diameter than those of the axial passage 51, the first radial passages 53a to 53c, the second radial passages 55a to 55c and the third radial passage 57, so that the throttle passage 190c enables to lead the refrigerant gas to the suction chamber 15a at a preferred pressure.

In this compressor, each cylinder bore 17a positioned adjacent to the rear part of the crank chamber 21 leaks blow-by gas containing a relatively large amount of lubricant, so that the refrigerant gas presents in the rear part of the crank chamber 21 contains a relatively large amount of lubricant. The lubricant is sprinkled by the rotation of the drive shaft 3 and the swash plate 5 radially and outwardly in the crank chamber 21, and flows down in the crank chamber 21 from the peripheral wall 13b to the front wall 13a, so that the plenty of lubricant presents in the front part of the crank chamber 21. That is, the refrigerant gas in the front part of the crank chamber 21 contains larger amount of lubricant than the refrigerant gas in the rear part of the crank chamber 21. On the other hand, the lubricant in the refrigerant gas existing around the longitudinal center of the crank chamber 21, specifically, the lubricant in the refrigerant gas existing around the insertion hole 5c of the swash plate 5 is reduced because the lubricant is sprinkled by the rotation of the drive shaft 3 and the swash plate 5 radially and outwardly in the crank chamber 21.

Accordingly, the refrigerant gas flowing from the communication passage 13e through the third radial passage 57 to the axial passage 51 contains larger amount of lubricant than the refrigerant gas introduced from the first radial passages 53a to 53c or the second radial passages 55a to 55c to the axial passage 51. The refrigerant gas introduced from the first radial passages 53a to 53c to the axial passage 51 contains larger amount of lubricant than the refrigerant gas introduced from the second radial passages 55a to 55c to the axial passage 51. In other words, the refrigerant gas introduced from the second radial passages 55a to 55c to the axial passage 51 contains the smallest amount of lubricant.

In this compressor, the refrigerant gas containing the lubricant in the crank chamber 21 is introduced into the suction chamber 15a through the third radial passage 57, the axial passage 51, the communication space 17d, and the throttle passage 190c to adjust the pressure within the crank chamber 21, so that the lubricant in the refrigerant gas suitably lubricates the second thrust bearing 37b, the sealing member 23 and the first slide bearing 25a. Particularly, the sealing member 23 is lubricated constantly because the third radial passage 57 is in constant communication with the crank chamber 21 through the first accommodation space 130 and the communication passage 13e.

In this compressor, the valve member 43 moves on the drive shaft 3 in the axial direction of the drive shaft 3 in conjunction with the inclination of the swash plate 5, so that the sum of the opening areas of the first radial passages 53a to 53c and the second radial passages 55a to 55c changes depending on the inclination angle of the swash plate 5 as shown in FIG. 6. Specifically, the sum of the opening areas of the first radial passages 53a to 53c and the second radial passages 55a to 55c reaches the maximum level at the minimum inclination angle or the maximum inclination angle of the swash plate 5. The sum of the opening areas gradually decreases with the increasing inclination angle of the swash plate 5 from the minimum inclination angle to the intermediate inclination angle. The sum of the opening areas is kept to the minimum level while the swash plate 5 is at the intermediate inclination angle. Then, the sum of the opening areas gradually increases with the increasing inclination angle of the swash plate 5 from the intermediate inclination angle to the maximum inclination angle. In this compressor, since the first radial passages 53a to 53c are in constant communication with the crank chamber 21, the opening areas of the first radial passages 53a to 53c are maintained constant, which does not reduce the sum of the opening areas of the first radial passages 53a to 53c and the second radial passages 55a to 55c to zero. The operation according to the change in the sum of the opening areas of the first radial passages 53a to 53c and the second radial passages 55a to 55c is described below.

In this compressor, as shown in FIG. 1, when the inclination angle of the swash plate 5 is at the maximum, the pressing surface 500 presses the valve member 43 on the drive shaft 3 axially toward the front part of the crank chamber 21 to move the valve member 43 away from the openings of the second radial passages 55a to 55c on the outer peripheral surface 30 of the drive shaft 3. That is, when the inclination angle of the swash plate 5 is at the maximum, the second radial passages 55a to 55c are connected to the crank chamber 21 and reach their maximum opening areas as described above. Accordingly, the refrigerant gas in the crank chamber 21 is introduced from each of the first radial passages 53a to 53c, the second radial passages 55a to 55c, and the third radial passage 57 into the suction chamber 15a through the axial passage 51, the communication space 17d, and the throttle passage 190c. When the sum of the opening areas of the first radial passages 53a to 53c and the second radial passages 55a to 55c is maximum, this compressor enables the reduction of the flow rate of the refrigerant gas introduced through the third radial passage 57 into the suction chamber 15a while ensuring the overall flow rate of the refrigerant gas introduced from the crank chamber 21 into the suction chamber 15a. Also, this compressor enables the decrease of the flow rate of the refrigerant gas introduced through the first radial passages 53a to 53 since the refrigerant gas is introduced through the second radial passages 55a to 55c in addition to the first radial passages 53a to 53c.

Since the refrigerant gas introduced through the second radial passages 55a to 55c from the crank chamber 21 contains only a small amount of lubricant as described above, the lubricant is not excessively introduced with the refrigerant gas through the second radial passages 55a to 55c into the suction chamber 15a when the second radial passages 55a to 55c are connected to the crank chamber 21, and the certain amount of the lubricant is secured in the crank chamber 21. Accordingly, when the inclination angle of the swash plate 5 is at the maximum, this compressor enables the reduction of the lubricant introduced from the crank chamber 21 into the suction chamber 15a while lubricating the sealing member 23 by the lubricant in the refrigerant gas introduced through the third radial passage 57. This compressor is unlikely to cause the insufficient lubrication in the crank chamber 21 when the inclination angle of the swash plate 5 is at the maximum.

In this compressor, the valve member 43 axially moves on the drive shaft 3 toward the rear part of the crank chamber 21 in conjunction with the decreasing inclination angle of the swash plate 5 from the maximum to gradually cover the openings of the second radial passages 55a to 55c on the outer peripheral surface 30 of the drive shaft 3, so that the sum of the opening areas of the first radial passages 53a to 53c and the second radial passages 55a to 55c gradually decreases as shown in FIG. 6 as the opening areas of the second radial passages 55a to 55c gradually decrease. Accordingly, the flow rate of the refrigerant gas introduced from the third radial passage 57 to the axial passage 51 gradually increases. As shown in FIG. 2, while the swash plate 5 is at the intermediate inclination angle, the valve member 43 covers the whole openings of the second radial passages 55a to 55c, and the second radial passages 55a to 55c are disconnected from the crank chamber 21 by the valve member 43 on the drive shaft 3. While the swash plate 5 is at the intermediate inclination angle, the refrigerant gas is not introduced from the crank chamber 21 into the suction chamber 15a through the second radial passages 55a to 55c and the axial passage 51.

In this compressor, when the sum of the opening areas of the first radial passages 53a to 53c and the second radial passages 55a to 55c is minimum, the flow rate of the refrigerant gas introduced from the third radial passage 57 to the axial passage 51 increases, thus, the lubricant in the refrigerant gas introduced from the third radial passage 57 lubricates the sealing member 23 in the first accommodation space 130 suitably. As the opening areas of the second radial passages 55a to 55c gradually decrease, the flow rate of the refrigerant gas introduced from the first radial passages 53a to 53c to the axial passage 51 gradually increases. As a result, when the swash plate 5 is at the intermediate inclination angle, this compressor prevents or inhibits the excessive accumulation of the lubricant in the crank chamber 21 and the heat generation of the lubricant caused by the agitation by the swash plate 5 in the crank chamber 21. The prevention of the excessive lubricant accumulation in the crank chamber 21 enables this compressor to eliminate or minimize the insufficient circulation of the lubricant in the refrigeration circuit in which this compressor is included.

In this compressor, the valve member 43 further moves axially on the drive shaft 3 toward the rear part of the crank chamber 21 and gradually away from the openings of the second radial passages 55a to 55c on the outer peripheral surface 30 of the drive shaft 3 with the decreasing inclination angle of the swash plate 5 from the intermediate inclination angle, so that the opening areas of the second radial passages 55a to 55c gradually increase as the second radial passages 55a to 55c gradually open to the crank chamber 21. As shown in FIG. 3, when the inclination angle of the swash plate 5 is at the minimum, the valve member 43 is completely away from the openings of the second radial passages 55a to 55c and the second radial passages 55a to 55c reach their maximum opening areas, thus, the sum of the opening areas of the first radial passages 53a to 53c and the second radial passages 55a to 55c reaches the maximum level. That is, as well as the case for the maximum inclination angle, when the inclination angle of the swash plate 5 is at the minimum, this compressor enables the decrease of the flow rate of the refrigerant gas introduced through the third radial passage 57 into the suction chamber 15a while ensuring decreasing the overall flow rate of the refrigerant gas introduced from the crank chamber 21 into the suction chamber 15a. Accordingly, this compressor enables the reduction of the lubricant introduced from the crank chamber 21 to the suction chamber 15a while ensuring the overall flow rate of the refrigerant gas introduced from the crank chamber 21 into the suction chamber 15a.

When the discharge volume per rotation of the drive shaft 3 is reduced at the minimum inclination angle of the swash plate 5, this compressor may slightly flow the refrigerant gas, which was discharged from the compression chamber 47 to the discharge chamber 15b, to the condenser. In this case, the lubricant, which was introduced with the refrigerant gas from the crank chamber 21 to the suction chamber 15a, is to the compression chamber 47 and then discharger) to the condenser through the discharge chamber 15b. When the inclination angle of the swash plate 5 is at the minimum, the lubricant flowing into the compressor with the refrigerant gas decreases because the flow rate of the refrigerant gas flowing from the evaporator into the suction chamber 15a through the suction port 15e decreases. However, even in this case, this compressor is unlikely to cause the insufficient lubrication in the crank chamber 21.

In the adjustment of the pressure within the crank chamber 21, this compressor enables the suitable control of the amount of the lubricant introduced with the refrigerant gas from the crank chamber 21 to the suction chamber 15a while ensuring the flow rate of the refrigerant gas introduced from the crank chamber 21 to the suction chamber 15a through the bleeding passage 59. Therefore, this compressor is capable of securing the lubricant in the crank chamber 21 depending on the inclination angle of the swash plate 5.

Accordingly, the compressor according to the first embodiment exhibits higher durability and controllability.

Particularly, this compressor has the first radial passages 53a to 53c in the drive shaft 3. This configuration enables the suitable control of the flow rate of the refrigerant gas introduced from the crank chamber 21 into the suction chamber 15a through the first radial passages 53a to 53c and the axial passage 51. This compressor further has the second radial passages 55a to 55c in the drive shaft 3. This configuration enables the suitable control of the flow rate of the refrigerant gas introduced from the crank chamber 21 to the suction chamber 15a through the second radial passages 55a to 55c and the axial passage 51 when the second radial passages 55a to 55c are connected to the crank chamber 21.

In this compressor, the openings of the second radial passages 55a to 55c are located away from the abutment portion 5d in the circumferential direction of the drive shaft 3, so that the openings of the second radial passages 55a to 55c do not face the abutment portion 5d, or, do not contact the abutment portion 5d in the insertion hole 5c of the swash plate 5. This configuration enables the suitable change of the inclination angle of the swash plate 5.

Second Embodiment

As shown in FIG. 7, the compressor according a second embodiment has three second radial passages, namely, second radial passages 61a to 61c in the drive shaft 3. As well as the second radial passages 55a to 55c according to the first embodiment, each of the second radial passages 61a to 61c communicates with the axial passage 51 and extends from the axial passage 51 in the radial direction of the drive shaft 3 to open on the outer peripheral surface 30 of the drive shaft 3 at the approximate longitudinal center of the drive shaft 3. The second radial passage 61a has a larger diameter than those of the second radial passages 61b, 61c and is disposed behind the second radial passages 61b, 61c in the axial direction of the drive shaft 3. In this compressor, the second radial passages 61a to 61c are formed at positions where whole the second radial passages 61a to 61c are covered by the valve member 43 while the swash plate 5 is at the intermediate inclination angle. The structure of the compressor according to the second embodiment is otherwise similar to the compressor according to the first embodiment and will not be further elaborated here.

According to the second embodiment, the second radial passage 61a has a larger diameter than those of the second radial passages 61b, 61c. This configuration enables the suitable adjustment of the opening degree of the second radial passages 61a to 61c along with the axial movement of the valve member 43. The operation of the compressor according to the second embodiment is otherwise similar to the compressor according to the first embodiment and will not be further elaborated here.

Although the present invention is described with the first and the second embodiments, the present invention is not limited thereto, and the invention may appropriately be modified within the gist of the present invention.

For example, instead of the third radial passage 57, the first radial passages 53a to 53c may be formed in the front part of the drive shaft 3 to open between the sealing member 23 and the lug member 41 on the outer peripheral surface 30 of the drive shaft 3.

The first radial passage of the present invention may be formed by the first radial passages 53a only without the first radial passages 53b, 53c. The drive shaft 3 may have an additional first radial passage other than the first radial passages 53a to 53c. The second radial passage of the present invention may be formed by the second radial passages 55a only without the second radial passages 55b, 55c. The drive shaft 3 may have an additional second radial passage other than the second radial passages 55a to 55c. The drive shaft 3 may have an additional third radial passage other than the third radial passage 57.

In the compressor according to the first embodiment, the first radial passages 53a to 53c, the second radial passages 55a to 55c, and the third radial passage 57 have the same diameter. According to the present invention; however, each of the first radial passages 53a to 53c may have a lager diameter than those of the second radial passages 55a to 55c and the third radial passage 57. Each of the second radial passages 55a to 55c may have a lager diameter than those of the first radial passages 53a to 53c and the third radial passage 57. The third radial passage 57 may have a lager diameter than those of the first radial passages 53a to 53c and the second radial passages 55a to 55c.

In the compressor according to the first embodiment, the displacement control valve 33 adjusts the opening degree of the feeding passage 31. The compressor may have, however, a displacement control valve which is configured to adjust the opening degree of the bleeding passage 59.

The present invention is applicable to air conditioners.

VARIABLE DISPLACEMENT TYPE SWASH PLATE COMPRESSOR

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CPC

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