Apparatus for Lubricating a Swash Plate Compressor

The present invention relates to a swash plate type compressor and in particular, to a swash plate type compressor for use in air conditioning systems for vehicles.

U.S. Pat. No. 3,352,485 of Akira Niki et al. and U.S. Pat. No. 3,1801,227 of Shozo Nakayama, disclose a multi-piston, double acting, single swash plate refrigerant gas compressor having a pair of horizontal axially aligned cylinder blocks forming a combined block.

The compressors of the type disclosed in the abovementioned Patent and Application are provided with an internal arrangement for distributing oil lubricant to movable parts or elements of such compressors, such as radial and thrust bearings and the pistons, so that the movable parts or elements are lubricated by the distributed oil lubricant during operation of the compressors. However, it has recently been found that these prior internal arrangements are incomplete, especially in lubricating steel ball bearings and shoes connecting the swash plate and the multi-pistons.

Therefore, the principal object of the present invention is to provide a general improvement for the internal lubricating arrangement of the prior type compressor, wherein the internal lubricating arrangement is improved so as to prevent seizure of the moving elements of the compressor during long continuous operation.

Another object of the present invention is to improve the internal lubricating arrangement of the prior art compressor so as to be capable of directly supplying oil lubricant to the steel ball bearings and shoes connecting the swash plate and the multi-pistons of the compressor.

That is to say, in accordance with the present invention, for a swash plate type compressor, there is provided an improvement comprising provision means for directly introducing a part of said oil particles suspended in the refrigerant gas which rushes into the combined block through one or more inlet ports formed in said combined block, and into a swash plate chamber for rotatably mounting the swash plate therein.

In accordance with the present invention, there is provided a further improvement comprising means for permitting the blow-by refrigerant gas in the swash plate chamber to flow into the suction chambers of cylinder heads positioned at the ends of the combined block via the bottom oil chamber of the compressor, whereby, during operation of the compressor, the oil lubricant separated from the refrigerant gas is distributed by the blow-by gas to the cylinder bores and other moving elements which are required to be lubricated by the oil lubricant.

The present invention will be made more apparent in detail from the ensuring description, reference being made to the accompanying drawings, wherein:

FIG. 1 is a longitudinal cross sectional view of a swash plate type compressor according to one embodiment of the present invention;

FIG. 2 is another longitudinal cross sectional view of the compressor of FIG. 1;

FIG. 3 is a vertical cross sectional view of one of the cylinder blocks of the compressor of FIG. 1, taken along the line III--III of FIG. 2;

FIG. 4 is a front view of the rear cylinder head of the compressor of FIG. 1, illustrating an internal construction of the cylinder head;

FIG. 5 is a front view of one of the valve plates employed for the compressor of FIG. 1;

FIG. 6 is a longitudinal cross sectional view of a swash plate type compressor according to another embodiment of the present invention.

The drawings of FIGS. 1 through 5 show an embodiment of the present invention, which is an improvement over the compressor of the type disclosed in the above-mentioned prior U.S. patent application.

Referring to FIGS. 1 through 5, the compressor has a pair of cylinder blocks, i.e. a front cylinder block 11a and a rear cylinder block 11b, combined with each other in an axial alignment. The combined block formed by the pair of cylinder blocks 11a and 11b is provided with three axially extending cylinder bores 13 arranged in parallel with each other, that is one upper cylinder bore and two lower cylinder bores. The combined block is also provided with a pair of oil separating sections 14a and 14b, discharge sections 15 for compressed refrigerant gas, a bottom oil reserving section 16, and a centrally arranged swash plate chamber 17. The respective sections 14a, 14b, 15 and 16 are formed in the spaces enclosed by the neighbouring cylinder bores 13 and the outer wall of the combined block. The combined block is further accompanied by a pair of front and rear cylinder heads 20 and 21 attached to the front and rear cylinder blocks 11a and 11b, respectively, via respective valve plates 18a and 18b and appropriate gaskets. The cylinder heads 20 and 21 are provided with, in their internal spaces, outer suction chambers 22 and 23, inner suction chambers 26 and 27, and exhaust chambers 24 and 25, respectively, which are defined by wall members 20a, 20b, 21a, and 21b projecting from internal end faces 48 and 49 of cylinder heads 20 and 21. As is apparent from FIG. 4, the outer and inner suction chambers are fluidly connected with each other, since each wall member 20b or 21b substantially formed in an annular shape has an opening for connection between outer and inner suction chambers. The valve plates 18a, 18b are provided with suction ports 28a, 28b connecting the oil separating sections 14a, 14b and the outer suction chambers 22, 23 respectively; discharge ports (not shown) connecting the exhaust chambers 24, 25 and the discharge sections 15; suction apertures 52 connecting the outer suction chambers 22, 23 and the cylinder bores 13; exhaust ports 29a, 29b connecting the cylinder bores 13 and the exhaust chambers 24, 25; and oil ports 30a, 30b connecting the oil separating sections 14a, 14b and the inner suction chambers 26, 27, respectively. These ports and apertures of the valve plates 18a and 18b are constituted by through-holes as shown in FIG. 5. The valve plates 18a and 18b are also provided with recessed channels 19a and 19b, respectively described later, which are grooved on the inner end faces of the valve plates so as to downwardly extend from the lowermost part of the centrally positioned bores 53a and 53b. Coaxially passing through both cylinder blocks 11a, 11b, front cylinder head 20, and front valve plate 18a, a drive shaft 31 is rotatably supported by needle bearings 32 provided at axially outer ends of the combined block, and is provided with a swash plate 33 secured to the middle of said drive shaft 31. The swash plate 33 is operatively connected with, via ball bearings 35 and shoes 36, double acting multi-pistons 34 which are slidably fitted in the three cylinder bores 13 arranged in parallel with the drive shaft 31. Therefore, when the swash plate 33 is rotated by the drive shaft 31, the multi-pistons reciprocate in the cylinder bores for effecting the compression action of the compressor. The axial loads produced by the reciprocating motions of the pistons 34 are borne by a pair of thrust bearings 37a and 37b arranged between both end faces of the boss of the swash plate 33 and respective cylinder blocks 11a and 11b. The needle bearings 32 supporting the drive shaft 31 are supplied with oil lubricant through the previously mentioned bores 53a and 53b of the valve plates 18a and 18b, and inner suction chambers 26 and 27 of the cylinder heads 20 and 21. The oil lubricant supplied to the needle bearings 32 is further capable of lubricating the thrust bearings 37a and 37b after passing through annular clearances 39a and 39b which act as oil supply passageways formed between the cylinder blocks 11a, 11b and the drive shaft 31. The reference numeral 40 designates a sealing member provided in the front cylinder block 11a. As shown in FIGS. 1, 2 and 3, the cylinder blocks 11a and 11b are provided with a pair of inlet ports 41 and 42, which open at the outer walls 12a and 12b of said cylinder blocks in order to introduce the refrigerant gas and the oil particles suspended in the gas, which are returned from the air-conditioning system of the vehicle, into the oil separating sections 14a, 14b of cylinder blocks 11a and 11b. However, as the inlet ports 41, 42 are formed so as to directly communicate with suction channels 43, 44 which are defined between the outer walls 12a, 12b of both cylinder blocks 11a, 11b and partition walls 17a, 17b of the swash plate chamber 17, and have relatively small vertically cross sectional areas, the returned refrigerant gas and oil particles are firstly introduced in the suction channels 43, 44 and subsequently led into the continuing oil separating sections 14a, 14b which have sector type vertical cross sections having areas larger than those of the suction channels 43, 44, respectively. The partition walls 17a, 17b of the swash plate chamber 17 are provided with through-holes 45, 46 for permitting a part of the oil particles suspended in the refrigerant gas introduced from the inlet ports 41, 42 to directly flow into the swash plate chamber 17 through said holes 45 and 46 due to the inertia of the stream of the refrigerant gas from the inlet ports 41 and 42. That is to say, the through-holes 45 and 46 are arranged to be nearly in alignment with inlet ports 41 and 42, respectively. The reference numeral 47 designates one of the outlet ports for enabling the compressed refrigerant gas, which is collected in the discharge sections 15 of the cylinder blocks 11a and 11b from the exhaust chambers 24, 25 of both cylinder heads 20, 21, to flow into the air-conditioning system of the vehicle. As shown in FIGS. 2 and 3, the swash plate chamber 17 is separated from the bottom oil reserving section 16 by lower partition walls 17c and 17d formed as one part of cylinder blocks 11a and 11b. The lower partition walls 17c and 17d are provided with outlet holes 50 and 51 through which the refrigerant gas and the oil particles in the swash plate chamber 17 can flow into the oil reserving section 16. It should be noted that the two outlet holes 50 and 51 may be replaced by a single outlet hole formed at the bottom face of the partition walls 17c and 17d. The refrigerant gas flowing out of the outlet holes 50 and 51 is introduced into the inner suction chambers 26, 27 of both cylinder heads 20, 21 after passing the oil reserving section 16 and the recessed channels 19a, 19b of the valve plates 18a, 18b. The refrigerant gas is then sucked together with the refrigerant gas which is introduced into the outer suction chambers 22, 23 after undergoing oil separation into cylinder bores 13 through suction apertures 52 so as to be compressed.

When the drive shaft 31 is driven, the compressor comes into operation for effecting compression of the refrigerant gas. During the operation of the compressor, the refrigerant gas together with the oil particles suspended in the gas, return from the air-conditioning system of the vehicle and rush into the suction channels 43, 44 of cylinder blocks 11a and 11b through inlet ports 41, 42. The major part of the refrigerant gas and oil particles then impinge upon the partition walls 17a and 17b of the swash plate chamber 17 and the flow is deflected in two opposed directions to the oil separating sections 14a and 14b, respectively. In the meantime, the remaining minor part of the refrigerant gas and the oil particles inertially flows into the swash plate chamber 17 through the through-holes 45 and 46 of the partition walls 17a and 17b, and the flow of the minor part impinges upon the rotating swash plate 33, so that the oil particles suspended in the refrigerant gas attach to or are splashed by the rotating swash plate. As a result, the oil particles wet the surface of the swash plate 33, ball bearings 35 and shoes 36 connecting the swash plate and the pistons 34, and thrust bearings 37a, 37b, so as to positively lubricate them. Since the swash plate chamber 17 is fluidly connected to the cylinder bores 13, it will be understood that the oil lubricant moved into the swash plate chamber 17 is also effective for lubricating the internal walls of the cylinder bores 13. The oil dropping down to the bottom of the swash plate chamber 17 enters into the bottom oil reserving section 16 through the holes 50 and 51 as described previously.

With respect to the previously described major part of the refrigerant gas and oil particles suspended in the gas, the oil particles are separated from the gas by the action of inertia when the flow is deflected into two opposed directions, and the separated oil flows towards the bottoms of the oil separating sections 14a and 14b. Further, the deflected flow of the refrigerant gas still containing oil particles comes into the oil separating sections 14a, 14b having larger cross sectional areas than the suction channels 43, 44, and as a result relatively heavy oil particles are then separated by gravity due to the retardation of the speed of the running flow. That is, the heavy oil particles fall down onto the bottom surface of the oil separating sections 14a and 14b. All of the separated oil in the front cylinder block 11a enters into the inner suction chamber 26 defined by wall member 20b through an oil port 30a of the valve plate 18a, and lubricates the seal member 40. The oil in the inner suction chamber 26 also wets the needle bearing 32 after passing through the bore 53a, and subsequently wets the thrust bearing 37a after passing through the oil supply channel 39a. In the case of rear cylinder block 11b, the entire portion of separated oil enters into the inner suction chamber 27 through an oil port 30b of the valve plate 18b, and lubricates the needle bearing 32 after passing through the bore 53b of the valve plate 18b. Subsequently, the oil also lubricates the thrust bearing 37b after passing through the oil supply channel 39b.

In the above embodiment of the present invention, the outer and inner suction chambers 22, 23, 26, 27 of front and rear cylinder heads 20 and 21 have a reduced internal pressure due to pumping of the pistons 34 during operation of the compressor. Therefore, the refrigerant gas flowing into the swash plate chamber 17 through the through-holes 45 and 46 are sucked into the inner suction chambers 26 and 27 via outlet holes 50 and 51 of the lower partition walls 17c and 17d, and the recessed channels 19a and 19b of the valve plates 18a and 18b. This refrigerant gas subsequently enters into cylinder bores 13 as shown by arrows B in FIG. 4, so that they are compressed in the cylinder bores 13. That is to say, it will be understood that during operation of the compressor, two refrigerant passageways in opposite directions are formed by the swash plate chamber 17, the outlet holes 50, 51, the bottom oil reserving sections 16, the recessed channels 19a, 19b, and the inner suction chambers 26, 27. These two refrigerant passageways are of course additional to the principal refrigerant passageways passing through the suction channels 43, 44, the oil separating sections 14a, 14b, and the outer suction chambers 22, 23. Arrows A in FIG. 4 show that the refrigerant gas passing through the principal refrigerant passageways, enters into the cylinder bores 13. It should be noted that the blow-by gas of high pressure, which leaks into the swash plate chamber 17 from the cylinder bores 13 during the compressing operation of the pistons 13, also flows through the outlet holes 50, 51, the bottom oil reserving section 16, and the recessed channels 19a, 19b, into the inner suction chambers 26, 27 so as to aid in forming the above-mentioned additional and novel refrigerant passageways. It should also be noted that the above-mentioned flow of the high pressure blow-by gas can be very effective for distributing the separated oil lubricant in the inner suction chambers 26, 27 to the cylinder bores, since the blow-by gas carries the oil lubricant into the cylinder bores 13 when it enters into said bores.

As is explained in detail with reference to one embodiment of the present invention, and in accordance with the present invention, there is provided means for directly introducing a part of the oil particles suspended in the refrigerant gas which returns from the air-conditioning system of a vehicle, into the swash plate chamber. Thus, the oil component in the refrigerant gas can be directly supplied especially to the ball bearings and the shoes connecting the swash plate and the multi-pistons, thereby definitely preventing seizure of the compressor. It should be understood that the present invention is particularly effective for a compressor having no pumping element for distributing the oil lubricant. Further, it should be noted that the oil particles entering into the swash plate chamber can have a low temperature and be of high viscosity, since they are immediately introduced from the inlet ports 41 and 42, and the through-holes 45 and 46. As a result, the lubricating effect of the high viscosity oil lubricant is excellent.

Also, when the compressor stops, it should be understood that the recessed channels 19a and 19b formed on the inner end faces of the valve plates 18a and 18b, and the wall member 20b and 21b of the cylinder heads 20 and 21 act as oil conduits guiding the separated oil in the oil separating sections 14a and 14b of the cylinder blocks into the bottom oil reserving section 16 of the combined block.

FIG. 6 shows another embodiment of the present invention. The compressor of this embodiment is different from the previous embodiment in that only a single inlet port 61 for introducing the refrigerant gas and the oil particles from the air-conditioning system of a vehicle into the compressor is provided, and also a single through-hole for directly introducing a part of the oil particles suspended in the returned refrigerant gas is formed in the partition wall of the swash plate chamber. Further, in the compressor of this embodiment, the oil separating sections 14a and 14b are fluidly connected to each other. The other portions are similar to the compressor of the previous embodiment, and therefore the same reference numerals are attached in FIG. 6. It will be easily understood that the embodiment of FIG. 6 exhibits the same advantageous lubricating effect as the embodiment of FIGS. 1 through 5 compared with the compressor of the known type.

In the foregoing description, the present invention is made apparent with reference to the two embodiments which are constructed on the basis of the swash plate type compressor of the type disclosed in the allowed U.S. patent application Ser. No. 188,897. However, it should be understood that the improvement of the present invention is similarly applicable to the compressor of the type disclosed in the U.S. Pat. No. 3,352,485.