Patent Grant
7547198
The present invention relates to a double-headed piston type compressor to compresses gas in front and rear compression chambers that are defined by double-headed pistons as the pistons reciprocate while a rotary shaft rotates.
Japanese Unexamined Patent Publication No. 7-63165 discloses a double-headed piston type compressor for a vehicle air-conditioner system.
As shown in
Referring back to
The shaft chamber 116a is open to the suction chamber 112 at the rear end of the rotary shaft 116. Refrigerant is introduced from an external circuit into the suction chamber 112. The refrigerant in the suction chamber 112 is introduced into the rear compression chamber 113B through the shaft chamber 116a of the rotary shaft 116 and the rear rotary valve 117B. Similarly, the refrigerant in the suction chamber 112 is introduced into the front compression chamber 113A through the shaft chamber 116a and the front rotary valve 117A.
However, since the front and rear rotary valves 117A and 117B are respectively utilized as the front and rear suction mechanisms 115A and 115B in the double-headed piston type compressor, the refrigerant gas that has been introduced from an external refrigerant circuit into the suction chamber 112 in the rear cylinder head 102 is distributed to the rear suction communication passage 118B and the front suction communication passage 118A. A gas path from the suction chamber 112 to the front rotary valve 117A is longer than that to the rear rotary valve 117B. The gas paths to the front and rear rotary valves 117A and 117B share a common part 119 of the shaft chamber 116a from the suction chamber 112 to the front end of the rear suction communication passage 118B as indicated by a double-headed arrow in
Namely, referring to both
The present invention provides a double-headed piston type compressor that introduces a sufficient amount of gas into a front compression chamber.
In accordance with the present invention, a double-headed piston type compressor includes a housing having a front housing and a rear housing and forming a plurality of first cylinder bores, a plurality of second cylinder bores and a suction chamber formed in the rear housing being located rearward of the second cylinder bores; a rotary shaft rotatably supported by the housing and having an inner chamber along the rotational axis, a first suction communication passage and a second suction communication passage, the inner chamber communicating with the suction chamber near a front end of the rear housing, wherein the first cylinder bores and the second cylinder bores are arranged around the rotational axis of the rotary shaft; a plurality of double-headed pistons connected to the rotary shaft, each of the pistons being accommodated in the first cylinder bore and the associated second cylinder bore to respectively define a first compression chamber and a second compression chamber, each of the pistons reciprocating for compressing gas in the first compression chambers and the second compression chambers as the rotary shaft rotates; a partition wall located in the inner chamber along the rotational axis of the rotary shaft for dividing the inner chamber into a first passage and a second passage, the first passage interconnecting the suction chamber and the first suction communication passage, the second passage interconnecting the suction chamber and the second suction communication passage, wherein the partition wall has a rear end portion that is closer to the suction chamber than a front end of the second communication passage; the gas in the first passage and the second passage maintaining substantially the same pressure as in the suction chamber, wherein the front end portion of the partition wall is fixed to an inner circumferential surface of the inner chamber so that a front end of the first passage is located frontward of a front end of the second passage and so that the first passage and the second passage are separately defined from each other; a first suction valve mechanism rotatably provided on the rotary shaft near a rear end of the front housing for introducing the gas from the suction chamber to the first compression chambers through the first passage, the first suction valve mechanism including a first rotary valve that has the first suction communication passage for sequentially interconnecting the first passage and the first compression chambers in a suction process as the first suction valve mechanism rotates synchronously with the rotary shaft; and a second suction valve mechanism rotatably provided on the rotary shaft near the front end of the rear housing for introducing the gas from the suction chamber to the second compression chambers through the second passage, the second valve mechanism including a second rotary valve that has the second suction communication passage for sequentially interconnecting the second passage and the second compression chambers in the suction process as the second suction valve mechanism rotates synchronously with the rotary shaft.
The present invention also provides a double-headed piston type compressor including a housing having a front housing and a rear housing and forming a plurality of first cylinder bores, a plurality of second cylinder bores and a suction chamber formed in the rear housing, the rear housing being located rearward of the second cylinder bores; a rotary shaft rotatably supported by the housing and having a rotational axis, the shaft having an inner chamber along the rotational axis, a first suction communication passage and a second suction communication passage. the inner chamber communicating with the suction chamber near a front end of the rear housing, wherein the first cylinder bores and the second cylinder bores are arranged around the rotational axis of the rotary shaft; a plurality of double-headed pistons connected to the rotary shaft, each of the pistons being accommodated in the first cylinder bore and the associated second cylinder bore to respectively define a first compression chamber and a second compression chamber, each of the pistons reciprocating for compressing gas in the first cornpression chambers and the second compression chambers as the rotary shaft rotates; a partition wall located in the inner chamber along the rotational axis of the rotary shaft for dividing the inner chamber into a first passage and a second passage, the first passage interconnecting the suction chamber and the first suction communication passage, the second passage interconnecting the suction chamber and the second suction communication passage, wherein the partition wall has a rear end poition that is closer to the suction chamber than a front end of the second suction communication passage: wherein a cross sectional area of the first passage is larger than a cross sectional area of the second passage: a first suction valve mechanism rotatably provided on the rotary shaft near a rear end o.f the front housing forintroducing the gas from the suction chamber to the first compression chambers through the first passage, the first suction valve mechanism including a first rotary valve that has the first suction communication passage for sequentially interconnecting the first passage and the first compression chambers in a suction process as the first suction valve mechanism rotates synchronously with the rotary shaft; and a second suction valve mechanism rotatably provided on the rotary shaft near the front end of the rear housing for introducing the gas from the suction chamber to the second compression chambers through the second passage, the second valve mechanism including a second rotary valve that has the second suction communication passage for seciuentially interconnecting the second passane and the second compression chambers in the suction process as the second suction valve mechanism rotates synchronously with the rotary shaft.
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 present invention is applied to a double-headed piston type fixed displacement compressor (hereinafter the compressor) that constitutes a part of a refrigerant circulation circuit in a vehicle air-conditioner system. A preferred embodiment according to the present invention will be described in reference to
A housing of the compressor includes a pair of a front cylinder block 11A and a rear cylinder block 11B, a front housing 13 and a rear housing 14. The rear housing 14 is also called a cylinder head that is arranged on the back side of compression chambers 40B. The front cylinder block 11A is fixed to the rear cylinder block 11B. The front housing 13 is fixed to the front cylinder block 11A via a front valve port assembly 12A. The rear housing 14 is fixed to the rear cylinder block 11B via a rear valve port assembly 12B. As illustrated in
A front discharge chamber 21A is defined in the front housing 13. Namely, the front discharge chamber 21A is defined in such a manner that a front surface 18A of the retainer plate 15A contacts a rear end surface 13a of the front housing 13 as shown in
As shown in
Referring back to
A rotary shaft 31 is rotatably supported in the cylinder blocks 11A and 11B. The rotary shaft 31 is inserted into a front accommodation hole 32A and a rear accommodation hole 32B that respectively extend through the center of the cylinder blocks 11A and 11B. Namely, the rotary shaft 31 is slidably supported by the cylinder blocks 11A and 11B in the front and rear accommodation holes 32A and 32B. A through hole 33 extends through the front valve port assembly 12A and the front housing 13. The front end portion of the rotary shaft 31 protrudes to the outside of the front housing 13 through the through hole 33 and is operationally connected to an engine Eg for being driven by the engine Eg of a vehicle. A shaft seal member 34 is arranged between the front housing 13 and the rotary shaft 31 in the through hole 33.
The cylinder blocks 11A and 11B define a crank chamber 36. A cam body 35 is provided on an outer circumferential surface 31a of the rotary shaft 31 in the crank chamber 36. The cam body 35 includes an annular base portion 35a and a swash plate portion 35b. The base portion 35a is secured to the outer circumferential surface 31a of the rotary shaft 31. The swash plate portion 35b is formed integrally with the base plate 35a. A front thrust bearing 37A is placed between the front surface of the base portion 35a of the cam body 35 and the opposing rear end surface of the front cylinder block 11A. A rear thrust bearing 37B is placed between the rear surface of the base portion 35a of the cam body 35 and the opposing front end surface of the rear cylinder block 11B. Since the base portion 35a of the cam body 35 is sandwiched by a pair of the thrust bearings 37A and 37B, the sliding movement of the rotary shaft 31 along a rotational axis L of the rotary shaft 31 is regulated.
A plurality of front cylinder bores 38A and a plurality of rear cylinder bores 38B are respectively formed in the cylinder blocks 11A and 11B and are arranged around the axial L of the rotary shaft 31. One of the front cylinder bores 38A and one of the rear cylinders 38B are shown in
The piston 39 is engaged with the swash plate portion 35b of the cam body 35 through a pair of shoes 41. As the cam body 35 rotates integrally with the rotary shaft 31, the rotation of the cam body 35 is transmitted to the piston 39 through the shoes 41 to reciprocate the piston 39 in the cylinder bores 38A and 38B frontward and backward. The cam body 35 and the shoes 41 constitute a crank mechanism that converts the rotation of the rotary shaft 31 into the reciprocating movement of the piston 39.
A plurality of front introduction passages 47A is formed in the front cylinder block 11A to interconnect each of the front cylinder bores 38A and the front accommodation hole 32A of the front cylinder block 11A. A plurality of rear introduction passage 47B is formed in the rear cylinder block 11B to interconnect each of the rear cylinder bores 38B and the rear accommodation hole 32B of the rear cylinder block 11B. A shaft chamber 45 is formed in the rotary shaft 31 and extends along the rotational axis L of the rotary shaft 31. The shaft chamber 45 communicates with the suction chamber 22 through an opening 31b that is formed at the rear end of the rotary shaft 31. The shaft chamber 45 includes a large-diameter cylindrical chamber 45a on the rear side and a small-diameter cylindrical chamber 45b on the front side whose diameter is smaller than that of the large-diameter chamber 45a. A step is formed by an annular wall surface 55 at a connecting part between the large-diameter chamber 45a and the small-diameter chamber 45b on an inner circumferential surface 31c of the rotary shaft 31, which defines the shaft chamber 45. The wall surface 55 faces the rear side.
A cylindrical partition wall 56 is fixedly inserted in the rotary shaft 31. The front end portion of the partition wall 56 is fixedly press-fitted into the small-diameter chamber 45b. A rear end portion 56a of the partition wall 56 protrudes from the shaft chamber 45 into the suction chamber 22. The cylindrical inner space of the partition wall 56 includes a partition wall front inner space 60A that is located in the shaft chamber 45 and a partition wall rear inner space 60B that is located in the suction chamber 22. The partition wall rear inner space 60B partially constitutes the suction chamber 22.
The partition wall 56 divides the shaft chamber 45 into an inner partition wall space and an outer partition wall space. The inner partition wall space includes the small-diameter chamber 45b and the partition wall front inner space 60A of the partition wall 56. The outer partition wall space is defined between outside the partition wall 56 and inside the shaft chamber 45 that is in the rearward of the wall surface 55. A front suction communication passage 48A interconnects the inner circumferential surface 31c of the rotary shaft 31 corresponding to the small-diameter chamber 45b and the outer circumferential surface 31a of the rotary shaft 31. The inner partition wall space communicates with the outside of the rotary shaft 31 through the front suction communication passage 48A. Accordingly, the inner partition wall space functions as a first passage 57A that interconnects the partition wall rear inner space 60B that is a part of the suction chamber 22 and the front suction communication passage 48A.
A rear suction communication passage 48B interconnects the inner circumferential surface 31c of the rotary shaft 31 corresponding to the large-diameter chamber 45a and the outer circumferential surface 31a of the rotary shaft 31. The outer partition wall space, which is outside the partition wall 56, communicates with the outside of the rotary shaft 31 through the rear suction communication passage 48B. Accordingly, the outer partition wall space functions as a second passage 57B that interconnects the suction chamber 22 and the rear suction communication passage 48B. As described above, the first and second passages 57A and 57B are separately defined in the shaft chamber 45.
As described above, the rear end portion 56a of the partition wall 56 protrudes from the shaft chamber 45 into the suction chamber 22. Thus, the rear end portion 56a is located in the rearward of a front end position P of the communication part or the border area between the rear suction communication passage 48B and the second passage 57B.
The cross section area of the first passage 57A is larger than that of the second passage 57B. The cross section area of the first passage 57A is defined as the cross section of the inner space of the partition wall 56 on the plane perpendicular to the rotational axis L. The cross section area of the second passage 57B is defined as the cross section of the annular region between the inner circumferential surface 31c of the rotary shaft 31 in the large-diameter chamber 45a and the outer circumferential surface of the partition wall 56 on the plane perpendicular to the rotational axis L.
The front suction communication passage 48A is formed to correspond to the front introduction passages 47A in the front cylinder block 11A. Also, the rear suction communication passage 48B is formed to correspond to the rear introduction passages 47B in the rear cylinder block 11B. As the rotary shaft 31 rotates, the front suction communication passage 48A intermittently interconnects the first passage 57A and the front introduction passages 47A. Similarly, as the rotary shaft 31 rotates, the rear suction communication passage 48B intermittently interconnects the second passage 57B and the rear introduction passages 47B. Accordingly, a part of the rotary shaft 31 surrounded the front accommodation hole 32A functions as a front rotary valve 50A that forms s a front suction valve mechanism 49A. The front rotary valve 50A includes the front suction communication passage 48A and is formed integrally with the rotary shaft 31. Also, a part of the rotary shaft 31 surrounded the rear accommodation hole 32B functions as a rear rotary valve 50B that forms a rear suction valve mechanism 49B. The rear rotary valve 50B includes the rear suction communication passage 48B and is formed integrally with the rotary shaft 31.
When the associated compression chambers 40A and 40B are in a suction process, the first and second passages 57A and 57B respectively communicate with the front and rear introduction holes 47A and 47B through the front and rear suction communication passages 48A and 48B. In this state, refrigerant gas in the suction chamber 22 is respectively introduced into the front and rear compression chambers 40A and 40B through the first and second passages 57A and 57B, the front and rear suction communication passages 48A and 48B, and the front and rear introduction passages 47A and 47B.
On the other hand, when the associated compression chambers 40A and 40B are in a compression process and or a discharge process, the communication between the first passage 57A and the front introduction passage 47A as well as the communication between the second passage 57B and the rear introduction passage 47B is blocked. In this state, the refrigerant gas is sequentially compressed in the front and rear compression chambers 40A and 40B, and the compressed refrigerant gas is respectively discharged from the front and rear discharge ports 27A and 27B into the front and rear discharge chambers 21A and 21B through the discharge valves 28A and 28B. The refrigerant gas that has been discharged into the front and rear discharge chambers 21A and 21B flows out to an external refrigerant circuit that is not shown. The external refrigerant circuit and the compressor are included in a refrigerant circulation circuit. The refrigerant gas that flows out to the external refrigerant circuit returns to the suction chamber 22. The refrigerant gas that circulates in the refrigerant circulation circuit includes lubricating oil, which is mist state in the refrigerant gas for lubricating parts inside the compressor.
Front and rear lubricating holes 51A and 51B extend through the rotary shaft 31 to interconnect the inner and outer circumferential surfaces 31a and 31c of the rotary shaft 31. The front and rear lubricating holes 51A and 51B are respectively formed at positions corresponding to the front and rear thrust bearings 37A and 37B. The lubricating oil in the shaft chamber 45 is respectively supplied to the front and rear thrust bearings 37A and 37B through the front and rear lubricating holes 51A and 51B due to centrifugal force according to the rotation of the drive shaft 31. In the present preferred embodiment, the front and rear lubricating holes 51A and 51B communicate with the second passage 57B. Thus, the lubricating oil in the second passage 57B is supplied to the front and rear thrust bearings 37A and 37B.
The front lubricating hole 51A is located near the wall surface 55 that is formed in the rotary shaft 31. The wall surface 55 is located in the front side of the front lubricating hole 51A. The wall surface 55 prevents the lubricating oil from flowing toward the front side along the inner circumferential surface 31c of the rotary shaft 31.
Meanwhile, while the refrigerant gas is compressed in the front and rear compression chambers 40A and 40B, the lubricating oil tends to accumulate in the crank chamber 36 due to leakage of the refrigerant gas from the compression chambers 40A and 40B through clearance between the piston 39 and the cylinder bore 38A or 38B. A front lubricating passage 58A is formed in the front cylinder block 11A to introduce the accumulated lubricating oil in the crank chamber 36 into the through hole 33, which accommodates the shaft seal member 34. Also, a rear lubricating passage 58B is formed in the rear cylinder block 11B to introduce the accumulated lubricating oil in the crank chamber 36 into the suction chamber 22.
The lubricating oil flow will be described after the lubricating oil is discharged from the crank chamber 36 to the through hole 33 and the suction chamber 22 through the front and rear lubricating passage 58A or 58B, respectively. A part of the lubricating oil introduced into the through hole 33 lubricates sliding portion between the shaft seal member 34 and the rotary shaft 31, and the rest of the lubricating oil is introduced into the small-diameter chamber 45b of the shaft chamber 45 through a through hole 59 that is formed in the rotary shaft 31. The lubricating oil in the small-diameter chamber 45b is further introduced into the front compression chambers 40A through the front suction valve mechanism 49A to lubricate the inside of the front cylinder bore 38A. Also, the lubricating oil in the suction chamber 22 is respectively introduced into the front and rear compression chambers 40A and 40B through the first and second passages 57A an 57B and the front and rear suction valve mechanisms 49A and 49B to lubricate the inside of the front and rear cylinder bores 38A and 38B.
According to the preferred embodiment, following advantageous effects are obtained.
(1) In the preferred embodiment, the first and second passages 57A and 57B are separately defined in the shaft chamber 45 in the rotary shaft 31. Thus, the refrigerant gas is separately introduced into the front suction communication passage 48A from the suction chamber 22 through the first passage 57A. The refrigerant gas is also separately introduced into the rear suction communication passage 48B from the suction chamber 22 through the second passage 57B. The rear end portion 56a of the partition wall 56 is located in the rearward of the front end position P of the communication part where the rear suction communication passage 48B and the second passage 57B communicate. In other words, the separation point of the first and second passages 57A and 57B for separately flowing the refrigerant gas flow from the suction chamber 22 to the front and rear compression chambers 40A and 40B is located in the rearward of the front end position P of the communication part. Thus, the refrigerant gas that is introduced from the suction chamber 22 toward the front suction communication passage 48A in the first passage 57A is prevented from being introduced into the rear suction communication passage 48B because the rear end portion 56a of the partition wall 56 is located in the rearward of the position P. In addition, the cross sectional area of the first passage 57A is consistently larger than that of the second passage 57B along the rotational axis L. Thereby, the refrigerant gas is sufficiently introduced into the front suction communication passage 48A, that is, the front compression chambers 40A. It substantially avoids the decrease in volumetric efficiency or the increase in compression ratio due to the decrease in the pressure of the front compression chambers 40A caused by an insufficient amount of the refrigerant gas introduced into the front compression chambers 40A. The increase in the compression ratio causes the temperature of the discharged refrigerant gas in the front discharge chamber 21A to rise. Namely, as a sufficient amount of the refrigerant gas is introduced into the front compression chambers 40A through the front suction communication passage 48A, the compression ratio does not relatively increase, and the temperature of the discharged refrigerant gas in the front discharge chamber 21A does not relatively rise. Therefore, thermal load is reduced on the seal members 19 placed between the front housing 13 and the front cylinder block 11A, and the life of the seal members 19 is extended.
As the refrigerant gas is sufficiently introduced into the front compression chambers 40A, the lubricating oil is also sufficiently introduced into the front compression chambers 40A. Thereby, the inside of the front cylinder bores 38A is efficiently lubricated, and heat due to sliding friction between the pistons 39 and the cylinder bores 38A is substantially prevented from being generated.
(2) The first passage 57A is longer than the second passage 57B. Thus, if the cross section of the first passage 57A were substantially the same as that of the second passage 57B, resistance of the refrigerant gas flow in the first passage 57A would be larger than that in the second passage 57B. Namely, based upon the above conditions, the amount of the refrigerant gas introduced into the front suction communication passage 48A of the front rotary valve 50A will be smaller than that into the rear suction communication passage 48B of the rear rotary valve 50B. However, since the cross section of the first passage 57A is larger than that of the second passage 57B in the present preferred embodiment, the resistance of the refrigerant gas flow in the first passage 57A and the second passage 57B is substantially equalized so that the amount of the refrigerant gas introduced into the front and rear compression chambers 40A and 40B is also substantially equalized.
(3) The rear end portion 56a of the cylindrical partition wall 56 protrudes from the shaft chamber 45 of the rotary shaft 31 into the suction chamber 22. Namely, the separation point of the first and second passages 57A and 57B that relates to the gas flow from the suction chamber 22 to the front and rear compression chambers 40A and 40B is located in the suction chamber 22. Thus, the refrigerant gas introduced from the suction chamber 22 into the first passage 57A is undisturbed by the gas flow from the suction chamber 22 toward the second passage 57B. Accordingly, the refrigerant gas is efficiently introduced from the suction chamber 22 into the first passage 57A.
(4) In the shaft chamber 45 of the rotary shaft 31, the cylindrical inner space of the cylindrical partition wall 56 forms the first passage 57A, and the outside surface of the cylindrical partition wall 56 partially forms the second passage 57B. Thereby, the first passage 57A is surrounded by the second passage 57B in the rotary shaft 31. The refrigerant gas introduced into the front compression chambers 40A is less thermally affected by the temperature of the outside of the rotary shaft 31 than the refrigerant gas introduced into the rear compression chambers 40B while the refrigerant gas moves in the first passage 57A. Therefore, the temperature of the refrigerant gas introduced into the front compression chambers 40A is prevented from rising so that the volumetric efficiency is not lowered.
The first passage 57A is longer than the second passage 57B. Thus, when the refrigerant gas moves in the first passage 57A, the refrigerant gas introduced into the front compression chambers 40A is exposed to the outside temperature of the rotary shaft 31 for a longer time than the refrigerant gas introduced into the compression chambers 40B. However, since the first passage 57A is surrounded by the second passage 57B, the refrigerant gas introduced into the front compression chambers 40A is less thermally affected by the outside temperature of the rotary shaft 31 than the refrigerant gas introduced into the compression chambers 40B. In this regard, the above structure of the present preferred embodiment is effective to prevent rising the internal refrigerant gas temperature in the first passage 57A.
Besides, the cylindrical partition wall 56 is inserted into the shaft chamber 45 of the rotary shaft 31 to divide the shaft chamber 45. Although the cross section of the first passage 57A is different from that of the second passage 57B, since the axis of the cylindrical partition wall 56 coincides with the rotational axis L of the rotary shaft 31 due to the same cylindrical structure, it is easy to appropriately maintain a rotational balance of the rotary shaft 31.
(5) In the rotary shaft 31, the front and rear lubricating holes 51A and 51B are respectively provided at the positions corresponding to the thrust bearings 37A and 37B for supplying the lubricating oil to the thrust bearings 37A and 37B. The front and rear lubricating holes 51A and 51B function as an entry route for the refrigerant gas from the crank chamber 36 to the shaft chamber 45 of the rotary shaft 31. Since the temperature of refrigerant gas tends to be higher in the crank chamber 36 than that in the suction chamber 22, the refrigerant gas in the crank chamber 36 enters to the rotary shaft 31 through the front and rear lubricating holes 51A and 51B. If the refrigerant gas in the crank chamber 36 hypothetically enters to the first passage 57A, the temperature of the refrigerant gas rises in the first passage 57A and the refrigerant gas is discharged from the front compression chambers 40A into the discharge chamber 21A at a relatively high temperature. In short, in this hypothetical case, it is disadvantageous to raise the temperature of the discharged refrigerant gas from the front compression chambers 40A.
However, in the present preferred embodiment, the front and rear lubricating holes 51A and 51B communicate with the second passage 57B. Thereby, the refrigerant gas in the crank chamber 36 is substantially prevented from entering into the first passage 57A. As a result, the refrigerant gas in the crank chamber 36 substantially fails to thermally affect the refrigerant gas in the first passage 57A, and the temperature of the refrigerant gas discharged from the front compression chambers 40A is prevented from excessively rising.
Also, since the front and rear lubricating holes 51A and 51B communicate with the second passage 57B and not with the first passage 57A, the lubricating oil in the first passage 57A is not applied to lubricate the front and rear thrust bearings 37A and 37B and is only introduced into the front compression chambers 40A through the front suction communication passage 48A. In comparison to an embodiment in which at least one of the front and rear lubricating holes 51A and 51B communicates with first passage 57A, the inside of the front cylinder bores 38A is efficiently lubricated.
(6) On the inner circumferential surface 31c of the rotary shaft 31, the wall surface 55 is provided near the front side of the front lubricating hole 51A for preventing the lubricating oil from flowing toward the front side along the inner circumferential surface 31c of the rotary shaft 31. Thereby, the lubricating oil sufficiently stays near the entry or the opening of the front lubricating hole 51A on the inner circumferential surface 31c of the rotary shaft 31. Accordingly, the lubricating oil is efficiently introduced into the front lubricating hole 51A, and the front thrust bearing 37A is efficiently lubricated.
(7) In the front cylinder block 11A, a discharging passage includes the front lubricating passage 58A, the through hole 33 and the through hole 59 and is provided for discharging the lubricating oil in the crank chamber 36 into the first passage 57A. Also, in the rear cylinder block 11B, the rear lubricating passage 58B is provided for discharging the lubricating oil in the crank chamber 36 into the suction chamber 22. Thereby, the inner surface of the front and rear cylinder bores 38A and 38B is efficiently lubricated. In addition to the lubricating oil introduced from the suction chamber 22 into the front cylinder bores 38A through the first passage 57A, the lubricating oil is introduced into the front cylinder bores 38A through the discharging passage including the front lubricating passage 58A, the through hole 33 and the through hole 59. Therefore, the lubrication of the inner surface of the front cylinder bores 38A is improved.
According to the present invention, the following alternative embodiments are also practiced. Although the wall surface 55 is provided at a position corresponding to the front lubricating hole 51A for preventing the lubricating oil from flowing toward the front side along the inner circumferential surface 31c of the rotary shaft 31 in the above-described preferred embodiment, an additional wall surface 62 is provided at a position corresponding to the rear lubricating hole 51B in a first alternative embodiment as shown in
Referring to
A step is formed by a wall surface 62 at a connecting part between the base portion 61a and the small-diameter portion 61b. The wall surface 62 has a function for preventing the lubricating oil from flowing toward the front side along the inner circumferential surface 31c of the rotary shaft 31. The wall surface 62 is located near the front side of the rear lubricating hole 51B. Thereby, the lubricating oil is efficiently introduced into the rear lubricating hole 51B, and the rear thrust bearing 37B is efficiently lubricated.
Also, in this structure, the front lubricating hole 51A communicates with the first passage 57A, and the rear lubricating hole 51B communicates with the second passage 57B. Accordingly, in comparison to another alternative embodiment to be disclosed with respect to
In a second alternative embodiment, the front and rear lubricating holes 51A and 51B communicate with the first passage 57A as shown in
Although a pair of the front and rear lubricating holes 51A and 51B are respectively provided at the positions corresponding to the front and rear thrust bearings 37A and 37B, a single lubricating hole is provided only at a position corresponding to one of the front and rear thrust bearings 37A and 37B or no lubricating hole is provided in a third alternative embodiment.
As shown in
In a fifth alternative embodiment, the opening of the rear end portion 56a of the partition wall 56 is widened toward the rear side. As shown in
The cylindrical partition wall 56 or 61 divides the shaft chamber 45 of the rotary shaft 31 in the above-described preferred embodiment or the first through sixth alternative embodiments. However, as shown in
In an eighth alternative embodiment, as shown in
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.
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| 20040197202 A1 | Oct 2004 | US |
