Scroll type compressor

Abstract: A rotary compressor is disclosed which is equipped with a bypass hole (70, 71, 80, 81) for bypassing a fluid under compression to the intake side and the capacity thereof is controlled through opening and closing of the bypass hole with a piston which is operated via a control valve (43), whereby the bypass hole is opened at or in the vicinity of a discharge port (41) of the compressor and the capacity of the compressor is made to be controllable in the range of one hundred to substantially zero percent. By the application of such a rotary compressor to the compressor for an air conditioner, capacity control in the range of about zero to 100% of discharge quantity can be accomplished so that it becomes possible to obtain cooling capability which is in response to the heat load.

Description: The present invention relates to a rotary compressor of such type as scroll type. As an example of the prior art there is shown a conventional scroll compressor in Fig. 1 to 4. Fig. 1 is a vertical sectional diagram of the scroll compressor in which the compressor main body 001 consists of a front case 011, a front nose 012 and a housing 013. A main bearing 021 is provided at about the the center of the front case 011, an auxiliary bearing 022 is provided in the front nose 012, and a main bearing 003 is supported rotatably by these bearings. On the other hand, a stationary scroll 004 and a revolving scroll 005 are arranged within the housing 013, and the stationary scroll 004 is fixed integrally in the housing 013 with a bolt 14. The stationary scroll 004 consists of an approximately disk-shaped end plate 041 and a spiral element 042. On the tip of the spiral element 042 there is mounted a tip seal 043 to give a better sealing, and a discharge port 044 is provided at about the central part of the end plage 041. Further, the revolving scroll 005 has an approximately disk-shaped end plate 051, a spiral element 052, and a boss 053 provided protruding in the end plate 051. A revolving bearing 023 for moving the revolving scroll 005 is installed within the boss 053, and a tip seal 054 is mounted on the tip of the spiral element 052 similar to the case of stationary scroll 004. The main shaft 003 has a balance wight 031 and a drive bush 032, and the drive bush 032 is supported rotatably by the revolving bearing 023 of the revolving scroll 005. In the front case 011 there is constructed a ball coupling which inhibits the rotation and permits the revolution of the revolving scroll 005 and receives a thrust force of the resolving scroll 005. Sealed small spaces 055, 056 and 057 are formed by engaging the spiral element 052 of the revolving scroll 005 with the spiral element 042 of the stationary scroll 004, with the phase of 180° between the spiral elements. Here, when the main shaft 003 is rotated by an engine or the like via a clutch (not shown), the revolving scroll 005 is driven via the drive bush 032. The revolving scroll 005 revolves aroung the stationary scroll 004 without rotation by means of the ball coupling 026. When the revolving scroll 005 revolves with a certain radius around the stationary scroll 004, the contact point of the spiral elements 042 and 052 moves from the outsied toward inside of the spirals. As a result, the sealed small space 055, 056 and 057 formed by the engagement of the scrolls 004 and 005 are moved toward the center of the spirals 042 and 052 while reducing their volumes. A referigerant gas sucked into an inlet chamber (not shown) from an external heat exchanger (not shown) or the like is sucked into the sealed small space 005 from a spiral outer end opening 058 of the spiral elements 042 and 052, compressed under the volume changes in the sealed small spaces 055, 056 and 057. Then, the gas moves successively toward the centers of the spiral elements 052 and 042, discharged to a discharge chamber 045 from the discharge port 044 provided on the ende plate 41 of the stationary scroll 004, and is sent to the outside of the compressor main body 001 from the discharge chamber 045. When such a compressor is used as the compressor for an air conditioner on motor vehicle, the cooling capability of the air conditioner is raised in proportion to the rotational frequency of the vehicle engine because the main shaft 003 of the compressor is driven by the engine. For this reason, the cooling capability of the air conditioner becomes too large and the vehicle room is cooled excessively when the engine is running at high speed, and consequently, the air conditioning feeling is lowered due to the intermittent operation of the compressor. Morevoer, it gives rise to a reduction in the traveling efficiency of the vehicle due to increase in tghe load of the compressor. In order to eleminate such an inconvenience there is sometimes provided a capacity control mechanism 100 (Fig. 2 is a vertical sectional diagram which is partially different from the vertical sectional diagram shown in Fig. 1 as shown in Fig. 2 and Fig. 3. First bypass holes 121a and 121b and second bypass holes 122a and 122b are provided to be opened to sealed small spaces 111 and 112, respectively, facing the end plate 041 of the stationary scroll 004. In addition, pistons 130a and 130b that open and close the pairs of the first and the second bypass holes 121a, 122a and 121b and 122b. The piston 130a is internally equipped with a spring 131a, and the piston is constructed so as to receive a working pressure from a pressure control valve 132 on the other end of the piston 101. At the time of full load, the working pressure from the pressure control valve 132 is raised to apply a high pressure to the other end 101 of the piston 130a to let the piston 130a close the bypass holes 121a and 122a. At the same time, the bypass holes 121b and 122b are closed with another piston 130b which is not shown in Fig. 2. On the other hand, at the time of capacity control, pressure from the pressure control valve 132 is lowered, the bypass holes 121a and 122a are opened by moving the piston 130a by means of the spring 131a, and the refrigerant gas is led from the sealed small spaces 111 and 112 to the bypass passage 123 via the bypass holes 121a and 122a to be led to the spiral outer end opening 058 or the inlet chamber (not shown), as may be understood by referring to Fig. 2. Now, the first bypass holes 121a and 121b and the second bypass holes 122a and 122b are ordinarily provided, as indicated in the volume-revolving angle relation shown in Fig. 4, at positions where the compressed volumes are in the vicinities of 50 - 60 % and 25 - 40 %, respectively, of the total volume of the compression space. Namely, the volume control used to be carried out so as to obtain a compressed volume in the vicinity of the position where it is 25 - 40 % of the total volume due to the action of the first and the second bypass holes. It is to be noted that the curve shown in Fig. 4 corresponds to the case where the top clearance volume that is generated from the revolving angle at which the two scrolls start to be separated at the central parts is neglected. As described in the above, in the case of the scroll compresor, the range of capacity control is not wide enough, similar to the case of the rotary compressor, so that there has been a problem that the air conditioning feeling is spoiled due to intermittent operation of the compressor. From the US-patent no.: 3.224.662 it is already known a capacity control system for a rotary compressor of the sliding vane type. This system is disclosed such that bypass sorts are disposed in a cylinder wall between the position of an inlet port and that of an exit port, said bypass ports communicating with a compression chamber and being provided along the direction of rotation of a compressor unit and said bypass ports are opened and closed by a spool piston of a spool valve, thereby controlling the capacity of the compressor within the maximal range of 90 % namely controlling it by lowering the output of the compressor down to 10 %. Further the French patent no.: 480.617 discloses an air compressor of the sliding vane type. According to its disclosure, when the working volume of compressed air of the compressor is lowered surplus air is returned to the suction side so as to reduce work loss of compression on one hand and when the working pressure of compressed air is lowered the valve 1 is opened so as to discharge compressed air to the compression chamber d, thereby reducing loss of compression work on the other hand. However, both discloses do not give any suggestions about capacity control or an about continious control of the capacity of the compressor within the range of 100 % to several or 0 %. The present invention was accomplished with the above in mind, and it is, therefore, the object of the invention to provide a scroll compressor which can resolve the above-mentioned problems, carrying out a continious operation, and generating a suitable output in response to the load. In order to achieve the above object, in a scroll compressor provided with a bypass hole which causes a fluid under compression to be bypassed to the inlet side, and controls its capacity by opening and closing the bypass hole with a piston that is operated via a control valve, the present invention has a constitution as characterized in (1) and (2) below. (1) The bypass hole is opened at a position of the revolving angle for which the compressed volume is in the range of zero to several percents of the volume of the compression space in the diagram representing the dependence of the compressed volume on the revolving angle, and the capacity of the compressor is made to be controllable in the range of 100 to substantially zero percent. (2) A plurality of the bypass holes are provided along the direction of rotation, and at least one of them is opened at the position of the revolving angle for which the compressed volume is in the range of zero to several percents of the volume of the compression space in the diagram showing the dependence of the compressed volume on the revolving angle, and the capacity of the compressor is made to be controlled in the range of 100 to substantially zero percent. The action of the present invention is as will be described below. The bypass hole is provided at the position for which the flow rate of bypassing of a gas under compression from the compression space to the inlet space is approprate in the compressed volume-revolving angle relation. Then, the opening and closing of the hole is controlled by the action of a piston operated via a control valve, and the capacity control is executed in the range of 0 to 100 % or several to 100 % of the actual discharge quantitiy of the compressor. From what is described in the above, the present invention can achieve the following effect. From the above, through capacity control of the compressor it is possible to obtain a suitable output in response to the load. Further, when this compressor is used in the air conditioner, it is possible to obtain a cooling capacity in response to the thermal load. Therefore, there is no action of a frost thermoswitch of the unit, so taht a continuous operation of the compressor becomes possible and an enhancement of cooling feeling and a reduction of power consumption can be achieved. Fig. 1 is a vertical sectional diagram showing a known scroll compressor, Fig. 2 is a sectional view of the bypass passage of a prior art scroll compressor equipped with the capacity control mechanism, Fig. 3 is a sectional view of the stationary scroll for the scroll compressor shown in Fig. 2, Fig. 4 is a diagram showing the volume (compressed volume) - revolving angle relation, Fig. 5 is the volume-revolving angle relation diagram of a first embodiment of the present invention as applied to the scroll compressor, Fig. 6 is a sectional diagram of a stationary scroll, Fig. 7 is a sectional diagram of the stationary scroll of a second embodiment of the present invention, Fig. 8 is an enlarged diagram of the inner portion of the spiral element, Fig. 9 is the volume-revolving angle diagram for a third embodiment of the present invention, Fig. 10 is a sectional diagram of the stationary scroll of the above embodiment, Fig. 11 is the volume-revolving angle diagram for a fourth embodiment of the present invention and Fig. 12 is a sectional diagram the stationary scroll of the above embodiment. Fig. 5 to Fig. 12 show embodiments (the first to the fourth embodiments) of the present invention as applied to the sealed motor driven type scroll compressor. Fig. 5 is a diagram showing the volume-revolving angle relation for the first embodiment of the present invention, that is, a diagram showing the relation between the compressed volume of the compression space and the revolving angle of the revolving scroll and Fig. 6 is a sectional diagram of the stationary scroll of the above embodiment. In the drawings, 004 is a stationary scroll which is composed of an end plate 041 and a spiral element 042 similar to the conventional device, and first bypass holes 121a and 121b are provided analogous to the conventional device. It is desirable to determine the range of opening of the first bypass holes 121a and 121b so as to cover, including the case of volume of 100 %, the lower volume percent region in the diagram for the volume-revolving angle relation. Second bypass hales 211a and 211b are provided in such a way what one end of the respective holes is opened to a discharge port 044, and the other end of the respective holes is provided on an end plate 041 of the stationary scroll 004 so as to be opened to a bypass passage 123a or 123b that is opened and closed by a piston (not shown). Components other than those mentioned above, namely, the piston, spring, bypass holes 123a and 123b, and pressure control valve are installed in the same way as in the conventional capacity control mechanism. By opening bypass holes to the discharge port as in the above, the range of the revolving angle of the revolving scroll for which the bypass holes are opened, ca be made to cover the range of 100-0 % of the compressed volume, so that it becomes possible to increase markedly the capacity control range of the conventional capacity control mechanism. That is, by increasing the capacity control range the cooling capability at the time of capacity control, even during the between season, winter season and the like, is decreased substantially, so that there will be no cooling capability generated that is more than what is necessary. As a result, the compressor can be operated continuously and degradation of the air conditioning feeling due to intermittent operation of the compressor can be avoided. It should be noted that the situation is analogous at the time of fast operation of the compressor. In the first embodiment, bypass holes at the position of compress value 0 % are opened at the discharge port. However, instead of these bypass holes 211a and 211b, in the second embodiment of the present invention shown in Fig. 7 and Fig. 8, second bypass holes 511a and 511b are provided in the regions that are on the inner side of the spiral element than the marginal points that are determined by the marginal angle for defining a due involute curve of the spiral element. In this case, capacity control in the range of 100-0 % becomes also possible similar to the first embodiment. Fig. 8 is an enlarged diagram of the inner end portion of the spiral element, and the way of determining its profile is shown, for example, in Japanese Patent Application 62-17074. The points B and E in the drawing represent the marginal points determined by the angle β of the marginal angle for defining a due involute curve. In the region on the inner side of teh points B and E, there are provided a small clearance Δ for avoiding abnormal collision with the revolving scroll. Because of this, engagement between both scrolls begins to be separated in the region on the inner side of the points B and E. If the top clearance volume that is generated by the separation of both scrolls in the inner central portion is neglected in the diagram for the volume-revolving angle relation, the compressed volume at the points B and E will become 0 %. The position on the stationary scroll at which the ratio of the compress volume to the volume of the compression space is about several percents or smaller is in the range of 3 x 360° x (0.08 to 0.05) = 86° to 54° since the number of spiral elements of a compressor of ordinary use is about three. That is, it is a position less than about 90° to the outside of the points B and E along the spiral. Fig. 9 and Fig. 10 representing the third embodiment shows an example in which the capacity control is arranged to cover the compressed volume in the range of 100 to several percents. Fig. 10 shows a sectional diagram of the stationary scroll of the present embodiment. Reference numerals 311a and 311b are bypass holes at the position of volume of about several percents provided in place of 511a and 511b of the second embodiment, and the remaining constitution of the embodiment is similar to the case of the second embodiment. The effect realizable is the same as the second embodiment. Fig. 11 is a diagram showing the volume-revolving angle relation in accordance with the fourth embodiment of the present invention and Fig. 12 is a sectional diagram of the stationary scroll of the present embodiment. This embodiment is provided with three pairs of bypass holes. Reference numerals 410a and 410b are first bypass holes, 411a and 411b are second bypass holes provided at the position of volume of about 30 %, and 412a and 412b are third bypass holes. The remaining The remaining portion is the same as that it can realize an effect of finer capacity control. The embodiments described in the foregoing may be summarized in the following. The first embodiment and the second embodiment are exampies in which , on the assumption that the volume at the time of intake shuttoff is 100 % and that at the time of discharge completion is 0 % in the diagram showing the volume-revolving angle relation of the compressor, bypass holes are provided at the discharge port or within marginal points determined by a marginal angle for defining a due involute curve, bypass passages are provided leading from the bypass holes to the inlet space, a capacity control valve is installed in a portion of a bypass passages, and the discharge quantitiy of the compressor is controlled in the range of 0 - 100 % by regulating the opening of the capacity control valve. The third embodiment is an example in which the position of the bypass hole for volume of 0 % is provided at a position for volume of several percents which is somewhat on the outside of that of 0 %, and the discharge quantity of the compressor is controlled in the range of several to 100 % by regulating the opening of the capacity control valve. The fourth embodiment is an example in which a bypass hole at the volume position of about 30 % in series to those of the sixth embodiment, and the discharge quantity is controlled in the range of several to 100 % by regulating the opening of the capacity control valve.

Claims: A scroll type compressor having a stationary scroll member (004) and a revolving scroll member (005), each disposed upright on the inside surface of an end plate thereof, said scroll members being engaged with each other, said revolving scroll member being caused to rotate relative to said stationary scroll member, whereby the compressing space formed by the engagement of said two scroll members can be reduced and then fluid in said compressing space is compressed and discharged from a discharge port (044) formed in the center of the end plate of said stationary scroll member, the end plate of said stationary scroll member is formed with bypass holes (121a, 121b, 122a, 122b) in communication with said compressing chamber and for bypassing fluid under compression to the suction side, the opening of said bypass holes being adjusted by piston valves (130a, 130b) so as to control the capacity of the compressor, characterized in, that a plurality of said bypass holes (121a, 121b) are formed along the spiral direction of said stationary scroll member, and that second bypass holes (211a, 211b) are positioned to the upmost central side of said stationary scroll member (004), which are caused to open at a position of the revolving angle for which the compressed volume is in the range of zero to within several percents of the volume of compression space, thereby controlling the capacity of the compressor from 100 % to within several percents of 0 %. A scroll type compressor, as claimed in claim 1, characterized in, that the second bypass holes (211a, 211b) positioned to the upmost central side are so disposed as to communicate with the discharge port (044) formed in the center of the end plate of said stationary scroll member, thereby controlling the capacity of the compressor within the range of 100 % to 0 %. A scroll type compressor, as claimed in claim 1, characterized in, that the second bypass holes (511a, 511b) positioned to said upmost central side are formed between marginal points (B, E) which are located on the surface of a spiral element (042) of the stationary scroll member (004) to be determined by a marginal angle for defining a due involute curve of said spiral element, thereby controlling the capacity of the compressor within the range of 100 % to 0 %. A scroll type compressor as claimed in claim 1, characterized in, that said second bypass holes (311a, 311b) positioned at said upmost central side are disposed in a position deflected outwardly for less than about 90° along said spiral element (042) from the marginal points (B, E) to be determined by a marginal angle for defining a due involute curve of said spiral element, thereby controlling the capacity of the compressor within the range of 100 % to several percents. A scroll type compressor as claimed in claim 3 or 4, characterized in, that said second bypass holes (511a, 511b, 311a, 311b) are disposed along the outer and inner curve of said spiral element (042).

Inventors: HIRANO TAKAHISA NAGOYA TECH IN, HIROOKA KATSUMI MITSUBISHI JUK, ONO TETSUO NAGOYA TECH INST MI, TANIGAKI RYUHEI MITSUBISHI JUK, HIRANO, TAKAHISA NAGOYA TECH.INST. MITSUBISHI, HIROOKA, KATSUMI MITSUBISHI JUKOGYO K.K., ONO, TETSUO NAGOYA TECH.INST. MITSUBISHI JUKOGYO, TANIGAKI, RYUHEI MITSUBISHI JUKOGYO K.K.
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI JUKOGYO KABUSHIKI KAISHA
Application year: 1989
Main classification: F04C29
IPC codes: F03C2, F04C18, F04C28, F04B49, F04B23