JP5588783B2 - Oil-cooled screw compressor - Google Patents

Description

  The present invention relates to an oil-cooled screw compressor, and more particularly to an improvement in a lubricating oil system that lubricates bearings.

  Generally, an oil-cooled screw compressor includes a drive-side screw rotor (usually a male rotor) connected to an external motor or the like, and a driven-side screw rotor (usually a female rotor) that meshes with the drive-side screw rotor. These rotors are housed in a bore formed in the main casing through a minute gap. A suction port is formed in the main casing on one end surface side of the bore, and a discharge casing in which a discharge port is formed is connected to the other end surface of the bore.

  The drive-side screw rotor and the driven-side screw rotor are provided with shafts. The suction-side shaft is rotatably supported by a suction-side bearing, and the discharge-side shaft is rotatably supported by a discharge-side bearing. The suction-side shaft of the drive-side screw rotor is connected to an external motor or the like, and when the drive-side screw rotor is driven to rotate, the driven-side screw rotor also rotates accordingly. It is configured to suck and compress and discharge from the discharge port.

The suction side bearing is provided on the suction side of the main casing via a partition wall, and the discharge side bearing is provided in the discharge casing. The suction-side bearing and the discharge-side bearing are supplied through an oil supply path formed in the main casing and the discharge casing from an oil reservoir provided in a lower part of the compressor and the like using the pressure of the compressed gas. The lubricant is lubricated while being cooled. The suction side bearing and the discharge side bearing are lubricated, and the lubricating oil accumulated in the spaces of the respective bearing chambers is collected on the suction side of the screw rotor.
In addition, there exists a thing of patent document 1 etc. as this kind of prior art.

JP 2002-21758 A

  In the above prior art, a large amount of lubricating oil tends to be accumulated in the bearing chamber, and when the lubricating oil accumulates, the bearing agitates more oil, so that the agitation loss increases and the power increases. In the thing of the said patent document 1, in order to collect | recover the lubricating oil collected in the space of the bearing chamber of a suction side bearing to the suction side of a compressor, collection | recovery of oil is carried out to the partition which partitions between the bearing chamber and the said screw rotor. A hole is formed. Since the gap between the outlet of the recovery hole and the screw rotor is small, it takes time for the discharge-side end surface of the screw rotor to block the recovery hole, and during that time, the lubricant cannot be recovered. For this reason, there is a problem that the oil recovery time is shortened, the oil is easily accumulated in the bearing chamber, and the oil agitation loss cannot be sufficiently reduced.

  In order to increase the amount of oil collected in the bearing chamber, it is conceivable to increase the diameter of the recovery hole or to provide another recovery hole. In this case, however, the casing becomes larger or the structure becomes complicated. Cost increases.

  In addition, in Patent Document 1, no consideration is given to a solution for a large amount of lubricating oil accumulated in the bearing chamber of the discharge-side bearing and an increase in stirring loss.

  An object of the present invention is to make it possible to increase the time for collecting the lubricating oil accumulated in the bearing chamber of the discharge-side bearing with a simple structure without increasing the size of the casing, thereby reducing the stirring loss of the lubricating oil. The object is to obtain an oil-cooled screw compressor capable of reducing the above.

To achieve the above object, the present invention provides a pair of screw rotors that sucks, compresses and discharges fluid, a main casing that houses these screw rotors, a discharge casing that covers a discharge side end surface of the main casing, A suction-side bearing that rotatably supports the suction-side end portion of the screw rotor, a discharge-side bearing that rotatably supports the discharge-side end portion of the screw rotor, a discharge port provided in the discharge casing, and this discharge Oil-cooled screw compression provided with an oil separator that separates oil from compressed gas discharged from an outlet, and an oil supply passage that supplies lubricating oil stored in the oil separator to the suction side bearing and the discharge side bearing In the machine, in order to recover the oil after lubricating the discharge side bearing from the bearing chamber containing the discharge side bearing to the screw rotor side, the discharge case An oil recovery passage formed in the ring, the oil recovery provided in an opening end of the passage and a recess and the circumferential direction of the elongated hole shape of the screw rotor, wherein the recess is lower screw rotor than the pressure of the bearing chamber The lubricating oil is formed in a position communicating with the working space of the screw rotor, and the lubricating oil can be recovered in the working space of the screw rotor even if the amount of lubricating oil accumulated in the bearing chamber increases or decreases. To do.

Here, it is preferable that the lubricating oil in the oil separator is supplied to the suction side bearing and the discharge side bearing by the pressure of the compressed gas in the oil separator.
It is preferable that the concave portion has a size larger than the rotor tooth width so that it always communicates with the working space on the low pressure side. Moreover, the said recessed part is good to form in the discharge side end surface of the discharge casing of the position which leads to the suction chamber of a screw rotor. Furthermore, it is preferable that the contour of the concave portion communicates only with the working space constituting the suction space of the screw rotor, and does not communicate with the working space after completion of the closing and the working space constituting the discharge space.

  More preferably, the recess is formed on the discharge side end face of the female rotor of the pair of screw rotors so as to open to the tooth tip side of the rotor. The concave portion may be formed in a long hole shape that is long in the circumferential direction of the rotor at a position facing the tooth tip side of the screw rotor.

  According to the present invention, it is possible to lengthen the time for collecting the lubricating oil collected in the bearing chamber of the discharge side bearing with a simple structure without increasing the size of the casing. The effect that the stirring loss by the lubricating oil can be reduced is obtained.

The horizontal sectional view which shows Example 1 of the oil-cooled screw compressor of this invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2. The figure which expands and shows the recessed part 14 vicinity in the discharge side end surface of the discharge casing shown in FIG. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

A first embodiment of the present invention will be described with reference to FIGS.
In FIG. 1, reference numeral 1 denotes a compressor main body of an oil-cooled screw compressor. The compressor main body 1 includes a male and female set of screw rotors (male rotors) whose axes are parallel to each other and twist directions are opposite to each other. 2 and the female rotor 3), a main casing 4 that accommodates these screw rotors through a minute gap, a discharge casing 5 provided so as to cover the discharge-side end face of the main casing 4, and the like.

  The male rotor 2 is connected to a drive source such as an external motor (not shown), and the female rotor 3 meshes with the male rotor 2, and a bore 4a formed in the main casing 4 is interposed through a minute gap. Is contained. A suction port 41 is formed in the main casing on one end face side of the bore 4a. Further, the other end face of the bore 4a is covered with the discharge casing 5, as shown in FIG. 3, and the discharge side end face 51 of the discharge casing 5 is formed with an axial discharge port 52. . In addition, you may make it provide the discharge port of a radial direction also in the discharge side end surface of the main casing 4 connected to the said discharge port 52. FIG. 53 is a discharge chamber in which the compressed gas from the discharge port 51 is ejected. Reference numeral 42 denotes a discharge passage connected to the discharge chamber 53. The compressed gas discharged to the discharge chamber 53 passes through the discharge passage 42 and is provided in the oil separator 20 (see FIG. 1, the oil separator is omitted in FIGS. 2 and 3, and the oil (lubricating oil) in the compressed gas is separated by the oil separator 20, and the oil reservoir 20 a in the oil separator 20 (FIG. 2). The compressed gas that has accumulated in (see below) and separated the oil is sent out for external use.

  As shown in FIG. 1, the driving-side male rotor 2 and the driven-side female rotor 3 are provided with shafts 2a, 2b, 3a, 3b, respectively, and the suction-side shafts 2a, 3a are connected to the suction-side bearing 6a. 7a, the discharge-side shafts 2b and 3b are rotatably supported by discharge-side bearings 6b and 7b, respectively. When the suction-side shaft 2a of the male rotor 2 is driven to rotate by a motor or the like, the driven-side female rotor 3 also rotates accordingly, thereby sucking and compressing fluid such as air from the suction port 41, and Discharge from the outlet 52.

  The suction side bearings 6 a and 7 a are provided in a bearing chamber 15 formed on the suction side of the main casing 4, and the discharge side bearings 6 b and 7 b are provided in a bearing chamber 16 in a discharge side bearing holding portion of the discharge casing 5. It has been. A bearing cover 10 is attached to the discharge-side bearing holding portion of the discharge casing 5 so as to form the bearing chamber 15.

  The suction-side bearings 6a and 7a and the discharge-side bearings 6b and 7b are provided with oil supply passages 8 formed in the main casing 4 and the discharge casing 5 using the pressure of compressed gas from the oil reservoir 20a. The bearings are lubricated while being cooled by the supplied lubricating oil. Further, the suction side bearings 6a and 7a and the discharge side bearings 6b and 7b are lubricated, and the lubricating oil accumulated in the spaces of the respective bearing chambers 15 and 16 is collected on the suction side of the screw rotor.

  The oil accumulated in the space 11 of the bearing chamber 16 holding the discharge side bearings 6b and 7b passes through the oil recovery passage 12 formed in the bearing cover 10 as shown in FIGS. The oil is discharged from the discharge side end face 51 of the discharge casing 5 toward the discharge side end face of the female rotor 3 through the oil recovery passage 13 formed in the discharge casing 5. The opening end face of the oil recovery passage 13 opens into a tooth space communicating with the suction port 41 in a tooth groove (working chamber or working space) of the female rotor 3, that is, a working space constituting a suction chamber (suction space). The oil discharged from the oil recovery passage 13 is recovered in the suction chamber.

  The structure of the opening end face of the oil recovery passage 13 will be described with reference to FIGS. FIG. 5 is an enlarged view showing the vicinity of the concave portion 14 on the discharge side end face of the discharge casing shown in FIG. 3. The bore 2, the male rotor 2 and the female rotor 3 of the main casing are indicated by dotted lines, and the positions of the concave portion 14 and the rotor side It is shown so that the relationship can be understood. 6 is a cross-sectional view taken along line VI-VI in FIG.

  As shown in these figures, the configuration of the opening end face portion of the oil recovery passage 13 is a long hole (or elliptical) concave portion 14 formed long in the circumferential direction of the female rotor 3, The recess 14 is opened at a position corresponding to the vicinity of the tip (tooth tip) of the teeth of the female rotor 3 and is formed in a long hole having a size larger than the tooth width of the female rotor. In this way, the opening end surface portion of the oil recovery passage 13 is formed in the recessed portion 14 having an elongated hole larger than the rotor tooth width, whereby the opening end surface portion of the oil recovery passage 13 is blocked by the discharge side end surface of the female rotor 3. Therefore, the oil in the space 11 of the bearing chamber 16 can always be recovered to the suction chamber side through the oil recovery passages 12 and 13 and the recess 14. Therefore, it is possible to reliably prevent a large amount of lubricating oil from being accumulated in the bearing chamber 16 and increasing the stirring loss.

  As described above, according to this embodiment, the opening end face of the oil recovery passage (the discharge side end face of the discharge casing) for recovering the oil that has lubricated and cooled the discharge side bearings 6b and 7b to the suction chamber side of the screw rotor. ) Is provided with a recess (opening) 14 having a size larger than the rotor tooth width, and the recess is always open without being blocked by the discharge-side end face of the rotor. There is an effect that 11 oil can be always recovered to the suction chamber side through the oil recovery passages 12 and 13. As a result, a large amount of oil can be secured, so that a large amount of lubricating oil can be prevented from accumulating in the bearing chamber, and power loss due to oil agitation loss can be reduced.

  Further, according to the present embodiment, only the opening end portion of the oil recovery passage 13 needs to be configured as the recess (opening portion) 14 having a size larger than the rotor tooth width, so that the hole diameter of the entire oil recovery passage needs to be increased. There is no need to provide a separate oil recovery passage. Accordingly, the size of the main casing, the discharge casing, etc. can be minimized, and the structure is not complicated so that the processing is facilitated, and the cost including the material cost and the manufacturing cost can be reduced.

  In the above-described embodiment, an example is described in which the concave portion 14 is configured to be larger than the rotor tooth width, thereby eliminating the time for the concave portion to be completely blocked by the rotor end face, and always opening. It is not limited to just things. That is, if the opening time is longer than that of the conventional one and the oil recovery time can be increased, more oil can be recovered, so the present invention is not limited to the configuration in which the recess 14 is configured to be larger than the rotor tooth width. As long as the concave portion 14 is formed in a shape that is long in the circumferential direction of the rotor, a configuration that is smaller than the rotor tooth width is also included in the present invention.

Moreover, the shape of the said recessed part 14 should just be a shape long in the circumferential direction of a rotor, and is not limited to a long hole or an elliptical shape.
Furthermore, although the said Example demonstrated the example which formed the said recessed part 14 in the female rotor 3 side, you may make it form in the male rotor 2 side. That is, the recess 14 is formed at the discharge side end surface 51 of the discharge casing 5 at the discharge side end surface 51 of the male rotor 2 so that the oil accumulated in the space 11 of the bearing chamber 16 is discharged toward the discharge side end surface of the male rotor 2. You may form in the position opened to the tooth space (working space used as the suction chamber) connected to the suction inlet 41 among working space). Even in this way, the oil discharged from the oil recovery passage 13 can be recovered to the suction chamber side.

  However, if the recess 14 is provided on the female rotor 3 side rather than the male rotor 2 side, the distance to the discharge port 52 can be kept large, so that the compressed gas discharged from the discharge port 52 passes through the recess 14. It is possible to more reliably prevent leakage to the suction side. Further, since the tooth width of the rotor is smaller in the female rotor than in the male rotor, the width of the recess 14 can be made smaller. From this point of view, the recess 14 is preferably provided on the female rotor side.

  In addition, the recess 14 is preferably configured to communicate with the suction chamber of the screw rotor, but the bearing chamber 16 (not the suction chamber but the space after the completion of suction (the working space after completion of the closing)). Oil can be recovered if the working space has a pressure lower than the pressure in the space 11). Therefore, the recess 14 may be formed so as to communicate with the low-pressure working space after the closing is completed, and the oil may be recovered.

1: compressor body 2, 3: screw rotor (2: male rotor, 2a, 2b: shaft, 3: female rotor, 3a, 3b: shaft)
4: Main casing (41: suction port, 42: discharge flow path, 4a: bore)
5: Discharge casing (51: discharge side end face, 52: discharge port, 53: discharge chamber)
6a, 7a: Suction side bearings 6b, 7b: Discharge side bearings 8, 9: Oil supply passage 10: Bearing cover 11: Space 12, 13: Oil recovery passage 14: Recess 15, 15: Bearing chamber 20: Oil separator ( 20a: oil sump).

Claims (7)

A pair of screw rotors that sucks in fluid, compresses and discharges, a main casing that houses these screw rotors, a discharge casing that covers the discharge side end surface of the main casing, and a suction side end of the screw rotor that is rotatable The suction side bearing to be supported, the discharge side bearing that rotatably supports the discharge side end of the screw rotor, the discharge port provided in the discharge casing, and the oil separated from the compressed gas discharged from the discharge port In an oil-cooled screw compressor comprising an oil separator and an oil supply passage for supplying the lubricating oil stored in the oil separator to the suction side bearing and the discharge side bearing,
An oil recovery passage formed in the discharge casing for recovering the oil after lubricating the discharge-side bearing from the bearing chamber containing the discharge-side bearing to the screw rotor side;
A concave portion provided in the opening end surface of the oil recovery passage and having a long hole shape in the circumferential direction of the screw rotor;
The concave portion is formed at a position communicating with the working space of the screw rotor that is lower than the pressure in the bearing chamber, and the lubricating oil is placed in the working space of the screw rotor even if the amount of lubricating oil accumulated in the bearing chamber increases or decreases. An oil-cooled screw compressor characterized in that it can be recovered .   The oil-cooled screw compressor according to claim 1, wherein the lubricating oil in the oil separator is supplied to the suction side bearing and the discharge side bearing by the pressure of the compressed gas in the oil separator. An oil-cooled screw compressor characterized by that.   3. The oil-cooled screw compressor according to claim 1, wherein the concave portion is configured to have a size larger than a rotor tooth width, and is configured to always communicate with a working space on a low-pressure side. Oil-cooled screw compressor.   The oil-cooled screw compressor according to any one of claims 1 to 3, wherein the recess is formed on a discharge side end face of a discharge casing at a position leading to a suction chamber of a screw rotor. Screw compressor.   5. The oil-cooled screw compressor according to claim 4, wherein the contour of the recess communicates only with the working space constituting the suction space of the screw rotor, and the working space constituting the working space and the discharge space after the closing is completed. An oil-cooled screw compressor characterized in that it does not communicate with the engine.   The oil-cooled screw compressor according to any one of claims 1 to 5, wherein the recess is a discharge-side end face of a female rotor of the pair of screw rotors and is open to a tooth tip side of the rotor. An oil-cooled screw compressor characterized by the above.   The oil-cooled screw compressor according to any one of claims 1 to 6, wherein the concave portion is formed in a long hole shape in a circumferential direction of the rotor at a position facing the tooth tip side of the screw rotor. Oil-cooled screw compressor.

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