JP2009191818A - Liquid-sealed vacuum pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid-sealed vacuum pump capable of further improving the pump efficiency while directly connecting a discharge pipe to a discharge chamber. <P>SOLUTION: In the liquid-sealed vacuum pump, a rotor chamber composed of a main body casing in which an impeller rotating about an eccentric axis is received and the discharge chamber arranged adjacently to the rotor chamber are separated by a port plate having a main discharge port and a plurality of auxiliary discharge ports with check valves, and the discharge pipe is connected to the discharge chamber. The upper and lower ends of a connecting position of the discharge pipe with respect to the discharge chamber are set to correspond in height to part of the main discharge port and part of at least one of the auxiliary discharge ports. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  According to the present invention, a rotor chamber in which an impeller rotating around an eccentric shaft center is housed in a main body casing, and a discharge chamber adjacent to the rotor chamber include a plurality of main discharge ports and check valves. The present invention relates to a liquid ring vacuum pump which is partitioned by a port plate in which an auxiliary discharge port is formed and a discharge pipe is connected to the discharge chamber.

  In the liquid ring vacuum pump, the main body casing is partitioned by a port plate into a rotor chamber in which the impeller is accommodated, a suction chamber and a discharge chamber, and centrifugal force is applied to the sealed water in the rotor chamber by the rotation of the impeller. Thus, a water ring is formed in the rotor chamber, and a plurality of divided spaces that expand and contract with the rotation of the impeller are formed between the adjacent blades and the sealing water surface, and the suction port formed in the port plate The target gas is sucked into the enlarged section space from the communicating suction chamber, and the target gas in the reduced section space is discharged from the discharge chamber communicating with the discharge port formed in the port plate. ing.

  Sealed water in the casing forms a water ring, sucks and pumps gas, absorbs gas compression heat generated by gas pumping, and seals movable parts such as shafts Have

  During the operation of the pump, a part of the sealed water in the casing is discharged together with the target gas and discharged from the discharge chamber to the discharge chamber. Therefore, the water is always supplied to the rotor chamber in an amount corresponding to the discharge amount. It is configured as follows.

  Such a liquid ring vacuum pump includes a so-called one-rotation one-acting type in which the target gas is sucked and discharged once in one rotation of the impeller, and a target gas suction and discharge in one rotation of the impeller. There is a so-called one-rotation and two-acting type that performs the operation twice. In recent years, a single-rotation and one-acting type liquid ring vacuum pump has become mainstream from the viewpoint of performance, price, and noise.

  In a one-turn, single-acting liquid-sealed vacuum pump, the impeller can rotate around an axis that is eccentric in a predetermined direction with respect to the radial direction of the main casing within the main casing having a cylindrical inner wall. It is pivotally supported.

  For example, in Patent Document 1, an intake / exhaust flow path and a working water replenishment water path are integrally formed in an outer casing, and a port plate, a casing cover, and a bearing portion are sequentially provided in an inlay manner on both sides in the axial direction of the outer casing. A one-turn, single-acting liquid ring vacuum pump is disclosed in which the shaft center of the impeller is pivotally supported in the vertically upward direction with respect to the inner casing.

  In the liquid ring vacuum pump described in Patent Document 1, a discharge chamber in which a part of the sealed water and target gas discharged from the discharge port formed in the port plate during operation of the pump is formed in the casing cover. Further, it is led to a discharge pipe through an exhaust passage formed between the outer casing and the inner casing and formed in the upper portion of the inner casing.

  An exhaust passage is formed in the upper part of the inner casing in order to avoid excessive discharge of the sealed water and to exhaust the discharged gas separately from the water.

JP 63-13039 A

  In the liquid ring vacuum pump described in Patent Document 1, a part of the sealed water and target gas discharged from the discharge port formed in the port plate during the operation of the pump is between the outer casing and the inner casing. Since it is guided to the discharge pipe through the formed narrow and complicated exhaust flow path, the cross-sectional area of the flow path is narrowed by the water discharged simultaneously with the target gas, and the resistance to the gas flow is increased. There was a problem that the shaft efficiency increased and the pump efficiency decreased.

  Therefore, as shown in FIG. 10, a liquid ring vacuum pump in which a discharge pipe is directly connected to the discharge chamber has been proposed. However, while avoiding excessive discharge of the sealed water, In order to evacuate separately, the connection position of the discharge pipe to the discharge chamber is set to be higher than the position of the discharge port formed in the port plate.

  However, the rotor chamber in which the impeller rotating around the axis eccentrically below the axis is accommodated in the main body casing, and the discharge chamber adjacent to the rotor chamber include a main discharge port and a check valve. In the liquid ring vacuum pump that is partitioned by a port plate in which a plurality of auxiliary discharge ports are formed and the discharge pipe is connected to the discharge chamber, the following new problem has occurred.

  In other words, since the auxiliary discharge port is arranged upstream of the main discharge port along the rotation direction of the impeller, the gas discharged from the main discharge port protrudes to the discharge chamber side. This is a problem that a further improvement in pump efficiency cannot be expected due to a pressure loss or the like generated when the flow path has a complicated shape narrowed by the check valve and rises against the sealed water.

  The liquid ring type vacuum pump provided with the impeller rotating around the axis eccentrically above the axis also has the same problem.

  The present invention has been made in view of the above-described conventional problems, and provides a liquid ring vacuum pump capable of further improving pump efficiency while directly connecting a discharge pipe to a discharge chamber. With the goal.

  In order to achieve the above-mentioned object, the first feature of the liquid ring vacuum pump according to the present invention is that, as described in claim 1 of the claims, an impeller rotating around an eccentric axis is provided. The rotor chamber accommodated in the main body casing and the discharge chamber adjacent to the rotor chamber are partitioned by a port plate in which a plurality of auxiliary discharge ports including a main discharge port and a check valve are formed, A liquid ring vacuum pump having a discharge pipe connected to a discharge chamber, wherein an upper end and a lower end of a connection position of the discharge pipe with respect to the discharge chamber are a main discharge port and at least one auxiliary discharge. The height is set across the part of the port.

  According to the above-described configuration, at least a part of the gas discharged from the main discharge port plate does not move against the water in the complicated and narrow flow path narrowed by the check valve, and the main discharge port. And can smoothly flow out to a discharge pipe connected at a height across a part of at least one auxiliary discharge port, reducing pressure loss and improving pump efficiency. .

  As described in claim 2, the second characteristic configuration includes, in addition to the first characteristic configuration described above, the auxiliary discharge port on the upstream side in the impeller rotation direction of the main discharge port. The opening end of the main discharge port on the auxiliary discharge port side, the midpoint of the opening end on the main discharge port side of the auxiliary discharge port closest to the opening end, and the rotation of the impeller The line connecting the center and the horizontal line passing through the center of the impeller is arranged within a range of ± 15 °, and the center of the connection position of the discharge pipe with respect to the discharge chamber is the center of the impeller This is in the range of ± 15 ° with respect to the horizontal line passing through the center.

  In the third feature configuration, as described in the third aspect, in addition to the first or second feature configuration described above, excess sealed water discharged from the discharge port is supplied to the discharge chamber. A drain port for draining water is formed.

  According to the above-described configuration, the excess sealed water discharged from the discharge port is quickly drained from the drain port provided in the discharge chamber to the outside of the pump, so that the gas and the excess sealed water are separated without being disturbed. Thus, it has become possible to prevent a situation in which the path from the discharge chamber to the discharge pipe becomes narrow due to the excess sealing water and the pressure loss increases.

  In the fourth feature configuration, in addition to any one of the first to third feature configurations described above, the rotor chamber is separated into two chambers in the central portion in the axial center direction. In addition, the discharge chamber is formed in each of the pair of casing covers, and discharge pipes connected to the discharge chambers are individually communicated with the steam-water separator.

  When each discharge pipe is connected to the steam / water separation section through a confluence pipe communicating with each other, pressure loss may occur due to the fluid from each discharge pipe facing the confluence section, which may reduce pump efficiency. However, according to the above-described configuration, such pressure loss does not occur, so that the pump efficiency can be further improved.

  In the fifth feature configuration, in addition to any one of the first to third feature configurations described above, the rotor chamber is separated into two chambers in the axially central portion. In addition, the discharge chamber is formed in each of the pair of casing covers, and the discharge pipe connected to each discharge chamber is connected to the junction pipe through the rectifying plate.

  According to the above-described configuration, since each discharge pipe merges with the merge pipe via the rectifying plate, the fluid from each discharge pipe does not face each other, reducing the piping cost and further increasing the pump efficiency. It became possible to improve.

  As described above, according to the present invention, it is possible to provide a liquid ring vacuum pump capable of further improving pump efficiency while directly connecting a discharge pipe to a discharge chamber.

  Below, the liquid ring vacuum pump by this invention is demonstrated based on drawing.

  As shown in FIGS. 1A and 1B, a liquid ring vacuum pump 1 includes a main body casing 3 having a cylindrical inner wall portion 3 a supported by a plurality of legs 2, and both sides of the main body casing 3. The casing cover 4 (4a, 4b) that closes the opening of the main body 3 and the impeller 6 accommodated in the main body casing 3 are provided.

  The impeller 6 includes a trunk portion 6a that is keyed to the main shaft 5, and a blade 6b that extends radially from the trunk portion 6a in a radial direction and that is curved at least at the tip side in a rotational direction with a predetermined curvature. The center P is supported by bearings 7 (7a, 7b) provided in the casing cover 4 (4a, 4b) so that the center P is eccentric downward with respect to the axis P ′ of the main body casing 3, and one end side of the main shaft 5 is the motor side. It protrudes from the casing cover 4b so as to be connectable to the drive shaft.

  Further, a central wall 6c extending in the radial direction over the entire circumference of the impeller 6 is formed at the central portion along the main shaft 5, and the intermediate wall is formed on the inner wall portion of the main body casing 3 via the central wall 6c and a predetermined gap. 3b is formed in the same plane.

  A through hole 8 is formed in the inner wall portion of the casing cover 4, the main shaft 5 is inserted into the through hole 8 via the main shaft sleeve 9, and a sealing material 10 is disposed between the through hole 8 and the main shaft sleeve 9.

  An annular port plate 15 (15a, 15b) is interposed between the end of the main body casing 3 and the casing cover 4 (4a, 4b), and the impeller 6 is supported by the port plate 15 (15a, 15b). Is partitioned, and the rotor chamber is partitioned to the left and right by a central wall 6c and an intermediate wall 3b.

  That is, the rotor chamber composed of the main body casing 3 in which the impeller 6 is accommodated is separated into two chambers at the central portion in the axial center direction.

  As shown in FIG. 2B, the port plate 15 (15a, 15b) is formed with a suction port 20, a main discharge port 21, an auxiliary discharge port 22, and a water supply port 23. The suction port 20 is a blade. The main discharge port 21 is formed so that the opening area gradually decreases along the rotation direction of the impeller 6, and the auxiliary discharge port 22 is formed. A plurality of small-diameter opening groups each having a check valve by a so-called ball check mechanism or the like are formed. The opening end of the main discharge port 21 on the auxiliary discharge port 22 side, the midpoint of the opening end of the auxiliary discharge port 22 closest to the opening end on the main discharge port 21 side, and the rotation of the impeller 6 A line connecting the centers substantially coincides with a horizontal line passing through the center of the impeller 6, and a center of a connection position of the discharge pipe 17 with respect to the discharge chamber 25 is also substantially coincident with a horizontal line passing through the center of the impeller 6.

  As shown in FIGS. 1A and 1B and FIGS. 2A and 2B, the casing cover 4 (4a and 4b) is compressed by the suction pipe 16 for sucking the target gas and the rotor chamber. A discharge pipe 17 for discharging the discharged gas is connected, and a water supply pipe 11 for supplying sealed water is connected from above.

  The casing cover 4 (so that the target gas sucked from the suction pipe 16 is guided to the rotor chamber through the suction port 20 and the gas compressed in the rotor chamber is discharged from the ports 21 and 22 and discharged to the pipe 17. 4 a, 4 b) and the port plate 15 (15 a, 15 b) are partitioned by a partition wall into a suction chamber 24 and a discharge chamber 25, and water from the water supply pipe 11 passes through the water supply port 23. It is comprised so that it may be supplied to a rotor chamber via.

  When the main shaft 5 is driven while the sealing water is poured into the rotor chamber through the water supply port 23 and the impeller 6 is rotated in the casing 3, centrifugal force is applied to the sealing water in the rotor chamber by the blade 6b, and the sealing water is As shown in FIG. 2C, an annular space S surrounded by the annular water surface LF of the sealed water L is formed in the rotor chamber.

  The annular space S is partitioned into a plurality of partitioned spaces S1 to S20 partitioned by adjacent blades of the impeller 6, and the partitioned spaces S1 to S20 that move with the rotation of the impeller 6 are bottom dead from the top dead center U. It shrinks when it goes to the point D, and it expands when it goes from the bottom dead center D to the top dead center U.

  Accordingly, the target gas sucked from the suction pipe 16 when the divided spaces S1 to S20 are expanded is sucked from the suction port 20, and the compressed gas is discharged from the discharge ports 21 and 22 to the discharge pipe 17 at the time of reduction.

  Each of the suction pipe 16 and the discharge pipe 17 is connected to the casing cover so that the pipe axis is in a substantially horizontal posture and at a height substantially equal to the axis of the impeller 6, and the suction chamber 24 and Drain ports 18a and 18b are formed in the lower part of the casing cover 4 forming the discharge chamber 25 to drain the excess sealing water leaked from the suction port 20 and the discharge ports 21 and 22 to the outside of the pump.

  Therefore, the gas discharged from the main discharge port 21 formed slightly below the axial center of the impeller 6 resists the complicated and narrow flow path of the discharge chamber 25 narrowed by the check valve against water. Without being moved, and smoothly flows out to the discharge pipe 17 connected at a height substantially parallel to the axis of the impeller 6, reducing pressure loss and improving pump efficiency. it can. If the upper end and the lower end of the connection position of the discharge pipe 17 are arranged at a height that spans a part of the main discharge port 21 and at least one auxiliary discharge port 22, the above-described effect can be obtained. If the connection position is set lower than that, the sealed water flows out, which is not preferable because it takes a long time to form a water ring when the pump is activated.

  Further, an auxiliary discharge port 22 is arranged on the upstream side in the rotation direction of the impeller 6 of the main discharge port 21, and the opening end of the main discharge port 21 on the auxiliary discharge port 22 side and the opening end are arranged. The line connecting the midpoint of the opening end of the closest auxiliary discharge port 22 on the main discharge port 21 side and the rotation center of the impeller 6 is within a range of ± 15 ° with respect to a horizontal line passing through the center of the impeller 6. The efficiency of the pump is such that the center of the connection position of the discharge pipe 17 with respect to the discharge chamber 25 is set in a range of ± 15 ° with respect to a horizontal line passing through the center of the impeller 6. This is preferable. Furthermore, it is more preferable that both angles are set in a range of ± 7.5 °. In such a case, the gas discharged from the side close to the auxiliary discharge port 22 of the main discharge port 21 is guided to the discharge pipe 17 most efficiently, so that the pump efficiency is improved.

  Furthermore, since the excess sealed water discharged from the discharge port 21 is quickly drained from the drain ports 18a and 18b provided in the discharge chamber 25 to the outside of the pump, the gas and the excess sealed water are separated without being disturbed. Thus, it is possible to prevent a situation in which the path from the discharge chamber 25 to the discharge pipe 17 becomes narrow due to excess sealing water and the pressure loss increases.

  A drain port 12 for draining the sealed water to the outside for maintenance is provided at the center lower part of the main casing 3. The drain port 12 is closed so as not to affect the water ring during operation, and is configured to be released for draining the sealed water from the casing 3 in the case of maintenance or the like.

  The impeller of such a liquid ring vacuum pump is casted by ductile cast iron such as FCD450 for a large one, and bronze cast such as CAC402 for a small one.

  In the liquid ring vacuum pump described above, as shown in FIG. 3A, each of the discharge pipes 60 connected to the discharge pipes 17 formed in each of the pair of casing covers is used as a steam-water separator. By communicating, pressure loss can be reduced and the pump efficiency can be further improved.

  Further, as shown in FIG. 3B, the discharge pipe 61 connected to each discharge pipe 17 is connected to the merging pipe 63 via the rectifying plate 62, and the steam-water separation unit is connected via the merging pipe 63. The same effect can be obtained by communicating with.

  Hereinafter, another embodiment will be described.

  In the above-described embodiment, the configuration in which the shaft center P of the main shaft 5 is supported by the casing cover 4 (4a, 4b) so as to be eccentric downward with respect to the shaft center P ′ of the main body casing 3 has been described. The present invention can also be applied to a configuration in which the fifth shaft center P is supported by the casing cover 4 (4a, 4b) such that the fifth shaft center P is eccentric upward with respect to the shaft center P ′ of the main casing 3. In general, the latter is used for small liquid ring vacuum pumps with suction pipes and discharge pipes of less than 200 mm in diameter, and the former is used for large liquid ring vacuum pumps with suction pipes and discharge pipes of 200 mm or more in diameter. The

  As shown in FIGS. 4A and 4B, the impeller 31 (31a, 31b) is pivotally supported with respect to the same main shaft 50, and a pair of port plates 32 are provided at positions opposed to the impeller 31 (31a, 31b). (32a, 32b), and the space formed between the port plates 32 (32a, 32b) is also applied to the liquid ring vacuum pump 100 in which the suction chamber 34 and the discharge chamber 35 are partitioned. Can do.

  In this case, each of the suction pipe 36 and the discharge pipe 37 is located at the position of the main body casing 30 corresponding to the suction chamber 34 and the discharge chamber 35 and at a height substantially equal to the axis of the impeller 6. The tube shaft centers are connected so as to have a substantially horizontal posture. Similarly, the drain port 38 is formed in the lower part of the main body casing 30 corresponding to the suction chamber and the discharge chamber.

  In the embodiment described above, the auxiliary discharge port 22 has been described as adopting a ball check structure as a check valve, but a check valve having another structure such as a swing check valve or a lift check valve is employed. It is also possible.

  The various embodiments described above are examples of the present invention, and the specific configuration, dimensions, and the like of each part can be appropriately changed and designed within the scope of the effects of the present invention.

  Examples of the present invention will be described below.

  As shown in FIG. 10, a liquid-sealed vacuum pump 200 (Comparative Example 1) having a standard shape in which the suction pipe 56 and the discharge pipe 57 are formed so that their center positions are higher than the axis P ″ of the impeller. The suction pipe 16 and the discharge pipe 17 have an air volume, a shaft power, and a center position with respect to each of the liquid ring vacuum pump 1 (Experimental Example 1) whose center position is substantially equal to the axis P of the impeller 6. An efficiency evaluation experiment was conducted, and characteristic graphs of the experimental results are shown in FIGS. 5 (a), (b), and (c).

  From the characteristic graph, the air volume is less in comparison with Comparative Example 1 in the region where the degree of vacuum is about -20 kPa to about -55 kPa, but compared with Example 1 in the region where the degree of vacuum is about -55 kPa to about -70 kPa. As compared with Example 1, shaft power was reduced in Experimental Example 1 as compared with Comparative Example 1, and it was confirmed that the efficiency increased and the maximum efficiency increased.

  Next, a liquid-sealed vacuum pump 200 (Comparative Examples 2, 3 and 4) having a standard shape in which the suction pipe 56 and the discharge pipe 57 are formed so that their center positions are higher than the axis P ″ of the impeller. The suction pipe 16 and the discharge pipe 17 are activated for each of the liquid ring vacuum pumps 1 (Experimental Examples 2, 3, and 4) whose center positions are substantially equal to the axis P of the impeller 6. Experiments were conducted to evaluate the time, torque, and power value from time to a predetermined degree of vacuum.

  FIG. 6 is a characteristic graph of experimental results in which the amount of sealed water injected into the casing is 140 L / min for both Comparative Example 2 and Experimental Example 2, and the predetermined degree of vacuum is −73 kPa for Comparative Example 2 and −70 kPa for Experimental Example 2. (A), (b) and (c).

From the characteristic graph, Experimental Example 2 has a shorter time from the start of the pump to a predetermined degree of vacuum, a smaller torque, and a smaller starting current than Comparative Example 2. That is, it was confirmed that the efficiency of the pump was increased.

  According to the experiment in which the amount of sealed water injected into the casing was 140 L / min in both Comparative Example 3 and Experimental Example 3, and the predetermined vacuum degree was -88 kPa in Comparative Example 3 and -86 kPa in Experimental Example 3 Compared with Comparative Example 3, the time from the start of the pump to a predetermined vacuum level is shorter, the torque is smaller, and the starting current is also smaller. That is, it was confirmed that the efficiency of the pump was increased.

  FIG. 7A is a characteristic graph of experimental results in which the amount of sealed water injected into the casing is 220 L / min in both Comparative Example 4 and Experimental Example 4, and the predetermined degree of vacuum is -87 kPa in both Comparative Example 4 and Experimental Example 4. ), (B), (c).

From the characteristic graph, Experimental Example 4 has a shorter time from the start of the pump to a predetermined degree of vacuum, a smaller torque, and a smaller starting current than Comparative Example 4. That is, it was confirmed that the efficiency of the pump was increased.

  Next, the suction pipe 16 and the discharge pipe 17 are sealed water discharged from the discharge port during the operation of the liquid ring vacuum pump 1 whose center position is substantially equal to the axis P of the impeller 6. Is drained from the drain port 18 (Experimental Example 5) and when it is not drained (Comparative Example 5), the air volume, shaft power, and efficiency are evaluated, and the characteristic graphs for the experimental results are shown in FIGS. ) And (c).

  From the characteristic graph, the amount of air is less in the region where the degree of vacuum is -23 kPa to about -50 kPa when drained from the drain port 18 (Experimental Example 5) than when not draining (Comparative Example 5). It was confirmed that the shaft power increased in the region from 60 kPa to about −72 kPa, and that the shaft power was reduced particularly in the region where the degree of vacuum was from about −23 kPa to −60 kPa. At this time, it was confirmed that the efficiency increased and the maximum efficiency also increased.

  As shown in FIGS. 3A and 3B, when a straight tubular discharge pipe 60 is connected to each discharge pipe 17 of the liquid ring vacuum pump 1 (Experimental Example 6), and a liquid ring vacuum pump 1 is connected to each discharge pipe 17 and an merging pipe 63 is connected to the discharge pipe 61 via a rectifying plate 62 (Comparative Example 6). An efficiency evaluation experiment was conducted, and characteristic graphs of the experimental results are shown in FIGS. 9 (a), 9 (b), and 9 (c).

  From the characteristic graph, it was confirmed that the air volume of Experimental Example 6 increased compared with Comparative Example 6, and the shaft power was reduced in the region where the degree of vacuum was about −26 kPa to about −65 kPa. At this time, it was confirmed that the efficiency increased and the maximum efficiency also increased.

(A) is a front sectional view of a liquid ring vacuum pump according to the present invention, and (b) is a plan sectional view. (A) is a side view of a liquid ring vacuum pump according to the present invention, (b) is an explanatory diagram of a port plate, (c) is an explanatory diagram of a rotor chamber when the impeller rotates. (A) is a connection diagram of a discharge pipe of a liquid ring vacuum pump according to the present invention, (b) is a connection diagram of a discharge pipe of a liquid ring vacuum pump according to the present invention. Another embodiment is shown, (a) is a front sectional view of a liquid ring vacuum pump according to the present invention, and (b) is a plan sectional view. It is the characteristic view obtained by the evaluation experiment of the liquid ring type vacuum pump by this invention, (a) is a characteristic view which shows the relationship between a vacuum degree and an air volume, (b) is a characteristic view which shows the relationship between a vacuum degree and shaft power. , (C) is a characteristic diagram showing the relationship between the degree of vacuum and pump efficiency It is the characteristic view obtained by the evaluation experiment of the liquid ring type vacuum pump by this invention, (a) is the characteristic view which shows the relationship between time and a vacuum degree, (b) is the characteristic view which shows the relationship between time and torque, c) Characteristic diagram showing the relationship between time and current value It is the characteristic view obtained by the evaluation experiment of the liquid ring type vacuum pump by this invention, (a) is the characteristic view which shows the relationship between time and a vacuum degree, (b) is the characteristic view which shows the relationship between time and torque, c) Characteristic diagram showing the relationship between time and current value It is the characteristic view obtained by the evaluation experiment of the liquid ring type vacuum pump by this invention, (a) is a characteristic view which shows the relationship between a vacuum degree and an air volume, (b) is a characteristic view which shows the relationship between a vacuum degree and shaft power. , (C) is a characteristic diagram showing the relationship between the degree of vacuum and pump efficiency It is the characteristic view obtained by the evaluation experiment of the liquid ring type vacuum pump by this invention, (a) is a characteristic view which shows the relationship between a vacuum degree and an air volume, (b) is a characteristic view which shows the relationship between a vacuum degree and shaft power. , (C) is a characteristic diagram showing the relationship between the degree of vacuum and pump efficiency Side view of a conventional liquid ring vacuum pump

Explanation of symbols

1: Liquid ring vacuum pump 2: Leg part 3: Main body casing 3a: Inner wall part 3b: Intermediate wall 4, 4a, 4b: Casing cover 5: Main shaft 6: Impeller 6a: Body part 6b: Blade 6c: Center wall 7 7a, 7b: Bearing 8: Through hole 9: Main shaft sleeve 10: Sealing material 11: Water supply pipe 12: Drain port 15, 15a, 15b: Port plate 16: Suction pipe 17: Discharge pipe 18: Drain port 20: Suction Port 21: Discharge port 22: Discharge port 23: Water supply port 24: Suction chamber 25: Discharge chamber 31, 31a, 31b: Impeller 32, 32a, 32b: Port plate 34: Suction chamber 35: Discharge chamber 36: suction pipe 37: discharge pipe 50: main shaft 56: suction pipe 57: discharge pipe 100: liquid ring vacuum pump 200: liquid ring vacuum pump L: sealed water LF: annular water surface S: annular space S1 S 0: Category Space U: top dead center D: bottom dead point P: axis P': axial P'': axis

Claims (5)

A rotor chamber in which an impeller rotating around an eccentric shaft center is housed in a main body casing, and a discharge chamber adjacent to the rotor chamber are a plurality of auxiliary discharge ports each having a main discharge port and a check valve A liquid ring vacuum pump that is partitioned by a port plate formed with a discharge pipe connected to the discharge chamber,
A liquid ring vacuum pump in which an upper end and a lower end of a connection position of the discharge pipe with respect to the discharge chamber are set to a height over a main discharge port and a part of at least one auxiliary discharge port.   The auxiliary discharge port is disposed upstream of the main discharge port in the impeller rotation direction, and the opening end of the main discharge port on the auxiliary discharge port side is closest to the opening end. Arranged so that the line connecting the midpoint of the opening end of the auxiliary discharge port on the main discharge port side and the rotation center of the impeller is within a range of ± 15 ° with respect to a horizontal line passing through the center of the impeller 2. The liquid ring vacuum pump according to claim 1, wherein the center of the connection position of the discharge pipe with respect to the discharge chamber is set in a range of ± 15 ° with respect to a horizontal line passing through the center of the impeller. .   The liquid ring vacuum pump according to claim 1 or 2, wherein a drain port for draining excess sealing water discharged from the discharge port to the outside of the pump is formed in the discharge chamber.   The rotor chamber is separated into two chambers at the central portion in the axial direction, the discharge chamber is formed in each of a pair of casing covers, and the discharge pipe connected to each discharge chamber is separated into air and water. The liquid ring vacuum pump according to claim 1, wherein the liquid ring vacuum pump is communicated with the portion.   The rotor chamber is separated into two chambers at the central portion in the axial center direction, the discharge chamber is formed in each of a pair of casing covers, and a discharge pipe connected to each discharge chamber is connected via a current plate. The liquid ring vacuum pump according to any one of claims 1 to 3, wherein the liquid ring vacuum pump is connected to a junction pipe.

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