JP2006200380A - Roots type fluid machinery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely reduce noise and pressure pulsation in Roots fluid machinery. <P>SOLUTION: In a Roots blower, five grooves 39a to 39e are continuously formed in both side faces of a discharge port 11 of an inner peripheral face of a casing 13 to make a pressure chamber continuous to the discharge port 11 communicate with a pressure chamber on the rear side thereof in a traveling direction. The five grooves 39a to 39e have different lengths L1 to L5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a roots type fluid machine.

  Conventionally, a roots type fluid machine represented by a roots type blower, a roots type vacuum pump or the like has been used in various industrial fields such as water treatment and pneumatic transportation.

  In a roots-type fluid machine, a rotor having a plurality of leaf pieces is synchronously rotated in opposite directions so that the leaf pieces are engaged with each other in a sealed casing, whereby a plurality of sections formed by the leaf pieces and the inner peripheral surface of the casing are formed. The pressure chamber moves from the suction port side to the discharge port side. Then, the fluid sucked into the pressure chamber from the suction port is transported to the discharge port side along with the movement of the pressure chamber, and is discharged from the discharge port.

  By the way, the discharge port side has a high pressure while the suction port side has a low pressure, and the pressure in the pressure chamber remains low until the pressure chamber is connected to the discharge port. On the other hand, at the moment when the moving pressure chamber is connected to the discharge port, a large pressure difference occurs between the high pressure on the discharge port side and the low pressure on the pressure chamber, and high-pressure fluid suddenly flows from the discharge port toward the pressure chamber. Backflow. For this reason, in the conventional roots type fluid machine, a large noise was generated due to the back flow. In addition, pressure pulsation may occur, leading to unstable driving.

Therefore, a technique for reducing noise and reducing pressure pulsation by suppressing the backflow of such a high-pressure fluid has been proposed. For example, Patent Document 1 discloses a Roots type fluid machine in which a plurality of grooves are provided on the inner peripheral surface of a casing to communicate a pressure chamber before being connected to a discharge port with the discharge port side. In this roots type fluid machine, since the high-pressure fluid on the discharge port side gradually flows through the grooves into the pressure chamber before connecting to the discharge port, at the moment when the pressure chamber is connected to the discharge port, the pressure side and the pressure The pressure difference from the chamber is alleviated to some extent, and a rapid reverse flow of the high-pressure fluid is prevented, thereby reducing noise and suppressing pressure pulsation.
JP 2001-82370 A (Page 4, FIGS. 8 and 9)

  However, in Patent Document 1, although the pressure difference between the discharge port side and the adjacent pressure chamber is alleviated to some extent, the plurality of grooves are all set to the same length. High-pressure fluid on the discharge port side flows into the pressure chamber all at once, and the pressure fluctuation generated in the pressure chamber becomes large, so that it is not possible to sufficiently reduce noise and suppress pressure pulsation.

  The present invention has been made in view of this point, and an object of the present invention is to reliably reduce noise and pressure pulsation.

  In order to achieve the above object, the present invention is characterized in that the length of the groove is devised.

  Specifically, the present invention includes a casing in which a suction port and a discharge port are formed and a pair of rotors housed in the casing and having a plurality of leaf pieces so that the leaf pieces mesh with each other. Root type fluid machine that draws fluid from the suction port into the casing and discharges it from the discharge port while forming a plurality of pressure chambers moving from the suction port side to the discharge port side by synchronously rotating in opposite directions to each other The following solution was taken.

  That is, the invention according to claim 1 is provided with a plurality of grooves that communicate between the pressure chamber connected to the discharge port and the pressure chamber on the rear side in the traveling direction from the pressure chamber on both sides of the discharge port on the inner peripheral surface of the casing. Are formed to be continuous with the discharge ports, and at least a part of the plurality of grooves is different in length from other grooves.

  The invention according to claim 2 is the invention according to claim 1, wherein the rotor is a three-leaf type having three leaf pieces, and the length of the groove is the rotation center of the rotor and the opening edge of the discharge port. The angle from the rotation center of the rotor with respect to the straight line connecting the two is set to fall within a range of 10 ° to 60 °.

  The invention according to claim 3 is characterized in that, in the invention according to claim 2, the angle difference between the maximum angle and the minimum angle exceeds 25 °.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the width of the groove is gradually increased as it approaches the discharge port.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, characterized in that the depth of the groove gradually becomes deeper as it approaches the discharge port.

  According to this invention, the pressure chamber moving to the discharge port side communicates with the discharge port in stages through the grooves having different lengths, so that the high-pressure fluid on the discharge port side gradually passes through the grooves. As the pressure chamber flows into the discharge port and the pressure chamber gradually increases in a stepwise manner as it moves to the discharge port side, the pressure difference from the discharge port side is already present at the moment when the pressure chamber is connected to the discharge port. It is greatly relaxed, and the backflow speed of the fluid from the pressure chamber on the discharge port side to the pressure chamber on the rear side in the traveling direction can be suppressed to a small value. Therefore, noise and pressure pulsation can be reliably reduced. Particularly, in the second and third aspects, when the rotor is a three-leaf type, the above-described effects can be realized. In the fourth and fifth aspects, the backflow velocity of the fluid from the pressure chamber on the discharge port side to the pressure chamber on the rear side in the traveling direction can be further reduced, so that the effect of reducing noise and pressure pulsation can be enhanced.

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

  2 to 4 show a Roots type blower as a Roots type fluid machine according to an embodiment of the present invention. 2 to 4, reference numeral 1 denotes a base. A blower body 3 is installed on the base 1, and a motor 5 is installed next to the blower body 3 via an installation table 7. The blower body 3 includes a sealed casing 13 having a suction port 9 at the upper end and a discharge port 11 at the lower end, and a pair of rotors 15 and 17 (hereinafter referred to as a drive rotor 15 and a driven rotor) are provided in the casing 13. 17) are accommodated horizontally. Each of the drive rotor 15 and the driven rotor 17 is a three-leaf type having three leaf pieces 15a and 17a, and shaft portions 15b and 17b are integrally projected at both ends. The number of leaf pieces 15a and 17a is not limited to three, and may be two or four or more.

  The shaft portions 15b and 17b penetrate the side walls 13a and 13b of the casing 13, and the drive rotor 15 and the driven rotor 17 have the side walls 13a and 13b of the casing 13 as bearing plates and the side walls 13a and 13b and the shaft portions 15b and 17b. Are supported by the casing 13 in a freely rotatable manner, and the leaf pieces 15a and 17a are engaged with each other in a non-contact state.

  A gear 21 is fixed to one shaft portion 15b, 17b of each of the drive rotor 15 and the driven rotor 17, and both the gears 21 mesh with each other. A gear case 23 is joined to one side wall 13a of the casing 13, and an oil chamber 25 is formed between the gear case 23 and the side wall 13a. The both gears 21 are accommodated in the oil chamber 25 so as to be exposed to oil. ing.

  A bearing cover 27 is joined to the other side wall 13b of the casing 13, and the shaft portion 15b on the other side (on the non-gear side) of the drive rotor 15 protrudes outside from the bearing cover 27 and is driven by a protruding end portion of the shaft portion 15b. A pulley 29 is fixed.

  On the other hand, a drive pulley 31 is fixed to the output shaft 5 a of the motor 5, and an endless belt 33 is wound around the drive pulley 31 and the driven pulley 29. Then, the rotational force of the motor 5 is transmitted to the shaft portion 15b via the drive pulley 31, the endless belt 33 and the driven pulley 29 to rotate the drive rotor 15, and this rotational force is transmitted to the driven rotor 17 via both gears 21. The plurality of pressure chambers R1 moving from the suction port 9 side to the discharge port 11 side by synchronously rotating the drive rotor 15 and the driven rotor 17 in opposite directions so that the leaf pieces 15a and 17a mesh with each other. The air as a fluid is sucked into the casing 13 from the suction port 9 and discharged from the discharge port 11 while partitioning R4. Specifically, the pressure chamber R1 connected to the suction port 9 has pressure chambers R2 and R3 sealed by the leaf pieces 15a and 17a and the inner peripheral surface of the casing 13 as the drive rotor 15 and the driven rotor 17 rotate. Then, the pressure chamber R4 connected to the discharge port 11 is obtained. As the pressure chamber moves in this way, the air sucked from the suction port 9 is conveyed and blown out from the discharge port 11.

  In FIG. 4, reference numeral 35 denotes a cylindrical silencer projecting upward from the suction port 9 of the casing 13. A ring-shaped air filter (not shown) is attached to the upper end of the silencer 35, and the air is sucked into the suction port. 9 is silenced and purified in the process of introduction. A belt cover 37 covers the driving pulley 31, the driven pulley 29, and the endless belt 33 from above.

  As an aspect of the present invention, as shown in an enlarged view in FIG. 1, the casing 13 connecting portion of the discharge port 11 has a rectangular shape, and five straight grooves are formed on both sides of the discharge port 11 on the inner peripheral surface of the casing 13. 39a to 39e are formed so as to be continuous with the discharge port 11, respectively. These grooves 39a to 39e are longest in the middle in FIG. 1, and are alternately shortened to the left and right, and the lengths L1 to L5 of all the grooves 39a to 39e are different. Not limited to this, it is sufficient that at least a part of the five grooves 39a to 39e is different in length from the other grooves. For example, the groove 39b and the groove 39c may have the same length. The number of grooves is not limited to five. Further, the grooves 39a to 39e may be zigzag grooves or helical grooves in addition to the linear shape. The grooves 39a to 39e allow the pressure chamber R4 connected to the discharge port 11 to communicate with the pressure chambers R2 and R3 on the rear side in the traveling direction (before connecting to the suction port 9) with respect to the pressure chamber R4. ing. The lengths L1 to L5 of the grooves 39a to 39e are such that the driving rotor 15 and the driven rotor 17 have a length L1 to a straight line connecting the rotation center O of the driving rotor 15 and the driven rotor 17 and the opening edge of the discharge port 11. The angle from the rotation center O is set so as to be within a range of 10 ° to 60 °. Further, it is assumed that the angle difference between the maximum angle α1 (groove 39a) and the minimum angle α2 (groove 39e) of the angle exceeds 25 °. Further, the width W of the grooves 39a to 39e gradually increases as the distance from the discharge port 11 increases, and the depth D of the grooves 39a to 39e increases gradually as the distance from the discharge port 11 decreases.

  Next, in the Roots-type blower configured as described above, air is sucked from the suction port 9 when the drive rotor 15 and the driven rotor 17 are rotated. The sucked air flows into a pressure chamber (pressure chamber R1 in FIG. 2) connected to the suction port 9. Next, when the front ends of the leaf pieces 15a and 17a in the rotational direction of the driving rotor 15 and the driven rotor 17 pass through the suction port 9, the pressure chamber is sealed. That is, the pressure chamber is a sealed pressure chamber (pressure chambers R2 and R3 in FIG. 2) defined by the front leaf pieces 15a and 17a in the rotation direction, the rear leaf pieces 15a and 17a, and the inner peripheral surface of the casing 13. Become. After that, when the leaf pieces 15a and 17a on the front side of the pressure chambers R2 and R3 pass through the head portions of the grooves 39a to 39e, the pressure chambers R2 and R3 are connected to the pressure chamber R4 on the discharge port 11 side through the grooves 39a to 39e. Communicate with. As a result, high-pressure air is gradually and gradually introduced from the pressure chamber R4 on the suction port 9 side into the pressure chambers R2 and R3 through the grooves 39a to 39e. Thereafter, the front leaf pieces 15 a and 17 a pass through the discharge port 11, and the pressure chamber becomes a pressure chamber R 4 connected to the discharge port 11, and the volume of the pressure chamber R 4 as the drive rotor 15 and the driven rotor 17 rotate. Will decrease. As a result, the air in the pressure chamber R4 is discharged from the discharge port 11.

  Thus, in this embodiment, high-pressure air is gradually and gradually introduced into the pressure chamber through the grooves 39a to 39e having different lengths before connecting to the discharge port 11. For this reason, the pressure difference with the discharge port 11 side is relieved greatly, the backflow speed of the air which goes to the pressure chamber of the advancing direction from the pressure chamber of the discharge port 11 side can be restrained small, and it connected with the discharge port 11 An abrupt reverse flow of high-pressure air to the pressure chamber is surely suppressed. Therefore, the generation of noise and pressure pulsation due to the backflow of high-pressure air can be effectively suppressed. This effect is that the lengths L1 to L5 of the grooves 39a to 39e are different, and the lengths L1 to L5 of the grooves 39a to 39e are the rotation centers O of the drive rotor 15 and the driven rotor 17 and the opening ends of the discharge ports 11. The angle from the rotation center O of the drive rotor 15 and the driven rotor 17 with respect to the straight line connecting the edges is set to fall within a range of 10 ° to 60 °, and the maximum angle α1 and the minimum of the above angles. This can be ensured by the fact that the angle difference from the angle α2 exceeds 25 °. Further, the groove 39a to 39e has a width W that gradually increases as it approaches the discharge port 11, and the depth D of the grooves 39a to 39e gradually increases as it approaches the discharge port 11. The spatial volume of ~ 39e can be gradually increased. Therefore, it is possible to further reduce the backflow velocity of the fluid from the pressure chamber on the discharge port 11 side to the pressure chamber on the rear side in the traveling direction, and to increase the effect of reducing noise and pressure pulsation. Incidentally, the pressure pulsation change data of the Roots blower according to this embodiment is shown in FIG. 5 in comparison with the data when the groove length is the same. In FIG. 5, the ● mark indicates the present embodiment, the ▲ mark indicates the comparative example, and the pressure pulsation is reduced in the present embodiment compared to the comparative example. I know that. In order to obtain this data, a blower having a diameter of 125 mm and an output of 22 kW was used, and the discharge pressure was set to 60 kPa.

  The roots type fluid machine according to the present invention is not limited to the roots type blower, but may be other roots type fluid machines such as a roots type vacuum pump.

  The present invention is useful as a roots type fluid machine.

It is the top view which looked at the discharge outlet from the casing inner side. It is a longitudinal cross-sectional view of a Roots type blower. It is a cross-sectional view of a roots type blower. It is a front view of a Roots type blower. It is the data of the pressure pulsation change of a Roots type blower.

Explanation of symbols

9 Suction port 11 Discharge port 13 Casing 15 Drive rotor 17 Driven rotor 15a, 17a Leaf pieces 39a to 39e Groove D Groove depth L1 to L5 Groove length R1 to R4 Pressure chamber W Groove width

Claims (5)

A casing having a suction port and a discharge port, and a pair of rotors housed in the casing and having a plurality of leaf pieces, the pair of rotors being synchronously rotated in opposite directions so that the leaf pieces are engaged with each other. Thus, a roots-type fluid machine that draws fluid from the suction port into the casing and discharges it from the discharge port while forming a plurality of pressure chambers moving from the suction port side to the discharge port side,
On both sides of the discharge port on the inner peripheral surface of the casing, a plurality of grooves that connect the pressure chamber connected to the discharge port and the pressure chamber on the rear side in the traveling direction from the pressure chamber are formed to be continuous with the discharge port, respectively. A roots type fluid machine characterized in that at least a part of the plurality of grooves is different in length from other grooves. The roots type fluid machine according to claim 1,
The rotor is a three-leaf type with three leaf pieces,
The length of the groove is set so that the angle from the rotation center of the rotor to the straight line connecting the rotation center of the rotor and the opening edge of the discharge port is within a range of 10 ° to 60 °. Roots type fluid machine. The roots type fluid machine according to claim 2,
A roots type fluid machine, wherein an angle difference between a maximum angle and a minimum angle exceeds 25 °. In the roots type fluid machine according to any one of claims 1 to 3,
A roots type fluid machine characterized in that the width of the groove gradually increases as it approaches the discharge port. The roots type fluid machine according to any one of claims 1 to 4,
A roots-type fluid machine characterized in that the depth of the groove gradually increases as it approaches the discharge port.

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