Centrifugal separator

Abstract

The present invention suppresses occurrence of contamination due to grease by means of a simple method. This centrifugal separator centrifugalizes a processing object by rotating a bowl supplied with the processing object around a rotation axis extending in the vertical direction. The centrifugal separator is characterized by including: a cylindrical bowl feed part that is formed at the lower end of the bowl and serves as a receiving port for the processing object; a bearing part for the bowl feed part; and a grease supply part that supplies grease toward a discharge port formed in the outer circumferential surface of the bearing part. The centrifugal separator is also characterized in that the outer circumferential surface of the bowl feed part facing the bearing part has formed thereon a feed shape part that transfers the grease discharged from the discharge port upward.

Description

Centrifugal separator

[0001] The present invention relates to a centrifugal separator in which a bowl rotates around a vertical rotation axis.

[0002] A centrifugal separator is known that applies a centrifugal force to a processed material supplied into a rotating bowl to perform a separation operation according to the purpose, such as solid-liquid separation, liquid-liquid separation, or solid-liquid-liquid separation. FIG. 8 is an enlarged view of the lower part of the bowl in a conventional centrifugal separator. FIG. 9 is an enlarged view of the vicinity of the bearing part in the centrifugal separator of FIG. 8.

[0003] A sleeve 102 is attached to the outer peripheral surface of a feed cylindrical part 101 formed at the lower end of a bowl 100, and a bearing part 201 is provided with a minute clearance from this sleeve 102. The bearing part 201 is also called a drag bushing. Grease for reducing friction is supplied between the sleeve 102 of the feed cylindrical part 101 and the bearing part 201 (see 0003 of Patent Document 1, FIG. 7, etc.).

[0004] Patent Document 2 discloses a vertical centrifugal separator provided with a non-contact type vibration suppression mechanism (magnetic bearing).

[0005] Japanese Patent Application Laid-Open No. 2023-110103 International Publication No. 2007 / 086114

[0006] The inventors of the present invention discovered a phenomenon in the centrifugal separator shown in FIGS. 8 and 9 that grease drops from the gap between the sleeve 102 and the bearing part 201 and is drawn into the inside of the bowl (see the dotted arrow shown in FIG. 8). When the grease is drawn into the inside of the bowl 100, the product is contaminated. On the other hand, although the non-contact type vibration suppression mechanism of Patent Document 2 can eliminate grease, since it is necessary to mount a magnetic bearing, the cost increases. An object of the present invention is to suppress the occurrence of contamination by grease by a simple method.

[0007] To solve the above problems, the present invention provides a centrifugal separator that (1) rotates a bowl into which a material is supplied around a vertically extending rotation axis to centrifuge the material, comprising: a cylindrical bowl feed section formed at the lower end of the bowl, which is a material receiving port; a bearing section for the bowl feed section; and a grease supply section that supplies grease toward a discharge port formed on the outer circumferential surface of the bearing section, wherein a feed shape section is formed on the outer circumferential surface of the bowl feed section facing the bearing section to transfer the grease discharged from the discharge port upward.

[0008] (2) The centrifugal separator according to (1) above, characterized in that the bowl feed section comprises a ring-shaped sleeve on which the feed shape section is formed.

[0009] (3) The centrifugal separator according to (1) or (2) above, characterized in that the feed shape portion is a spirally formed screw groove.

[0010] (4) The centrifugal separator according to (3) above, characterized in that the threads of the screw groove make surface contact with the bearing portion during centrifugal separation.

[0011] (5) The centrifugal separator according to (1) or (2) above, characterized in that the feed shape portion is a screw blade.

[0012] According to the present invention, the feeding action of the feed-shaped section that operates during centrifugal separation allows the grease discharged from the bearing section to be transferred upward. This makes it less likely for the grease to be drawn into the bowl, thus easily suppressing the occurrence of contamination.

[0013] This is a schematic diagram of a centrifugal separator. This is an enlarged view of a part of the centrifugal separator, including the lower part of the bowl. This is an enlarged view of the area Rect 1 shown by the dotted line in Figure 2. This is an enlarged view of the sleeve in Figure 3. This is a modified version of the sleeve in Figure 4. This is a modified version of the sleeve (with a non-ridged shape in the center). This is a modified version of the sleeve (with a non-ridged shape at the upper end). This is an enlarged view of the lower part of the bowl of a conventional centrifugal separator. This is an enlarged view of the vicinity of the bearing in Figure 8.

[0014] Figure 1 is a schematic diagram of the centrifugal separator of this embodiment. The centrifugal separator 1 comprises a motor 11, a belt drive mechanism 12, a spindle 13, a bowl 14, and a casing 15. Generally, centrifugal separators in which the rotation axis of the bowl 14 extends horizontally are called "horizontal type," and centrifugal separators in which the rotation axis of the bowl 14 extends vertically are called vertical type. The centrifugal separator of the present invention is a vertical type centrifugal separator.

[0015] The belt drive mechanism 12 transmits the power generated by the motor 11 to the spindle 13, which in turn rotates the bowl 14 around a vertically extending axis V via the spindle 13. The "V" in axis V stands for "vertical". The rotational speed of the bowl 14 is preferably 15,000 revolutions per minute or more. The bowl 14 is housed in a casing 15, and a cover 151 is detachably provided on the top of the casing 15.

[0016] Figure 2 is an enlarged view of a part of the centrifugal separator, including the lower part (bowl bottom) of bowl 14. The arrows in Figure 2 indicate the movement of the grease. Figure 3 is an enlarged view of the area Rect 1 shown by the dotted line in Figure 2. "Rect" in "Rect 1" is an abbreviation for "Rectangle". "RT" is an abbreviation for "rotate".

[0017] Referring to these figures, a cylindrical bowl feed portion 140 is provided at the lower end of the bowl 14. The bowl feed portion 140 has a main body portion 141 and a sleeve 142. The main body portion 141 is formed in a cylindrical shape, the upper end opening of the main body portion 141 communicates with the inside of the bowl 14, and a feed nozzle 30 is inserted into the lower end opening of the main body portion 141.

[0018] The material ejected from the feed nozzle 30 is supplied to the inside of the bowl 14 via the main body 141. In other words, the bowl feed section 140 functions as a receiving port for the centrifugal separator 1 to receive the material.

[0019] The main body 141 has a thinned portion 141A formed on a part of its outer circumferential surface, where the diameter is reduced toward the axial center. The sleeve 142 is formed in a ring shape and is attached to the thinned portion 141A of the main body 141. The sleeve 142 can be attached to the main body 141 by screwing together the screw grooves (not shown) formed on the outer circumferential surface of the thinned portion 141A and the inner circumferential surface of the sleeve 142. By using fastening as the method of attachment for the sleeve 142, the sleeve 142 can be easily replaced. However, the attachment method is not limited to fastening and may be other methods (for example, welding).

[0020] A ring-shaped bearing portion 60 is provided around the sleeve 142. A small clearance is formed between the sleeve 142 and the bearing portion 60. The reason for leaving a small clearance and positioning the bearing portion 60 is to suppress the wobble of the bowl 14 when it rotates. In other words, if the wobble of the bowl 14 becomes large during centrifugal separation, the sleeve 142 of the bowl feed portion 140 comes into contact with the bearing portion 60, thereby suppressing excessive wobble.

[0021] A grease passage 61, indicated by a dotted line, is formed in the bearing portion 60. The discharge port 60A of the grease passage 61 is formed on the inner surface of the bearing portion 60 facing the sleeve 142. The starting end of the grease passage 61 is in communication with the grease cup 70. When the grease cup 70 is rotated, grease can be discharged from the discharge port 60A via the grease passage 61. This forms a boundary lubrication film of grease between the bearing portion 60 and the sleeve 142 during centrifugal separation, thereby reducing friction. The grease cup 70 and the grease passage 61 work together to realize a "grease supply unit".

[0022] The sleeve 142 will be described in detail. A feed-shaped portion 142A is formed on the outer circumferential surface of the sleeve 142 (in other words, the surface facing the bearing portion 60). During centrifugal separation, the sleeve 142 rotates together with the main body portion 141. At this time, the grease discharged between the bearing portion 60 and the sleeve 142 is transported upward by the feed action of the feed-shaped portion 142A.

[0023] The grease that is transported upward is discharged into the space between the bowl 14 and the casing 15. This effectively prevents contamination by grease entering the inside of the bowl 14.

[0024] Since a feed-shaped portion 142A is formed on the outer surface of the sleeve 142, and the transfer action by the feed-shaped portion 142A is generated by the rotational force of the bowl 14, contamination can be prevented in a simple manner. In other words, since there is no need to provide expensive mechanisms such as magnetic bearings, costs can be reduced.

[0025] Here, when the bearing section 60 is divided into upper and lower regions equally, and these regions are defined as the upper region, middle region, and lower region, it is preferable to form the discharge port 60A in the middle region. Since the grease is supplied manually by the grease cup 70, the supply speed is not stable. Therefore, if the discharge port 60A is formed in the lower region, there is a risk that some of the grease will fall by gravity after being discharged and leak out from the lower end of the bearing section 60. On the other hand, if the discharge port 60A is formed in the middle region, the feeding action of the feeding shape section 142A can change the direction of movement of the grease upward before it falls from the lower end of the bearing section 60.

[0026] However, the present invention does not prevent the discharge port 60A from being formed in the lower region. Even when the discharge port 60A is formed in the lower region, it is more effective in preventing contamination than the conventional structure without the feed shape portion 142A (see Figure 9).

[0027] If the discharge port 60A is formed in the upper region, the area of ​​the boundary lubrication film decreases, thus reducing the friction reduction effect. By forming the discharge port 60A in the middle region, the area of ​​the boundary lubrication film increases, thereby enhancing the friction reduction effect.

[0028] The feed shape section 142A is preferably a spirally formed screw groove. The spiral direction should be one that allows the grease to be transported upward during centrifugal separation. When viewed from the top side of the centrifugal separator 1, if the bowl 14 rotates clockwise (right rotation), the feed shape section 142A can be formed by cutting a right-hand thread on the outer circumferential surface of the sleeve 142. If the bowl 14 rotates counterclockwise (left rotation), the feed shape section 142A can be formed by cutting a left-hand thread on the outer circumferential surface of the sleeve 142. Figures 2 and 3 show the centrifugal separator when the bowl 14 rotates clockwise. The screw pitch of the screw groove is preferably 1 mm or more and 3 mm or less.

[0029] The threads of the screw groove preferably make surface contact with the bearing portion 60. The shape of the threads that make surface contact is illustrated in Figures 4 and 5. Figure 4 is an enlarged view of the sleeve of Figure 3. Figure 5 is a modified example of the sleeve of Figure 4. The screw grooves of Figures 4 and 5 are similar in that they consist of a continuous trapezoidal section made up of an upper base 142A1 and a pair of hypotenuses 142A2. The trapezoidal section of Figure 4 differs from the trapezoidal section of Figure 5 in that adjacent trapezoidal sections are connected by connecting lines 142A3 that extend in a direction parallel to the upper base 142A1. The trapezoidal section of Figure 5 differs from the trapezoidal section of Figure 4 in that adjacent trapezoidal sections are directly connected by hypotenuses 142A2. In both cases, the upper side 142A1 of the trapezoidal section makes contact (surface contact) with the bearing portion 60.

[0030] By forming the threads of the screw groove (feed-in shape portion 142A) in a shape that makes surface contact with the bearing portion 60, the contact area between the feed-in shape portion 142A and the bearing portion 60 is increased, thereby reducing the load on the contact area. In contrast, if the spiral-shaped screw groove is made into a triangular screw, the contact between the feed-in shape portion 142A and the bearing portion 60 becomes a line contact, increasing the load on the contact area. However, the present invention does not prevent the spiral-shaped screw groove from being made into a triangular screw. This is because the effects of the invention (moving grease upwards) can still be achieved even with a triangular screw.

[0031] In the above-described embodiment, screw grooves (feed-shaped portion 142A) are formed on the entire outer surface of the sleeve 142. However, the present invention is not limited to this, and as shown in Figures 6 and 7, a portion may be a non-rough portion 142B. However, if the length of the feed-shaped portion 142A is excessively short, the grease transport effect will decrease. Therefore, when the length of the feed-shaped portion 142A (length in the vertical direction) is L1 and the length of the non-rough portion 142B is L2, it is desirable to form the non-rough portion 142B such that L1 > L2. The length L2 of the non-rough portion 142B is preferably 5 mm or less. In Figure 6, the non-rough portion 142B is formed in the middle region, and screw grooves are formed in the upper and lower regions. In Figure 7, the non-rough portion 142B is formed in the upper region, and screw grooves are formed in the middle and lower regions. Even with these structures, the grease can be transported upward by the feeding action of the feed-shaped portion 142A during centrifugal separation. Furthermore, since the non-ridged portion 142B ensures a sufficient contact area with the bearing portion 60, the load on the contact portion can be reduced.

[0032] (Modification 1) In the above embodiment, the feed shape portion 142A is formed by a spiral screw groove, but the present invention is not limited thereto, and may be a screw blade. If a screw blade is formed on the outer surface of the sleeve 142, a screw effect will be generated during centrifugal separation, and the grease can be transferred to the upper side.

[0033] (Modification 2) In the above embodiment, the feed shape portion 142A was formed on the sleeve 142 attached to the main body portion 141, but the present invention is not limited thereto, and the feed shape portion may be formed directly on the outer circumferential surface of the main body portion 141.

[0034] (Modification 3) The screw threads that make surface contact with the bearing portion 60 are not limited to trapezoidal screws, but may be square screws, for example. Since the cross-sectional shape of the screw threads of a square screw is approximately rectangular (including square), it can make surface contact with the bearing portion 60.

[0035] 1. Centrifugal separator 11. Motor 12. Belt drive mechanism 13. Spindle 14. Bowl 15. Casing 60. Bearing section 60A. Discharge port 61. Grease passage 70. Grease cup 140. Bowl feed section 141. Main body 142. Sleeve 142A. Feed shape section

Claims

1. A centrifugal separator that rotates a bowl into which a material is supplied around a vertically extending axis to centrifugally separate the material, comprising: a cylindrical bowl feed section formed at the lower end of the bowl, which is a material receiving port; a bearing section for the bowl feed section; and a grease supply section that supplies grease toward a discharge port formed on the outer circumferential surface of the bearing section, wherein a feed shape section is formed on the outer circumferential surface of the bowl feed section facing the bearing section to transfer the grease discharged from the discharge port upward.

2. The centrifugal separator according to claim 1, characterized in that the bowl feed section comprises a ring-shaped sleeve on which the feed shape section is formed.

3. The centrifugal separator according to claim 1 or 2, characterized in that the feed shape portion is a spirally formed screw groove.

4. The centrifugal separator according to claim 3, characterized in that the threads of the screw groove make surface contact with the bearing portion during centrifugal separation.

5. The centrifugal separator according to claim 1 or 2, characterized in that the feed shape portion is a screw blade.

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