JP2014005767A - Method of sterilization-in-place for uniaxial eccentric screw pump and uniaxial eccentric screw pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an uniaxial eccentric screw pump in which cleaning-in-place can be performed inside of a casing, when performing sterilization-in-place using steam at 120°C to 130°C, sterilization inside of a stator can be performed and even while the pump is in an operating state, the stator can be prevented from being damaged.SOLUTION: In an uniaxial eccentric screw pump 1, a cavity 3 defined by a space in which a rotor 2 and a stator 4 are opposed to each other, is provided only in one location. When performing sterilization-in-place using steam, the rotor 2 is rotated intermittently to an angle excluding a phase where the cavity 3 becomes a sealed space, in such a manner as to provide a non-sealed state in which the cavity 3 in the one location is communicated to a suction side or a discharge side of the stator 4. The stator 4 which is rotated together is then rotated intermittently at the predetermined angle every time.

Description

  The present invention relates to a uniaxial eccentric screw pump that pumps a viscous liquid (transported material) such as a food raw material in a fixed amount.

  Conventionally, as this type of uniaxial eccentric screw pump, for example, there is one disclosed in Patent Document 1. As illustrated in FIG. 4, in the uniaxial eccentric screw pump 100, a male screw-like rotor 103 is housed in a stator 112 made of a fixed elastic material having a female screw-like inner surface. A cavity (sealed space) 120 is defined by the facing space between the rotor 103 and the stator 112. The rotor 103 is connected to a drive shaft 102 via a universal joint 106, and the drive shaft 102 is connected to a shaft of a motor (not shown).

  According to the single-shaft eccentric screw pump 100, when the drive shaft 102 is rotated by a motor, the rotor 103 performs an eccentric motion while rotating with respect to the shaft center of the stator 112, whereby viscous liquid is sucked from the suction side 113. The viscous liquid drawn into the cavity 120 and sucked into the cavity 120 can be pumped to the discharge side 114.

JP 59-153992 A

  However, when performing sterilization in place (SIP: Sterilizing In Place) using steam at 120 ° C. to 130 ° C., the uniaxial eccentric screw pump 100 rotates the rotor due to high temperatures when the pump is operated in steam at 120 ° C. to 130 ° C. Since the sliding resistance between the stator 103 and the stator 112 increases, the stator 112 is easily damaged. Therefore, stationary sterilization is performed with the pump stopped. However, since the discharge side 114 and the suction part 115 side of the rotor 103 are separated by the cavity 120 which is a sealed space, steam can flow. It was difficult to completely sterilize the stator.

Further, since the stator 112 is fixed, the rotor 103 rotates while receiving a large reaction force, so that the linear portion of the inner surface of the stator 112 is easily worn, and the performance is deteriorated at an early stage. In particular, damage to the stator 112 due to the pump operation during the above-described stationary sterilization appears more prominently.
Furthermore, since the rotation axis of the rotor 103 revolves around the axis of the stator 112, it is necessary to interpose a universal joint 106 between the drive shaft 102 and the rotor 103. Therefore, the inside of the casing 130 in which the universal joint 106 is inevitably has a long flow path, which is difficult to clean and difficult to perform in-place cleaning (CIP: Cleaning In Place).

  Therefore, the present invention has been made paying attention to such problems, and in a single-shaft eccentric screw pump that quantitatively pumps viscous liquids (transported materials) such as food materials, it is easy to clean the casing in place. In addition, when performing stationary sterilization using steam at 120 ° C. to 130 ° C., a stationary sterilization method for a uniaxial eccentric screw pump and a uniaxial eccentric screw pump that can sterilize the inside of the stator and prevent damage to the stator. It is intended to provide.

  In order to solve the above-mentioned problem, a stationary sterilization method for a uniaxial eccentric screw pump according to an aspect of the present invention includes a stator having a female screw-shaped inner surface, and a rotor in which a male screw-shaped spiral portion is inserted into the stator. A cavity is defined by a space where the rotor and the stator face each other, and the rotor sucks into the cavity from the suction side by performing an eccentric motion while rotating with respect to the axis of the stator. This is a method for stationary sterilization of a uniaxial eccentric screw pump configured to pump a liquid to the discharge side, and is applied to one in which the cavity is provided at one place, and when performing stationary sterilization using steam, The rotor is positioned so that the cavity becomes a sealed space so that the one cavity is in an unsealed position communicating with the suction side or the discharge side of the stator. Wherein the rotating intermittently at a predetermined angle excluding.

  Here, in the stationary sterilization method for a uniaxial eccentric screw pump according to an aspect of the present invention, the uniaxial eccentric screw pump includes a stator having a female screw-like inner surface that is rotatably supported, and a male screw-like spiral portion on the stator. And a rotor having a linear base end portion directly connected to the drive shaft of the motor, the rotation axis of the rotor being arranged eccentrically by a predetermined distance with respect to the rotation axis of the stator, and The stator is configured to follow and rotate at half the rotation speed of the rotor by the rotational force of the rotor, and by rotating the rotor intermittently to the predetermined angle, a rotating stator is provided. It is preferable to rotate intermittently by a predetermined angle.

  A uniaxial eccentric screw pump according to an aspect of the present invention includes a stator having a female screw-shaped inner surface, and a rotor in which a male screw-shaped spiral portion is inserted into the stator, and the rotor and the stator face each other. A cavity is defined by the space, and the viscous liquid sucked into the cavity is pumped from the suction side to the discharge side by performing an eccentric motion while rotating the rotor with respect to the axis of the stator. The uniaxial eccentric screw pump is a uniaxial eccentric screw pump in which the cavity is provided only at one place, and includes a motor drive unit that drives the motor, and the motor drive unit performs stationary sterilization using steam. A stationary sterilization control means for the non-tight sterilization control means, wherein the one cavity communicates with the suction side or the discharge side of the stator. As the position, characterized in that to intermittently rotate said rotor at a predetermined angle excluding the phase in which the cavity is a sealed space.

Here, in the single-shaft eccentric screw pump according to an aspect of the present invention, the single-shaft eccentric screw pump includes a stator that is rotatably supported and has a female screw-like inner surface, and a male screw-like spiral portion is inserted into the stator. And a rotor whose linear base end is directly connected to the drive shaft of the motor, the rotational axis of the rotor being arranged eccentrically by a predetermined distance with respect to the rotational axis of the stator, and the rotational force of the rotor The stationary sterilization control means is configured to rotate the rotor intermittently at the predetermined angle to rotate the stator at a predetermined rotational speed that is half the rotational speed of the rotor. Is preferably rotated intermittently by a predetermined angle.
In the uniaxial eccentric screw pump according to one aspect of the present invention, it is preferable that a steam introduction pipe for introducing steam into the stator from both sides of the stator is provided.

  According to the present invention, when only one cavity defined between the rotor and the stator is provided, and the stationary sterilization is performed, the one cavity is provided on the suction side or the discharge side of the stator. Since the rotor is intermittently rotated at a predetermined angle excluding the phase where the cavity becomes a sealed space so as to be in a non-sealed state in communication, there is no position that constitutes a space in which the steam and the stator are hermetically sealed, Steam can be distributed throughout the stator. Therefore, even when performing stationary sterilization with steam, sterilization inside the stator, which has been difficult until now, can be performed reliably.

It is explanatory drawing of one Embodiment of the uniaxial eccentric screw pump which concerns on 1 aspect of this invention. The figure shows a cross section including the axis. It is explanatory drawing of the normal phase state of a rotor and a stator (The phase state which forms the space where the vapor | steam was sealed by the rotor and the stator). It is explanatory drawing of the phase state (phase state which does not form the space by which the vapor | steam was sealed) of the rotor and stator of the present invention. It is a figure explaining an example of the conventional uniaxial eccentric screw pump which used the universal joint between the drive shaft and the rotor, The figure has shown the cross section containing an axis line.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate.
As shown in FIG. 1, the uniaxial eccentric screw pump 1 has a bracket 11 that also serves as a casing of the motor 40 on the pump side. That is, the motor 40 includes, as a casing, a body portion 45 at the center in the axial direction, a rear portion 46 that covers the rear end of the body portion 45, and the bracket 11 that covers the front end of the body portion 45.

A shaft 43 of the motor 40 is rotatably supported in the body 45 by both bearings 44 and 44 between the front and rear 46 of the body 45. The bearing structure of the motor 40 can sufficiently receive a thrust load and a radial load applied to the rotor 2 described later, and can withstand a high temperature of 80 ° C. to 130 ° C.
The shaft 43 has a through hole 43a that is coaxially formed with a single inner diameter along its own axial direction. A permanent magnet 41 is provided on the outer periphery of the shaft 43, and a permanent magnet brushless motor is configured by disposing a stator 42 in the body portion 45 with a gap in a direction opposite to the permanent magnet 41. Yes. This permanent magnet brushless motor can sufficiently output the torque required for the single-shaft eccentric screw pump 1 in the rotation region where the motor rotation speed is 50 to 1000 min ⁻¹ .

  The bracket 11 is provided with a pump housing 7 on a front end surface 11a on the pump side. The housing 7 includes a suction portion 7a, a main body portion 7b, and a discharge portion 7c in this order from the suction side (the right side in the figure). The suction portion 7a of the housing 7 is formed with a suction port 8 for a viscous liquid (transported material) such as a food raw material that is a pumping fluid, and the discharge portion 7c is formed with a discharge port 9 for the viscous liquid.

  Here, when the stationary sterilization mode (stationary sterilization control), which will be described later, is performed on the suction unit 7a and the discharge unit 7c, steam introduction is provided so that high-temperature (for example, 120 ° C to 130 ° C) steam can be introduced. Pipe line 10 is piped. The steam introduction pipe line 10 has an on-off valve 10a in the middle part of itself. The on-off valve 10a is closed in a normal operation state (normal mode (normal control) described later). On the other hand, in the in-place sterilization mode (in-place sterilization control), the open state is established, and the suction part 7a and the discharge part 7c are brought into communication with each other by the steam introduction pipe line 10.

  The front end surface 11a of the bracket 11 and the suction portion 7a, the suction portion 7a and the main body portion 7b, and the main body portion 7b and the discharge portion 7c are detachably fixed by a known ferrule clamp 22. The uniaxial eccentric screw pump 1 includes a housing 4 having a female screw-shaped inner surface in a housing 7 and a rotor 2 in which a male screw-shaped spiral portion 2 a is housed in the stator 4.

  Specifically, the rotor 2 integrally includes a spiral portion 2a formed on the distal end side and a linear base end portion 2b. The spiral portion 2a of the rotor 2 has a circular cross section that is eccentric with respect to its own rotation axis L2. Seals 30 and 31 having sanitary properties are provided between the middle portion of the base end portion 2b and the bracket 11, and between the suction portion 7a and the discharge portion 7c and the stator outer cylinder 4b (described later). ing. The seal 30 prevents the viscous liquid flowing from the suction port 8 from flowing into the bracket 11 through the gap between the base end portion 2 b of the rotor 2 and the suction portion 7 a of the housing 7.

  The rotor 2 has a slightly smaller diameter at the rear than the stepped portion 2f of the base end portion 2b, and this small diameter portion is integrally formed as a drive shaft 2c. The drive shaft 2c is formed in the through hole 43a of the shaft 43 so as to be slidable in the thrust direction and inserted coaxially. A female screw 2e is formed at the rear end of the drive shaft 2c. As a result, the bolt 50 is fastened to the female thread 2e via the washer 51 with respect to the rear end surface 43b of the shaft 43, whereby the axial position is defined at the position where the stepped portion 2f contacts the front end surface 43a of the shaft 43. Is done. It should be noted that the shaft 43 and the drive shaft 2c are configured to rotate integrally with the key 47 being restrained from moving in the mutual rotation direction. As a result, the rotor 2 is fixed in a state where the drive shaft 2c is inserted into the through hole 43a, so that the shaft 43 and the drive shaft 2c are directly connected without using a speed reducer or the like. It is supported in a cantilever structure by bearings 44, 44 on both sides of the shaft 43.

  Both ends of the stator 4 are rotatably supported in the housing 7 via rolling bearings 5 and 6 capable of receiving a radial load and a thrust load. In this example, a concave step portion 7 t is formed on the inner peripheral surface of the main body portion 7 b constituting the housing 7. Further, on the outer peripheral surface (stator outer cylinder 4b described later) of the stator 4 itself, on the outer peripheral surface are formed step portions 4u on which the rolling bearings 5 and 6 are respectively fitted, and the step portions 4u and 7t are formed on both ends. Therefore, the movement of the bearings 5 and 6 is restricted.

  The stator 4 includes a single stator inner cylinder 4a disposed at the center in the axial direction, and a stator outer cylinder 4b that is integrally formed to cover the outer peripheral surface of the stator inner cylinder 4a. The stator inner cylinder 4a is made of elastomer, and the stator outer cylinder 4b is made of metal. The stator inner cylinder 4a is integrally molded on the inner peripheral surface of the stator outer cylinder 4b so that the inner surface of the female screw has a constant thickness. The internally threaded helical portion 4 e that is molded has a female threaded pitch twice that of the helical portion 2 a of the rotor 2. The spiral portion 4e of the stator 4 has an oval cross section, and the rotation axis L2 of the rotor 2 is arranged so as to be eccentric by a predetermined eccentric amount E with respect to the rotation axis L1 of the stator 4, and is a half of the rotor 2. The stator 4 follows and rotates at the number of rotations.

  Then, the spiral portion 2a of the rotor 2 is housed in the stator 4 in which a spiral portion 4e having a female-thread-like oval cross section is formed on the inner surface, and the opposing space between the spiral portion 2a of the rotor 2 and the spiral portion 4e of the stator 4 A cavity 3 is defined. This uniaxial eccentric screw pump 1 is provided with only one cavity 3 defined by the space between the rotor 2 and the stator 4 facing each other. Note that the length of the stator 4 in the axial direction is added with the length of the margin in addition to the length required to form one cavity 3.

  Here, the motor 40 has a phase detector (not shown) (for example, a magnetic sensor) that detects its own rotation angle (phase information). The phase information detected by the phase detection unit is input to a motor drive unit (not shown) including a motor driver circuit and the like. The motor driver unit can drive the motor 40 by feedback control based on the detected phase information while monitoring the rotation angle of the motor 40.

  And this motor drive part is set so that the normal mode (normal control) shown in FIG. 2 and the stationary sterilization mode (static sterilization control) shown in FIG. 3 can be selected. That is, in the normal mode (normal control) shown in FIG. 2, the motor drive unit continuously drives the motor 40 to drive the drive shaft 2c to rotate. When the drive shaft 2c rotates, the rotor 2 rotates about its rotation axis L2, and the stator 4 is driven in synchronization with the rotation of the rotor 2 about its rotation axis L1 as the spiral portion 2a of the rotor 2 moves. By rotating, the viscous liquid is pumped from the suction port 8 to the discharge port 9. At this time, the one cavity 3 is basically driven and controlled by a motor drive unit so as to form a sealed space. Even if the cavity 3 is in a phase where the sealed space is not completely formed, the pump function is not impaired.

  On the other hand, when the stationary sterilization mode (in-place sterilization control) shown in FIG. 3 is set and executed, the motor drive unit intermittently rotates the motor 40 by a predetermined angle. Here, the intermittent rotation control is performed so that the cavity 3 is in a non-sealed state as shown in the figure when one cavity 3 communicates with either the suction side or the discharge side of the stator. The rotor is intermittently rotated at a predetermined angle excluding the phase that becomes the sealed space, and the rotating stator is controlled to rotate following the predetermined angle intermittently. Since the phase at which the cavity 3 becomes a sealed space is known in advance, the motor drive unit can reliably avoid the phase that becomes the sealed space by feedback control based on the detected phase information. The phase monitored by the motor drive unit can be controlled by observing a fixed point of the phase that becomes the sealed space.

  Specifically, for example, in the example shown in FIG. 2, in the rightmost phase of the stator 4 in FIG. 2 ((a) in FIG. 2), the upper part of the rotor 2 coincides with the upper part of the stator 4. However, this is a time when the cavity 3 is set as a sealed space when rotated in this phase (this is a fixed point for monitoring). At this monitoring fixed point, the injection-side steam A introduced into the suction port 8 and the discharge-side steam B guided from the suction port 8 to the discharge port 9 through the steam introduction pipe line 10 are sealed spaces. It becomes the state divided | segmented by the sealing vapor | steam C in 3. As shown in FIG. On the other hand, as shown in FIG. 3, in the phase on the rightmost side of the stator 4 corresponding to FIG. 2, the rotor 2 is inclined in FIG. Different. And by setting it as such a position, since the subsequent phase also shifts | deviates, the cavity 3 can be made into an unsealed space. That is, if the phase is other than the monitoring fixed point, the injection-side steam A and the discharge-side steam B are brought into a communication state via the non-sealed portion of the cavity 3. Therefore, the steam can be spread over the entire stator 4. Since the seal line (contact portion between the stator 4 and the rotor 2) is also moved sequentially by the intermittent operation of the rotor 2, it is possible to prevent local exposure to high-temperature steam continuously.

Next, the operation of this uniaxial eccentric screw pump and its operation and effect will be described.
The single-shaft eccentric screw pump 1 includes a rotor 2 having a male screw-like spiral portion 2a directly connected to a drive shaft 2c, and is rotatably supported, and its rotation axis L1 is connected to the rotation axis L2 of the rotor 2. And a stator 4 having an internal thread-like spiral portion 4e arranged eccentrically with respect to the inner surface, and the rotor 2 rotates to perform an eccentric motion with respect to the axis of the stator 4 to discharge viscous liquid from the suction side. When the drive control executed by the motor drive unit is in the normal mode (normal control), when the shaft 43 is rotated by the drive of the motor 40 and the drive shaft 2c rotates, the rotor 2 rotates its axis of rotation. The stator 4 rotates around L2, and the stator 4 also rotates following the rotation of the rotor 2 around the rotation axis L1 as the spiral portion 2a of the rotor 2 moves. , It is possible to pump the viscous liquid from the suction port 8 to the discharge port 9.

  Thus, according to this uniaxial eccentric screw pump 1, since it can be set as a structure which does not use a universal joint, the structure is simple, especially in the pressure feed of food, the problem of washing of the dead space of a universal joint also occurs. This eliminates the inflow of viscous liquid in the suction part on the suction side, and the stationary cleaning is easy.

And according to this uniaxial eccentric screw pump 1, even when performing stationary sterilization using the steam of 120 to 130 degreeC, for example, stationary sterilization can be performed effectively.
That is, the single-shaft eccentric screw pump 1 is provided with only one cavity 3 defined between the rotor 2 and the stator 4 and the motor drive unit performs in-place sterilization in the in-place sterilization mode (in-place sterilization control). Sometimes, the rotor 2 is intermittently set at a predetermined angle excluding the phase in which the cavity 3 becomes a sealed space so that the cavity 3 in one place communicates with the suction side or the discharge side of the stator 4. Since the rotating stator 4 is intermittently rotated by a predetermined angle, the position of the cavity 3 constituting the space in which the steam is hermetically sealed by the rotor 2 and the stator 4 can be eliminated.

The single-shaft eccentric screw pump 1 is provided with a steam introduction conduit 10 having an on-off valve 10a attached to the suction portion 7a and the discharge portion 7c so that steam can be introduced. In the sterilization control), if the on-off valve 10a is opened, steam can be introduced from both sides of the stator 4, and the steam can be distributed throughout the stator 4. Therefore, even when performing stationary sterilization with steam, sterilization inside the stator 4, which has been difficult until now, can be reliably performed.
The single-shaft eccentric screw pump according to the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the uniaxial eccentric screw pump 1 includes a stator 4 having a female screw-like inner surface that is rotatably supported, a male screw-like spiral portion inserted into the stator 4, and a linear base end portion. A rotor 2 directly connected to the drive shaft of the motor 40, the rotation axis of the rotor 2 is arranged eccentrically by a predetermined distance with respect to the rotation axis of the stator 4, and the stator 4 is rotated by the rotational force of the rotor 2. Although an example has been described in which the follow-up rotation is performed at a half rotation number, the present invention is not limited to this.

  In other words, the main configuration of the present invention is a one-stage (one pitch) type single-shaft eccentric screw pump in which only one defined cavity is provided. It is in the point which manages to the excluded predetermined angle (rotor angle where two places do not become a seal), and supplies high temperature steam from the suction side and the discharge side at the predetermined angle. Therefore, this main configuration is effective for both the type in which the stator is driven and rotated as in the above embodiment and the type in which the conventional stator is fixed and the rotor is eccentrically rotated by a universal joint, as described in Patent Document 1. It is. However, as described above, the type in which the stator is driven and rotated as in the present embodiment is significantly more sanitary than the type in which the stator is fixed and the rotor is eccentrically rotated by a universal joint. According to the uniaxial eccentric screw pump 1, for example, when performing stationary sterilization using steam at 120 ° C. to 130 ° C., it is more suitable for effectively performing stationary sterilization.

1 Uniaxial Eccentric Screw Pump 2 Rotor 3 Cavity 4 Stator 5 Rolling Bearing 7 Housing 8 Suction Port 9 Discharge Port 10 Steam Inlet Pipe 11 Bracket 30 Seal 40 Motor 41 Permanent Magnet 42 Stator 43 Shaft 44 Bearing A Injection Side Steam B Discharge Side Steam C Sealed steam E Eccentricity L1 Rotation axis L2 Rotation axis

Claims (5)

A stator having a female screw-like inner surface, and a rotor in which a male screw-like spiral portion is inserted into the stator, and a cavity is defined by a space between the rotor and the stator, the axis of the stator being A method of sterilizing a uniaxial eccentric screw pump configured to pump the viscous liquid sucked into the cavity from the suction side to the discharge side by performing an eccentric motion while the rotor rotates,
When this is applied to the case where the cavity is provided only at one place, and the stationary sterilization using steam is performed, the cavity at the one place is in an unsealed position communicating with the suction side or the discharge side of the stator. A stationary sterilization method for a uniaxial eccentric screw pump, wherein the rotor is intermittently rotated at a predetermined angle excluding a phase where the cavity becomes a sealed space. The single-shaft eccentric screw pump has a female screw-shaped inner surface that is rotatably supported, a male screw-shaped spiral portion inserted in the stator, and a linear base end portion directly connected to a drive shaft of the motor. And the rotor rotation axis is eccentrically arranged with respect to the stator rotation axis by a predetermined distance, and the stator is rotated by following the rotation speed of the rotor by a half of the rotation speed of the rotor. Is configured to allow
2. The stationary sterilization method for a single-shaft eccentric screw pump according to claim 1, wherein a rotating stator is intermittently rotated by a predetermined angle by rotating the rotor intermittently to the predetermined angle. A stator having a female screw-like inner surface, and a rotor in which a male screw-like spiral portion is inserted into the stator, and a cavity is defined by a space between the rotor and the stator, the axis of the stator being In the uniaxial eccentric screw pump configured to pump the viscous liquid sucked into the cavity from the suction side to the discharge side by performing eccentric motion while rotating the rotor,
A uniaxial eccentric screw pump in which the cavity is provided only in one place,
A motor drive unit for driving the motor, the motor drive unit having a stationary sterilization control means for performing stationary sterilization using steam, wherein the stationary sterilization control means has the cavity in the one place as described above; A uniaxial eccentric screw pump, wherein the rotor is intermittently rotated at a predetermined angle excluding a phase where the cavity becomes a sealed space so as to be in an unsealed position communicating with a suction side or a discharge side of a stator. The single-shaft eccentric screw pump includes a rotatably supported stator having a female screw-shaped inner surface, a male screw-shaped spiral portion inserted into the stator, and a linear base end portion directly connected to a drive shaft of a motor. And the rotor rotation axis is eccentrically arranged with respect to the stator rotation axis by a predetermined distance, and the stator is rotated by following the rotation speed of the rotor by a half of the rotation speed of the rotor. Is configured to let
4. The single-shaft eccentric screw pump according to claim 3, wherein the stationary sterilization control means intermittently rotates the rotating stator by a predetermined angle by rotating the rotor intermittently to the predetermined angle. 5. .   The single-shaft eccentric screw pump according to claim 3 or 4, wherein a steam introduction pipe for introducing steam into the stator from both sides of the stator is provided.

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