Patent Description:
Conventionally, a tube pump has been known where a tube having flexibility is intermittently compressed by a plurality of rollers so as to supply a liquid in the tube under pressure. The tube pump intermittently supplies the liquid under pressure and hence, pulsation (an operation where an increase and a decrease in flow rate is repeated) is generated in the liquid supplied under pressure.

<CIT> (patent document <NUM>) discloses the following problem. When a tube compressed by a roller returns to the original shape, pulsation is generated due to a phenomenon that a liquid is drawn back toward the tube pump side from a path on the downstream side. Patent document <NUM> discloses a technique where, to suppress such pulsation, when one of a pair of roller units passes through a separation position, at which the roller unit separates from the tube, the pressure of a liquid in the tube closed due to contact with the pair of roller units is caused to rise. According to patent document <NUM>, the pressure of a liquid in the tube is caused to rise and hence, it is possible to suppress the phenomenon that a liquid is drawn back toward the tube pump side.

<CIT> discloses tube pump system is provided, which includes a pair of roller units <NUM>, <NUM> which are rotated around the axis line X1 from a contact position Po1 to a separate position Po2 in a state where the pair of roller units compress the tube <NUM>, a pair of drive units which rotate the pair of roller units <NUM>, <NUM> respectively, and a control unit which controls each of the pair of drive units, wherein the control unit controls each of the pair of drive units such that, when one of the pair of roller units <NUM>, <NUM> passes the separate position Po2, an angular velocity of the other of the pair of roller units <NUM>, <NUM> toward the separate position Po2 is gradually decreased.

When the flow rate of a liquid discharged from a tube pump system is set to an arbitrary target flow rate which is instructed by an operator or the like, the pressure of a liquid in a pipe on the downstream side of the tube pump system varies corresponding to the variation of the target flow rate. Accordingly, the pulsation state also varies with such variation of the pressure of the liquid. In addition to the above, when the hardness or the like of the tube varies due to continuous use of the tube, the pulsation state also varies with such variation of hardness.

However, patent document <NUM> fails to disclose a specific method for suppressing pulsation when such dynamic variation occurs in the pulsation state.

The present disclosure has been made in view of such circumstances, and an object thereof is to provide a tube pump system and a method for controlling the tube pump system where even when the pulsation state dynamically varies, pulsation can be appropriately suppressed in accordance with such variation.

To solve the above-described problem, a tube pump system as defined by attached claim <NUM> is provided.

According to one aspect of the present disclosure, there is provided a tube pump system including: a housing unit which has an inner peripheral surface formed into a circular-arc shape around an axis line; a tube having flexibility which is arranged along the inner peripheral surface; a pair of roller units which are housed in the housing unit, and are rotated around the axis line from a closing position to a releasing position around the axis line in a state where the pair of roller units close the tube; a pair of drive units which are configured to respectively rotate the pair of roller units around the axis line in a same direction; a control unit which is configured to control each of the pair of drive units such that a liquid which flows into the tube from one end of the tube is discharged from the other end of the tube; and a pressure detection unit which is configured to detect a pressure of a liquid in a pipe connected to the other end of the tube, wherein the control unit is configured to control a first rotation angle around the axis line and a second rotation angle around the axis line such that fluctuation of the pressure of the liquid detected by the pressure detection unit when the pair of roller units are rotated through at least one revolution falls within a predetermined value, the first rotation angle being formed between the pair of roller units when a first roller unit of the pair of roller units passes through the closing position, and the second rotation angle being formed between the pair of roller units when a second roller unit of the pair of roller units passes through the releasing position.

According to the tube pump system of one aspect of the present disclosure, the pair of roller units are respectively rotated by the pair of drive units around the axis line in the same direction and hence, the pair of roller units reach the releasing position from the closing position in a state of compressing the tube. The control unit controls each of the pair of drive units, thus causing a liquid which flows into the tube from one end of the tube to be discharged from the other end of the tube. The fluctuation of the pressure of a liquid detected by the pressure detection unit when the pair of roller units rotate through at least one revolution indicates the magnitude of the pulsation of a liquid supplied by the tube pump system under pressure. When one of the pair of roller units passes through the releasing position and the tube compressed by the roller unit returns to the original shape, the larger a pressure difference between the pressure of liquid on the downstream side of the releasing position and the pressure of liquid on the upstream side of the releasing position, the larger the fluctuation of the pressure becomes.

The pressure difference between liquid on the downstream side of the releasing position and liquid on the upstream side of the releasing position corresponds to the first rotation angle and the second rotation angle. That is, the larger a difference between the first rotation angle and the second rotation angle, the higher the pressure of a liquid in the tube which is closed by contact with the pair of roller units becomes. The smaller a difference between the first rotation angle and the second rotation angle, the lower the pressure of a liquid in the tube which is closed by contact with the pair of roller units becomes. Accordingly, in the tube pump system according to one aspect of the present disclosure, the control unit controls the first rotation angle around the axis line and the second rotation angle around the axis line such that the fluctuation of a pressure detected by the pressure detection unit falls within a predetermined value, the first rotation angle being formed between the pair of roller units when the first roller unit passes through the closing position, and the second rotation angle being formed between the pair of roller units when the second roller unit passes through the releasing position. According to the tube pump system of one aspect of the present disclosure, even when the pulsation state dynamically varies, pulsation can be appropriately suppressed in correspondence with such variation.

In the tube pump system according to one aspect of the present disclosure, it may be configured such that the control unit performs control such that the second rotation angle becomes smaller than the first rotation angle.

According to the tube pump system having this configuration, a rotation angle formed between the pair of roller units which close the tube is reduced to the rotation angle formed between a point where the closed state of the tube is started and a point where the closed state of the tube is released. Accordingly, it is possible to cause the pressure of a liquid in the tube to rise to a desired pressure.

In the tube pump system having the above-mentioned configuration, it may be configured such that the control unit increases an angular velocity of the first roller unit from a first predetermined velocity to a second predetermined velocity in a period from a point where the first roller unit passes through the closing position to a point where the second roller unit passes through the releasing position.

According to the tube pump system having this configuration, the angular velocity of the following first roller unit is increased from the first predetermined velocity to the second predetermined velocity and hence, the rotation angle formed between the pair of roller units which close the tube is reduced to the rotation angle formed between a point where the closed state of the tube is started and a point where the closed state of the tube is released. Accordingly, a pressure difference between the pressure of liquid on the downstream side of the releasing position and the pressure of liquid on the upstream side of the releasing position is decreased and hence, pulsation of the liquid is suppressed.

In the tube pump system having the above-mentioned configuration, the control unit may control the pair of drive units such that, as the fluctuation falls within a predetermined value, an angular velocity of the first roller unit which moves toward the releasing position is gradually decreased after the second roller unit passes through the releasing position.

In the case where the first roller unit is rotated at a fixed angular velocity after the second roller unit passes through the releasing position, a distance from a position where the first roller unit compresses the tube to the releasing position gradually decreases. Accordingly, the pressure of liquid on the upstream side of the releasing position rises as the first roller unit approaches the releasing position. In view of the above, in the tube pump system having this configuration, after the second roller unit passes through the releasing position, an angular velocity of the first roller unit which moves toward the releasing position is gradually decreased.

Accordingly, the pressure rise of liquid on the upstream side which is caused by approach of the first roller unit to the releasing position can be offset by a decrease in the pressure of liquid which is caused by a decrease in the angular velocity of the first roller unit. Further, according to the tube pump system having this configuration, control is performed such that, after the fluctuation of the pressure of liquid falls within a predetermined value, the angular velocity of the first roller unit which moves toward the releasing position is gradually decreased. According to the tube pump system having this configuration, pulsation can be promptly suppressed with high accuracy compared with the case where such control is performed when the fluctuation of the pressure of liquid is larger than the predetermined value.

In the tube pump system having the above-mentioned configuration, the control unit may adjust the angular velocity of each of the pair of roller units corresponding to the first rotation angle such that a flow rate per unit time of a liquid discharged from the other end of the tube is maintained at a predetermined flow rate.

In the tube pump system having this configuration, the control unit adjusts the first rotation angle and the second rotation angle such that the fluctuation of a pressure falls within a predetermined value to suppress pulsation. However, when the flow rate of a liquid varies to suppress pulsation, the pressure of liquid in the pipe on the downstream side of the tube pump system varies corresponding to the variation of the flow rate of a liquid. The pulsation state also varies with this variation of pressure of liquid so that variations of the flow rate and pulsation are repeated whereby it becomes difficult to appropriately suppress pulsation within a short time.

In view of the above, in the tube pump system having this configuration, the control unit adjusts the angular velocity of each of the pair of roller units corresponding to the first rotation angle such that the flow rate per unit time of a liquid discharged from the other end of the tube is maintained at a predetermined flow rate. Accordingly, for example, even when the first rotation angle and the second rotation angle are controlled to suppress pulsation, the flow rate per unit time of a liquid discharged from the other end of the tube is maintained at a predetermined flow rate. Therefore, it is possible to suppress that the pulsation state varies with variation of the flow rate of a liquid and hence, pulsation can be appropriately suppressed within a short time.

The present invention provides also a method for controlling a tube pump system as defined by attached claim <NUM>. According to one aspect of the present disclosure, a method for controlling a tube pump system includes:
a housing unit which has an inner peripheral surface formed into a circular-arc shape around an axis line; a tube having flexibility which is arranged along the inner peripheral surface; a pair of roller units which are housed in the housing unit, and are rotated around the axis line from a closing position to a releasing position around the axis line in a state where the pair of roller units compress the tube; and a pair of drive units which are configured to respectively rotate the pair of roller units around the axis line in a same direction, the method including: a controlling step where each of the pair of drive units is controlled such that a liquid which flows into the tube from one end of the tube is discharged from the other end of the tube; and a pressure detecting step where a pressure of a liquid in a pipe connected to the other end of the tube is detected, wherein in the controlling step, a first rotation angle around the axis line and a second rotation angle around the axis line are controlled such that fluctuation of the pressure of the liquid detected in the pressure detecting step when the pair of roller units are rotated through at least one revolution falls within a predetermined value, the first rotation angle being formed between the pair of roller units when a first roller unit of the pair of roller units passes through the closing position, and the second rotation angle being formed between the pair of roller units when a second roller unit of the pair of roller units passes through the releasing position.

In the method for controlling a tube pump system according to one aspect of the present disclosure, in the controlling step, the first rotation angle around the axis line and the second rotation angle around the axis line are controlled such that fluctuation of the pressure detected in the pressure detecting step falls within a predetermined value, the first rotation angle being formed between the pair of roller units when the first roller unit passes through the closing position, and the second rotation angle being formed between the pair of roller units when the second roller unit passes through the releasing position. According to the method for controlling a tube pump system of one aspect of the present disclosure, even when the pulsation state dynamically varies, pulsation can be appropriately suppressed in correspondence with such variation.

It is an object of the present disclosure to provide a tube pump system and a method for controlling the tube pump system where even when the pulsation state dynamically varies, pulsation can be appropriately suppressed in correspondence with such variation.

Hereinafter, a tube pump system and a method for controlling the tube pump system according to one embodiment of the present disclosure are explained with reference to drawings.

Hereinafter, a tube pump system <NUM> according to one embodiment of the present disclosure will be explained with reference to drawings.

The tube pump system <NUM> of this embodiment is an apparatus that supplies a liquid under pressure from an inflow end <NUM> to an outflow end <NUM> and, at the same time, controls a flow rate of the liquid supplied under pressure by a tube pump <NUM>.

As shown in <FIG>, the tube pump system <NUM> of this embodiment includes: the tube pump (peristaltic pump) <NUM> that supplies a liquid under pressure; a pipe <NUM> through which the liquid is conveyed from the tube pump <NUM> to a needle valve <NUM>; a pressure sensor (pressure detection unit) <NUM> that detects a pressure of the liquid flowing through the pipe <NUM>; a flowmeter <NUM> that measures a flow rate of the liquid flowing through the pipe <NUM>; a needle valve <NUM> that adjusts a pressure of the liquid flowing through the pipe <NUM> arranged on the upstream side of the needle valve <NUM>; and a control unit <NUM> that controls a discharge amount of the liquid discharged from the tube pump <NUM>.

Hereinafter, respective configurations of the tube pump system <NUM> of this embodiment are explained.

The tube pump <NUM> is a device that supplies a liquid under pressure from the inflow end <NUM> to the outflow end <NUM>. The tube pump <NUM> supplies the liquid under pressure by repeating an operation where rollers are moved in a state where a tube having flexibility is compressed by the rollers. The liquid discharged from the tube pump <NUM> to the pipe <NUM> passes through the flowmeter <NUM> and the needle valve <NUM>, and reaches the outflow end <NUM>. The tube pump <NUM> will be mentioned later in detail.

The pipe <NUM> is a pipe through which a liquid is conveyed from the tube pump <NUM> to the needle valve <NUM>. The pipe <NUM> is made of a material (for example, a resin material such as a silicone rubber) having flexibility that is elastically deformed due to a pressure of the liquid supplied under pressure by the tube pump <NUM>. The pipe <NUM> can maintain a pressure of the liquid flowing through the inside of the pipe <NUM> at a predetermined pressure which is higher than an atmospheric pressure by adjusting an opening degree of the needle valve <NUM> mentioned later. A flow path length L of the pipe <NUM> is desirably set to approximately <NUM>, for example.

The pressure sensor <NUM> is a device that detects a pressure of the liquid flowing through the inside of the pipe <NUM>. The pressure sensor <NUM> is arranged on the pipe <NUM> through which the liquid is introduced from the tube pump <NUM> to the needle valve <NUM>, at a position on the upstream side of the flowmeter <NUM>. The pressure sensor <NUM> transmits the detected pressure to the control unit <NUM>.

The flowmeter <NUM> is a device that measures a flow rate of the liquid flowing through the inside of the pipe <NUM>. The flowmeter <NUM> is arranged on the pipe <NUM> through which the liquid is introduced from the tube pump <NUM> to the needle valve <NUM> at a position on the downstream side of the pressure sensor <NUM>. The flowmeter <NUM> transmits the measured flow rate to the control unit <NUM>.

The needle valve <NUM> is a device that adjusts a pressure of the liquid flowing through the inside of the pipe <NUM> such that the pressure of the liquid becomes higher than an atmospheric pressure by adjusting an insertion amount of a needle-shaped valve body (illustration is omitted) with respect to a valve hole (illustration is omitted). The needle valve <NUM> forms a region having a minimum flow path cross sectional area in a path through which the liquid is introduced from the tube pump <NUM> to the outflow end <NUM>.

The needle valve <NUM> is made to have a minimum flow path cross sectional area in order to allow the needle valve <NUM> to have a highest pipe resistance in the path through which the liquid is introduced from the tube pump <NUM> to the outflow end <NUM>. Therefore, the liquid in the pipe <NUM> on the upstream side of the needle valve <NUM> is maintained at a high static pressure. In this embodiment, the opening degree of the needle valve <NUM> is adjusted such that a pressure of a liquid flowing through the inside of the pipe <NUM> becomes higher than an atmospheric pressure.

In this embodiment, the first predetermined pressure Pr1 is desirably set to a value which falls within a range of equal to or more than <NUM> kPaG and equal to or less than <NUM> kPaG. Particularly, the first predetermined pressure Pr1 is desirably set to a value which falls within a range of equal to or more than <NUM> kPaG and equal to or less than <NUM> kPaG. Reference character "G" denotes a gauge pressure.

The pipe <NUM>, where a liquid is maintained in the inside of the pipe <NUM> with a high static pressure, is made of a flexible resin material. This is because when a static pressure in the pipe <NUM> is further increased by pulsation of the liquid, the pipe <NUM> is elastically deformed and hence, transmission of pulsation of the liquid to the downstream side can be suppressed.

As described above, in the path through which a liquid is introduced from the tube pump <NUM> to the outflow end <NUM>, the pipe <NUM> made of a flexible resin material is arranged on the upstream side of the needle valve <NUM> having the highest pipe resistance and hence, pulsation of the liquid supplied under pressure from the tube pump <NUM> can be suppressed.

The control unit <NUM> is a device that controls each of a first drive unit <NUM> and a second drive unit <NUM> to be mentioned later such that a liquid which flows into a flexible tube <NUM> of the tube pump <NUM> from one end of the tube <NUM> is discharged from the other end of the tube <NUM>. The control unit <NUM> controls each of the first drive unit <NUM> and the second drive unit <NUM> such that a flow rate measured by the flowmeter <NUM> conforms to a predetermined target flow rate. A method for controlling the first drive unit <NUM> and the second drive unit <NUM> by the control unit <NUM> will be mentioned later in detail.

As shown in <FIG>, the control unit <NUM> includes a memory unit <NUM>. The memory unit <NUM> stores a program performed by the control unit <NUM>. The control unit <NUM> reads and performs the program stored in the memory unit <NUM>, thus performing respective processes mentioned later. The memory unit <NUM> is formed of a nonvolatile memory capable of rewriting data, for example. As will be mentioned later, the control unit <NUM> adjusts a control waveform for controlling the first drive unit <NUM> and the second drive unit <NUM>, and stores the adjusted control waveform in the memory unit <NUM>. The control unit <NUM> reads the control waveform stored in the memory unit <NUM> so that the control unit <NUM> can control the first drive unit <NUM> and the second drive unit <NUM> using the adjusted control waveform.

Next, the tube pump <NUM> of the tube pump system <NUM> will be explained.

The tube pump <NUM> of this embodiment shown in <FIG> is a device where a first roller unit <NUM> (first contact member) and a second roller unit <NUM> (second contact member) are rotated around an axis line X1 (first axis line) in the same direction so as to make a fluid in a tube <NUM> which flows into the tube <NUM> discharge from an inflow-side end portion 101a to an outflow-side end portion 101b. The pipe <NUM> is connected to the outflow-side end portion 101b. <FIG> shows the tube pump <NUM> in a state where a cover <NUM> shown in <FIG> is removed.

As shown in <FIG> which is a front view, in the tube pump <NUM>, the tube <NUM> is arranged in a circular-arc shape around the axis line X1 along an inner peripheral surface 82b of a recess 82a of a roller housing unit <NUM> that houses the first roller unit <NUM> and the second roller unit <NUM>. As shown in <FIG>, the first roller unit <NUM> and the second roller unit <NUM> housed in the roller housing unit <NUM> are rotated around the axis line X1 along a counter-clockwise rotation direction (a direction shown by an arrow in <FIG>) while being in contact with the tube <NUM>.

As shown in a longitudinal cross-sectional view of <FIG> and an exploded perspective view of <FIG>, the tube pump <NUM> of the embodiment includes: the first roller unit <NUM> and the second roller unit <NUM> that rotate around the axis X1 while being in contact with the tube <NUM>; a drive shaft <NUM> (a shaft member) that is arranged on the axis X1 and is coupled to the first roller unit <NUM>; a drive cylinder (a cylindrical member) <NUM> that is coupled to the second roller unit <NUM>; a first drive unit <NUM> that transmits a drive force to the drive shaft <NUM>; a second drive unit <NUM>; and a transmission mechanism <NUM> (a transmission unit) that transmits a drive force of the second drive unit <NUM> to the drive cylinder <NUM>.

The first roller unit <NUM> has: a first roller <NUM> that rotates around an axis parallel to the axis X1 while being in contact with the tube <NUM>; a first roller support member <NUM> coupled to the drive shaft <NUM> so as to integrally rotate around the axis X1; and a first roller shaft <NUM> both ends of which are supported by the first roller support member <NUM>, and to which the first roller <NUM> is rotatably attached.

The second roller unit <NUM> has: a second roller <NUM> that rotates around an axis parallel to the axis X1 while being in contact with the tube <NUM>; a second roller support member <NUM> coupled to the drive cylinder <NUM> so as to integrally rotate around the axis X1; and a second roller shaft <NUM> both ends of which are supported by the second roller support member <NUM>, and to which the second roller <NUM> is rotatably attached.

As shown in <FIG>, the first drive unit <NUM> and the second drive unit <NUM> are housed inside a casing (a housing member) <NUM>. A gear housing unit <NUM> for housing the transmission mechanism <NUM>, and a support member <NUM> that supports the first drive unit <NUM> and the second drive unit <NUM> are attached to an inside of the casing <NUM>. In addition, the roller housing unit <NUM> for housing the first roller unit <NUM> and the second roller unit <NUM> is attached to an upper part of the casing <NUM>.

The roller housing unit <NUM> has the recess 82a that houses the first roller unit <NUM> and the second roller unit <NUM>. The recess 82a has the inner peripheral surface 82b formed into a circular-arc shape around the axis line X1. As shown in <FIG>, the tube <NUM> is arranged in a circular-arc shape around the axis line X1 along the inner peripheral surface 82b.

A first through hole <NUM> that extends along the axis X1 and a second through hole <NUM> that extends along an axis X2 are formed in the support member <NUM>. The first drive unit <NUM> is attached to the support member <NUM> by a fastening bolt (illustration is omitted) in a state where a first drive shaft <NUM> is inserted into the first through hole <NUM> formed in the support member <NUM>. Similarly, the second drive unit <NUM> is attached to the support member <NUM> by a fastening bolt (illustration is omitted) in a state where a second drive shaft <NUM> is inserted into the second through hole <NUM> formed in the support member <NUM>. As described above, each of the first drive unit <NUM> and the second drive unit <NUM> is attached to the support member <NUM>, which is the integrally formed member.

Here, with reference to <FIG>, there will be explained a structure in which the first drive unit <NUM> transmits a drive force to the first roller unit <NUM>. In <FIG>, a portion shown by continuous lines is the portion included in the structure of transmitting a drive force of the first drive unit <NUM> to the first roller unit <NUM>.

As shown in <FIG>, the first drive unit <NUM> has the first drive shaft <NUM> that is arranged on the axis X1 and is coupled to the drive shaft <NUM>. The first drive shaft <NUM> is attached to a lower end of the drive shaft <NUM> in a state where a pin 51a that extends in a direction perpendicular to the axis X1 is inserted into the first drive shaft <NUM>. The drive shaft <NUM> is fixed to the first drive shaft <NUM> by the pin 51a so as not to relatively rotate around the axis X1. Therefore, when the first drive unit <NUM> rotates the first drive shaft <NUM> around the axis X1, a drive force of the first drive shaft <NUM> is transmitted to the drive shaft <NUM>, and the drive shaft <NUM> rotates around the axis X1.

The first drive unit <NUM> has; the first drive shaft <NUM>; the first electric motor <NUM>; and a first reducer <NUM> that reduces a velocity of rotation of a rotation shaft (illustration is omitted) rotated by the first electric motor <NUM>, and transmits the rotation to the first drive shaft <NUM>. The first drive unit <NUM> rotates the first drive shaft <NUM> around the axis X1 by transmitting a drive force of the first electric motor <NUM> to the first drive shaft <NUM>.

A position detecting member 51b that rotates around the axis X1 together with the first drive shaft <NUM> is attached to the first drive shaft <NUM>. In the position detecting member 51b, in an annularly formed outer peripheral edge, a slit (illustration is omitted) for detecting a rotation position of the first roller unit <NUM> around the axis X1 is formed in a peripheral direction around the axis X1.

As shown in <FIG>, a position detection sensor <NUM> is arranged so as to sandwich an upper surface and a lower surface of the outer peripheral edge of the position detecting member 51b. The position detection sensor <NUM> is the sensor in which a light-emitting element is arranged on one of an upper surface side and a lower surface side, and in which a light-receiving element is arranged on the other of the upper surface side and the lower surface side. The position detection sensor <NUM> detects a rotation position indicating which position the first roller unit <NUM> is arranged around the axis X1 by detecting by the light-receiving element through the slit that light emitted by the light-emitting element passes through in connection with the rotation of the position detecting member 51b around the axis X1, and transmits it to a control unit <NUM>.

The lower end of the drive shaft <NUM> is coupled to the first drive shaft <NUM>, and an upper end thereof is inserted into an insertion hole formed in the cover <NUM>. A third bearing member <NUM> that rotatably supports a tip of the first drive shaft <NUM> around the axis X1 is inserted into the insertion hole of the cover <NUM>. In addition, the drive shaft <NUM> is rotatably supported around the axis X1 on an inner peripheral side of the drive cylinder <NUM> by a cylindrical first bearing member <NUM> inserted along the outer peripheral surface, and a cylindrical second bearing member <NUM> formed independently from the first bearing member <NUM>.

As described above, in the drive shaft <NUM>, the outer peripheral surface of a lower end side is supported by the first bearing member <NUM>, the outer peripheral surface of a central portion is supported by the second bearing member <NUM>, and the outer peripheral surface of a tip side is supported by the third bearing member <NUM>. Therefore, the drive shaft <NUM> smoothly rotates around the axis X1 in a state of holding a central axis on the axis X1. Here, a reason why the first bearing member <NUM> and the second bearing member <NUM> are arranged in the axis X1 direction in a state of being separated from each other as shown in <FIG> is that an endless annular projection part 40a that extends around the axis X1 is formed at an inner peripheral surface of the drive cylinder <NUM>.

The first roller support member <NUM> of the first roller unit <NUM> is coupled to the tip side of the drive shaft <NUM> so as to integrally rotate around the axis X1. As described above, the drive force by which the first drive unit <NUM> rotates the first drive shaft <NUM> around the axis X1 is transmitted from the first drive shaft <NUM> to the first roller unit <NUM> through the drive shaft <NUM>.

Next, with reference to <FIG>, there will be explained a structure in which the second drive unit <NUM> transmits a drive force to the first roller unit <NUM>. In <FIG>, a portion shown by continuous lines is the portion included in the structure of transmitting the drive force of the second drive unit <NUM> to the second roller unit <NUM>. The structure shown in <FIG> has: the second roller unit <NUM>; the drive cylinder <NUM>; the second drive unit <NUM>; and the transmission mechanism <NUM>.

The transmission mechanism <NUM> shown in <FIG> has: a first gear unit <NUM> that rotates around the axis X2 (a second axis) parallel to the axis X1; and a second gear unit <NUM> to which a drive force of the second drive shaft <NUM> is transmitted from the first gear unit <NUM>. The transmission mechanism <NUM> transmits the drive force of the second drive shaft <NUM> around the axis X2 to the outer peripheral surface of the drive cylinder <NUM>, and rotates the drive cylinder <NUM> around the axis X1.

As shown in <FIG>, the second drive unit <NUM> has; the second drive shaft <NUM> arranged on the axis X2; a second electric motor <NUM>; and a second reducer <NUM> that reduces a velocity of rotation of a rotation shaft (illustration is omitted) rotated by the second electric motor <NUM>, and transmits the rotation to the second drive shaft <NUM>. The second drive unit <NUM> rotates the second drive shaft <NUM> around the axis X2 by transmitting a drive force of the second electric motor <NUM> to the second drive shaft <NUM>.

The second drive shaft <NUM> is inserted into an insertion hole formed in a central portion of the first gear unit <NUM> formed in a cylindrical shape around the axis X2. The first gear unit <NUM> is fixed to the second drive shaft <NUM> by fastening a fixing screw 71a in a state where the second drive shaft <NUM> is inserted into the first gear unit <NUM>, and making a tip of the fixing screw 71a abut against the second drive shaft <NUM>. In a manner as described above, the first gear unit <NUM> is coupled to the second drive shaft <NUM>, and rotates around the axis X2 together with the second drive shaft <NUM>.

A first gear 71b of the first gear unit <NUM> formed around the axis X2 is engaged with a second gear 72b of the second gear unit <NUM> formed around the axis X1. Therefore, a drive force by rotation of the first gear unit <NUM> around the axis X2 is transmitted as the drive force that rotates the second gear unit <NUM> around the axis X1.

A position detecting member 71c that rotates around the axis X1 together with the second drive shaft <NUM> is formed at the first gear unit <NUM>. In the position detecting member 71c, in an annularly formed outer peripheral edge, a slit (illustration is omitted) for detecting a rotation position of the second roller unit <NUM> around the axis X1 is formed in a peripheral direction around the axis X2.

As shown in <FIG>, a position detection sensor <NUM> is arranged so as to sandwich an upper surface and a lower surface of an outer peripheral edge of the position detecting member 71c. The position detection sensor <NUM> is the sensor in which a light-emitting element is arranged on one of an upper surface side and a lower surface side, and in which a light-receiving element is arranged on the other of the upper surface side and the lower surface side. The position detection sensor <NUM> detects a rotation position indicating which position the second roller unit <NUM> is arranged around the axis X1 by detecting by the light-receiving element through the slit that light emitted by the light-emitting element passes through in connection with the rotation of the position detecting member 71c around the axis X2, and transmits it to the control unit <NUM>.

The drive cylinder <NUM> is inserted into an insertion hole formed in a central portion of the second gear unit <NUM> formed in a cylindrical shape around the axis X1. The insertion hole is a hole having an inner peripheral surface coupled to the outer peripheral surface of the drive cylinder <NUM>.

The second gear unit <NUM> is fixed to the drive cylinder <NUM> by fastening a fixing screw 72a in a state where the drive cylinder <NUM> is inserted into the second gear unit <NUM>, and making a tip of the fixing screw 72a abut against the drive cylinder <NUM>. In a manner as described above, the second gear unit <NUM> is coupled to the drive cylinder <NUM>, and rotates around the axis X1 together with the drive cylinder <NUM>.

As shown in <FIG>, the drive cylinder <NUM> is arranged in a state of sandwiching the first bearing member <NUM> and the second bearing member <NUM> on an outer peripheral side of the drive shaft <NUM>. Therefore, the drive cylinder <NUM> can be rotated around the axis X1 independently from the drive shaft <NUM>. The drive shaft <NUM> rotates around the axis X1 by the drive force by the first drive unit <NUM>, and the drive cylinder <NUM> rotates around the axis X1 by the drive force by the second drive unit <NUM> in a state of being independent from the drive shaft <NUM>.

The second roller support member <NUM> of the second roller unit <NUM> is coupled to a tip side of the drive cylinder <NUM> so as to integrally rotate around the axis X1. As described above, the drive force by which the second drive unit <NUM> rotates the second drive shaft <NUM> around the axis X2 is transmitted to the outer peripheral surface of the drive cylinder <NUM> by the transmission mechanism <NUM>, and is transmitted from the drive cylinder <NUM> to the second roller unit <NUM>.

Next, discharging of a liquid performed by the tube pump system <NUM> of this embodiment will be explained with reference to drawings.

As shown in <FIG>, the tube pump system <NUM> of this embodiment detects a pressure of the liquid discharged from the tube pump <NUM> to the pipe <NUM> by the pressure sensor <NUM>, and transmits the pressure of the liquid to the control unit <NUM>. The tube pump system <NUM> also measures a flow rate of the liquid flowing through the pipe <NUM> by the flowmeter, and transmits the flow rate of the liquid to the control unit <NUM>. The control unit <NUM> controls angular velocities of the first roller unit <NUM> and the second roller unit <NUM> around the axis line X1 such that the flow rate of the liquid flowing through the pipe <NUM> agrees with a target flow rate.

In the tube pump system <NUM> shown in <FIG>, a control signal for controlling the first drive unit <NUM> and the second drive unit <NUM> of the tube pump <NUM> is transmitted from the control unit <NUM> to the tube pump <NUM>.

The tube pump <NUM> may be formed as a device in which the control unit <NUM> is incorporated. In this case, the control unit <NUM> incorporated in the tube pump <NUM> generates a control signal for controlling the first drive unit <NUM> and the second drive unit <NUM>, and transmits the control signal to the first drive unit <NUM> and the second drive unit <NUM>.

<FIG> is a front view showing the tube pump <NUM> in a state where the first roller unit <NUM> reaches a closing position Po1. <FIG> is a front view showing the tube pump <NUM> in a state where the second roller unit <NUM> reaches a releasing position Po2. The closing position Po1 indicates a position around the axis line X1 at which a state of the first roller unit <NUM> or the second roller unit <NUM> changes over from a state of not closing the tube <NUM> to a state of closing the tube <NUM>. Further, the releasing position Po2 indicates a position around the axis line X1 at which a state where the first roller unit <NUM> or the second roller unit <NUM> closes the tube <NUM> is released so that a state of the first roller unit <NUM> or the second roller unit <NUM> changes over to a state of not closing the tube <NUM>. Each of the first roller unit <NUM> and the second roller unit <NUM> is independently rotated around the axis line X1 in a state where the first roller unit <NUM> or the second roller unit <NUM> closes the tube <NUM> in cooperation with the inner peripheral surface 82b from the closing position Po1 to the releasing position Po2.

<NUM>°, <NUM>°, <NUM>° and <NUM>° shown in <FIG> indicate rotation angles around the axis line X1, and indicate angles in the counterclockwise direction with the position of <NUM>° as a reference. The closing position Po1 is at a rotation angle of <NUM>°, for example. The releasing position Po2 is at a rotation angle of <NUM>°, for example.

The first rotation angle Θ1 shown in <FIG> is a rotation angle around the axis line X1 formed between the first roller unit <NUM> and the second roller unit <NUM> when the first roller unit <NUM> passes through the closing position Po1. A second rotation angle Θ2 shown in <FIG> is a rotation angle around the axis line X1 formed between the first roller unit <NUM> and the second roller unit <NUM> when the second roller unit <NUM> passes through the releasing position Po2.

<FIG> is a cross-sectional view of an area in the vicinity of the first roller unit <NUM> of the tube pump <NUM> shown in <FIG>. As shown in <FIG>, when the first roller unit <NUM> reaches the closing position Po1, a state of the tube <NUM> changes over from a state of not being closed to a state of being closed. At this point of operation, a flow path cross sectional area of the tube <NUM> changes over to zero from a value larger than zero.

<FIG> is a cross-sectional view of an area in the vicinity of the second roller unit <NUM> of the tube pump <NUM> shown in <FIG>. As shown in <FIG>, when the second roller unit <NUM> reaches the releasing position Po2, a state of the tube <NUM> changes over from a state of being closed to a state of not being closed. At this point of operation, a flow path cross sectional area of the tube <NUM> changes over to a value larger than zero from zero.

<FIG> is a transverse cross-sectional view showing the tube <NUM> in a state of being closed by the first roller unit <NUM> or the second roller unit <NUM>. <FIG> is a transverse cross-sectional view showing the tube <NUM> where a closed state brought about by the first roller unit <NUM> or the second roller unit <NUM> is released. The flow path cross sectional area of the tube <NUM> shown in <FIG> is zero, whereas the flow path cross sectional area of the tube <NUM> shown in <FIG> is a value larger than zero.

Next, a process performed by the control unit <NUM> will be described. <FIG> is a flowchart showing the process performed by the control unit <NUM>. The control unit <NUM> performs a control such that the flow rate of a liquid which flows through the pipe <NUM> agrees with the target flow rate. The control unit <NUM> also performs a control such that even when the pulsation state dynamically varies, the pulsation is appropriately suppressed in correspondence with such variation.

When power is supplied, or when a target flow rate Ft [ml/min] is set and the start of control is instructed by an operator, the control unit <NUM> starts the respective processes shown in <FIG>. The control unit <NUM> controls the first drive unit <NUM> and the second drive unit <NUM> such that the flow rate of a liquid measured by the flowmeter <NUM> agrees with the target flow rate Ft [ml/min].

In step S1301, the control unit <NUM> determines whether or not a control waveform adjusted in the respective processes mentioned later is stored in the memory unit <NUM>. When the determination is YES, the control unit <NUM> advances the process to step S1302. When the determination is NO, the control unit <NUM> advances the process to step S1303. The control unit <NUM> controls the first drive unit <NUM> and the second drive unit <NUM> based on the control waveform such that the first roller unit <NUM> and the second roller unit <NUM> are rotated with a correspondence between the rotation angle and the angular velocity shown by the control waveform.

In step S1302, the control unit <NUM> controls the first drive unit <NUM> and the second drive unit <NUM> based on the reference control waveform, thus controlling angular velocity of the first roller unit <NUM> and the second roller unit <NUM> at each rotation angle.

In step S1303, the control unit <NUM> reads the adjusted control waveform from the memory unit <NUM>, and controls the first drive unit <NUM> and the second drive unit <NUM> based on the adjusted control waveform. A method for adjusting a control waveform will be mentioned later.

<FIG> is a graph showing a correspondence between a rotation angle of the roller unit (the first roller unit <NUM> and the second roller unit <NUM>) and an angular velocity of the roller unit. A solid line in <FIG> indicates a reference control waveform, and a broken line in <FIG> indicates a basic control waveform. Numerical values of the rotation angle taken on an axis of abscissas in <FIG> correspond to numerical values of the rotation angles shown in <FIG> and <FIG>. The first roller unit <NUM> and the second roller unit <NUM> are respectively disposed at different rotation angles, but have the same angular velocity at each rotation angle.

The basic control waveform is stored in advance in the memory unit <NUM>. For example, the basic control waveform is a control waveform which generates almost no pulsation in a liquid discharged to the pipe <NUM> in a state where the pressure sensor <NUM> detects <NUM> kPaG. The basic control waveform is formed by being adjusted in advance by the manufacturer when the tube pump system <NUM> is manufactured. The basic control waveform is stored in the memory unit <NUM>. When the rotation of the first roller unit <NUM> and the second roller unit <NUM> is controlled based on the basic control waveform, the tube pump system <NUM> discharges a liquid at a predetermined basic flow rate F0 [ml/min] to the pipe <NUM>.

When the control unit <NUM> rotates the first roller unit <NUM> and the second roller unit <NUM> based on the basic control waveform, as shown in <FIG>, the angular velocity of each roller unit at the rotation angle of <NUM>° to <NUM>° and <NUM>° to <NUM>° assumes Vr0. On the other hand, when the control unit <NUM> rotates the first roller unit <NUM> and the second roller unit <NUM> based on the reference control waveform, an angular velocity of each roller unit at the rotation angle of <NUM>° to <NUM>° and <NUM>° to <NUM>° assumes Vrt11. Vrt11 satisfies the following formula (<NUM>).

As shown in formula (<NUM>), Vrt11 in the reference control waveform is a value obtained by multiplying Vr0 by a ratio of the target flow rate Ft to the basic flow rate F0. The control unit <NUM> thus generates a reference control waveform by multiplying an angular velocity at each rotation position of the basic control waveform stored in the memory unit <NUM> by Ft/F0. In this embodiment, it is assumed that the basic control waveform and the basic flow rate F0 are stored in advance in the memory unit <NUM>.

The control unit <NUM> calculates Ft/F0 from the target flow rate Ft, instructed by the operator, and the basic flow rate F0, stored in the memory unit <NUM>, and then the control unit <NUM> multiplies the basic control waveform by Ft/F0, thus generating the reference control waveform. The control unit <NUM> controls the first drive unit <NUM> and the second drive unit <NUM> using the generated reference control waveform, thus causing the first roller unit <NUM> and the second roller unit <NUM> to rotate around the axis line X1.

<FIG> is a graph showing one example of variation over time of a pressure detected by the pressure sensor <NUM> when the control unit <NUM> controls the first drive unit <NUM> and the second drive unit <NUM> based on the reference control waveform generated by the control unit <NUM>. The example shown in <FIG> shows variation of pressure when the first roller unit <NUM> and the second roller unit <NUM> are rotated through three revolutions around the axis line X1. As shown in <FIG>, a pressure detected by the pressure sensor <NUM> periodically fluctuates between a minimum value Pmin and a maximum value Pmax so that a fluctuation ΔP of pressure is Pmax-Pmin. Pave in <FIG> indicates the average value of pressure.

This periodical pressure fluctuation is generated mainly due to a pressure difference between the pressure of liquid on the downstream side of the releasing position Po2 and the pressure of liquid on the upstream side of the releasing position Po2 when one of the first roller unit <NUM> and the second roller unit <NUM> passes through the releasing position Po2 and the tube <NUM> compressed by the roller unit returns to the original shape. The control unit <NUM> adjusts the control waveform mentioned later such that a fluctuation ΔP of pressure falls within a predetermined value Pdif.

In step S1304, the control unit <NUM> detects the pressure of a liquid which flows through the pipe <NUM> using the pressure sensor <NUM>. The control unit <NUM> causes the memory unit <NUM> to store a pressure detected by the pressure sensor <NUM> when the first roller unit <NUM> and the second roller unit <NUM> are rotated around the axis line X1 through at least one revolution (one revolution, three revolutions, for example).

In step S1305, the control unit <NUM> determines with reference to the pressure stored in the memory unit <NUM> whether or not the fluctuation ΔP of pressure when the first roller unit <NUM> and the second roller unit <NUM> are rotated around the axis line X1 through at least one revolution falls within the predetermined value Pdif. When the fluctuation ΔP does not fall within the predetermined value Pdif, the control unit <NUM> advances the process to step S1306. On the other hand, when the fluctuation ΔP falls within the predetermined value Pdif, the control unit <NUM> advances the process to step S1308.

In step S1306, the fluctuation ΔP of pressure is larger than the predetermined value Pdif and hence, the control unit <NUM> adjusts the first rotation angle Θ1 shown in <FIG> and the second rotation angle Θ2 shown in <FIG> so as to reduce the fluctuation ΔP of pressure. The reason for the adjustment of the first rotation angle Θ1 and the second rotation angle Θ2 is that a pressure difference between liquid on the downstream side of the releasing position Po2 and liquid on the upstream side of the releasing position Po2 is a value which corresponds to the first rotation angle Θ1 and the second rotation angle Θ2. That is, the larger a difference between the first rotation angle Θ1 and the second rotation angle Θ2, the higher the pressure of a liquid in the tube <NUM> which is closed by contact with the pair of roller units becomes. The smaller a difference between the first rotation angle Θ1 and the second rotation angle Θ2, the lower the pressure of a liquid in the tube <NUM> which is closed by contact with the pair of roller units becomes.

The control unit <NUM> adjusts a control waveform based on which the first drive unit <NUM> and the second drive unit <NUM> are controlled such that the second rotation angle Θ2 is smaller than the first rotation angle Θ1. The control waveform is adjusted as described above so as to cause a liquid which flows into the tube <NUM> at a pressure substantially equal to the atmospheric pressure to be discharged to the pipe <NUM> in a state where the pressure of the liquid is set higher than the atmospheric pressure. When the second rotation angle Θ2 is set smaller than the first rotation angle Θ1, the pressure of a liquid discharge to the pipe <NUM> is set higher than the atmospheric pressure.

<FIG> is a graph showing a correspondence between the rotation angle of the roller unit and an angular velocity of the roller unit, and showing the reference control waveform before the first rotation angle Θ1 and the second rotation angle Θ2 are adjusted, and a control waveform after the first rotation angle Θ1 and the second rotation angle Θ2 are adjusted. Specifically, the control unit <NUM> changes, in the reference control waveform generated in step S1302, a rotation angle R1, at which an angular velocity reaches Vrt12 after being increased from Vrt11, to a rotation angle R21, and the control unit <NUM> changes a rotation angle R12, at which a decrease in an angular velocity from Vrt12 to Vrt11 starts, to a rotation angle R22. The example shown in <FIG> is an example where the rotation angle R11 and the rotation angle R12 are the same angle. Note that the angular velocity Vrt11 and the angular velocity Vrt12 are adjusted in the process in step S1307 mentioned later so that the angular velocity Vrt11 is set to an angular velocity Vrt21, and the angular velocity Vrt12 is set to an angular velocity Vrt22.

As shown in <FIG>, in the range of the rotation angle before and after the roller unit passes through the releasing position Po2, the adjusted control waveform agrees with the reference control waveform. Accordingly, there is no variation of the manner of operation of the roller unit when the roller unit passes through the releasing position Po2 between the reference control waveform and the adjusted control waveform.

On the other hand, in the range of the rotation angle from the closing position Po1 to <NUM>°, the adjusted control waveform is different from the reference control waveform. Specifically, a range of the rotation angle from the completion of an increase in angular velocity to the start of a decrease in angular velocity is increased to (R22-R21) from (R12-R11). In the example shown in <FIG>, R12 is equal to R11 (R12=R11) so that an increase amount of the range of the rotation angle from the completion of an increase in angular velocity to the start of a decrease in angular velocity is (R22-R21).

The larger the value of (R22-R21), the longer a period during which the angular velocity of roller unit assumes Vrt22 becomes so that a difference between the first rotation angle Θ1 and the second rotation angle Θ2 is increased. The control unit <NUM> repeats the change of the range of the rotation angle from the rotation angle R21 to the rotation angle R22, and a process of checking the fluctuation ΔP of pressure detected in step S1304, thus adjusting the control waveform such that the fluctuation ΔP falls within the predetermined value Pdif. The control unit <NUM> identifies the value of (R22-R21) at which the fluctuation ΔP assumes a minimum value by increasing or decreasing the value of (R22-R21).

The value of (R22-R21) is adjusted by being increased or decreased such that the fluctuation ΔP falls within the predetermined value Pdif. Appropriately setting the initial value of (R22-R21) can shorten the adjustment time. In this embodiment, the initial value of (R22-R21) is set by the following procedure.

Firstly, based on the target flow rate Ft instructed by the operator and based on a function of the target flow rate stored in the memory unit <NUM> and the pressure of a liquid in the pipe <NUM>, the control unit <NUM> estimates a pressure Pt of the liquid in the pipe <NUM> from the target flow rate Ft. <FIG> is a graph showing a function of the target flow rate Ft and the pressure of a liquid in the pipe <NUM>. The function (for example, a linear function with a target flow rate as a variable) shown in <FIG> is stored in advance in the memory unit <NUM>.

Secondly, based on the pressure Pt of the liquid in the pipe <NUM>, which is estimated from the target flow rate Ft, and based on a function of the pressure of a liquid in the pipe <NUM> and an angle difference between the first rotation angle Θ1 and the second rotation angle Θ2, the function being stored in the memory unit <NUM>, the control unit <NUM> estimates an angle difference ΔR which can be estimated from the pressure Pt. <FIG> is a graph showing the relationship between the pressure of a liquid in the pipe and the angle difference ΔR between the first rotation angle Θ1 and the second rotation angle Θ2. The function (for example, a linear function with a pressure as a variable) indicated by a solid line in <FIG> is stored in advance in the memory unit <NUM>.

Thirdly, from the angle difference ΔR calculated from the target flow rate Ft, the control unit <NUM> sets an initial value of (R22-R21), which is a range of a rotation angle from the rotation angle R21 to the rotation angle R22. A function which indicates the relationship between the angle difference ΔR and (R22-R21) is stored in advance in the memory unit <NUM>. The control unit <NUM> sets the value of (R22-R21) for realizing the angle difference ΔR, which is calculated from the target flow rate Ft, as the initial value.

In step S1307, the control unit <NUM> adjusts an angular velocity of the first roller unit <NUM> and the second roller unit <NUM> such that the flow rate per unit time of a liquid discharged to the pipe <NUM> from the end portion of the tube <NUM> is maintained at the target flow rate Ft (predetermined flow rate). The control unit <NUM> adjusts the angular velocities of the first roller unit <NUM> and the second roller unit <NUM> such that the larger the first rotation angle Θ1, the lower an average angular velocity becomes, whereas the smaller the first rotation angle Θ1, the higher an average angular velocity becomes. The reason the angular velocity of the first roller unit <NUM> and the second roller unit <NUM> is adjusted as described above is that the first rotation angle Θ1 decides the amount of liquid closed in the tube <NUM> by the first roller unit <NUM> and the second roller unit <NUM>.

The larger the first rotation angle Θ1, the larger the amount of liquid which is closed in the tube <NUM> becomes. Whereas the smaller the first rotation angle θ1, the smaller the amount of liquid which is closed in the tube <NUM> becomes. The control unit <NUM> controls the angular velocity of the first roller unit <NUM> and the second roller unit <NUM> corresponding to the amount of liquid closed in the tube <NUM>, thus maintaining the target flow rate Ft (predetermined flow rate).

As shown in <FIG>, in the control waveform adjusted by the control unit <NUM>, an angular velocity is increased from Vrt21 (first predetermined velocity) to Vrt22 (second predetermined velocity) in an angle range from the rotation angle R21 to the rotation angle R22. This angle range is included in a period from a point where the first roller unit <NUM> passes through the closing position Po1 to a point where the second roller unit <NUM> passes through the releasing position Po2. As described above, the control unit <NUM> causes a rotation angle formed between the first roller unit <NUM> and the second roller unit <NUM> to be gradually reduced in a state where the tube <NUM> is closed by the first roller unit <NUM> and the second roller unit <NUM>. Accordingly, the second rotation angle Θ2 is smaller than the first rotation angle Θ1 so that the pressure of a liquid discharge to the pipe <NUM> is higher than the atmospheric pressure.

The example shown in <FIG> is an example where the rotation angle R21 agrees with the closing position Po1. However, there may be the case where the rotation angle R21 is an angle smaller than the closing position Po1 (an angle close to <NUM>°), or the case where the rotation angle R21 is an angle larger than the closing position Po1. The rotation angle R21 is set to either of the rotation angle of the first roller unit <NUM> when the first roller unit <NUM> passes through the releasing position Po2 and is separated from the tube <NUM> or the rotation angle of the first roller unit <NUM> when the preceding second roller unit <NUM> passes through the releasing position Po2.

The value of (R22-R21) which is set when the control unit <NUM> determines YES in step S1305 is different from the value of (R22-R21) which is set as the initial value. This is because the tube <NUM> used for setting the initial value of (R22-R21) and the tube <NUM> used when (R22-R21) is actually adjusted differ from each other in conditions (a raw material, the degree of deterioration and the like).

Using an angle difference ΔR' between the first rotation angle Θ1 and the second rotation angle Θ2 introduced from the value of (R22-R21) which is set when the control unit <NUM> determines YES in step S1305, the control unit <NUM> corrects a function indicated by a solid line in <FIG>, and stores a function indicated by a broken line in the memory unit <NUM>. Using the function corrected in step S1303, the control unit <NUM> controls the first drive unit <NUM> and the second drive unit <NUM> based on the adjusted control waveform. The initial value of (R22-R21) is appropriately set and hence, an adjustment time for adjusting (R22-R21) is shortened.

<FIG> is a graph showing one example of variation over time of a pressure detected by the pressure sensor <NUM> when the control unit <NUM> controls the first drive unit <NUM> and the second drive unit <NUM> based on the control waveform where the first rotation angle Θ1 and the second rotation angle Θ2 are adjusted. The example shown in <FIG> shows variation of pressure when the first roller unit <NUM> and the second roller unit <NUM> are rotated through three revolutions around the axis line X1.

As shown in <FIG>, a pressure detected by the pressure sensor <NUM> periodically fluctuates between the minimum value Pmin and the maximum value Pmax so that a fluctuation ΔP of pressure is Pmax-Pmin. Pave in <FIG> indicates the average value of pressure. The scale on an axis indicating pressure in <FIG> is identical to the scale on an axis indicating pressure in <FIG>. The fluctuation ΔP of pressure shown in <FIG> falls within the predetermined value Pdif, and is smaller than the fluctuation ΔP of pressure shown in <FIG>.

As described above, the control unit <NUM> adjusts the first rotation angle Θ1 and the second rotation angle Θ2, thus performing control such that a fluctuation ΔP of pressure assumes the predetermined value Pdif or less. When it is determined YES in step S1305, the control unit <NUM> advances the process to step S1308.

In step S1308 to step S1311, the fluctuation ΔP of pressure is the predetermined value Pdif or less and hence, the control unit <NUM> adjusts the control waveform to further reduce the fluctuation ΔP of pressure. <FIG> shows a correspondence of the rotation angle of the roller unit and the angular velocity of the roller unit. A control waveform before an adjustment is performed in step S1308 to step S1310 is indicated by a broken line, and a control waveform adjusted in step S1308 to step S1310 is indicated by a solid line.

As indicated by the solid line in <FIG>, to increase the pressure of a liquid closed between the first roller unit <NUM> or the second roller unit <NUM> and the other preceding roller unit after the first roller unit <NUM> or the second roller unit <NUM> passes through the closing position Po1, an angular velocity is increased from Vrt31 (first predetermined velocity) to Vrt32 (second predetermined velocity). An angular velocity difference between Vrt31 and Vrt32 corresponds to the amount of an increase in angular velocity which is increased after the roller unit passes through the closing position Po1.

In step S1308, the control unit <NUM> adjusts an angular velocity difference D shown in <FIG>. As indicated by the solid line in <FIG>, when the first roller unit <NUM> or the second roller unit <NUM> passes through the releasing position Po2, an angular velocity of the roller unit is temporarily increased from Vrt31 to Vrt33. The angular velocity is increased so as to suppress a phenomenon that a fluid is drawn back from the downstream side of the releasing position Po2 toward the upstream side of the releasing position Po2 when a state where the roller unit compresses the tube <NUM> is released. The angular velocity difference D is an angular velocity difference between Vrt31 and Vrt33. The control unit <NUM> identifies the angular velocity difference D at which the fluctuation ΔP of pressure assumes an extremely small value by increasing or decreasing the angular velocity difference D.

The angular velocity difference D is adjusted by being increased or decreased such that the fluctuation ΔP assumes an extremely small value. Appropriately setting the initial value of the angular velocity difference D can shorten an adjustment time. In this embodiment, the initial value of the angular velocity difference D is set by the following procedure.

Based on the pressure Pt estimated from a function of a target flow rate and the pressure of a liquid in the pipe <NUM> shown in <FIG>, and based on a function of the pressure Pt and the angular velocity difference D stored in the memory unit <NUM>, the control unit <NUM> estimates the angular velocity difference D. <FIG> is a graph showing a function of the pressure Pt of a liquid and the angular velocity difference D. The function indicated by a solid line in <FIG> is stored in advance in the memory unit <NUM>, and the control unit <NUM> sets the angular velocity difference D calculated from the target flow rate Ft as an initial value.

Each time step S1308 is performed where the angular velocity difference D is adjusted, the control unit <NUM> corrects the function indicated by a solid line in <FIG> using the adjusted angular velocity difference D', and stores a function indicated by a broken line in the memory unit <NUM>. In step S1303, the control unit <NUM> controls the first drive unit <NUM> and the second drive unit <NUM> based on the adjusted control waveform using this corrected function. The initial value of the angular velocity difference D is appropriately set and hence, an adjustment time for adjusting the angular velocity difference D is shortened.

In step S1310, the control unit <NUM> controls the first drive unit <NUM> and the second drive unit <NUM> such that after the second roller unit <NUM> passes through the releasing position Po2, the angular velocity of the following first roller unit <NUM> which moves toward the releasing position Po2 is gradually decreased. In the same manner, the control unit <NUM> controls the first drive unit <NUM> and the second drive unit <NUM> such that after the first roller unit <NUM> passes through the releasing position Po2, the angular velocity of the following second roller unit <NUM> which moves toward the releasing position Po2 is gradually decreased.

As shown in <FIG>, the control unit <NUM> causes, in a range of the rotation angle from <NUM>° to <NUM>°, the angular velocity of the roller unit which moves toward the releasing position Po2 to be gradually decreased from Vrt34 to Vrt31. This is because when the roller unit approaches the releasing position Po2, the volume of the tube <NUM> and the pipe <NUM> ranging from the roller unit to the needle valve <NUM> decreases and hence, the pressure of liquid on the downstream side of the roller unit rises. Pulsation can be suppressed by offsetting the pressure rise in the liquid on the downstream side of the roller unit which is caused by approach of the roller unit to the releasing position Po2 by a reduction in pressure caused by a decrease in the angular velocity of the roller unit.

In step S1310, the control unit <NUM> adjusts the angular velocity of the first roller unit <NUM> and the second roller unit <NUM> such that the flow rate per unit time of a liquid discharged to the pipe <NUM> from the end portion of the tube <NUM> is maintained at the target flow rate Ft (predetermined flow rate). The control unit <NUM> adjusts the angular velocity of the first roller unit <NUM> and the second roller unit <NUM> such that the larger the first rotation angle Θ1, the lower an average angular velocity becomes, whereas the smaller the first rotation angle Θ1, the higher the average angular velocity becomes. The reason the angular velocity of the first roller unit <NUM> and the second roller unit <NUM> is adjusted as described above is that the first rotation angle Θ1 decides the amount of liquid closed in the tube <NUM> by the first roller unit <NUM> and the second roller unit <NUM>.

In step S1311, the control unit <NUM> determines whether or not the target flow rate Ft is changed or the finish of the control is instructed by the operator. When the determination is YES, the process of this flowchart is finished. When the determination is NO, the control unit <NUM> repeats the process following after step S1304.

<FIG> is a graph showing one example of variation over time of a pressure detected by the pressure sensor <NUM> when the first drive unit <NUM> and the second drive unit <NUM> are controlled based on the control waveform adjusted in step S1308 to step S1310. The example shown in <FIG> shows variation of pressure when the first roller unit <NUM> and the second roller unit <NUM> are rotated through three revolutions around the axis line X1.

As shown in <FIG>, a pressure detected by the pressure sensor <NUM> periodically fluctuates between the minimum value Pmin and the maximum value Pmax so that a fluctuation ΔP of pressure is Pmax-Pmin. Pave shown in <FIG> indicates the average value of pressure. Pave shown in <FIG> has the same value as Pave shown in <FIG> and <FIG>.

The scale on an axis indicating pressure in <FIG> is identical to the scale on an axis indicating pressure in <FIG> and <FIG>. The fluctuation ΔP of pressure shown in <FIG> falls within the predetermined value Pdif, and is smaller than the fluctuation ΔP of pressure shown in <FIG>. As described above, the control unit <NUM> performs a control such that the fluctuation ΔT of pressure is further decreased from the predetermined value Pdif by repeating the adjustment performed in step S1308 to step S1311.

The description will be made with respect to the manner of operation and advantageous effects of the above-described tube pump system <NUM> of this embodiment.

According to the tube pump system <NUM> of this embodiment, the pair of roller units are respectively rotated by the pair of drive units around the axis line X1 in the same direction and hence, the pair of roller units reach the releasing position Po2 from the closing position Po1 in a state of compressing the tube <NUM>. The control unit <NUM> controls each of the pair of drive units, thus causing a liquid which flows into the tube <NUM> from one end of the tube <NUM> to be discharged from the other end of the tube <NUM>.

The fluctuation of the pressure of liquid detected by the pressure sensor <NUM> when the pair of roller units rotate through at least one revolution indicates the magnitude of the pulsation of a liquid supplied by the tube pump system <NUM> under pressure. When one of the pair of roller units passes through the releasing position Po2 and the tube <NUM> compressed by the roller unit returns to the original shape, the larger a pressure difference between the pressure of liquid on the downstream side of the releasing position Po2 and the pressure of liquid on the upstream side of the releasing position Po2, the larger the fluctuation of the pressure becomes.

The pressure difference between liquid on the downstream side of the releasing position Po2 and liquid on the upstream side of the releasing position Po2 corresponds to the first rotation angle Θ1 and the second rotation angle Θ2. That is, the larger a difference between the first rotation angle Θ1 and the second rotation angle Θ2, the higher the pressure of a liquid in the tube <NUM> which is closed by contact with the pair of roller units becomes. The smaller a difference between the first rotation angle Θ1 and the second rotation angle Θ2, the lower the pressure of a liquid in the tube which is closed by contact with the pair of roller units becomes.

Accordingly, in the tube pump system <NUM> of this embodiment, the control unit <NUM> controls the first rotation angle Θ1 around the axis line X1 and the second rotation angle Θ2 around the axis line X1 such that the fluctuation ΔP of a pressure detected by the pressure sensor <NUM> falls within the predetermined value Pdif, the first rotation angle Θ1 being formed between the pair of roller units when the first roller unit <NUM> passes through the closing position Po1, and the second rotation angle Θ2 being formed between the pair of roller units when the second roller unit <NUM> passes through the releasing position Po2. According to the tube pump system <NUM> of this embodiment, even when the pulsation state dynamically varies, pulsation can be appropriately suppressed in correspondence with such variation.

According to the tube pump system <NUM> of this embodiment, a rotation angle formed between the pair of roller units which close the tube <NUM> is reduced to the rotation angle formed between a point where the closed state of the tube <NUM> is started and a point where the closed state of the tube <NUM> is released. Accordingly, it is possible to cause the pressure of a liquid in the tube <NUM> to rise to a desired pressure.

According to the tube pump system <NUM> of this embodiment, the angular velocity of the following first roller unit <NUM> is increased from the first predetermined velocity to the second predetermined velocity and hence, the rotation angle formed between the pair of roller units which close the tube <NUM> can be reduced to a rotation angle formed between a point where the closed state of the tube <NUM> is started and a point where the closed state of the tube <NUM> is released.

In the tube pump system <NUM> of this embodiment, after the second roller unit <NUM> passes through the releasing position Po2, the angular velocity of the first roller unit <NUM> which moves toward the releasing position Po2 is gradually decreased. Accordingly, the pressure rise of liquid on the upstream side which is caused by approach of the first roller unit <NUM> to the releasing position Po2 can be offset by a decrease in the pressure of liquid which is caused by a decrease in the angular velocity of the first roller unit <NUM>. Further, according to the tube pump system <NUM> of this embodiment, control is performed such that, after the fluctuation ΔP of the pressure of liquid falls within the predetermined value Pdif, the angular velocity of the first roller unit <NUM> which moves toward the releasing position Po2 is gradually decreased. According to the tube pump system <NUM> of this embodiment, pulsation can be promptly suppressed with high accuracy compared with the case where such control is performed when the fluctuation ΔP of the pressure of liquid is larger than the predetermined value Pdif.

Claim 1:
A tube pump system (<NUM>) comprising:
a housing unit (<NUM>) which has an inner peripheral surface formed into a circular-arc shape around an axis line;
a tube (<NUM>) having flexibility which is arranged along the inner peripheral surface;
a pair of roller units (<NUM>, <NUM>) which are housed in the housing unit (<NUM>), and are rotated around the axis line from a closing position to a releasing position around the axis line in a state where the pair of roller units (<NUM>, <NUM>) close the tube (<NUM>);
a pair of drive units (<NUM>, <NUM>) which are configured to respectively rotate the pair of roller units (<NUM>, <NUM>) around the axis line in a same direction;
a control unit (<NUM>) which is configured to control each of the pair of drive units (<NUM>, <NUM>) such that a liquid which flows into the tube (<NUM>) from one end of the tube (<NUM>) is discharged from the other end of the tube (<NUM>); and
a pressure detection unit (<NUM>) which is configured to detect a pressure of a liquid in a pipe (<NUM>) connected to the other end of the tube (<NUM>), wherein
the control unit (<NUM>) is configured to control a first rotation angle around the axis line and a second rotation angle around the axis line on the basis of the pressure of the liquid in the pipe (<NUM>) detected by the pressure detection unit (<NUM>) such that fluctuation of the pressure of the liquid detected by the pressure detection unit (<NUM>) when the pair of roller units (<NUM>, <NUM>) are rotated through at least one revolution falls within a predetermined value, the first rotation angle being formed between the pair of roller units (<NUM>, <NUM>) when a first roller unit (<NUM>) of the pair of roller units (<NUM>, <NUM>) passes through the closing position, and the second rotation angle being formed between the pair of roller units (<NUM>, <NUM>) when a second roller unit (<NUM>) of the pair of roller units (<NUM>, <NUM>) passes through the releasing position.