JP7444705B2 - rotary positive displacement pump - Google Patents

Description

The present invention relates to rotary positive displacement pumps.

A rotary displacement pump including a rotary compressor (for example, see Patent Document 1) has a cylindrical rotor that eccentrically rotates or eccentrically swings inside a cylinder in an annular space, and a cylinder that is divided into a suction chamber and a compression chamber. a vane that abuts or is integral with the rotor. In general, a method in which the inside of a cylinder is divided by an eccentrically rotating rotor and vanes in contact with it is called a rotary type, and a method in which the inside of a cylinder is divided by an eccentrically oscillating rotor and vanes integrated with it is called a swing rotary type. It is.

Japanese Patent Application Publication No. 11-13664

In the conventional rotary type disclosed in Patent Document 1, it is necessary to increase the contact surface pressure at the contact portion between the rotor and the vane (particularly the U-shaped portion at the tip of the vane) in order to ensure sealing performance. There is. Further, in the conventional swing rotary type, it is necessary to reduce the clearance between the vanes and the bushing portion that supports the vanes in order to ensure sealing performance.

In this way, the sliding conditions for the rotary type and swing rotary type are severe, resulting in excessive sliding loss during pump operation. There is a problem in that it is extremely difficult to ensure high sealing performance while reducing dynamic resistance.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rotary displacement pump that can achieve both low sliding resistance and high sealing performance.

The rotary positive displacement pump according to the present invention has a suction port and a discharge port for the transfer fluid, introduces the transfer fluid into the interior through the suction port, and transfers the transfer fluid to the discharge port by pumping operation due to rotation. a pump body that discharges water from the discharge port; and a rotational drive mechanism that has a rotational shaft and applies rotational driving force to the pump body to cause a pump operation via the rotational shaft. In the positive displacement pump, the pump body is attached to a cylinder housing having a pump chamber formed of an annular space communicating with the suction port and the discharge port, and a rotation shaft of the rotary drive mechanism via an eccentric shaft, and a cylindrical rotor housed in the pump chamber so as to be eccentrically rotatable while contacting the inner peripheral surface of the chamber; and a cylindrical rotor that contacts a part of the outer peripheral surface of the rotor to divide the pump chamber into a suction chamber and a compression chamber; , and a swing lever provided to be swingable in response to eccentric rotation of the rotor.

In one embodiment of the present invention, the rotor is attached via a bearing to the eccentric shaft attached to the rotating shaft of the rotary drive mechanism, and contacts the inner circumferential surface of the pump chamber while rolling during eccentric rotation. .

In another embodiment of the present invention, the swing lever swings around a support shaft, and the contact portion with the outer circumferential surface of the rotor is located between the center of the support shaft and the center of the rotation shaft of the rotary drive mechanism. The cylinder housing is attached to the cylinder housing so as to be located closer to the compression chamber than a plane passing through the cylinder housing.

In yet another embodiment of the present invention, the swing lever has a curve indicating a movement locus of the contact portion with the outer circumferential surface of the rotor, which corresponds to the contact portion from the bottom dead center to the top dead center of the rotor. It oscillates so as to approximate a hypocycloid curve that shows the locus of movement of the part.

In yet another embodiment of the present invention, the swing lever further includes a torque applying mechanism that applies rotational torque in a direction to press the rotor.

In yet another embodiment of the present invention, the torque applying mechanism includes one or more magnets provided on the cylinder housing and a magnet or magnetic body provided on the swing lever, or one or more magnets provided on the cylinder housing. Alternatively, it includes a plurality of magnetic bodies and a magnet provided on the swing lever, and applies the rotational torque by at least one of a magnetic attraction force and a magnetic repulsion force between the cylinder housing and the swing lever.

In yet another embodiment of the present invention, the rotor is made of a resin member, and the swing lever is made of a metal member.

In yet another embodiment of the present invention, the pump body includes a first cylinder housing and a second cylinder housing arranged in the direction of the rotation axis of the rotational drive mechanism, and is housed in a pump chamber of the first cylinder housing. a first rotor and a second rotor housed in a pump chamber of the second cylinder housing, and the suction port of the first cylinder housing and the suction port of the second cylinder housing are connected to a first flow The discharge port of the first cylinder housing and the discharge port of the second cylinder housing communicate via a second flow path, and the first rotor and the second rotor They are arranged so that the phases of eccentric rotation differ by 180°.

According to the present invention, it is possible to achieve both low sliding resistance and high sealing performance.

1 is a perspective view showing the overall configuration of a rotary positive displacement pump according to an embodiment of the present invention. It is a front view of the same rotary displacement pump. 3 is a sectional view taken along line AA in FIG. 2. FIG. 4 is a sectional view taken along line BB in FIG. 3. FIG. 4 is a sectional view taken along the line CC in FIG. 3. FIG. It is a rear view of the same rotary displacement pump. 7 is a sectional view taken along line DD in FIG. 6. FIG.

Hereinafter, a rotary positive displacement pump according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments do not limit the invention according to each claim, and not all combinations of features described in the embodiments are essential to the solution of the invention. .

Furthermore, in the embodiments below, the same or corresponding components are given the same reference numerals and redundant explanations will be omitted. Furthermore, in the embodiments, the scale and dimensions of each component may not match the actual ones, or some components may be omitted.

FIG. 1 is a perspective view showing the overall configuration of a rotary positive displacement pump (hereinafter referred to as "pump") 1 according to an embodiment of the present invention, and FIG. 2 is a front view of the rotary positive displacement pump 1. 3 is a sectional view taken along line AA in FIG. 2, FIG. 4 is a sectional view taken along line BB in FIG. 3, FIG. 5 is a sectional view taken along line CC in FIG. A rear view of the pump 1, FIG. 7 is a sectional view taken along the line DD in FIG. 6.

As shown in FIG. 1, the pump 1 according to the present embodiment includes a pump body 2 that transfers air as a transfer fluid by pumping operation, and a part of a rotational drive mechanism that applies rotational driving force to the pump body 2. and a motor 3 constituting the motor. Note that the pump 1 is connected to a control unit (controller) not shown, and the pump operation can be controlled.

As shown in FIG. 3, the pump body 2 is provided on the axially distal end side (hereinafter also referred to as the "front side" or "front") of the rotating shaft 4 of the motor 3 that extends so as to penetrate inside the pump body 2. It has a first cylinder housing 5 and a second cylinder housing 6 provided on the base end side in the axial direction (hereinafter also referred to as "rear side" or "rear").

A central plate 7 is disposed between the first cylinder housing 5 and the second cylinder housing 6, and a front plate 8 and a rear plate are provided on the front side of the first cylinder housing 5 and the rear side of the second cylinder housing 6, respectively. 9 are attached, and these are fixed in a sealed state by a plurality of bolts 10 passing through them. Note that the bolt 10 is attached from the front plate 8 side via a screw washer and a plate washer 10a (not shown in FIG. 3).

Further, as shown in FIG. 2, the front plate 8 is positioned and fixed to the first cylinder housing 5 by a positioning pin 11. As shown in FIG. 6, the rear plate 9 is similarly positioned and fixed to the second cylinder housing 6 by positioning pins 11.

Further, the pump main body 2 configured in this manner is integrally attached to the motor 3 by attaching the rear plate 9 to the motor 3 with a cap bolt 12 (see FIG. 3). The first and second cylinder housings 5, 6 and each of the plates 7 to 9 are made of a metal member such as aluminum, and each of the plates 7 to 9 of this embodiment is further coated with hard alumite treatment having a film thickness of 40 μm. is applied.

As shown in FIG. 4, in the first cylinder housing 5, a first suction side pump head 14, which has a suction port 13 through which air is sucked, is installed, for example, at the diagonal upper part on the right side when viewed from the front, through a gasket 15. installed. Further, a first discharge side pump head 17 having a discharge port 16 through which air is discharged is attached to the first cylinder housing 5 via a gasket 15, for example, at the diagonal upper part on the left side when viewed from the front. .

On the other hand, as shown in FIG. 5, a second suction side pump head 35 is attached to the second cylinder housing 6 via a gasket 15, for example, at the diagonally upper part on the right side when viewed from the front. The internal space 35a of the second suction side pump head 35 is connected to the suction port 13 and the internal space 14a (see FIG. 4) of the first suction side pump head 14 of the first cylinder housing 5, and the first flow path 34 (see FIG. 4). and FIG. 7).

Further, a second discharge side pump head 37 is attached to the second cylinder housing 6 via a gasket 15, for example, at the diagonally upper portion on the left side when viewed from the front. The internal space 37a of the second discharge side pump head 37 is connected to the discharge port 16 and the internal space 17a (see FIG. 4) of the first discharge side pump head 17 of the first cylinder housing 5, and the second flow path 36 (see FIG. 4). (see).

Note that the first and second flow paths 34 and 36 are formed, for example, in the second suction side and second discharge side pump heads 35 and 37, as shown in FIG. 7 (the discharge side is not shown). It is formed inside a pipe portion 38 that extends toward the first suction side and first discharge side pump heads 14 and 17 so as to be able to fit therein. O-rings 34a are attached to the fitting portions of the pipe portion 38 to the first suction side and first discharge side pump heads 14, 17 for sealing.

The first suction side and first discharge side pump heads 14, 17 and the second suction side and second discharge side pump heads 35, 37 each have a rectangular outer shape, and have a screw washer and a plate washer 18a (not shown). It is attached to the first and second cylinder housings 5, 6 by a plurality of bolts 18 via (see FIGS. 1, 2, and 6).

As shown in FIG. 4, inside the first cylinder housing 5, an internal space 14a and a suction port 13 of the first suction side pump head 14 and an internal space 17a and a discharge port 16 of the first discharge side pump head 17 are provided. An annular space communicating with the rotor is formed, and a cylindrical first rotor 20A, which is a rotating body, is housed in this annular space.

On the other hand, as shown in FIG. 5, an annular space that communicates with the internal space 35a of the second suction side pump head 35 and the internal space 37a of the second discharge side pump head 37 is formed inside the second cylinder housing 6. A cylindrical second rotor 20B, which is a rotating body, is also housed within this annular space. The first cylinder housing A first pump chamber 19 is formed in the cylinder housing 5 , and a second pump chamber 39 is formed in the second cylinder housing 6 .

Note that a reed valve 41 that opens only in the direction in which air is discharged is provided between the internal spaces 17a, 37a of the first and second discharge side pump heads 17, 37 and the first and second pump chambers 19, 39. It is being The reed valve 41 is attached to the first and second cylinder housings 5 and 6 with screws 40.

Here, the rotor 20 is made of a resin member such as polyamide-imide (PAI) resin. In addition, as shown in FIGS. 4 and 5, the rotor 20 has an eccentric shaft unit 23a (see FIG. 3) attached to the rotating shaft 4 of the motor 3 in the first and second pump chambers 19, 39. It is attached to the shaft 23 via a bearing portion 24 made of, for example, a ball bearing and an O-ring 24a. The rotating shaft 4 of the motor 3 is rotatably supported by a bearing portion 8a provided on the front plate 8 in the direction indicated by an arrow CW in the figure (clockwise direction).

As a result, the rotor 20 is rotated within the first and second pump chambers 19, 39 by a rotational driving force in the direction indicated by arrow CW in the figure (clockwise direction), for example. It rotates eccentrically on the inner circumferential surfaces 19a, 39a of , while rolling in the direction indicated by arrow CCW in the figure (counterclockwise direction). Note that at this time, the rotor 20 rolls while pressing the inner circumferential surfaces 19a, 39a of the first and second pump chambers 19, 39 due to the elastic force of the O-ring 24a, so that the rotor 20 is compressed with the suction chamber 21, which will be described later. Sealing performance with the chamber 22 is ensured.

Note that the first rotor 20A and the second rotor 20B are arranged such that the phases of eccentric rotation differ by 180 degrees in the first and second pump chambers 19 and 39. Therefore, the pump operation in the first pump chamber 19 and the pump operation in the second pump chamber 39 are in opposite phases.

Further, above the first and second pump chambers 19 and 39, a swing lever 30 is provided which can swing according to eccentric rotation of the rotor 20. The swing lever 30 is made of a metal member such as SUS440 series stainless steel. The swing lever 30 is swingably supported by a support shaft 31. The support shaft 31 is disposed such that its axial center is located on a perpendicular line passing through the axial center of the rotating shaft 4 of the motor 3. The swing lever 30 is fixed to the support shaft 31 by, for example, a fixing pin 31a and a set screw 31b.

Further, the support shaft 31 is rotatably supported individually in the first and second cylinder housings 5 and 6 by a plurality of bearings 32 provided on the front plate 8, the center plate 7, and the rear plate 9. ing. Note that a plate portion 33 made of a resin material such as polytetrafluoroethylene (PTEF) resin is disposed between the swing lever 30 and the bearing portion 32 in order to reduce friction during swinging.

By contacting the outer circumferential surface 20a of the rotor 20, the swing lever 30 separates the first and second pump chambers 19, 39 into a suction chamber 21 on the suction port 13 side and a compression chamber 22 on the discharge port 16 side (in FIG. (not shown). The suction chamber 21 and the compression chamber 22 change their volumes as the rotor 20 rotates. Note that the swing lever 30 has a contact portion C with the outer circumferential surface 20a of the rotor 20 on the lever tip side that is compressed more than a plane passing through the center of the support shaft 31 and the center of the rotating shaft 4 (a vertical plane in the illustrated example). It is attached to the first and second cylinder housings 5 and 6 so as to be located on the chamber 22 side. That is, as shown in FIG. 4, even at the bottom dead center of the rotor 20, when the swing lever 30 swings most toward the suction port 13, the contact portion C on the lever tip side is closer to the compression chamber 22 than the above-mentioned perpendicular line. It is set up to be located at.

In addition, on the suction chamber 21 side of the first and second cylinder housings 5 and 6, there is provided a structure for buffering the collision between the rotor 20 and the first and second cylinder housings 5 and 6 at the top dead center of the rotor 20. A damper 42 made of an elastic material such as rubber is provided. Further, in the portions of the first and second cylinder housings 5 and 6 surrounding the base end side of the swing lever 30, a radial seal is provided which contacts the base end side of the swing lever 30 to seal the suction chamber 21 and the compression chamber 22. A unit 43 is provided.

The swing lever 30 provided in this manner has a curve M1 indicating a movement locus of the contact portion C with the outer circumferential surface 20a of the rotor 20 at a portion corresponding to the contact portion C from the bottom dead center to the top dead center of the rotor 20. It is desirable to swing so as to approximate the hypocycloid curve M2 (curve M1≈curve M2) indicating the movement locus of . This is because the sliding movement between the swing lever 30 and the rotor 20 during the compression stroke can be theoretically reduced to zero. Here, the hypocycloid curve M2 has, for example, a radius from the axis center of the rotating shaft 4 of the first and second pump chambers 19 and 39, and a radius from the center to the outer peripheral surface 20a of the rotor 20, and When the rotation angle of the rotor 20 is θ, and radius a>radius b>0, the parameter expression x=(ab) cos θ+b cos {(ab/b) θ}, y=(ab) It can be expressed as sin θ−bsin {(ab/b) θ}.

Therefore, when designing the pump chambers 19 and 39, the rotor 20, and the swing lever 30 in the first and second cylinder housings 5 and 6, it is necessary to make contact from the center position of the support shaft 31 of the swing lever 30, for example. Using various numerical values such as the distance to the part C and the swing angle as variables, a curve M1 showing the movement locus of the contact part C of the swing lever 30 with the rotor 20 is used to calculate the movement of the part of the rotor 20 corresponding to the contact part C. By approximating the hypocycloid curve M2, which is a locus, by the method of least squares, etc., and determining the various variables described above, it is possible to determine the optimal setting value of the swing lever 30.

In order to ensure more reliable sealing at the contact portion C between the swing lever 30 and the rotor 20, the pump body 2 is provided with a torque applying mechanism for applying rotational torque to the swing lever 30, for example. ing. As shown in FIGS. 4 and 5, the torque applying mechanism includes a plurality of magnets 44a, such as neodymium magnets, provided at predetermined locations on the base end side of the swing lever 30 of the first and second cylinder housings 5 and 6, for example. 44b, and a magnet 44c provided on the base end side of the swing lever 30 at a location that can face these magnets 44a and 44b at the top dead center and bottom dead center of the rotor 20.

By further providing such a torque applying mechanism, when the swing lever 30 swings due to the eccentric rotation of the rotor 20, an attractive force due to different polarities is generated between the magnets 44a and 44c, and an attractive force is generated between the magnets 44b and 44c. Generates a repulsive force due to the same polarity. This allows the swing lever 30 to generate rotational torque in the direction of pressing the rotor 20, as shown by the arrow R in FIG. be able to.

In addition to the structure using the magnets 44a to 44c described above, the torque applying mechanism may have a structure in which a magnetic body is arranged in place of the magnet 44a, or a structure in which the magnet 44b is omitted and either of the magnets 44a and 44c is used. It is also possible to replace one of the magnets with a magnetic material.

Next, the operation of the rotary positive displacement pump 1 configured as described above will be explained.
First, attention will be paid to the first cylinder housing 5. The stroke in which the first rotor 20A moves from the top dead center to the bottom dead center shown in FIG. 4 is a suction stroke. In the suction stroke, air, which is a transfer fluid, is introduced from the suction port 13 into the suction chamber 21 and further transferred to the compression chamber 22 side. During this time, since the compression chamber 22 is also under negative pressure, the reed valve 41 is closed, and no air is discharged from the compression chamber 22 of the first cylinder housing 5 to the discharge port 16.

The stroke in which the first rotor 20A moves from the bottom dead center to the top dead center shown in FIG. 4 is a compression stroke. In the compression stroke, the reed valve 41 is in an open state, and the air in the compression chamber 22 is discharged from the discharge port 16. On the second cylinder housing 6 side, a pump operation with a phase opposite to that on the first cylinder housing 5 side is performed. Therefore, air is alternately discharged from the compression chamber 22 of the first cylinder housing 5 and the compression chamber 22 of the second cylinder housing 6, and air is continuously discharged from the discharge port 16.

The pump 1 of this embodiment has the pump main body 2 configured as described above, so that the sliding of each part in the first and second pump chambers 19 and 39 is improved compared to the conventional rotary type and swing rotary type. It becomes possible to both reduce resistance and sliding loss and ensure high sealing performance.

Specifically, by attaching the rotor 20 to the eccentric shaft 23 via a bearing portion 24 such as a ball bearing, the rotor 20 in each pump chamber 19, 39 rotates eccentrically while rolling during pump operation. do. Therefore, the outer peripheral surface 20a of the rotor 20 does not rub against the inner peripheral surfaces 19a, 39a of the pump chambers 19, 39. As a result, the frictional resistance can be reduced to about 1/100 compared to, for example, the sliding friction of the swing rotary type, and the loss due to friction can be significantly reduced.

Further, the contact portion C of the swing lever 30 with the outer circumferential surface 20a of the rotor 20 is of a type in which the side portion of the swing lever 30 contacts the outer circumferential surface 20a of the rotor 20 that is rolling. The sliding distance can be reduced. In particular, if the curve M1 representing the movement trajectory of the contact portion C is approximated to the hypocycloid curve M2, which is the movement trajectory of the portion of the rotor 20 corresponding to the contact portion C, the sliding distance between the rotor 20 and the swing lever 30 theoretically becomes zero. In particular, if the curves M1 and M2 can be matched in the compression stroke from the bottom dead center to the top dead center of the rotor 20, where the adhesion force between the two is highest, high sliding resistance will occur in the sliding part during high compression. Compared to the swing rotary type, sliding resistance can be significantly reduced.

Furthermore, for example, the rotor 20 is made of PAI resin with a low coefficient of linear expansion, and the swing lever 30 is made of SUS440, which also has a low coefficient of linear expansion. can be prevented. Therefore, in the so-called non-lubricated pump 1, it is possible to achieve both low sliding resistance and high sealing performance. Further, if the contact portion C of the swing lever 30 with the rotor 20 is coated with, for example, DLC (diamond-like carbon), the sliding resistance can be further reduced.

Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.

1 Rotary displacement pump 2 Pump body 3 Motor 4 Rotating shaft 19 First pump chamber 20 Rotor 21 Suction chamber 22 Compression chamber 23 Eccentric shaft 30 Swing lever 31 Support shaft 39 Second pump chamber

Claims (7)

A pump body having a suction port and a discharge port for the transfer fluid, which introduces the transfer fluid into the interior through the suction port, transfers the transfer fluid to the discharge port by a pumping operation due to rotation, and discharges the transfer fluid from the discharge port. and,
a rotational drive mechanism having a rotational shaft and applying rotational driving force to the pump body to cause a pump operation via the rotational shaft;
In a rotary positive displacement pump with
The pump body is
a cylinder housing having a pump chamber formed of an annular space communicating with the suction port and the discharge port;
a cylindrical rotor that is attached to the rotating shaft of the rotary drive mechanism via an eccentric shaft and housed in the pump chamber so as to be eccentrically rotatable while contacting an inner circumferential surface of the pump chamber;
a swing lever that contacts a part of the outer circumferential surface of the rotor to divide the pump chamber into a suction chamber and a compression chamber, and is provided to be swingable in response to eccentric rotation of the rotor;
Equipped with
The swing lever is
The rotor is oscillated so that the curve representing the movement trajectory of the contact portion with the outer peripheral surface of the rotor approximates the hypocycloid curve representing the movement trajectory of the portion corresponding to the contact portion from the bottom dead center to the top dead center of the rotor. move
A rotary displacement pump characterized by: The rotor is
The rotary type according to claim 1, wherein the rotary type is attached to the eccentric shaft attached to the rotating shaft of the rotary drive mechanism via a bearing, and contacts the inner circumferential surface of the pump chamber while rolling during eccentric rotation. volumetric pump. The swing lever is
Swings around the support shaft,
The cylinder housing is configured such that the contact portion with the outer circumferential surface of the rotor swings to be located closer to the compression chamber than a plane passing through the center of the support shaft and the center of the rotation shaft of the rotational drive mechanism. The rotary positive displacement pump according to claim 1 or 2, wherein the rotary positive displacement pump is attached. The rotary positive displacement pump according to any one of claims 1 to 3 , further comprising a torque applying mechanism that applies a rotational torque in a direction to press the rotor to the swing lever. The torque applying mechanism is
One or more magnets provided on the cylinder housing and a magnet or magnetic body provided on the swing lever, or one or more magnetic bodies provided on the cylinder housing and a magnet provided on the swing lever. 5. The rotary displacement pump according to claim 4 , wherein the rotational torque is applied by at least one of a magnetic attraction force and a magnetic repulsion force between the cylinder housing and the swing lever. The rotary positive displacement pump according to any one of claims 1 to 5 , wherein the rotor is made of a resin member, and the swing lever is made of a metal member. The pump body is
a first cylinder housing and a second cylinder housing arranged in the direction of the rotation axis of the rotational drive mechanism;
a first rotor housed in a pump chamber of the first cylinder housing and a second rotor housed in a pump chamber of the second cylinder housing;
The suction port of the first cylinder housing and the suction port of the second cylinder housing communicate through a first flow path,
The discharge port of the first cylinder housing and the discharge port of the second cylinder housing communicate through a second flow path,
The rotary positive displacement pump according to any one of claims 1 to 6 , wherein the first rotor and the second rotor are arranged so that phases of eccentric rotation differ by 180°.

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