Rotor assembly and progressive cavity pump

Rotor assembly and progressive cavity pump

The invention relates to a progressive cavity pump, which has anti-interference safety characteristics. The invention also extends to a progressive cavity pump, which is characterized by an improved sealing structure and rotor assembly.

The eccentric screw pump, also known as the progressive cavity pump, is widely used in the gunpowder industry because of its low pulsation, low shear, and ability to process products with 40% particles. Progressive cavity pumps can also be used for sewage treatment in the food industry, and other applications that require pumping of highly abrasive materials.

A typical progressive cavity pump usually includes a rotor installed in and rotating in a stator defined as a pumping chamber. In a typical configuration, the rotor is a spiral with a wide pitch, and the stator is considered to be a double-start spiral with twice the pitch of the rotor. As a result, the delivery space (cavity) is formed in the pumping chamber between the stator and the rotor.

During pumping, the cavity is filled with product and continuously moves from the inlet to the outlet. Since it is smoothly transported from one cavity to the next, there is almost no pulsation during pumping. The conveying space is sealed by the interference between the stator and the rotor. The stator is usually made of elastic material and fixed in a hard shell, but other configurations such as an elastic layered rotor can also be used. The volume of the cavity remains constant during movement. Other configurations include the use of a wide-pitch spiral rotor in a double-start spiral stator, and a wide-pitch elliptical cross-section spiral rotor such as a three-start spiral stator. Due to the special configuration of the rotor/stator, the rotor moves radially in the stator according to a defined trajectory. See, for example, the title "New NM Series-Who would have thought of improving NEMO," Netzsch Mohnopumpen GMBH, Waldkraiburg, Germany, published in June 1994^®Pump? Product catalog.

In a typical prior art pump, the rotor is driven by the drive shaft. Rotational movement is driven by electricity, oil pressure, air pressure or other types of motors. In order to be suitable for the trajectory movement of the rotor, the drive shaft is made of flexible materials, such as spring steel or hard structures, but is connected by universal gears or joints at its ends.

The seal or elastic cover is provided to prevent pumped materials such as gunpowder from entering the joint. Sometimes, instead of two separate covers, a complete elastic sleeve is used to connect between the two joints and enclose the shaft. Likewise, in some configurations, a single cover can be used. See patents such as US Patent No. 3,930,765 to Waite. It is best to lubricate the joint with lubricating oil. In this case, the seal, cover, or sleeve not only prevents the pumped material from contacting the joint, but also keeps the lubricant from contacting the pumped material.

When pumping gunpowder with a progressive cavity pump, it must be prevented from overheating. During normal operation, the heat is carried away from the progressive cavity pump by the pumped gunpowder, thus preventing the occurrence of over-temperature. However, the over-temperature system can be generated during the detention operation and the idling of the pump.

The stagnant operation (ie stagnant pumping) occurs when the flow is blocked in the pump. This happens at the outlet of the pump or downstream of the outlet. The stagnant pumping is the most potential hazard, which occurs when the gunpowder is pumped. During stagnant pumping, if the drive motor does not stop rotating, all of its drive energy is applied to the pump and converted into heat energy, which will be absorbed by the gunpowder remaining in the pump, the rotor and the stator.

The speed of temperature rise depends on the power input of the system, the heat dissipation capacity and the heat diffusion. When the decomposition temperature of the gunpowder is reached (that is, the emulsification temperature exceeding 200°C), all the gunpowder stored in the pump will suddenly burn. The result is usually the pump damage, damage to surrounding objects, and serious injury to personnel close to the pump.

Moreover, if a pump fragment with sufficient vibration impacts the gunpowder of an adjacent pump to cause it to explode, the event may cause another event to occur. The accident of stagnant pumping is a matter that the gunpowder industry attaches great importance to, and every effort is made to minimize its occurrence.

When the progressive cavity pump is running but there is nothing to suck on the suction end of the stator, the progressive cavity pump will run idly. When the pump runs in this idling condition, it will get heat due to the work derived from friction and the deformation of the stator elastic body. Since no product carries heat away, the heat must be absorbed by the rotor, stator, and the residual gunpowder film in the stator. When the temperature rises, the stator will expand inward due to the hard shell. The result is to accelerate the temperature rise and can cause the gunpowder in the residual pump to explode.

The idling problem of the pump is usually not more serious than the stagnant operation, because the idling of the pump has very little gunpowder in the pump, but it is still very dangerous. At the same time, the idling system of the pump tends to happen frequently. For example, when an operator handles an air-sealed pump, the problem will be solved by keeping the pump running instead of taking time to activate the pump. The operator will also allow the unsafe steps to continue to use by invalidating the safety mechanism. This unfortunate fact is due to the need for a security system that is difficult to refuse. As discussed below, the present invention can overcome this problem.

The third danger is when the cover, seal, or casing ruptures around the joint, and gunpowder overflows from the joint at the end of the drive shaft. The joints will be reduced in efficiency due to fatigue, wear, chemical erosion or freezing caused by long-term use. This can cause problems caused by seal failure to be undetectable from the outside world. Although the sliding speed of the joint is reduced, the contact pressure between the two metal parts is still very high, which will increase the friction, especially when the lubrication is lost and replaced by gunpowder. Gunpowder is sensitive to friction and even worse after crystals and moisture disappear. The friction at the joint is thus as high as the explosive powder. This is dangerous and unexpected.

When pumping materials other than gunpowder, the danger of explosion certainly does not exist. However, the appearance of the pumped material at the joint is undesirable because it will shorten the service life of the pump and metal particles and lubricants will contaminate the pumped material.

In response to the aforementioned problems, various methods have been used in previous techniques. The method used is usually electronic in nature to sense the presence or absence of flow, the level of pressure, or whether the temperature is too high, which are all indicators for unsafe conditions. The devices used in these methods are usually sensitive and quite sophisticated. Therefore, these devices work well in a controlled environment, but are unreliable in harsh environments, such as gunpowder pumping trucks or underground gunpowder loading equipment. Another disadvantage is that these devices are very easy to bypass.

Regarding the problem that occurs with the stagnant operation and the idling of the pump, one of the solutions in the previous art is to provide a pump including a rotor. The pump has a longitudinally long circular cavity that receives a rotor whose lateral dimension is smaller than the diameter of the cavity. axis. The gap between the cavity wall and the rotor shaft is filled with fusible metal bonding material to form a connecting member. When the pump is operating, if the temperature in the stator rises above the melting temperature of the alloy, the alloy will soften and the rotor shaft will rotate freely in the rotor cavity (see European Patent Application 0 255 issued) 336). The heat build-up in the pumped material is almost reduced because the rotor member no longer rotates in the stator of the pump. This solution still has shortcomings. In normal operation, the ability of the connecting member to transmit torsion force to the rotor member depends on the connecting force of the cavity wall/connecting member and the rotor shaft/connecting member. The combined force of connecting the connecting member to the connecting member is only due to the interface connection between the bonding material of the connecting member and the rotor member and the rotor shaft manufacturing material. The interface connection is basically a chemical bond between compatible materials. The ability of chemical bonding to resist the huge shear stresses normally encountered during operation is very important to avoid premature failure of connecting components. Consequently, special and carefully executed manufacturing steps must be followed to ensure that the bonding force with sufficient strength is established between the connecting member and the connected member when manufacturing the rotor assembly. If not, the result is poor performance due to premature failure of the bond. In some cases, even if the manufacturing process is satisfactory, the bonding will age due to excessive fatigue, such as repeated cooling/heating cycles when the pump is repeatedly started and stopped by the connecting member, resulting in chemical changes in the bonding material, etc. . Therefore, even in the normal operation of the pump, when the rotor shaft is subjected to shear stress, the bonding system will break.

Invention description and subject matter

One of the objects of the present invention is to provide a pump with improved safety characteristics.

Another subject of the present invention is to provide a progressive cavity pump, which is specifically provided for problems such as stagnant operation, idling of the pump, and integrity of joint seals.

Another object of the present invention is to provide a progressive cavity pump with improved safety features that are not easily bypassed.

In the following examples and extensive descriptions, the present invention provides a progressive cavity pump, which includes: a) a housing, which defines a pumping chamber, and the housing includes:-a feed port for receiving the pump The delivered material enters the pumping chamber;-the discharge port is for the pumped material to be discharged from the pumping chamber; b) the rotor is installed in the housing, and the rotor can rotate and track in the housing Movement, so that the material to be pumped is displaced in the pumping chamber between the inlet and the outlet; c) the drive shaft, which causes the rotor to rotate; d) the sealing mechanism, which supplies the drive shaft and the pumping chamber For isolation, the sealing mechanism provides devices for: i) adapting to the rotational movement of the drive shaft; ii) adapting to the trajectory movement of the drive shaft.

As far as the subject of the present invention is concerned, "trajectory movement" means that the rotor member moves around a continuous path located at a reference position away from the centerline of the rotor member. The path is preferably circular, but it can also be elliptical or other shapes. The reference position of the rotor moving around along a continuous path is the centerline of the stator. It should be noted that the reference position depends on the geometry of the rotor/stator configuration, so it is different in this best example. On the other hand, "rotational movement" means that a part of the drive shaft moves around the corner of the centerline of the part. For example, when the end portion of the drive shaft connected to the rotor makes an angular displacement around the center line of the end portion that usually coincides with the center line of the rotor, the drive shaft is regarded as rotating.

When it is desired to separate the drive shaft structure from the rotor, the sealing mechanism is used as a reference point. All structural parts and components that are connected to the drive shaft for trajectory and rotational movement, and are restricted to the pumping chamber, are regarded as part of the rotor. On the other hand, all components that are connected to the rotor through the sealing mechanism and stretched out of the delivery chamber are regarded as part of the drive shaft.

"Isolation" and its derivatives used in the description of the present invention refer to the fact that the drive shaft is separated from the pumping material. This expression should not be completely interpreted as the drive shaft system is completely sealed or there will be no material and drive shaft or joint connection, and the material and drive shaft or contact should be ignored according to the type of pumping material.

The progressive cavity pump according to the present invention is a major improvement of the prior art device, because the cavity pump is safe to operate. The drive shaft is arranged outside the original pumping chamber to avoid the accumulation of pumping materials at the joints of the drive shafts. If the aforementioned situation occurs, the pump will suddenly explode when handling explosive materials.

In the best example, the sealing mechanism that isolates the drive shaft from the suction chamber is a composite structure, which includes a seal positioned around the end of the shaft, the end is connected to the rotor, and includes two separate sealing members, one The sealing member can adapt to the rotational movement of the drive shaft, while the other sealing member is adapted to the trajectory of the shaft. It is suitable for the bearing system so that the seal positioning ring is positioned concentrically around the rotor shaft, and the rotational movement of the rotor shaft hardly generates friction. A lip seal is installed behind the bearing, which is combined with the surface of the drive shaft to form a barrier to prevent the pumped material from overflowing when the drive shaft rotates.

The second sealing member, that is, the sealing member adapted to the trajectory movement of the drive shaft, includes a flexible annular barrier spanning the distance between the sealing positioning ring and the pump housing. The structure of the annular blocking block allows the sealing positioning ring to be displaced relative to the housing due to the compression/expansion of the blocking. This allows the drive shaft to move orbit, and at the same time prevents the pumped material from overflowing from the suction chamber on the side of the drive shaft.

In a variation, the composite seal system includes a support ring for blocking and the ring system can rotate in the housing to adapt to the trajectory of the drive shaft. Under this structure, the annular barrier (ie, the support ring) does not need to be a flexible structure. It is best to be made of hard materials, that is, made of materials that are more flexible and harder than the soft seal, so it is more resistant to tearing and actual impact. The rotational movement of the ring-shaped block makes the drive shaft and the rotor component move along with the path of the trajectory. Obviously, the trajectory radius (the distance between the trajectory path and the center line of the pumping chamber) is fixed and determined by the relative position of the rotor and the support ring. Objectively speaking, compared with the aforementioned example of using a flexible seal, the structure needs to have strict manufacturing tolerances, because the geometry of the trajectory path is fixed and only tolerates small changes.

In the examples and extensive descriptions. The present invention also provides a progressive cavity pump, wherein the sealing mechanism includes a support ring located between the pumping chamber and the drive shaft, the support ring can rotate in the housing; a first sealing mechanism is eccentric It is fixed on the rotor and has a device to adapt to the rotation of the rotor. The pump also includes a second sealing member fixed to the housing. The second member is eccentrically positioned around the support ring. The pole has a device to adapt to the rotation of the support ring. , Therefore: a) the trajectory movement of the rotor makes the support ring rotate; and b) the second sealing member adapts to the rotation of the support ring.

In a preferred embodiment, the pump further includes a first bearing device adapted to the rotational movement of the rotor in the support ring, and further includes a second bearing device adapted to the rotational movement of the support ring in the housing. Preferably, the first and second sealing members are lip-shaped sealing members, and the first and second bearing devices are double-row ball bearings.

In another example, the pump system includes a device for generating a radial reaction force to substantially offset the radial force generated by the rotor on the stator during pumping. This feature is to reduce the friction of the stator. In a preferred embodiment, there is a bearing, which includes a ring mounted on the drive shaft in a concentric manner and has a rolling surface, which is preferably elastic, and is continuously in contact with a part of the housing. The bearing system limits the pressure generated by the rotor on the stator, thereby restricting the friction of the stator.

Another concept of the present invention also provides a rotor assembly for use by a pump. The rotor assembly includes: a) a rotor component including a cavity; b) a rotor shaft, at least one part of which extends into the cavity C) a connecting member, which establishes the driving relationship between the rotor shaft and the rotor member in the cavity, and the rotational movement added to the rotor shaft is transmitted through the intermediate connecting member; d) the rotor member can be meshed with the connecting member; e) The connecting member has the ability of the thermal structure to fail, so as to terminate the driving relationship when a predetermined temperature is reached.

The present invention also provides a progressive cavity pump. The pump system includes: a) a housing, which defines a pumping chamber, and the housing includes:-an inlet for accommodating materials that need to be pumped into the pumping chamber; --An outlet to discharge the pumped material from the pumping chamber; b) A rotor assembly, which is installed in the housing, and includes: i) a rotor component including a cavity; ii) a rotor shaft, At least a part extends into the cavity; iii) a connecting member, which establishes the driving relationship between the rotor shaft and the rotor member in the cavity, and the rotational movement applied to the rotor shaft is transmitted by the intermediate connecting member; iv) a The rotor member can be engaged with the connecting member; v) the connecting member has the ability of thermal sensing structure to fail, so as to terminate the driving relationship when a predetermined temperature is reached.

In this description, the term "engageable" refers to a configuration in which the rotor components or rotor shafts are mechanically connected to the connecting members; in this way, the torque transmission system is completely independent or only partially dependent on the connecting member/rotor. The adhesion force on the surface of the component or the surface of the connecting component/rotor shaft. For example, a mechanical interconnection system can be achieved between the connecting member and the rotor member by a member having a protruding part that is accommodated in a close recessed portion of the other member. In a specific example, but should not be limited to this example, the rotor shaft system includes a series of longitudinally extending protrusions distributed over the entire length of the shaft at right-angle intervals. The protruding part forms a tooth-like body that is mechanically coupled to the connecting member. In a similar way, the connecting members between the protruding parts on the rotor shaft also form teeth to mesh with the protruding parts. The connection between the connecting member and the rotor shaft is similar to the connection of a rack. A similar rack connection is provided between the rotor member and the connecting member. In this example, it is a double meshing situation, and the meshing between the rotor member and the connecting member, and between the rotor shaft and the connecting member.

To establish meshing between the connecting member, the rotor member or the rotor shaft, the aforementioned interconnecting protrusions/recesses must be used, but the full-length meshing of the connecting members is not required. The protruding portion/recessed portion may only extend at a part of the length of the connecting member. The number and interval of the protruding parts/recessed parts can also be changed without departing from the spirit of the present invention. One possibility is to use a protruding part of the connecting member to engage with a mating recess on the rotor member and another protruding part on the connecting member to engage with a mating recess on the rotor member, or vice versa. Another possibility to establish the engagement of the connecting member with the rotor shaft is to use a rotor shaft with a non-circular cross-section along at least part of its length. For example, a square, polygon, triangle or ellipse axis can be used. A slightly different possibility is to use a non-linear rotor shaft. The shaft system is like a section and the rest is angled to establish a mechanical connection with the connecting member. In a specific example, the axis may include a main longitudinal image extension. Its end is tied with a cross joint to form a protruding part that is combined with the connecting member body. Another possibility is to consider forming the rotor shaft into a helical shape, or the usual twisted shape structure. There is another possibility to consider providing a rotor shaft with a circular cross-section, but it is eccentrically arranged in the cavity of the rotor member.

"Heat conductive structure failure" refers to the loss of at least a part of the structure of the material constituting the connecting member and no longer has the ability to transmit rotational movement from the rotor shaft to the rotor member. In a preferred embodiment, the connecting member is made of a low melting point alloy, which transforms into a liquid state when the temperature exceeds the melting point. At this time, the rotor shaft system rotates freely in the liquid alloy and the non-rotational motion is transmitted to the rotor shaft member. The material is best to melt or almost melt. Bismuth alloy, 55.5% bismuth and 44.5% lead bismuth alloy system is the most satisfactory. Other possibilities will exist. For example, the connecting member can be a special structure, that is, its molecules are arranged in a matrix of low melting point alloys, or usually a material that can disintegrate or transform into a liquid state at a predetermined temperature. When the temperature is below the predetermined temperature, the connecting member has a unified structure. When the pump is overheated, the bonds of molecules break and move freely with each other. Therefore, the rotor shaft and the rotor member are separated from each other. It is also possible to consider a possibility that the material or structure of the connecting member is sufficiently weakened at a predetermined temperature to break the structure of the connecting member, and no longer has the ability to transmit rotational movement to the rotor member, but does not melt the connecting member.

It is best to use a low-melting point alloy, because the connecting member becomes liquid and only produces a small resistance to the rotating shaft. Obviously, when any significant resistance is applied to the rotating shaft, it will have the effect of continuing to drive the rotor member, which of course is not what we want to see.

In a preferred embodiment, the rotor assembly system further includes a device for allowing the rotor shaft to contact the rotor member when the connecting member fails, and the device for preventing contact includes bushings arranged at each end of the rotor shaft.

Another concept is that the rotor assembly further includes a device to prevent longitudinal displacement of the rotor member relative to the rotor shaft when the connecting member fails, and preferably to prevent longitudinal displacement of the rotor member. The device includes a ball arranged in the cavity of the rotor member .

The subject matter and characteristics of the present invention will become clearer with reference to the following description and drawings.

<p>2Shell</p><p>3Cylindrical surface</p><p>4Import</p><p>6Exit</p><p>8Jingzi</p><p>10Spiral rotor</p><p>11Suction Chamber</p><p>12Interval</p><p>13Rotor shaft</p><p>14Motor</p><p>16Second axis</p><p>18First axis</p><p>20Connector</p><p>22Connector</p><p>24Seal locating ring</p><p>24aSeal locating ring</p><p>26Ball Bearing</p><p>26aBall Bearing</p><p>28Lip seal</p><p>28aLip seal</p><p>29Lip seal</p><p>30Overflow slot</p><p>30'Overflow slot</p><p>32Elastic ring</p><p>32aElastic ring</p><p>33Clip</p><p>34Hollow Torque Arm</p><p>35Fixed ring</p><p>35aFixed ring</p><p>36Sleeve</p><p>37Screw</p><p>37aScrew</p><p>38Space</p><p>39Sealed</p><p>40Ball</p><p>42Insert</p><p>52Ball Bearing</p><p>54Support ring</p><p>56Ball Bearing</p><p>60Lip seal</p><p>62Lip seal</p><p>70Bearing</p><p>72Inner seat ring</p><p>74Ball</p><p>76Outer seat ring</p><p>78flexible coverage</p>

The following is a description of the best examples with reference to the accompanying drawings, where the drawings include: Figure 1 is a vertical longitudinal section view of a progressive cavity pump with improved safety features according to the first concept of the present invention; Figure 2 is based on The vertical longitudinal section view of the progressive cavity pump of the present invention to illustrate the first example of the sealing mechanism and the improved rotor assembly; Figure 3 is the vertical longitudinal section view of the progressive cavity pump according to the first concept of the present invention to illustrate the sealing The second example of the mechanism; Figure 4 is a vertical longitudinal section view of the progressive cavity pump according to the first concept of the present invention to illustrate the third example of the sealing mechanism and the shaft support roller; Figure 5 is along the line 5-5 in Figure 4 A cross-sectional view taken to illustrate the sealing mechanism; Fig. 5a is a cross-sectional view similar to Fig. 5 to illustrate the support ring at a different angular position; Fig. 6 is a cross-sectional view taken along line 6-6 in Fig. 4 to illustrate Shaft support bearing; Figure 7 is a cross-sectional view taken along the line 7-7 in Figure 2 to illustrate the rotor assembly according to another concept of the present invention; Figure 8 is a cross-sectional view similar to Figure 7 to illustrate the best rotor Assembly.

Referring to FIG. 1, the progressive cavity pump system according to the present invention is particularly helpful for pumping gunpowder and includes a housing 2 having an inlet 4 and an outlet 6. The housing also includes a stator 8 to receive a spiral rotor 10. The stator defines a pumping chamber, which includes a suction chamber 11 formed downstream of the inlet 4 in the stroke direction of the pumped material, and a transport space such as the interval 12 is defined in the recess between the stator 8 and the rotor 10. The transportation space is sealed by the interference between the rotor and the stator. During pumping, the transportation space is filled with the pumped material and continuously and smoothly transferred. As a result, it provides almost no bounce operation of the pump.

The usable rotor/stator configuration includes a wide-pitch helical rotor and a double-start helical stator. The stators pitch is twice that of the rotor (considered as a 1/2 geometry), or a A wide-pitch helical rotor with an elliptical cross-section is in a three-start helical stator. The pitch of the stator is three times the pitch of the rotor (considered as a 2/3 geometry). Due to the special configuration of the rotor/stator, the rotor travels around the central axis of the stator along a trajectory in the stator (illustrated by the dashed line B in Fig. 4). In the progressive cavity pump, the 1/2 geometry rotor completes one trajectory per rotation and the 2/3 geometry rotor in the progressive cavity pump has two trajectories per rotation. Other rotor/stator configurations are also available.

The stator can be completely elastic or the thickness of the wall is the same. The fully elastic stator consists of a steel tube in which an elastic lining of the desired shape is cast. The stator of uniform wall thickness includes a shell of the desired shape, which is lined with an elastomer of uniform thickness, and the thickness depends on the size of the pump. Because the lining is consistent throughout the pump, the pressure generated by the entire line contact is consistent. Two types of statics are very popular and can be obtained from similar manufacturers. Those skilled in the art also recognize that other types of statics within the scope of the present invention can also be used.

The spiral rotor 10 can be made of any suitable material such as stainless steel or aluminum with a surface coating. In terms of thermal diffusion characteristics, aluminum is the best one. For the reasons explained here, the most important thing for the rotor is to have good thermal conductivity, in order to quickly respond to the over-temperature in the pump caused by the stagnant operation or the pump idling. Good thermal diffusion characteristics are also important to avoid the formation of so-called "hot spots", which are caused by excessive friction between the rotor and the stator in a special area, which is a defect on the surface of the rotor or stator.

The rotor 10 includes a shaft 13. The rotor 10 and the shaft 13 can be a single mechanical component or two independent components connected to each other, which will be discussed in detail below.

The rotor 10 is connected to a motor 14 by a composite drive shaft. The composite drive shaft includes a first shaft 18 and a second shaft 16. The motor can be electric, hydraulic, pneumatic, or other types. The rotor 10 can be connected to the drive shaft in any conventional manner. If necessary, the rotor 10 and the drive shaft can be connected in a unidirectional connection configuration. When the motor is suddenly driven in the opposite direction, the connection will be separated immediately to prevent any danger that may be established in an accident.

Joints 20 and 22 are located at each end of the second shaft 16. The joint needs to enable the motor 14 to generate a torque suitable for the trajectory movement of the rotor to the rotor. The joints 20 and 22 are preferably universal joints, but can also be toothed, pin or co-acting joints.

Contrary to the drive shaft system of the traditional progressive cavity pump located in the pumping chamber, the drive shaft system of the progressive cavity pump of the present invention is isolated from the pumping chamber. This is achieved by the special sealing mechanism detailed in Figure 2, Figure 3, and Figure 4.

The first example of the sealing mechanism according to the present invention is explained with reference to FIG. 2. According to the first example, a seal positioning ring 24 is arranged at the first end of the rotor shaft, which end is adjacent to the joint 20. Suitable bearings, such as ball bearings 26, are used to install the seal locating ring 24 on the rotor and adapt to the rotation of the rotor. The ball bearing 26 may include, for example, a metal ball in a plastic race, or a plastic ball in a metal race. If the pumped material is corrosive, it is recommended to use plastic. The seal positioning ring itself does not rotate, but follows the rotor to make a trajectory movement, which will be discussed in detail below.

The seal positioning ring 24 includes a first sealing member, which includes two lip seals 28 and 29. The lip seals 28 and 29 are attached to the surface of the rotor 10 and allow the rotor to rotate in the seal positioning ring, while forming a barrier to prevent the pumped material from overflowing from the pump suction chamber 11, which is a part of the pumping chamber share. If for any reason, the pumped material passes over the lip seal 28, it will overflow the seal positioning ring 24 through the radial overflow slot 30 without contacting the ball bearing 26 and the joint 20. Other types of seals can also be used, and the rotor must be allowed to rotate in the seal positioning ring while preventing the pumped material from overflowing there.

The outside of the sealing positioning ring 24 is isolated from the suction chamber by a second sealing member, and the second sealing member includes a foldable flexible annular barrier spanning between the sealing positioning ring 24 and the housing. The seal positioning ring system does not rotate in the flexible block and the flexible block system adapts to the trajectory movement of the rotor and the seal positioning ring under compression/expansion. Therefore, the second sealing member allows the seal positioning ring 24 to move with the trajectory of the rotor shaft, and at the same time isolates the drive shaft from the suction chamber 11.

In terms of general gunpowder application, the second sealing member must be able to support a negative pressure of about 9 meters of water column and a positive pressure of about 10 meters of water column, and accept a radial deflection of about ±8 mm. A seal that can be used as the second sealing member of the present invention is illustrated in FIG. 2. The seal includes an elastic ring 32 with a V-shaped cross-section, the inner periphery of which is fixed to the seal positioning ring 24 by a clamp 33, and The outer periphery is fixed to the casing 2 of the pump by a fixing ring 35 and a screw 37.

In order to prevent the seal positioning ring 24 from rotating in the second sealing member due to the friction between the rotor shaft 13 and the lip seals 28, 29, a hollow torsion arm 34 should be provided to securely lock the seal positioning ring 24 so that it cannot rotate. The torsion arm system includes a long slot (not shown) for receiving the screw 37 in a sliding manner. When the seal locating ring 24 traverses, the torsion arm 34 slides over the screw 37 to allow the trajectory movement, but prevents the seal locating ring from rotating. If there is very little friction between the rotor shaft 13 and the lip seal 28, the torsion arm is not needed.

Referring to Fig. 3, a second example of the sealing mechanism according to the present invention is explained. The second example is characterized by a denser seal design to reduce the length of the pump. In the second example, the first and second sealing members are similar to the first and second sealing members of the first example and respectively include a suitable lip seal 28a and a flexible annular stopper, the stopper including an elastic The ring 32a is fixed to the seal positioning ring 24a and the housing 2 by an appropriate fixing ring 35a and screws 37a. In this particular example, the ball bearing 26a is located close to the first sealing member (lip seal 28a), thus making the seal positioning ring 24a shorter than the seal positioning ring 24 of the first example. The seal positioning ring system of the second example does not include a radial overflow slot, but can evacuate any pumped material passing through the lip seal 28a. It is best to provide bearings 26a that do not make any metal-to-metal contact due to the aforementioned reasons, and also provide bearings without outer lip seals to allow any pumped material to pass through the lip seal 28a to reach the bearing 26a. Pump The delivered material passes through but does not remain in the bearing 26a.

The third example of the sealing mechanism is described with reference to Figure 4, Figure 5 and Figure sa. The special sealing mechanism denoted by the reference number 50 has the advantage of integrating the first sealing member adapted to the rotational movement of the rotor and the second sealing member adapted to the trajectory movement of the rotor in one unit.

According to this example, a first sealing member is provided. The member includes a lip seal 60 which is squeezed to fit inside a support ring 54. The lip seal 60 surrounds the rotor in a concentric manner (Figure 5) and is adapted to Rotational movement of the rotor. Contrary to the first and second examples, the support ring does not need to be a flexible structure and preferably a rigid structure. FIG. 5 more specifically illustrates that the shape of the support ring 54 is that the first sealing member 60 is arranged in the support ring 54 in an eccentric manner. More specifically, the shape of the support ring 54 enables the first sealing member 60 to correctly move with the trajectory of the rotor shaft 13 around the central axis of the stator (refer to B in FIGS. 4 and 5). Therefore, the lip seal 60 can prevent the pumped material from overflowing from the gap between the rotor and the support ring 54.

In this example, there is a second sealing member. The member includes a lip-shaped seal 62 to fit inside the housing 2 in a squeeze manner. The lip-shaped seal 62 is arranged in a concentric manner around the support ring 54 and is adapted to the following The support ring rotates. The lip seal 62 prevents the pumped material from overflowing from the gap between the support ring 54 and the housing 2.

In order to facilitate the rotational movement of the rotor shaft 13 and the support ring 54, an appropriate bearing is provided in this example. A first double-row ball bearing 52 is fixed inside the support ring 54 adjacent to the lip seal to accommodate the rotation of the rotor shaft 13. Similarly, a second double-row ball bearing 56 is fixed inside the housing 2 to accommodate the rotational movement of the support ring 54. The first and second double row ball bearings 52 and 56 are separated from the suction chamber by the first and second sealing members 60 and 62, respectively.

During pump operation, the rotor shaft 13 is freely rotated in the first sealing member 60 and the first bearing device 52, and the support ring 54 is freely rotated in the second sealing member 62 and the second bearing device 56, so the rotor shaft 13 The trajectory motion is given to the support ring 54 to rotate (see Figure 5a). As a result, the sealing mechanism can accommodate the rotation and trajectory motion of the rotor shaft while isolating the drive shaft from the suction chamber.

Although the description of the third example uses double-row ball bearings, single-row ball bearings or double-row or single-row roller bearings can also be used. In another example (not shown), it is also possible to provide an additional lip seal arranged adjacent to the lip seals 60 and 62 and a channel arranged between the two rows of seals to allow pumping materials in the first One row of seals passes outside and overflows out of the sealing mechanism without touching the second row of seals (the first example illustrated in Figure 2).

Since the pumped material passing through the lip seals 60 and 62 will touch the bearings 52 and 56, it is best to provide a bearing that does not make metal-to-metal contact due to the aforementioned reasons in the third example. Likewise, these bearings do not include any integral seals to prevent material from being retained in the bearings. Any material passing outside the bearing will overflow the pump through the radial slot 30' and not touch the drive shaft.

The inventor understands that arranging the joint of the progressive cavity pump on the outside of the suction chamber may sometimes cause the stator to wear out prematurely, especially in the vicinity of the suction chamber (defined as the "stator inlet" in the subject of this description), and elasticity It's true when Jingzi. Without being restricted by any special principle, it is believed that the premature wear is caused by the excessive radial force applied to the stator by the rotor, especially in the area of the suction chamber 11. Indeed, at the outlet of the pump, the pressure of the material will generate a force that acts on the rotor and causes it to shift to the right, as shown in Figure 4. This force is offset by the relative force generated by the drive shaft on the rotor. Due to the angular relationship between the rotor and the drive shaft, the relative force system has a horizontal force component and a radial force component. The radial component of the relative force results in an increase in the pressure at the rotor/stator interface, especially in the area at the entrance of the stator, which accelerates the wear of the stator.

The importance of the relative force radial component depends on the angle of the drive shaft relative to the longitudinal axis of the rotor and the distance between the stator inlet and the first joint of the drive shaft. Generally speaking, angle and distance combine into a more important radial force component. In order to prevent premature wear of the stator inlet, users are faced with two options. First, usually the previous technical users should make the joint as close as possible to the stator inlet. This solution has the disadvantages discussed below. The second possibility is to provide a long drive shaft to reduce the angular drive shaft/rotor. At the same time, this method can isolate the drive shaft from the suction chamber, but has the disadvantage of increasing the length of the progressive cavity pump.

Refer to Figures 4 and 6, to prevent premature wear on the inlet of a progressive cavity pump with a drive shaft isolated from the suction chamber, it should have a bearing so that the radial component force is absorbed by the pump casing instead of Act on the elastic coating of the stator.

FIG. 4 specifically illustrates that the bearing 70 is arranged between the sealing mechanism and the joint 20. The bearing 70 includes an inner race 72 fixed to the rotor shaft 13, and an outer race 76 continuously contacts the inside of the casing 2. Therefore, the radial component is absorbed by the pump casing 2 instead of the stator inlet, and two races Intermediate balls or rollers 74 will reduce friction. When the rotor moves orbits, the outer race 76 of the bearing 70 will roll against the inner cylindrical surface 3 of the housing to generate a reaction force to offset the radial component force acting on the rotor.

In a best example, the outer race 76 of the bearing may have an elastic covering 78 to compensate for the misalignment between the central axis of the stator (dotted line B) and the central axis of the housing, wherein the bearing 70 will roll or compensate for any housing The slight deformation. The elastic surface can also reduce noise and eliminate the need for lubricants.

Another concept of the present invention is that the progressive cavity pump includes an improved rotor assembly, which is designed to automatically stop rotating when it reaches a predetermined temperature to prevent the temperature from continuing to rise. The rotor assembly is an improvement of the prior art rotor assembly and especially the rotor assembly described in the previous and European Patent Application No. 0255336, and the assembly uses a fusible metal bonding material to establish the gap between the rotor shaft and the rotor components The bonding.

More particularly, the inventors discovered that the problem of fracture of the adhesion between the shaft and the rotor can be avoided by providing a connecting member between the rotor shaft and the rotor, that is, relying on a mechanical coupling (meshing) with the rotor member or the rotor member and the rotor shaft. ) Perform torque transmission. In a preferred example illustrated in FIGS. 2 and 7, the improved rotor assembly includes a rotor member 10, and the rotor member includes a longitudinally extending cylindrical cavity. A rotor shaft 13 includes a first end adjacent to the joint 20 and a second end adjacent to the outlet end of the pump, and has a diameter that is smaller than the diameter of the cavity in which the rotor member is located. The plastic bushing 36 is arranged near the first and second ends of the rotor shaft to prevent the rotor shaft from contacting the rotor member when the connecting member as described below changes from a solid state to a liquid state. The surface of the rotor shaft 13 and the inner wall of the rotor member 10 define a space 38 (see FIG. 7).

FIG. 7 more particularly illustrates that the inner surface of the rotor member 10 and the surface of the rotor shaft 13 include protruding parts and recessed parts that alternate longitudinally with each other. When the space 38 is filled with a suitable material, a connecting member is formed, so that both the rotor member and the rotor shaft and the connecting member are in meshing state. More particularly, the material forming the connecting member is liquefied and injected into the space. When the material is solidified, it becomes a connecting member, and not only by surface bonding as discussed in the introduction of this description, a driving relationship between the rotor shaft 13 and the rotor member 10 will be established.

The predetermined melting temperature of the material forming the connecting member is determined by the nature of the pumped material. In the case of gunpowder, the melting temperature of the material (and connecting components) is about 20°C to 40°C at the maximum pumping temperature (that is, the highest temperature normally reached inside the pump), but it should be lower than the decomposition temperature of the gunpowder. As mentioned above, the emulsification temperature is about 200°C. The maximum pumping temperature of non-detonator-sensitive powder is usually about 80°C, while the maximum pumping temperature of detonator-sensitive powder is about 95°C. The expected melting point is obtained by selecting an alloy suitable for eutectic or close to eutectic. The best alloy for gunpowder is a mixture containing 55.5% bismuth and 44.5% lead and its melting point is 124°C. The alloy system can be obtained from Canadian Metals Limited and its trademark is CERROBASE (No. 5550-1). The alloy also has sufficient creep strength to support the shear stress imposed on the material by the rotor shaft. Its strength is estimated to be about 50 psi when the pump has a 2/3 geometry. Those skilled in this art recognize that other materials with thermally induced structural failure can also be used, but they must have the required creep strength.

If the temperature inside the pump rises as a result of the stagnation operation or the idling of the pump, the temperature of the rotor components will also rise and heat will be transferred to the connecting components. When the material melting point temperature is reached, the connecting member will melt, so the driving relationship between the rotor shaft 13 and the rotor member 10 is terminated. The rotor shaft is free to rotate in the bush 36 without adding any movement to the rotor member, and the rotor member 10 does not generate significant heat. This prevents the gunpowder in the pump from absorbing more heat, thus avoiding possible explosions. The seal 39 located adjacent to the bushing 36 prevents the molten material and the pumped material from overflowing from the space 38.

The inner surface of the rotor component and the surface of the rotor shaft are used as connecting components, that is, the meshing between the rotor shaft and the rotor component. Therefore, the connection between the rotor shaft 13 and the rotor component 10 of the rotor assembly does not need to rely on adhesion, but on a connection. The strength of the connection depends on the creep strength of the material constituting the connection member. The meaning of "creep" is due to Shape change or deformation caused by long-term stress. Although the rotor assembly of the present invention does not exclude the formation of adhesion, it does not completely rely on adhesion.

Regarding the requirements for creep strength, the material constituting the connecting member must have sufficient creep strength for the connecting member to withstand the shear stress imposed on the material by the rotor shaft in normal operation/conditions. As mentioned above, for a pump with a 2/3 geometry, the shear stress imposed by the rotor shaft is about 50 psi and the material must be able to withstand this stress at the pumping temperature. And care must be taken to ensure that the material system can withstand the stress not only at room temperature. Suitable materials with required creep strength and melting point temperature can be selected by those skilled in the art through routine tests. Similarly, the size of the protruding part or the recessed part that enables the connecting member to establish a driving relationship between the rotor shaft and the rotor member depends on the creep strength of the material, and regular tests are required to determine the correct size.

In a preferred embodiment, a rotor shaft with a diameter of 50 mm has teeth about 2.5 mm deep, and the inner surface of the rotor component also has teeth about 2.5 mm deep. The gap between the rotor shaft and the rotor components is about 2mm and the cavity is filled with CERROBASE (No. 5550-1).

It has been noted that in the foregoing example, the connecting member is prone to premature failure when the pump temperature approaches the predetermined melting temperature of its constituent material. When the temperature is lower than the predetermined melting temperature, the material constituting the connecting member is affected by the aforementioned peristalsis. In the example shown in Fig. 7, the peristaltic system may cause the rotor shaft to be unable to mesh with the rotor member. Visible failure usually occurs when the connecting member is broken due to stress, so continuous cracks are formed in the gap area between the rotor shaft and the rotor member. When this happens, the rotor shaft does not have a driving relationship with the rotor member, even when the connecting member material is not completely melted.

In order to eliminate the possibility of premature failure of the connecting member, the normal operating temperature of the pump should be kept below the melting point of the connecting member material for the configuration shown in Figure 7. In the case of the aforementioned pump, the gap between the rotor shaft and the inner surface of the rotor member can basically be maintained at a constant 2mm, and the operating temperature of the pump can be kept below 35°C below the connecting member to eliminate this. problem. This allows the material of the connecting member to have sufficient creep strength to maintain the meshing between the rotor shaft and the rotor member.

However, keeping the operating temperature of the pump lower than the melting point of the connecting member material 35°C will result in delaying the thermal failure of the connecting member.

Fortunately, the design of other connecting components can also reduce and/or eliminate this premature connection component failure. In the examples, the cross-sectional gaps between the rotor shaft and the rotor components are not consistent. In a best example, the maximum gap distance (at any known cross section) is 10% greater than the minimum gap distance. In the best system, the maximum gap distance is 50%, 100%, or even 200% greater than the minimum gap distance.

Using the example of this technology, ordinary geometric shapes can be used to achieve the required gap distance change. For example, a hexagonal rotor shaft inside the dodecagonal shape of the rotor component, as shown in Figure 8, can provide sufficient gap distance change to reduce the potential for premature failure of the connecting component. In FIG. 8, the rotor shaft 13 is arranged inside the rotor member 10 and defines a gap area 38. It should be noted that the thickness of the void region 38 varies from the minimum value 38a to the maximum value 38b.

In this design, the minimum cross-sectional gap distance is 1.5mm, and the maximum cross-sectional gap distance is 5mm, and the gap distance is increased by 233%.

Other configurations are also possible, such as a triangular rotor shaft in a square rotor member; an elliptical rotor shaft in a circular rotor member; a square rotor shaft in a circular rotor member; or an eccentricity in a circular rotor member Round rotor shaft. Other configurations may also include providing gap thickness variations in an irregularly shaped rotor shaft in an irregularly shaped rotor member. The best design is to arrange a 6 to 12 side rotor shaft in the 8 to 14 side rotor components, wherein the number of sides of the rotor shaft is preferably less than the number of sides of the rotor component.

Without being constrained by the principle, it is believed that this method can reduce the chance of premature failure, because this method can eliminate the possibility of equidistant circular paths from the rotor shaft and rotor components. Therefore, any creeping or tearing stress at the thickness of a connecting member material may be reduced by being transferred to the adjacent thicker connecting member material area.

When close to the melting point of the material, the connecting member material "softens" or begins to exhibit low creep strength, the connecting member material begins to become a high-viscosity liquid. However, the meshing between the rotor shaft and the rotor components, in this case, is still maintained by the flow resistance from the high clearance area to the low clearance area. When "flow" occurs, the rotor shaft and the rotor member are kept in mesh-even when the rotor shaft and the rotor member rotate at slightly different relative speeds. In other words, while maintaining a driving connection with the rotor member, the rotor shaft system can rotate relative to the rotor member.

The driving connection is terminated at one point, that is, when the connecting member material has melted into a low-viscosity "fluid" to allow the material to pass from the high-void area to the low-void area without driving the rotor member.

The effect referred to here is a "viscosity wedging effect", which describes the meshing situation caused by the flow resistance from the high void area to the low void area.

It should be noted that the "viscosity wedging effect" that has not been developed in the design of Figure 7 is due to the fact that the gap area between the rotor shaft and the rotor components remains the same at 2mm. The material remaining in the 2.5mm deep teeth of the rotor shaft and the rotor components is not affected by this "viscosity wedging effect". Because of the low creep strength caused by temperature, the material in the teeth does not need to flow. .

When adopting this design modification, the connecting component system can choose the one whose melting point temperature is higher than the normal maximum pump temperature by 20°C, and preferably higher than 15°C. With this design, when the pump is over-temperature, it can more quickly respond to the failure of the thermal conduction structure of the connecting member.

It should be noted that the maximum cross-sectional size of the rotor shaft must be smaller than the minimum cross-sectional size inside the rotor component to prevent the rotor shaft from impacting the rotor component when the thermal conduction structure of the connecting component fails.

Once the connecting member is melted, the remaining pump pressure acting on the surface of the rotor at the pump outlet can cause the rotor member 10 to make a longitudinal displacement relative to the rotor shaft 13. If such displacement occurs, the friction force generated by the tip of the rotor shaft against the bottom of the cavity of the rotor member receiving the rotor shaft can generate enough friction to cause the rotor member to rotate. In order to prevent the longitudinal displacement of the rotor component and the unintended driving combination result, a hard ball 40 should be arranged in the cavity of the rotor component, and its position should be between the rotor component and the second end of the rotor shaft (see Figure 2). If the connecting member melts, the ball can prevent the rotor member from longitudinal displacement to reduce the friction generated by the second end of the rotor shaft, and also enable the rotor shaft 13 to rotate freely in the rotor member. In a preferred embodiment, the end of the rotor shaft 13 may have a hard insert 42 to prevent the shaft from wearing in the contact area of the rotor shaft ball 40. Other devices, such as a thrust bearing located between the rotor member 10 and the joint 20 or between the rotor member 10 and the first end of the rotor shaft, can also be used for the same reference.

If necessary, the pump can be equipped with a sensor device, which can cause the motor to stop rotating when the rotor member is separated.

The foregoing description of a best example shall not be interpreted as any limitation, because modifications and improvements can be made within the spirit and scope of the present invention. The scope of the present invention is defined in the attached patent application scope and its equivalent documents.