JP2011001955A - Device including gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear pump device capable of preventing a tooth flank from being worn due to polishing particulates contained in a fused substance in the application of use for extruding the polishing polymer fused substance.SOLUTION: This device including the gear pump is constituted by arranging a coupling unit 22 for compensating eccentricity between a driving unit 7 and individual shaft 2, 3 between each gear 11, 12 and the driving unit 7 and arranging a rotary encoder and sensor units 24, 25 between the center of the gear and the center of individual driving unit.

Description

  The invention relates to a device according to the preamble of claim 1.

  A gear pump consists of two intermeshing gears attached to a shaft, generally with one shaft coupled to the drive unit. The shaft that is not driven by the drive unit is driven by transmission of torque from the driven shaft through the tooth surface.

  Excessive contact pressure due to torque transmission often causes wear problems on the tooth surfaces. That is, the pressure load generated by the differential pressure needs to be transmitted from the driven shaft to the driven shaft via the tooth surface, while the friction needs to be overcome on the other side. Tooth surfaces by ablation or wear (pitting, microwelding, ablation), especially in the production of polymers in large polymerization facilities or in the formulation of plastics with a very high back pressure and high throughput at high temperatures, ie at high overall torque May cause damage.

  In order to avoid these damages, two shaft drives have already been used, for which the propulsion is carried out by one drive unit (motor) and then the force is transferred to two gears by means of a mechanical transmission box. Distributed to the pump shaft.

  Furthermore, a gear pump is known from Swiss Pat. No. 659290, in which the two shafts are driven by respective drive units. Each of the two gears draws the required driving force from the associated drive unit. Only a relatively small amount of power is transmitted between the two gears.

  A gear pump is known from EP 0 886 068, in which also two drive units are provided for individually driving the shafts, the phase and angular speed of the meshed gears being meshed. The gear teeth are adjusted so that lifting of the tooth surfaces is avoided and excessive torque on the meshing gear teeth is avoided.

  In known gear pumps, it has been found that wear can be severe, especially when conveying abrasive media.

  Especially in highly filled abrasive polymer melt extrusion applications, abrasive particles contained in the melt are rubbed between the tooth surfaces, which can cause significant tooth wear problems due to ablation, As a result, the problem of premature failure of the gear shaft occurs. This can cause damage and ablation of the tooth surface. Furthermore, the addition of the filler material increases the viscosity of the melt, which increases the required torque of the entire pump or individual shafts and may exceed the allowable contact pressure on the tooth surface. Become.

Swiss patent No. 659290 European Patent No. 0886068

  The object of the present invention is therefore to provide a device with a gear pump, which achieves an improvement with respect to at least one of the aforementioned drawbacks.

  This object is achieved by the features described in the characterizing part of claim 1. Preferred embodiments are set forth in the other claims.

  The invention further relates to a device having a gear pump having a pump housing, two intermeshing gears housed in the pump housing, and two shafts operatively coupled to the gear and penetrating through the pump housing. Each of the two shafts is operably coupled to an individual drive unit. According to the present invention, the connecting unit for compensating for the eccentricity between the drive unit and the individual shafts is arranged between each gear and the drive unit, and the rotary encoder and the sensor unit are arranged between the center of the gear and each of the gears. It is arrange | positioned between the center of the drive device of this.

  In one embodiment of the device according to the invention, the rotary encoder and the sensor unit are offset on both sides by at most 10% of the distance between the center of the gear and the center of the drive device, between the center of the gear and the center of the drive device. Are arranged in the axial region defined by

  Another embodiment of the device according to the invention is characterized in that the rotary encoder and the sensor unit are each arranged in the middle between the respective center of the gear and the respective center of the drive device.

  Another embodiment of the device according to the invention is that the rotary encoder and the sensor unit are radial to the axis of rotation of the individual shafts that are larger than the outer radius of the gear, preferably at least twice the outer radius of the gear. It has a distance.

  Another embodiment of the device according to the invention is characterized in that the rotary encoder and sensor unit are optical or magnetic rotary encoders and sensor units.

  Another embodiment of the device according to the invention is that the rotary encoder and the sensor unit extend through the corresponding rotary encoder and sensor unit and the connecting line extending perpendicularly from the shaft has two rotational axes on the suction side. An angle of 35 ° to 55 °, preferably 40 ° to 50 °, preferably 45 ° is formed in combination with a plane extending in the middle between the two.

  Another embodiment of the device according to the invention is characterized in that each drive unit has a rotor and a stator, the rotor being axially movable relative to the stator.

  Another embodiment of the device according to the invention is characterized in that the drive unit has a differential bearing unit that radially supports the rotor of the drive unit on the side remote from the gear pump.

  Another embodiment of the device according to the invention is characterized in that the rotor of the drive unit is coupled to the individual shafts of the gear pump via a coupling unit.

  Another embodiment of the device according to the invention is characterized in that the coupling unit is a membrane coupling.

  In another embodiment of the device according to the invention, flanges are arranged between the pump housing and the stators of the individual drive units, the flanges having holes, the coolant being connected to the temperature It is characterized in that it circulates to adjust.

  Another embodiment of the device according to the invention is characterized in that the drive unit can be coupled to the individual shafts of the gear pump from the side remote from the gear pump.

  Another embodiment of the device according to the invention is characterized in that the coupling between the drive unit and the individual shafts of the gear pump is a conical polygonal coupling.

  Another embodiment of the device according to the invention is characterized in that the drive unit is of the torque motor type.

  In another embodiment of the device according to the invention, one drive unit, the gear pump and the other drive unit are each housed in a temperature zone whose temperature can be adjusted to a predetermined value, preferably adjacent An isolation region is provided between the temperature zones that meet each other.

  Another embodiment of the device according to the invention is such that the current position of one gear can be determined with respect to the current position of the other gear, and the current position of one gear is determined according to a specified predetermined operating condition. The present position of the gears can be continuously adjusted.

  Another embodiment of the device according to the invention allows the determination of the current position of one gear relative to the current position of the other gear to be determined before normal operation of the gear pump or during interruption of normal operation of the gear pump. It can be adjusted via a reference value.

  Another embodiment of the device according to the invention is characterized in that the reference value is in the middle between the tooth surfaces of the gear tooth space, preferably in the middle of the tooth surface of the gear tooth space.

Another embodiment of the device according to the invention is characterized in that the reference value can be determined as follows. That is,
One gear can be driven by the other gear with a predetermined torque,
A first angular difference can be determined by calculating the difference between the values measured by the rotary encoder and the sensor unit;
The other gear can be driven by one gear with a predetermined torque,
A second angular difference can be determined by calculating the difference between the values measured by the rotary encoder and the sensor unit;
The difference between the first angular difference and the second angular difference can be determined;
A reference value can be specified in the determined range of differences.

  Thus, an apparatus having a gear pump that can be automatically calibrated is provided. The device can perform this calibration before the start of operation and during a maintenance interruption without any other action by the operator. According to this apparatus, the difference between the first angle difference and the second angle difference also changes or increases, so that possible wear of the tooth surface can be detected. Thus, excessive wear can be detected simply when the threshold is exceeded.

Another embodiment of the device according to the invention is characterized in that at least one of the following current values can be monitored:
The first angular difference,
The difference between the first angle difference and the reference value,
The second angular difference,
The difference between the second angle difference and the reference value,
Also, if at least one of the current values is below or above a predetermined value, at least one of the following actions can be performed:
-Visual warning,
-Visual indication,
-Sound warning,
-Changes in gear pump operating conditions.

  Another embodiment of the device according to the invention allows rotary encoders and sensor units to be used for the determination of the current position of one gear and the other gear, each rotary encoder and sensor unit being an individual gear. It is characterized in that it is arranged in the center between the teeth of the motor and the rotor of the individual drive unit.

  The central arrangement of the rotary encoder and sensor unit has the advantage that the influence of the existing twist angle due to the non-ideal stiffness of the entire drive train on the measurement error of the system is reduced. The measurement error is halved by the central arrangement.

  Another embodiment of the device according to the invention is characterized in that a given gear lash can be adjusted between two intermeshing gears.

  Another embodiment of the device according to the invention is such that the tooth of the tooth meshing in the tooth gap contacts the following tooth surface in the direction of rotation of one gear and the tooth surface of the other gear in rotation. It is characterized in that the tooth surface of the tooth meshing with the gap of the other side contacts the subsequent tooth surface in the rotational direction of one gear in the rotational direction of the other gear.

  This operating condition is also referred to as tooth surface switching because the tooth surfaces in contact with each other change during the extrusion process.

  Another embodiment of the device according to the invention is characterized in that one gear drives the other gear with a predetermined torque, the predetermined torque being greater than half of the total torque produced by both drive devices. .

  Accurate torque setting can be performed by appropriately controlling the relative rotation speed or the current position of the gears. Thus, the tooth surfaces transmit any adjustable torque, but the tooth surfaces will not lift from each other during operation if the prescribed tooth surface sealing is always performed.

  Another embodiment of the device according to the invention is such that the rotational speed of the shaft driven by the drive unit is adjusted synchronously so that the pressure of the conveyed medium is substantially constant on the discharge side of the gear pump. It is characterized by being able to.

  A related advantage is that there are no disturbing pulsations on the discharge side of the gear pump that are reflected in the quality of the extrudate.

  Another embodiment of the device according to the invention is characterized in that the pressure of the conveyed medium can be measured on the discharge side of the gear pump and the rotational speed can be adjusted according to the measured pressure of the medium. .

  Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments of the present invention.

FIG. 2 shows a known arrangement with one gear pump and one drive unit. 5 is a cross-sectional view of an arrangement according to the invention with a gear pump and a drive unit, seen along line AA shown in FIG. Figure 2 is a schematic view of an arrangement according to the invention with information in temperature zones. It is a figure which shows the position of the rotary encoder and sensor unit for determining the present position of a gearwheel. It is a cross-sectional view perpendicular to the axis of rotation of the shaft in the region of the gear for illustrating the first operating condition. It is a cross-sectional view perpendicular to the axis of rotation of the shaft in the region of the gear for illustrating the second operating condition. FIG. 6 is a cross-sectional view perpendicular to the axis of rotation of the shaft in the region of the gears for illustrating a third operating condition. It is a cross-sectional view perpendicular to the axis of rotation of the shaft in the region of the gear for illustrating the fourth operating condition. It is a graph which shows the rotational speed curve, pressure curve, and torque curve regarding time.

  FIG. 1 shows a known device having a gear pump 1, which transports a medium F that is transported from a suction side S to a discharge side D. FIG. 1 shows a pump housing 10 with two shafts 2 and 3 extending outwardly through the pump housing 10. The shaft 3 extending outward is connected to the drive unit 7 via a first universal joint 4, a shaft segment 6 of adjustable length, and a second universal joint 5. Thus, the outwardly extending shaft 2 is also connected to another drive unit (not shown in FIG. 1) via corresponding first and second universal joints and corresponding shaft segments. . That is, each gear (not shown in FIG. 1) is driven by its own drive unit.

  A double universal joint consisting of a first universal joint 4 and a second universal joint 5 in cooperation with an adjustable shaft segment 6 provides a lateral and angular deviation of the drive unit relative to the shaft 2 or 3. It is provided for. Due to the double universal joint cooperating with the adjustable shaft segment 6, an additional bearing force acts on the shaft bearing housed in the pump housing 10. This additional supporting force is generated by the double universal joint and the own weight of the shaft segment 6. Since the distance between the pump bearings arranged in the pump housing 10 for supporting the shafts 2 and 3 relative to the length of the double universal joint is relatively short, the additional supporting force is considerably increased.

  FIG. 2 shows a cross-sectional view of a device according to the invention with a gear pump 1, in which the cutting plane is according to the cutting plane AA shown in FIG. 14 through the sensor 25. For the sake of clarity, FIG. 2 shows only half of the gear pump 1. Thus, only one drive unit 7 is shown. The drive unit 7 is pressed against the pump housing 10 or the cover of the pump housing 10 directly via the flange 15, that is, without the intermediate gear device. The rotating portions of the drive unit 1 such as the hub 16, the membrane coupling 22, and the rotor 18 are coupled to the shaft 3 of the gear pump 1 through screws 21. If necessary, the screw 21 can be loosened, whereby the drive unit 7 itself can be removed from the gear pump 1. After loosening the screw 40 that joins the flange 15 to the pump housing 10 or the pump housing cover and loosening the screw 21, the entire drive unit 7 can be removed from the gear pump 1. The shafts 2, 3 and the bearing unit of the gear pump 1 remain in the gear pump 1 and can be disassembled individually.

  In addition to the flange 15 and the hub 16, the drive unit 7 further includes a rotor 18, a stator 17, and a drive device cover 19 having an opening 20. The drive device cover 19 closes the drive unit 7 on the side far from the gear pump 1 and is connected to the stator 17, and the opening 20 is arranged on the extension of the rotation axis 13 of the shaft 3 so as to be centered. Has been. On the side closer to the gear pump 1, the stator 17 is coupled to the flange 15.

  As already mentioned, the gear pump 1 is coupled to the drive unit 7 directly, i.e. without an intermediate gear device. For this purpose, a screw 21 is provided, and the rotor 18 is fixed in the axial direction via the hub 16 and the flange 15 by this screw 21. When the drive unit 7 is assembled to the gear pump 1, the screw 21 is passed through the opening 20 of the drive unit 7 along the rotation axis 13 of the shaft 3 and is tightened in a corresponding hole provided in the shaft 3. Thereby, the hub 16 is connected to the shaft 3 via a so-called conical polygonal connection, which allows a precise alignment of the rotor 18 with the shaft 3, the rotor 18, the drive unit 7, A very twist-free connection with the driven shaft 3 of the gear pump 1 is possible.

  By comparing the prior art device according to FIG. 1 with the device according to the invention according to FIG. 2, the device according to the invention is very short by comparison, and the anti-twisting connection due to the short rotary shaft connection between the rotor 18 and the gear 11. It is already clear that This is particularly important in connection with the method according to the invention which is further described below.

  Like the double universal joint shown in FIG. 1, the device according to FIG. 2 also requires angular and lateral compensation, so that the membrane coupling on the gear pump side of the rotor 18 for angular compensation. 22 and the stator 17 and the rotor 18 are configured such that the rotor 18 can be moved axially relative to the stator 17 to allow lateral compensation.

  For example, as is apparent from FIG. 2, it is conceivable that the membrane coupling 22 and the hub 16 are a single part, in which case the only member is connected to the shaft 3 in the left half on the drive side. In the right half, this only member has a thin wall and acts as a membrane coupling.

  In addition to the aforementioned support of the rotor 18 to the stator 17 on the side of the gear pump 1 by means of the flange 15 and the hub 16 via the conical polygon coupling and the screw 21, a differential bearing unit 23 on the side far from the gear pump 1. The differential bearing unit 23 holds the rotor in a radial direction at a predetermined position with respect to the stator 17.

  The eccentricity of the rotation axis 13 of the shaft 3 relative to the rotation axis of the differential bearing 23 due to manufacturing tolerances can be compensated by the membrane coupling 22. In practice, the eccentricity due to manufacturing tolerances causes an additional load on the gear pump bearing, but the result is that the distance of the membrane coupling 22 to the bearing receiving the load is short and only moderate angular orientation compensation can be performed. The resulting moment response remains in a relatively narrow range.

  For example, a so-called torque motor is used as the drive unit 7, and this torque motor is a multi-pole, permanently excited, with a hollow rotor shaft for direct connection to the gear pump 1 described above. It is a three-phase synchronous motor. Torque motors are especially characterized by a short and compact design and low skew slackness (high torsional rigidity).

  As will become apparent from the following description of the operation of the device with the gear pump 1, accurate information regarding the current position of one gear relative to the other gear is important. At the same time, a direct and unbiased influence of the drive unit on the gears of the gear pump is required. One criterion is the already mentioned low slack (high rigidity) between the drive unit and the driven gear. Another criterion is the most accurate measurement of the current position of one gear relative to the current position of the other gear.

  In the embodiment shown in FIG. 2, this is achieved by the fact that a rotary encoder 24 that interacts with a sensor unit 25 coupled to the stator 17 is located at the periphery of the hub 16. For example, a grid pattern is provided on the hub 16, and this grid pattern can be read by the sensor unit 25. Instead of such an optical measuring device, a corresponding magnetic measuring device or another method for determining the position can be used.

  In order to minimize the possibility of measurement errors due to eccentricity between the rotary encoder 24 and the gear teeth, the diameter of the rotary encoder 24 is made as large as possible. The eccentricity of the rotary encoder 24 itself is reduced to a minimum by incorporating a receiving portion for the rotary encoder 24 in the hub 16. Because the hub 16 is formed as a single piece, extremely small manufacturing tolerances can be maintained for the receiving portion for the rotary encoder 24.

  The positions of the rotary encoder 24 and the sensor unit 25 are preferably selected between the middle of the rotor 18 and the stator 17 and the middle of the driven gear 11 of the gear pump. For uniform stiffness distribution over the drive train (ie between the center of the rotor 18 and stator 17 and the center of the driven gear 11 of the gear pump 1), the rotary encoder 24 is preferably connected to the rotor 18 and stator. It is arranged in the middle between the center of 17 and the center of the driven gear 11 of the gear pump 1.

  One possible area of use of a device with a gear pump is the pressure increase downstream of the extruder in the transport of plastic melt in the extrusion line. In these uses, the polymer melt is conveyed at a temperature of 300 ° C. against high discharge pressures (eg 300 bar). For this, a high driving force and a high torque with it are required. Thus, gear pumps and pump housings are heated to a temperature of, for example, 300 ° C. by the conveyed medium, whereas the temperatures of the drive units 7 and 8 are especially for the electronic circuits used with these drive units. Should not exceed 60 ° C. To illustrate these situations, FIG. 3 shows a device with a gear pump according to the invention, in which the gear pump 1 and the two laterally arranged drive units 7 and 8 are simply Shown as a block. The individual components are housed in temperature zones 32, 33 and 34 which must have an allowed or required temperature value according to the previous description. That is, the gear pump 1 is accommodated in the temperature zone 33 that is operated at the temperature of the medium to be conveyed, for example, 300 ° C. On the drive side, drive units 7 and 8 are provided in temperature zones 32 and 34, respectively, and the maximum value of these temperature zones is not allowed to exceed 60 ° C. for proper operation. This device requires that an electrical member be placed in the immediate vicinity of the gear pump 1. Since the gear pump is heated to 300 ° C., insulating isolation walls 30 and 31 are required which are provided between temperature zones 32 and 33 and between temperature zones 33 and 34, respectively. In addition to the isolation walls 30 and 31, other means are required as needed so that the temperatures in the cold zones 32 and 34 do not reach unacceptable values. For example, an additional means is to provide an active cooling system (eg, an active water cooling system).

  It is also conceivable to protect the rotor 18 (FIG. 2) from overheating by inserting cooling of the flange 15 between the hub 16 and the gear pump 1. In this case, the cooling is provided, for example, as a star-shaped hole provided in the flange. As a result, turbulent flow with high deflection is generated, so that very good cooling characteristics are achieved. The hub is cooled across the flange sides by radiation and forced convection.

  FIG. 4 shows a possible arrangement of the sensor unit 25 used to determine the current position of one gear relative to the other gear, and a cross section perpendicular to the rotational axes 14 and 13 of the shafts 2 and 3. Is shown. The conveyed medium is sent from the suction side S to the discharge side D in the direction of the arrow. As a result, a force component is generated in the directions of the arrows P and P ′, and this force component acts on the bearing of the shaft of the gear pump, causing a slight displacement of the shafts 2 and 3 (FIG. 2).

  In order to compensate for the eccentricity caused by this deviation, the sensor unit 25 is now arranged in the direction of deviation, i.e. in the direction of deflection of the shaft. The mounting is done for example at 45 ° and is therefore the average of the possible deflection angles depending on the differential pressure and viscosity. In the case of insufficient accuracy caused by shaft deflection and deflection, the sensor unit 25 can be arranged, for example, depending on the gear width and backlash value.

  Based on FIGS. 5 to 9, various different operating conditions that can be defined as a predetermined procedure for the operation of a device having a gear pump are described below.

  FIG. 5 shows a cross section perpendicular to the rotational axes 13 and 14 in the region of the gears 11 and 12. The medium F to be conveyed is picked up by the tooth gap on the suction side S, and then conveyed to the discharge side D along the pump housing, and the medium F is pushed out by the meshed gears 11 and 12 on the discharge side D.

  During operation of the gear pump, a "trapped volume" is formed in the area of engagement between the tooth bottom and end face surfaces that are sealed by tooth surfaces that are almost in contact with each other before and after this volume. ing. However, for fluid purposes, flow gaps can be created particularly where a large flow gap is desired for tribological reasons (optimal gap width with respect to the relative speed of the tooth surface). The ratio of these two sealing gaps can be actively controlled by the existing position control of the shaft. Once the gap moving ahead of the “captured volume” can be minimized, the subsequent gap of the “captured volume” can be minimized. That is, it is possible to actively influence the extrusion process from this “trapped volume”, thereby optimizing the flow uniformity.

In order to adjust the various operating conditions and conditions of the device according to the invention, the current position of one gear 11 relative to the current position of the other gear 12 must be known. This information constitutes the actual initial conditions necessary for further adjustment of the gears relative to each other. One possibility to determine this information consists of performing the following process steps that make up the calibration:
In the first step, the first shaft 2 drives the second shaft 3 with a predetermined torque. Thereby, the first absolute rotation angle difference determines the difference between the measured value of one sensor unit 25 and the measured value of the other sensor unit 25 ′, thereby the sensor units 25 (see FIG. 2) determined by the aforementioned rotary encoder 24 in cooperation with.

  In the second step, the second shaft 3 drives the first shaft 2 with the same predetermined torque as in the first step. Thereby, the second absolute rotation angle difference again determines the difference between the measured value of one sensor unit 25 and the measured value of the other sensor unit 25 ', so that the sensor units 25 in the respective axes 2 and 3 again. Determined by the aforementioned rotary encoder 24 cooperating with (FIG. 2).

  In the third step, the difference between the first absolute rotation difference and the second absolute rotation difference is determined. If the predetermined torque used in the first and second steps for measurement is not exceeded, this difference is the actual range in which the gears can move relative to each other. In this range, a reference value can now be specified and the current position of the gear relative to this reference value is indicated. The reference value is then the origin of the defined coordinate system. For example, the reference value is in the middle between the tooth surfaces of the tooth gap so that the absolute value of the maximum displacement is the same.

  For the operating conditions described with reference to FIG. 5, a constant force FO is transmitted between the gears 11 and 12, as shown in the detailed diagram X on the right side of FIG.

  Thus, the operating conditions can now be selected after designation of the reference point in the first setting so that the gear transmits half of the total torque plus a defined percentage. Thus, the other gear then transmits half of the total torque minus a predetermined percentage.

  In these operating conditions, a defined sealing between the tooth surfaces can be achieved. The application area of these operating conditions is intended for the transport of low viscosity fluids that require a sealing action between the tooth surfaces in order to achieve a sufficient sealing between the discharge side D and the suction side S.

  Another setting is that the gear lash between the tooth surfaces of the two meshing gears is selected as the operating condition. That is, for example, in a 10% step, from the contact of the tooth surface (without gear lash), the tooth surface is re-established via central alignment (ie, the tooth meshed with the tooth groove is located in the middle of the tooth groove). Until they contact each other, this time the tooth surfaces belong to the delayed tooth surface.

  FIG. 6 shows again the operating conditions described above in a section perpendicular to the rotational axes 13 and 14 in the region of the gears 11 and 12. Here again, the section X in the region of the meshed gears 11 and 12 is shown enlarged and in detail, and the preset gear lash 26 is emphasized.

  This operating condition is selected when the medium F to be conveyed has a medium viscosity. Depending on the setting of the gear lash 26, the extrusion pressure can preferably be set equal to the pressure on the discharge side D. Excessive gear lash 26 leading to an extrusion pressure smaller than the pressure on the discharge side D has to be avoided because an insufficient sealing effect is obtained between the discharge side D and the suction side S. Operating conditions in which a certain size of gear lash 26 is present (ie, there is no tooth contact) are performed using a gear corrosion resistant (and often flexible) coating without causing damage due to ablation. Can.

  Another setting is that a mode for switching the tooth surface is proposed as an operating condition. This causes the gear to change the tooth surface during the theoretical roll-off of the tooth in the line of action. Extrusion pressure discharge always takes place towards the suction side S.

A mode with tooth surface switching will be described with reference to FIG. 7, which again shows a cross section perpendicular to the rotational axes 13, 14 in the region of the gears 11, 12. On the left side of FIG. 7, the state where the tooth Z ₁ ′ of the gear 11 is engaged with the tooth groove of the gear 12 and is in contact with the tooth Z ₁ is shown. On the right side of FIG. 7, a state is shown in which the tooth Z ₂ of the gear 12 is engaged with the tooth groove of the gear 11 and is in contact with the tooth Z ₁ ′. Thereby, the switching of the tooth surface is performed during this time.

The mode in which the tooth surface is switched provides at least one of the following advantages:
-Minimization of pulsation due to extrusion pressure by discharge of extrusion pressure to suction side S-Minimization of applied torque by minimization of extrusion pressure energy-Reduction of temperature rise by minimization of extrusion pressure energy The operating conditions in the mode in which the switching takes place apply, for example, to very viscous media where the extrusion pressure is high and so a very large torque is required to generate the extrusion pressure energy. This is because extrusion pressure energy means a pure loss from an energy point of view.

  The extrusion operation can be varied in particular using the flexibility of the electronic control system, depending on the properties of the pumped medium, ie the fluidity or solid loading of the polymer being transported. In this way, an optimal velocity distribution can be assigned to each polymer type.

  With reference to FIG. 8, another aspect of the method according to the invention is described. For example, from the application of the step for calibration, the current position of one gear 11 with respect to the current position of the other gear 12 is known, and the maximum backlash for the current position of one gear 11 with respect to the current position of the other gear 12. Knowing the (difference between the first absolute rotation difference and the second absolute rotation difference) can explain the wear of the gears 11 and 12. For example, this is the case when the maximum backlash for a certain torque transmitted from one gear 11, 12 to the other gear 12, 11 changes. For example, if the backlash is increased beyond a predetermined maximum threshold, this is interpreted that the gear and / or the shaft with the gear must be replaced immediately. For example, a system failure must be predicted immediately. In other words, in the case of the gear pump set according to the left half of FIG. 8 which always pushes out to the suction side, if the maximum allowable wear (ie the maximum allowable backlash on one side starting from the reference value) is exceeded, the operating conditions are Adapted automatically, or after the corresponding manual intervention of the supervisor. Thereby, the adaptation of the operating conditions can then take place so that the required sealing is transmitted to the other tooth surface. According to the right half of FIG. 8, this is the tooth surface on the advancing side of the teeth that mesh with the tooth gap.

  In the case of finding wear, the current position of one gear relative to the current position of the other gear may be changed so that the optimum operating conditions originally desired are maintained. For example, the tooth surface may be lifted due to wear. A corresponding modification to restore the desired operating condition is to change the current position of one gear relative to the current position of the other gear so that the tooth surfaces re-contact each other in the desired manner and the desired backlash is obtained again. Is to change.

  Wear monitoring is such that a audible and / or visual warning is provided to the supervisor so that if a predetermined wear is found, a warning can be given in advance to avoid failure of the pump system. It can also be used. It is conceivable that a replacement shaft or gear will be ordered from the manufacturer early enough so that the alarm is activated so that the necessary spare parts are prepared in the field before a pump system failure occurs.

  In some extrusion systems where a gear pump is used, pressure fluctuations due to the extrusion process of the remaining volume between the gears are hindered. These pressure fluctuations, also called pulsations, cause irregularities in the product produced by extrusion. For this reason, various means have been proposed to reduce pressure fluctuations. Helical gears or helical gears are used, both of which have system-related drawbacks.

  According to the invention, pressure fluctuations are eliminated or at least significantly reduced by actively affecting the rotational speed of the two gear shafts.

  The apparatus according to the invention and the method according to the invention can change the course of the rotational speed for each extrusion process so that the pressure on the discharge side is in a narrow range or the pressure on the discharge side is constant. . That is, the extrusion process of the conveyed medium is controlled from the bottom of the tooth, in particular via the current value of one gear relative to the current position of the other gear.

  It turns out that it is generally generally desirable that pressure fluctuations can be completely eliminated. However, in certain applications, certain pressure fluctuations may be desirable to obtain adequate fluctuations in the extrudate thickness. The method according to the invention thus opens up new manufacturability in the field of extrusion, in particular with regard to the device according to the invention with a gear pump.

  In order to achieve simple and simultaneous complete elimination of pressure fluctuations, a contact ratio of 1 must be chosen. When a contact ratio of 1 is chosen, only one pair of teeth is engaged in displacement, ie extrusion (see Vogel Fachbuch Jarosia and Monika Ivantysyn: "Hydrostatische Pumpen und Motoren", 1993, p. 319). ). In this case, a sinusoidal curve is obtained due to the displacement volume flow. Using a sinusoidal compensation table (eg a so-called “reference” table), the sinusoidal curve can be easily and efficiently corrected.

  FIG. 9 shows a rotation speed curve 90 of the gear pump shaft, a pressure curve 91 of the pressure on the discharge side of the gear pump, and a torque curve 92 of the torque of the gear pump shaft. The rotational speed curve 90, the pressure curve 91, and the torque curve 92 are plotted with respect to time. The rotational speed of the gear pump shaft is adjusted with respect to time such that the pressure on the discharge side of the gear pump is constant or at least within a predetermined tolerance range. The rotational speed curve 90 shown in FIG. 9 has a periodicity of a period T. This period T is a period in which engagement with the corresponding groove occurs. Here, if the rotational speeds of both shafts are controlled synchronously according to the rotational speed curve 90, the pulsation can be completely compensated.

  It is pointed out that pulsation compensation can be combined with all operating conditions or specifications outlined in this specification.

  Due to the periodicity, the rotation speed curve 90 can be stored in the storage unit (reference table). The value for the rotational speed to be set is then read in a given cycle, and a predetermined cycle occurs on the discharge side with the pressure to be set.

  Alternatively, it is also possible to use the rotational speed based on the measured pressure in order to measure the discharge side pressure with a pressure sensor and set the rotational speed. This so-called on-line pressure setting operation is actually expensive to perform, but other applications are possible to realize a specific manufacturing process in the field of extrusion.

  A specific operation of position control, as described above, to avoid or reduce pressure pulsations on the discharge side of the gear pump is used to reduce the total shear load for shear sensitive materials You can also. For this reason, care is taken when determining the rotational speed curve so as not to exceed the maximum shear stress.

  The present invention makes it possible for the first time to have a specific influence on the effect of pulsation, extrusion pressure and tribological behavior. Depending on the settings, all effects that are important in a particular case can be taken into account, or individual operating conditions can be taken into account according to priority. This means that the operating conditions should have a greater impact on the overall system operation.

  The advantage of the involute tooth profile normally used for gear pumps is that the speed transmission ratio of the two rotational speeds is constant during one revolution, which is fundamental for constant volume flow. It is a precondition. In contrast, arcuate gear teeth have the disadvantage that the flow of the conveyed medium pulsates because the speed transmission ratio of the rotational speed of the shaft changes periodically. The use of the invention with two controlled drive units makes it possible for the first time to use arc-shaped gear teeth without undesired pulsations of the transported medium flow. In other words, by providing a sufficiently large backlash, the shaft drive speed can be corrected and compensated for using a reverse speed distribution, so an arc with a constant speed transmission ratio and thus a constant volume flow. Shaped gear teeth are possible.

  In addition to the arcuate gear teeth, other tooth shapes are also conceivable. Therefore, only the velocity distribution needs to be adapted.

  1 gear pump, 2, 3 shafts, 4, 5 universal joint, 6 shaft segment, 7 drive unit, 10 pump housing, 11, 12 gears, 13, 14 rotation axis, 15 flange, 16 hub, 17 stator, 18 rotor, 19 drive device cover, 20 opening, 21 screw, 22 membrane coupling, 23 differential bearing unit, 24 rotary encoder, 25 sensor unit, 40 screw, 25, 25 'sensor, 26 gear lash, 30, 31 insulating separation wall, 32 , 33, 34 Temperature zone, S suction side, D discharge side

Claims (16)

  A device having a gear pump (1), wherein the pump housing (10), two meshed gears (11, 12) housed in the pump housing (10), and the gears (11, 12) are operated. And two shafts (2, 3) that are connected to each other and extend through the pump housing (10). The two shafts (2, 3) are connected to the individual drive units (7, 7). 8) in the type operatively coupled to each of the coupling units (22) for compensating for the eccentricity between the drive units (7, 8) and the individual shafts (2, 3). Arranged between the gears (11, 12) and the drive units (7, 8), the rotary encoder and the sensor unit (24, 25) are arranged between the centers of the gears and the individual drive units. Gears characterized by being Apparatus having a pump (1).   The rotary encoder and sensor unit (24, 25) is offset in the center between the center of the gear and the center of the drive unit on both sides at most 10% of the distance between the center of the gear and the center of the drive unit. The apparatus of claim 1, wherein the apparatus is disposed in an axial region defined by   3. The device according to claim 2, wherein the rotary encoder and sensor unit (24, 25) are respectively arranged in the middle between the individual centers of the gears and the individual centers of the drive unit.   The rotary encoder and sensor unit (24, 25) is an individual shaft that is larger than the outer radius of the gear (11, 12), preferably at least twice the outer radius of the gear (11, 12). 4. The device as claimed in claim 1, wherein the device has a radial distance to the rotational axis (13, 14) of (2, 3).   Device according to any one of claims 1 to 4, wherein the rotary encoder and sensor unit (24, 25) is an optical or magnetic rotary encoder and sensor unit.   A connecting line through which the rotary encoder and sensor unit passes through the corresponding rotary encoder and sensor unit (24, 25) and extends perpendicularly from the shaft (2, 3) has two rotational axes (13 , 14) with a centrally extending plane between 35 ° to 55 °, preferably 40 ° to 50 °, preferably 45 °. Item 6. The device according to any one of Items 1 to 5.   Each drive unit (7, 8) has a rotor (18) and a stator (17), the rotor (18) being axially movable relative to the stator (17). The device according to any one of the above.   The drive unit (7, 8) has a differential bearing unit (23) for supporting the rotor (18) of the drive unit (7, 8) in the radial direction on the side farther from the gear pump (1). The apparatus of claim 7.   The rotor (18) of the drive unit (7, 8) is coupled to the individual shafts (2, 3) of the gear pump (1) via the coupling unit (22), so that on the gear side 9. The device as claimed in claim 8, wherein the device supports the rotor (18).   The device according to any one of the preceding claims, wherein the coupling unit (22) is a membrane coupling.   A flange (15) is arranged between the pump housing (10) and the stator (17) of each drive unit (7, 8), and the flange (15) has a hole. 11. The device according to claim 1, wherein a coolant is circulated to adjust the temperature.   11. The drive unit (7, 8) according to any of claims 1 to 10, wherein the drive unit (7, 8) is connectable to an individual shaft (2, 3) of the gear pump (1) from the side remote from the gear pump (1). A device according to claim 1.   Device according to claim 12, wherein the coupling between the drive unit (7, 8) and the individual shafts (2, 3) of the gear pump (1) is a conical polygon coupling.   14. The device according to claim 1, wherein the drive unit is a torque motor type. 15.   One drive unit (7, 8), the gear pump (1), and the other drive unit (8, 7) are each housed in a temperature zone in which the temperature can be adjusted to a predetermined value. The device according to claim 1, wherein an insulating region is provided between adjacent temperature zones.   The current position of one gear (11, 12) is determinable with respect to the current position of the other gear (12, 11), and the current position of one gear (11, 12) is determined according to a specified predetermined operating condition. 16. The device as claimed in claim 1, wherein the device is continuously adjustable with respect to the current position of the other gear (12, 11).

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