EP0620369B1 - Gear pump - Google Patents

Abstract

A gear pump is proposed in which, the rotors (1) being supported in plain bearings (sleeve bearings, journals), the bearing clearance (9) or, if the rotors are axially sealed, a sealing gap (9), respectively, can be adjusted. <IMAGE>

Description

The present invention relates to a gear pump according to the Preamble of claim 1 and a method for rinsing the Seal on such a gear pump according to the preamble of claim 13.

When performing gear pump shafts through the Housing wall, for example for drive purposes, it is indispensable, between the pump delivery chamber on the one hand and On the other hand, to provide a surrounding atmosphere. In the case of gear pump shafts that are not carried out, for example roller bearings, it is in most cases necessary, a seal between the pumping chamber and Rolling bearings to be provided.

It is known to have non-contact seals for these purposes to be provided between the shaft and the stator, with a defined sealing gap, for example labyrinth seals. Such Seal can usually, the usual shaft eccentricity and thus taking into account the usual seal play, only optimally effective from a certain operating point be sealed, for example depending on the pump speed Differential pressure, temperature and the medium to be sealed, especially material to be conveyed.

For example, in known, for the above-mentioned purpose labyrinth seals used variable radial play, depending on the operating pressure and temperature, which the Change the sealing effect.

Is the seal, as with gear pumps in most cases, provided for an axial passage of the material to be conveyed prevent along the shaft, so it can be seen that depending on the material to be extracted and the degradation properties this good has different requirements the formation of the sealing gap between the rotating shaft and stationary stator or housing must be provided. So it is often necessary to use the provided pumps with the same pumps Seals for goods to be conveyed differently interpret what is either the use of different Pumps required for different goods or at least changing sealing parts, such as on the stator side, which defines the sealing play Rifles.

From US-A 4 575 100 a gear pump is known in which the rotor shaft lubricated in a bearing area is slidably mounted. Progressing to the outside, connects the mentioned storage area a displacement fluid-filled Channel system in which the displacement fluid pressure Prevents material from escaping. Using hydraulic oil actuators The flow cross-section in the membrane mentioned channel system for the displacement fluid set. With the membrane areas mentioned, radially aligned in Form of ring surfaces, surface sections are on stator-side sealing surface areas created that with respect to surface sections on the shaft side, in axial Direction relative to each other, hydraulically operated are movable.

Providing one in a duct system hydraulic variable cross-section guided displacement fluid for Sealing against the discharge of conveyed goods is extremely complicated.

Starting from a gear pump of the latter type, is it is an object of the present invention to provide a gear pump create, with the flexible sealing conditions can be changed, and this much easier.

This is done on a gear pump of the type mentioned above their training according to the characterizing part of claim 1 solved.

Problems similar to those of the seals mentioned occur but also on bearings of slide-mounted gear pump rotors on. The functionality of such plain bearings is only in a relatively narrow range of storage temperature and the load capacity of the goods to be conveyed in the warehouse. Both sizes mentioned, i.e. storage temperature and load capacity, but are dependent on the radial bearing play; the bigger the bearing clearance is the lower the one in the bearing gap heat generated by shear and thus storage temperature, each But the bearing capacity is also lower.

With regard to bearings, gear pumps with sliding bearings have also been used up to now for a relatively narrow viscosity range of the conveyed material designed. The pump according to US Pat 575 100 a fixed, medium to be handled Bearing gap. Depending on the goods to be conveyed, a suitably dimensioned one was designed Plain bearings used. Here too are increasing Gear pumps for conveyed goods in a wide range Varying viscosity requires what for processing with one and the same gear pump also with regard to plain bearings is highly problematic. Either is for a low-viscosity Conveyed goods the storage clearance too large and thus the Load capacity is insufficient, or the same bearing clearance is for Highly viscous products too small with the result that the storage temperature is too high.

This is very similar to the sealing problem discussed above stored storage problem is solved on an inventive Gear pump according to the preamble of claim 2 their training according to the characterizing part of this claim solved.

If one further takes into account that, for example, with increasing Pressure, i.e. increasing pump load, on the one hand the Increasing the load capacity of the plain bearing is what, as mentioned a reduction in the bearing clearance was required made, and that at the same time the increased pump load also increases the sealing requirements, which is a decrease of the sealing gap, it can be seen that in certain cases a gear pump according to the wording of claim 4 represents an optimized solution in which a seal gap adjustment at the same time as the bearing clearance adjustment done in the same sense.

The situation is particularly simple if, according to the wording of claim 5, the seal of claim 1 and / or the plain bearing according to claim 2 are in ambient atmosphere, because then an intervention in the axially relatively to be shifted Stator / rotor sections directly from the outside of the pump can be done.

In a second preferred variant, one according to the invention closes Seal on one side, especially on the delivery chamber side, to a roller bearing for the rotor.

To adjust the seal or bearing play, a shaft-side area is shifted axially or a stator-side area. A shaft-side shift of the mentioned sealing or Storage area is by axially moving one another Wave sections possible. In this case, such an axial displacement a shaft part with sealing part e.g. of a Rolling bearings can be added easily.

Preferred embodiments of the invention, see below the aspect of sealing, storage or both specified in the further claims 5 to 12.

In the gear pump according to the wording of claim 10 the storage temperature and / or the differential pressure between The suction and pressure sides of the pump are detected and functioning of one measurement signal or as a function of a combination of both acted on an actuator by which, in the sense of the present invention, the sealing clearance and / or the Camp play be put.

With regard to the seal, there is often a need, especially when sealing against degradable material, the Rinse seal from time to time. This is according to the wording of claim 12 achieved in that practically with a two-point actuator, possibly a continuous one superimposed, the sealing gap by moving of the sealing surfaces is enlarged so that the seal is never more would be guaranteed, but a flow of the Medium against which the seal acts in the sealing position, a flushing of the stator / shaft area provided for sealing makes.

Accordingly, a method according to the invention is in claim 13 specified for flushing the seal on a gear pump, which in addition to the continuous adjustment of the sealing gap can be used or, according to the invention, insulated, that is to say on a seal according to the invention, with an axial relative displacement of the sealing surfaces is intended exclusively for the rinsing process.

The invention is then described, for example, with reference to Figures explained.

Fig. 1

schematisch anhand eines Zahnradpumpen-Wellenausschnittes, das Prinzip der an der erfindungsgemässen Zahnradpumpe realisierten verstellbaren Dichtung bzw. des stellbaren Gleitlagers;

Fig. 2

ausgehend von der Darstellung gemäss Fig. 1, einen axial verstellbaren Wellenabschnitt eines Rotors einer erfindungsgemässen Zahnradpumpe;

Fig. 3

schematisch eine Realisationsform eines axial verstellbaren Dichtungs- oder Lagerbereiches am Stator einer erfindungsgemässen Zahnradpumpe;

Fig. 4

schematisch eine erfindungsgemässe Kombination von Gleitlager und Dichtung gemäss vorliegender Erfindung;

Fig. 5

schematisch eine erfindungsgemässe Dichtung mit Spülvorkehrung;

Fig. 6

anhand eines Signalfluss/Funktionsblockdiagrammes ein erfindungsgemässes Stell-Regelverfahren für Lagerspalt und/oder Dichtspalt.

Show it:

Fig. 1

schematically on the basis of a gear pump shaft section, the principle of the adjustable seal or the adjustable slide bearing realized on the gear pump according to the invention;

Fig. 2

1, an axially adjustable shaft section of a rotor of a gear pump according to the invention;

Fig. 3

schematically a realization of an axially adjustable sealing or bearing area on the stator of a gear pump according to the invention;

Fig. 4

schematically an inventive combination of slide bearing and seal according to the present invention;

Fig. 5

schematically a seal according to the invention with rinsing device;

Fig. 6

on the basis of a signal flow / functional block diagram, an actuating and control method according to the invention for the bearing gap and / or sealing gap.

In Fig. 1 is the one toothed rotor 1 of a gear pump Stator 3 shown schematically in longitudinal section. The rotor 1 comprises a shaft 5 which is mounted on the stator 3. For It is an explanation of the procedure according to the invention for the time being regardless of whether shaft 5 is passed through stator 3 is, e.g. to be coupled to a drive unit or is only pivoted in it. There is an area on shaft 5 5a, which, as shown, is frustoconical is trained. That adjacent to the frustoconical section 5a Section 7a of the stator-side shaft bore 7 is formed in the shape of a truncated cone, the opening angle of the two conical surfaces 5a and 7a are preferably the same. Between the frustoconical surface 5a and the stator side 7a, a gap 9 is defined.

As indicated by the double arrow V, is according to the invention provided that by means of a not shown here Adjustment device axially with respect to the two areas 5a and 7a the axis A of the rotor 1 shifted relative to each other can be. As can be easily seen, it follows thereby the possibility of varying the width of the gap 9. According to the invention, this procedure can be carried out either for one 1 basically designed seal used are and / or for a slide bearing designed according to FIG. 1 the shaft 5 on the stator 3.

As mentioned at the beginning, there is a seal and plain bearing the need, depending on the operating conditions of the gear pump flexibly to vary the gap 9 specifically, according to Fig. 1 is done by the relative displacement V.

It goes without saying that both seals and the taper inclinations, as in dashed lines, also on slide bearing areas shown, inverted with respect to the delivery room can be. While in the implementation as a plain bearing a conical or frustoconical formation of the interacting Bearing surfaces 5a, 7a is necessary, the invention, with seal realization, can also be carried out by exclusively radially aligned, circular surfaces on shaft and stator, the distance between them due to the relative displacement V is changed. Such radially popping Sealing surfaces can be formed, for example, by the end face la of the rotor gear and immediately adjacent stator End face 3a.

1 is a relative axial displacement according to the invention areas 5a and 7a. This can either done by an axially fixed, stator side Surface 7a and an axially displaceable, shaft-side surface 5a or vice versa.

A shaft 5 is shown schematically in FIG which the truncated cone region 5a is designed to be axially displaceable is. For this purpose, the shaft 5 is formed in two parts, with parts 5 'and 5 ", for example the shaft part 5' is fixedly connected to the gear, not shown here. The part 5 "slides axially in a corresponding Bore 11 in part 5 'and is in it, as by means of groove / comb connections 13 rotatably mounted. So that the area 5a with respect to the gear on part 5 'axially, as with V' shown, shifted and therefore with respect to the Stator according to FIG. 1, the truncated cone surface 7a.

3, again schematically, shows the stator 3 with the stator-side frustoconical section 7a. Of the Here, stator 3 basically also comprises two parts 3 ′ and 3 ", the part 3 'of the puncture delivery space, not shown here Are defined. In the stator part that is fixed with respect to the delivery chamber 3 'is axially displaceable a second stator part 3 ", as shown schematically at 15, rotationally fixed, axially displaceable, V ', which part 3 "the frustoconical Surface area 7a of the stator-side shaft bore 7 wearing.

Depending on the axial position of the bearing or sealing area according to the invention is constructively the variant of FIG. 2 or the variant of FIG. 3 simpler.

Designed as a seal according to the invention, the arrangement 1 against a shaft carried out against Surround or can seal, if a rolling bearing is provided shaft 7, e.g. between pump delivery chamber and rolling bearing be provided to prevent material to enter the To prevent rolling bearings.

4 shows an inventive combination of an inventive one Plain bearing and an inventive Seal on one and the same shaft 5 of a gear rotor 1 shown schematically. Following the gear of the rotor 1 is a slide bearing according to the invention with shafts side, frustoconical bearing surface 25a provided with interacting, on the stator side, a truncated cone Storage area 27a. The two bearing surfaces 27a and 25a are movable relative to one another, as represented by V ', by analogy to Fig. 2, the shaft 5 one with the gear connected part 5 'and in this regard axially displaceable 5 "includes.

Axially outwards adjoining the bearing 25a, 27a a seal according to the invention is provided. There the Shaft or the shaft part 5 "a second frustoconical Area 35a, interacting with a stator-side, frustoconical sealing surface 37a. The stator 3 is for the realization of an independent of the bearing 25a, 27a adjustable seal, in analogy to the explanations for Fig. 3, with a stationary part 3 'defining a conveying space trained and in this regard, as shown again with V ", axially displaceable, defining the sealing surface 37a Part 3".

A schematically represented feed element 40, such as a hydraulic one Piston arrangement or a spindle adjusting device, acts axially on the part 5 "of the shaft 5 with respect to the stationary Stator part 3 ', with which the shaft-side bearing surface 25a axial, increasing or reducing bearing gap 29, shifted can be.

Despite the change in the bearing gap 29, the sealing gap 39 remain the same between the sealing surfaces 37a and 35a the feed of the part 5 "also on the axially displaceable Stator part 3 "transferred.

The sealing gap becomes independent of the bearing gap conditions 39 by the further, schematically represented actuating arrangement 41 adjusted, again e.g. through a hydraulic Actuator arrangement or a spindle drive.

Of course, the control ratios can be decisive be simplified that bearing gap 29 and sealing gap 39 can be adjusted synchronously in time and distance by using the 4 provided stator part 3 "also as axially immovable Part is formed.

By choosing the truncated cone angle on the bearing part and the sealing part can be the effectiveness of a common shift of part 5 "on the two columns 29 and 39 preselected will. Are the frustoconical surfaces as shown in trained inclined in the same direction, so takes place both a bearing and a sealing gap enlargement or reduction. Should an inverse bearing gap / sealing gap change be realized, so the truncated cone surfaces designed relative to each other with opposite inclination.

5, again schematically, shows a further embodiment variant shows which seal or bearing area can be adjusted in analogy to FIG. 3 in that a part 3 "of the stator 3 with respect to a stationary stator part 3 'can be moved axially to seal or bearing gap to change. 5 as Seal formed, so are the position signs in Analogous to Fig. 4 used, in addition to the preferred continuous actuating device 43, in analogy to FIG. 4, a step control unit 45 is provided with which a control intervention S mechanically, pneumatically or hydraulically, the sealing gap 39 is expanded in one step is - in the example shown by sliding to the right of the stator part 3 "that a largely unobstructed flushing flow can be done through the sealing gap 39 and that as Pumped medium used by axial grooves 46 or a radial channel 47 can emerge.

In this way it becomes possible, in pump operation, by opening the seal designed according to the invention Rinsing to achieve what is particularly degradable when promoting Conveyed goods are highly advantageous.

6 shows on the basis of a function block / signal flow diagram how, according to the invention, a gear pump, bearing gap and / or sealing gap can be automatically controlled according to the invention. The differential pressure Δp _x between the suction-side pressure p _s and the pressure-side pressure p _{D is} measured on the gear pump 50. Furthermore, the bearing temperature 52 is measured on the slide bearing designed according to the invention, schematically represented by 52, and on the seal 54 designed according to the invention preferably a signal m ˙ that is significant for the leakage through the seal 54. Differential pressure Δ _p , bearing temperature ϑ ₅₂ and possibly leakage indication signal m ˙ are fed to a calculation unit 56, which, in particular as a function of differential pressure and bearing temperature, generates a controlled variable X ₁ for the bearing gap actuator 58, in analogy to the actuator 40 from FIG. 4 and a sealing gap control variable X ₂ for setting a sealing gap actuator 60, in analogy to the actuator 41 from FIG. 4.

The control variables X ₁ and X ₂ calculated on the unit 56 are formed with predeterminable control variables W ₁ and W ₂ to form respective control differences.

Of course, the one and / or other control loop can be omitted if, for example, only bearings or only seals are designed or to be regulated according to the invention. If the sealing gap is to be adjusted synchronously with the bearing gap, a single controlled variable X _{1,2 is} determined, for example, which, optimized, takes into account both the bearing and the sealing gap requirements in function, in particular of the pump differential pressure Δ _p and the bearing temperature.

Claims (13)

1. A gear pump with at least one shaft seal (5a, 7a) which acts between a rotor shaft (5) and stator (3) against axial passing of material to be conveyed, and which has axially extended sealing surfaces placed on the stator side (7a) and on the shaft side (5a) and facing each other, whereby the sealing surfaces (5a, 7a) facing each other have at least in one surface portion (5a, 7a) a radial orientation component, and the shaft region with portion (5a) and the housing region with portion (7a) are axially movable (v) relative to each other, characterized in that the shaft seal is in contact with the material to be conveyed and the axially extended sealing surfaces are axially movable relative to each other by means of the sealing elements that support them, such that for different materials to be conveyed in the pump, sealing gap (9) is adjustable along sealing surfaces (5a, 7a).
2. A gear pump with at least one shaft which is mounted at least on one side on a slide bearing and lubricated inside or outside by the material to be conveyed, and which comprises a bearing surface placed on the stator side (7a) and a bearing surface placed on the shaft side (5a), characterized in that said bearing surfaces placed on the stator side and on the shaft side (7a, 5a) are truncated and the bearing clearance is adjustable by means of axial relative displacement (v) of bearing surfaces (5a, 7a), such that for different materials to be conveyed in the pump, bearing clearance (9) is adjustable along bearing surfaces (5a, 7a).
3. The gear pump according to claim 1, characterized in that the shaft is mounted at least on one side on a slide bearing and lubricated inside or outside by the material to be conveyed and there are provided to that end a bearing surface placed on the shaft side (5a) and a bearing surface placed on the stator side (7a), and in that said bearing surfaces placed on the stator side and on the shaft side are truncated and are axially movable relative to each other such that bearing clearance (9) between said bearing surfaces (7a, 5a) is adjustable and said gear pump can be used to convey different materials.
4. The gear pump according to claim 3, characterized in that the relative displacement of sealing surfaces (5a, 7a) is at the same time the relative displacement of bearing surfaces (5a, 7a).
5. The gear pump according to any of claims 1 to 4, characterized in that seal (5a, 7a) or slide bearing (5a, 7a) is connected on one side to the surrounding atmosphere.
6. The gear pump according to claim 1 or 5, characterized in that the seal acts on one side against a rolling bearing for the shaft.
7. The gear pump according to any of claims 1 to 6, characterized in that a shaft region provided with the sealing surface placed on the shaft side (5a) and/or with the bearing surface placed on the shaft side (5a) is axially movable relative to the gears (1) of the pump.
8. The gear pump according to any of claims 1 to 7, characterized in that a stator region (3") provided with the sealing surface placed on the stator side (7a) and/or with the bearing surface placed on the stator side (7a) is axially movable relative to a gear pump housing.
9. The gear pump according to any of claims 1 to 8, characterized in that between parts that are axially movable relative to each other, on the shaft and the stator with the respective bearing and/or sealing surfaces, there are provided adjusting members for the mutual position.
10. The gear pump according to any of claims 1, 3 to 9, characterized in that there is provided a sensing device which delivers a signal (m ˙) that is univocally assigned to the quantity of product flowing through seal (54), said signal is compared to a theoretical value signal (W₂) and the quantity coming out is regulated by acting upon an adjusting element (60) for the relative axial position of the sealing surfaces.
11. The gear pump according to any of claims 1 to 10, characterized in that there are provided a bearing temperature measuring device (ϑ) and/or a measuring device for differential pressure (Δp) over the pump, and in that depending on the measuring signal or signals an adjusting device (58, 60) is operated for the relative axial position of the regions.
12. The gear pump according to any of claims 1, 3 to 11, characterized in that there is provided an adjusting member (45, 43) which axially widens the sealing surface by a predetermined value in order to free the seal for rinsing.
13. A method for rinsing the seal in a gear pump according to any of claims 1, 3 to 12, characterized in that sealing surfaces (35a, 37a) are moved away from each other by means of the axial displacement such that a product which is prevented by the seal from passing through flows between sealing surfaces (35a, 37a) with a predetermined rinsing flow.

Images