EP0232421B1 - Screw machine - Google Patents

Abstract

PCT No. PCT/SU85/00061 Sec. 371 Date Mar. 20, 1987 Sec. 102(e) Date Mar. 20, 1987 PCT Filed Jul. 22, 1985 PCT Pub. No. WO87/00571 PCT Pub. Date Jan. 29, 1987.The screw machine comprises consecutively mounted screw mechanisms (6, 7 and 8, 9) incorporating coaxially arranged stators (10, 12 and 14, 16) and rotors (11, 13 and 15, 17) disposed therein whose axes are offset with respect to the central axis of the stators (10, 12 and 14, 16) by the amount of eccentricity "e" of the screw mechanisms (6, 7 and 8, 9). The screw mechanisms (6, 7 and 8, 9) are grouped into modules (4, and 5) and the modules proper are grouped into blocks (3). The axes of the rotors (11, 13, 15, 17) of the screw mechanisms (6, 7 and 8, 9) in the module (4 and 5) and the modules (4, and 5) proper in the block (3) are arranged symmetrically relative to the central axis.

Description

The invention relates to a screw machine with a plurality of screw mechanisms arranged one after the other, which have stators which are arranged coaxially and are rigidly connected to one another and rotors arranged therein and connected to one another by flexible shafts, the axes of the rotors being offset by the size of the eccentricity with respect to the central axis of the stators, and which are combined into groups and the groups into blocks, the axes of the rotors of the screw mechanisms of each group and in each block being arranged symmetrically to the central axis of the stators, and in each group the distances between the axes of the rotors of the adjacent screw mechanisms being the same.

Such a screw machine is known from GB-A-436 843. The flexible shafts through which the rotors are connected serve to transmit the axial force as well as the torque. As a result of this type of transmission of the axial forces and the torque, torsions occur which do not guarantee a compensation of the inertial forces of the runners with one another, so that considerable torsional loads occur which have a negative effect on the service life of the screw machine.

The object of the invention is to improve a screw machine of the type mentioned in such a way that the torsional loads of the individual runners are almost balanced, but in any case are significantly reduced.

This object is achieved by a screw machine with the features of the claim.

The presence of the connecting elements makes it possible to ensure that the predetermined alignment of all the rotors of the screw mechanisms relative to one another is ensured, that the sum of all the inertial forces acting in the screw machine is zero, since the vectors of the inertial forces which pass through the rotor axes are symmetrical to the central axis of the stators are arranged.

Each connecting element is designed as a crank, which is connected to the adjacent runners by means of bearings, the axis of which coincides with the axis of the respective rotor. This structural design of the connecting element makes it possible to simplify the assembly of the screw machine.

The central angle of the symmetrical displacement of the rotor axis of each subsequent screw mechanism to the rotor axis of the previous screw mechanism is determined by the number of screw mechanisms in the group. In the same way, the angle of mutual displacement of the groups depends on their number in the block.

Depending on the number of screw mechanisms in each individual group and depending on the number of individual groups in the block, the inertial forces and their moments can be significantly reduced and fully compensated in most embodiments, which jumps the vibration level of stators, threaded sleeves and other machine elements allowed to lower.

The reduced vibration level of the screw machine increases the quality of the drilled borehole when a screw machine is used as the borehole sole motor and stabilizes the mode of operation during its operation.

By using the connecting elements, which increase the safety when aligning the rotors of the screw mechanisms, the use of additional procedural measures during the assembly of the motor, which are mandatory in the absence of connecting elements, is avoided.

By using the cranks as connecting elements, the actual assembly is simplified and the assembly time is shortened.

• Fig. 1a, 1 a' die Gesamtansicht einer Schraubenmaschine im Längsschnitt;
• Fig. 2 den Schnitt nach Linie 11-11 in Fig. 1;
• Fig. 3 den Schnitt nach Linie 111-111 in Fig. 1;
• Fig. 4 eine Verbindungsvariante für Läufer von Schraubenmechanismen;
• Fig. 5 das Schema eines Blocks einer Schraubenmaschine, die aus drei Gruppen besteht, die jeweils zwei nacheinander angeordnete Schraubenmechanismen umfassen;
• Fig. 6 die schematische Anordnung der Läufer in einer Gruppe der Schraubenmaschine nach
• Fig. 5;
• Fig. 7 die schematische Anordnung der Läufer im Block der Schraubenmaschine nach Fig. 5;
• Fig. 8 das Wirkungsschema der Trägheitskräfte bei der Schraubenmaschine nach Fig. 5;
• Fig. 9 die Anordnung eines Blocks einer Schraubenmaschine aus zwei Gruppen, die jeweils drei nacheinander angeordnete Schraubenmechanismen umfassen;
• Fig. 10 die schematische Anordnung der Läufer in einer Gruppe der Schraubenmaschine nach
• Fig. 9;
• Fig. 11 die schematische Anordnung der Läufer im Block der Schraubenmaschine nach Fig. 9;
• Fig. 12 das Wirkungsschema der Trägheitskräfte bei der Schraubenmaschine nach Fig. 9;
• Fig. 13 die Gesamtansicht einer Schraubenmaschine, die als Pumpe eingesetzt wird im Längsschnitt;
• Fig. 14 die Gesamtansicht einer Schraubenmaschine, die als Verdichter eingesetzt wird im Längsschnitt.

Further objects and advantages of the present invention will become apparent from the following description of exemplary embodiments with reference to drawings. Show it:

• Fig. 1a, 1 a 'the overall view of a screw machine in longitudinal section;
• Figure 2 shows the section along line 11-11 in Fig. 1.
• 3 shows the section along line 111-111 in Fig. 1.
• 4 shows a connection variant for rotors of screw mechanisms;
• 5 shows the diagram of a block of a screw machine, which consists of three groups, each comprising two screw mechanisms arranged in succession;
• Fig. 6 shows the schematic arrangement of the rotor in a group of the screw machine
• Fig. 5;
• FIG. 7 shows the schematic arrangement of the rotors in the block of the screw machine according to FIG. 5;
• FIG. 8 shows the action diagram of the inertial forces in the screw machine according to FIG. 5;
• 9 shows the arrangement of a block of a screw machine from two groups, each comprising three screw mechanisms arranged one after the other;
• Fig. 10 shows the schematic arrangement of the rotor in a group of the screw machine
• Fig. 9;
• 11 shows the schematic arrangement of the rotors in the block of the screw machine according to FIG. 9;
• 12 shows the action diagram of the inertial forces in the screw machine according to FIG. 9;
• 13 shows the overall view of a screw machine that is used as a pump in longitudinal section;
• Fig. 14 is an overall view of a screw machine that is used as a compressor in longitudinal section.

A screw machine in an embodiment as a borehole sole motor contains an actuating device 1 (FIGS. 1a, 1a ') and a bearing element 2. In the present structural embodiment, the actuating device 1 comprises a single block 3, the components of which are two groups 4 and 5. The number of blocks 3 in the screw machine is determined by its output data (torque, speed, pressure drop) and can be increased if necessary.

The first group 4 comprises two screw mechanisms 6 and 7 arranged one after the other; the second group 5 accordingly contains screw mechanisms 8 and 9.

Each of the screw mechanisms 6, 7, 8, 9 includes a stator and a rotor housed therein. In the screw mechanism 6 it is the stator 10 and the rotor 11, in the mechanism 7 the stator 12 and the rotor 13, in the mechanism 8 the stator 14 and the rotor 15, in the mechanism 9 the stator 16 and the rotor 17.

The stators 10, 12, 14 and 16 of the actuating device 1 and the bearing element 2 are connected to one another by means of threaded sleeves 18 and have a common central axis 00 which corresponds to the axis of the screw motor. The axes of the rotors 11, 13, 15 and 17 are offset from this common axis 00 by the size of the eccentricity "e". The rotor 17 is connected to a shaft 19 of the bearing element 2 by means of a flexible shaft 20. The axis of the shaft 19 also coincides with the axis 00. A stone-destroying tool is attached to the output end of the shaft 19 (not shown in FIG. 1a, 1 a ').

For each screw mechanism 6, 7, 8 and 9, the interacting rotors 11, 13, 15 and 17 and the stators 10, 12, 14 and 16 associated therewith form working chambers A which define the interior of the screw mechanisms 6, 7, 8 and 9 in Divide high and low pressure rooms.

The rotors 11 and 13, 13 and 15, 15 and 17 are each connected via a flexible shaft 21, 22 and 23, by means of which the transmission of the axial force from one rotor 11, 13 and 15 to the respectively adjacent rotor 13, 15 and 17 and the transmission of the largest share of torque is achieved. The runners 11, 13, 15, 17 are connected to the flexible shafts 21, 22, 23 via smooth conical surfaces 24.

The runners 11 and 13, 13 and 15, 15 and 17 are also connected to each other to secure their symmetrical axis displacement by means of connecting elements 25 which transmit a certain residual torque. The axes of the rotors 11, 13, 15 and 17 are offset with respect to one another along a circular line with a radius "e" equal to the eccentricity of the screw mechanisms and a center coinciding with the central axis 00. In the present embodiment, the connecting elements 25 are designed as cranks 26, 27 and 28, the running surfaces 29 and 30 of which are supported in the respective runners 11, 13, 15 and 17 by means of bearings 31 and 32, so that the rotatability of the cranks 26, 27, 28 relative to the runners 11, 13, 15, 17 is made possible with the simultaneous transmission of a certain proportion of torque.

Through this design, in which the flexible shaft 21 receives the crank 26, while the connection of the rotor 11 and 13 for transmitting the axial force and the torque via the flexible shaft 21 on the smooth conical surfaces 24, one is predetermined by the crank 26 Axial position of the rotor 11 and 13 with respect to the common central axis 00 of the stators 10 and 12 guaranteed.

Similarly, the predetermined axis position of the rotors 15 and 17 with respect to the common central axis 00 of the stators 14 and 16 is ensured by means of the crank 28, which is accommodated within a flexible shaft 23.

In this way the symmetrical axis alignment of the rotors 11, 13, 15 and 17 of the screw mechanisms 6, 7, 8 and 9 in the respective group 4 and 5 takes place.

The actual groups 4, 5 are also aligned symmetrically with respect to one another by means of a similar connecting element 25, a crank 27, which is mounted between the runners 13 and 15 and arranged in the flexible shaft 22, which also on the smooth conical surfaces 24 with the runners 13 and 15 is connected.

The central angle of the symmetrical arrangement of the axes of the rotors 11, 13 and 15, 17 of the screw mechanisms 6, 7 and 8, 9 in the respective groups 4 and 5, which are distanced from the central axis 00 by the size of the eccentricity "e", becomes determined from the total number of screw mechanisms in each individual group. The angle of the symmetrical displacement of the actual groups 4 and 5 in block 3 is also dependent on the number of groups in the block and is defined according to the axis position of the respective outer runners 11 and 15 or 13 and 17.

As can be seen from the observation of the cross sections shown in FIGS. 2 and 3, the axes of the rotors 11 and 13 of the preceding and the subsequent screw mechanisms 6 and 7 are offset from the common central axis 00 of group 4 by the size of the eccentricity "e" and take a symmetrical diametrically opposite position.

FIG. 4 shows a constructive connection variant for the rotors 33 and 34 of two screw mechanisms 35 and 36 arranged one after the other. In this modification, a flexible shaft 37 is accommodated within a crank 38. As with the construction described above, the running surfaces 39 of the crank 38 are rotatably mounted in bearings 40 at the end sections of the runners 33 and 34 to be connected. The stators 41 and 42 of the screw mechanisms 35 and 36 are connected to one another by means of a threaded sleeve 43 and, together with the runners 33 and 34 arranged inside, form a group 44.

5 comprises three groups 45, 46 and 47, each of which consists of two screw mechanisms 48 and 49, 50 and 51, 52 and 53. The connection of the runners 54 and 55, 56 and 57, 58 and 59 of the screw mechanisms 48, 49, 50, 51, 52, 53 and their alignment and the connection of the runners 54, 55, 56, 57, 58, 59 of the adjacent groups 45, 46, 47 take place by means of the flexible shafts 20, 21, 22, 23 and the connecting elements 25 according to one of the embodiments described above.

The symmetrical axis alignment of the rotors 54, 55, 56, 57, 58, 59 in each individual group 45, 46, 47 is achieved by their successive displacement in relation to one another by the angle α = 180 °, because the number of screw mechanisms 48, 49 , 51, 52, 53 in each group 45, 46, 47 is two (Fig. 6).

The symmetrical alignment of the actual groups 45, 46 and 47 (FIG. 7), the total number of which in a block 60 is three, is achieved by displacing the axis of the rotor 56 of the screw mechanism 50 in the group 46 with respect to the axis of the rotor 54 of the screw mechanism 48 in the group 45 by the angle β = 120 ° because the number of groups 45, 46, 47 in the block 60 is three. Similarly and in the same direction, the axis of the rotor 58 of the screw mechanism 52 in the group 47 is offset with respect to the axis of the rotor 56 of the screw mechanism 50 in the group 46. The axes of the rotors 54, 55, 56, 57, 58, 59 of the screw mechanisms 48, 49, 50, 51, 52 53 are offset along a circular line with a radius "e", which corresponds to the eccentricity of the screw mechanisms 48, 49, 50 , 51, 52, 53 corresponds and is the same for all mechanisms 48, 49, 50, 51, 52, 53.

Fig. 8 shows the effect diagram of the inertial forces in the screw machine. The inertial forces Fjs ₄ and Fjss, Fjsε and Fjs ₇ , Fjs ₈ and Fjs ₉ are the same size and also directed in pairs in opposite directions, whereby a complete compensation is guaranteed not only for the inertial forces but also for their moments. This is achieved in that the axes of the rotors 54, 55, 56, 57, 58 and 59 are arranged symmetrically to the central axis 00 of the screw machine and the axial spacings of the rotors 54 and 55, 56 and 57, 58 and 59 are the same.

The block 61 of a screw machine (FIG. 9) comprises two groups 62 and 63, each of which consists of three screw mechanisms 64, 65 and 66 or 67, 68 and 69. The axes of the rotors 70, 71 and 72 of the screw mechanisms 64, 65 and 66 are within the first group 62 (FIG.

10) successively offset with respect to one another by the angle a = 120 °, and the axis spacings of the rotors 70, 71 and 72 are therefore the same. The axis displacement of the rotors 73, 74 and 75 of the screw mechanisms 67, 68 and 69 in the second group 63 is designed in a similar manner.

The actual groups 62 and 63 (FIG. 11) are aligned with one another such that the angle between the axes of the rotor 70 of the screw mechanism 64 in the first group 62 and the rotor 73 of the screw mechanism of the second group 63 is 6 = 180 °.

As in the previously described embodiment, the symmetrical axis displacement of the rotors 70, 71, 72 takes place along a circular line with a radius "e", which is the same as the eccentricity of the screw mechanisms 64, 65, 66, 67, 68, 69, which is the same for all mechanisms . The center of this circular line coincides with the central axis 00 of the screw machine and all screw mechanisms 64, 65, 66, 67, 68, 69. 12 shows the action diagram of the inertial forces in the screw machine in question. According to the size defined by the mass of the runners 70, 71, 72, 73, 74 and 75, they are the same. For each individual group 62 and 63, the inertial forces (Fj ₇₀ , Fj ₇₁ , Fj ₇₂ in the first group 62 and Fj ₇₃ , Fj ₇₄ and Fj ₇₅ in the second group 63) are completely balanced, since their sum is zero. The moments of inertial forces are just as completely balanced in that the axes of the rotors 70, 71, 72, 73, 74 and 75 are arranged symmetrically to the central axis 00 of the screw machine, the axial spacings of the rotors 70, 71 and 72 being the case with the first group 62 and the runners 73, 74 and 75 in the second group 63 are the same.

13 shows a screw machine according to the invention as a pump. The pump housing 76 receives a bearing element 77 and a drive shaft 78 which is connected to the rotor 80 of a screw mechanism 81 via an articulated connection 79. The rotor 80 is located within a stator 82, which is connected to the pump housing se 76 is rigidly connected. The stators 82, 83, 84 and 85 are connected to one another in a coaxial manner via threaded sleeves 86. In order to ensure the transmission of the hydraulic axial load and the torque and to ensure the predetermined axis displacement of the rotors 80, 87, 88, 89, the rotors 80, 87, 88 and 89 are connected to one another in accordance with one of the variants considered above, namely by means of flexible shafts 90 and connecting elements 91 designed as crank 92. The connecting elements 91 are rotatably accommodated in the respective runners 80, 87, 88, 89 by means of bearings 93.

The stators 82, 83, 84 and 85 and the rotor 80, 87, 88 and 89 respectively arranged therein form screw mechanisms 81, 94, 95 and 96 which are combined in pairs to form groups 97 and 98, which in the present modification only have one form a single block 99 of an actuating device 100.

The pump has an inlet space B and an outlet space C through which the working fluid or another liquid medium is supplied or discharged.

The screw machine shown in Fig. 14 is used as a compressor. The compressor housing 101 accommodates an actuating device 102, which comprises a block 103 composed of screw mechanisms 104, 105, 106, and 107. The screw mechanisms 104 and 105 and 106, 107 are combined in pairs to form groups 108 and 109. The rotors 110, 111, 112 and 113 of the screw mechanisms 104, 105, 106 and 107 are connected to one another in an equiaxial manner via threaded sleeves 114. The rotors 115, 116, 117 and 118 of these screw mechanisms 104, 105, 106, 107 are connected to one another in accordance with one of the arrangements considered above by means of flexible shafts 119 and connecting elements 120 designed as crank 121 in order to transmit the hydraulic axial force and the torque as well as the predetermined one To ensure axis displacement of the rotor 115, 116, 117 and 118. The crank 121 is rotatably supported in the respective runners 115, 116, 117, 118 by means of bearings 122.

The outer rotor 118 of the screw mechanism 107 is rigidly connected to an articulated connection 123 and this is connected to a drive shaft 124. The articulated connection 123 and the drive shaft 124 are arranged in a bearing element 125 which is rigidly connected to the housing 101, within which cooling spaces are arranged. The compressor has an inlet E and an outlet space F, through which the gas medium to be conveyed is fed in or out.

In its embodiment as a downhole sole motor for bringing down boreholes, the screw machine works as follows.

The flushing liquid is fed from the drill pipe cavity (not shown in FIG. 1 a, 1 a ') to the working chambers A of the first screw mechanism 6. Under the effect of the pressure drop created, an active torque is generated on the rotor 11, which rotates it. The rotation is transmitted from the rotor 11 via the flexible shafts 21, 22 and 23 successively to the rotor 13, 15 and 17, further to the bearing element 2 and then to the rock-destroying tool (not shown). The torques created under the effect of the pressure gradient on the rotors 11, 13, 15 and 17 are summed and also transmitted to the stone-destroying tool via the shaft 19 of the bearing element 2.

After the flushing liquid has flowed through the working chambers A of the screw mechanism 6, it enters the working chambers A of the screw mechanism 7 via the interior of the threaded sleeve 18. The pressure drop in the working chambers A of the screw mechanism 7 generates an additional torque on the rotor 13. The flushing liquid thus flows through the working chambers A of all screw mechanisms 7, 9 in succession and, via the bearing element 2, reaches the stone-destroying tool, through which it exits to the bottom of the borehole.

The principle of operation of the screw machines shown in FIGS. 13 and 14 has a single difference, which is only that the rotors 80, 87, 88 and 89, 115, 116, 117 and 118 are driven by a motor (not shown in the drawings) the drive shafts 78, 124 are driven and the working fluid (or the gas medium) from the room B (E) through the working chambers A of the screw mechanisms 81, 94, 95, 96, 104, 105, 106, 107 into the rooms C (F) is promoted.

The present invention can be used particularly effectively as a drive for rock-destroying tools when drilling oil and gas wells.

The invention can also be used as a borehole probe pump unit to extract water, petroleum or other mineral resources which are pumped around in liquid form.

The invention can also be used in reliable pump or compressor units with which liquid, gaseous or mixed media are to be pumped.

Claims (1)

1. A screwing machine, particularly for borehole drives with a plurality of serially disposed screwing mechanisms (6, 7, 8, 9) which comprise equiaxially disposed and rigidly connected stators (10, 12, 14, 16) and, disposed therein and connected to one another by flexible shafts (21, 22, 23) rotors (11, 13, 15, 17), the axes of the rotors (11, 13, 15, 17) being offset in relation to the central axis of the stators (10, 12, 14, 16) by the magnitude of the eccentricity (e), and which are combined into groups (4, 5) while the groups (4, 5) are combined into blocks (3), the axes of the rotors (11, 12, 14, 16) of the screwing mechanisms (6, 7, 8, 9) of each group (4, 5) and in each block (3) being disposed symmetrically in relation to the central axis of the stators (10, 12, 14, 16) while in each group (4, 5) the distances between the axes of the rotors (11, 13, 15, 17) of the adjacent screwing mechanisms (6, 7, 8, 9) are identical, characterised in that in each block (3) - and accordingly in each group (4, 5) between the rotors (11, 13, 15, 17) of the individual screwing mechanisms (6, 7, 8, 9) there are in addition as further connecting elements (25) cranks (26, 27, 28) for maintaining the predetermined axial position of the rotors (11, 13, 15, 17) inter se, these connecting elements (25) being mounted to rotate in bearings (31, 32) in the relevant rotors (11, 13, 15, 17).

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