DE102021203966A1 - axial piston machine - Google Patents

Abstract

Disclosed is a hydrostatic axial piston machine with a first subassembly with a swash plate that can be adjusted at an angle, on which working pistons are supported by cylinder-piston units connected in a torque-proof manner to a drive shaft, and an adjusting piston that is coupled to the swash plate and of which a control pressure chamber is delimited, which is connected via a electromagnetically actuable pilot valve of the axial piston machine can be charged with actuating pressure medium and from which actuating pressure medium can be released via the pilot valve, and with a second assembly with an electronic control unit for controlling at least the adjustment.

Description

The invention relates to an axial piston machine according to the preamble of patent claim 1.

The invention relates to a hydrostatic axial piston machine with a pivoting cradle, the angle of which can be adjusted via an adjustment mechanism. In this case, the adjusting mechanism has a hydrostatically driven adjusting cylinder with adjusting piston, with a pilot valve being able to control the supply and discharge of pressure medium into or out of the adjusting pressure space delimited by the adjusting piston.

The publication going back to the registration ring DE 10 2018 214 481 A1 shows a generic axial piston machine, the adjustment mechanism having a high level of integration, in that the pilot valve and its actuating electromagnet are arranged coaxially with the actuating piston and are designed to be screwed in the sense of a screw-in cartridge.

For some hydraulic systems to function reliably, it is necessary to know the angle at which the pivoting cradle of the axial piston machine is oriented. A common method of detecting this angle is to use a Hall sensor to determine the angular orientation of a magnet attached to the swivel cradle. Here, the so-called target, which carries the magnet, is attached to the swivel cradle in such a way that the magnet is concentric with the axis of rotation of the swivel cradle. The sensor is also aligned with this axis and attached to the outside of the housing of the axial piston machine. The sensor signal is provided by means of a plug/cable connection for further processing by a separate control unit of the axial piston machine.

Disadvantages here are a complex and error-prone assembly of the sensors inside and outside the housing, a necessary wiring of the control unit and, due to the isolation of the control unit, a less compact design.

In contrast, the invention is based on the object of creating an axial piston machine with a more compact design.

This problem is solved by an axial piston machine with the features of patent claim 1.

Advantageous developments of the axial piston machine are described in the dependent patent claims.

A hydrostatic axial piston machine has an in particular hydromechanical, first subassembly with a swash plate that can be adjusted at an angle, on which working pistons of cylinder-piston units non-rotatably connected to a drive shaft are supported. The displacement volume is adjusted by adjusting the angle. The axial piston machine can be designed to be operable as a hydraulic pump and/or as a hydraulic motor. It has an adjusting piston coupled to the swash plate and articulating it. An actuating pressure space delimited by this can be charged with actuating pressure medium for adjustment via an electromagnetically actuable pilot valve of the axial piston machine. In this case, actuating pressure medium can also be released from the actuating pressure chamber via the pilot valve for adjustment in the other direction. In addition, the axial piston machine has, in particular, an electronic, second assembly with an electronic control unit (ECU) at least for controlling the adjustment. According to the invention, the second subassembly is releasably attached to the first subassembly, in particular as a whole or in a modular manner.

In this way, a more compact axial piston machine is created.

In a further development, the axial piston machine has at least one inductive unit with components distributed over the two assemblies for the control. The distribution is selected in such a way that manufacture, assembly and/or configuration of the axial piston machine, in particular the control unit, is simplified.

In one development, the distribution is determined by a functional gap, in particular an air gap, in the inductive unit. In particular, the gap is formed between at least two of the components of the unit. In this way, a boundary between the assemblies is determined.

In a development, the components are assembled into the unit by fastening the second assembly group to the first assembly group. In particular, the unit is functionally assembled by fastening.

In one development, the at least one inductive unit is an actuator or a sensor. In addition, of course, one or more further inductive units can be provided, which is or are divided among the assemblies as described above.

In a preferred development, the actuator is an electromagnet for actuating the pilot valve and the sensor is a displacement pickup for detecting a position of the adjusting piston. The angle is then determined from the position via the control unit and from this the set displacement volume can be determined.

In a preferred development, a movable component is assigned to the at least one inductive unit of the first assembly and a component fixed to the housing of the at least one inductive unit is assigned to the second assembly.

In a preferred development, the movable component is an armature which is coupled, in particular decoupled, to a valve body of the pilot valve, and the component fixed to the housing is an exciter coil or an exciter coil arrangement. In an alternative or additional, preferred development, the movable component is an armature which is coupled to the adjustment piston, in particular coupled away, and the component fixed to the housing is a coil or coil arrangement.

In a further development, the adjustment or actuating piston is lengthened towards the associated coil or coil arrangement, in particular via a rod element which is attached to it or formed in one piece with it and which forms the armature or is coupled to it. The position of the actuating piston can thus be determined via the rod element using a suitable, in particular inductive, measuring principle.

A sealing of an actuating pressure chamber of the adjusting or actuating piston against a low pressure, in particular against a housing interior, is formed in a further development by a gap seal of the rod element with a screw plug passing through it. The latter is assigned in particular to the first assembly.

Installation is easier if, according to a further development, a pressure- and/or fluid-tight seal is fastened between the movable component and the component fixed to the housing on the first subassembly.

Specifically, in a preferred development, the seal is the respectively required pole tube. This extends in particular in the shape of a hat into the coil or coil arrangement.

When configured with at least two inductive units, in particular with the actuator and the sensor, a further development proves to be easy to assemble in which the central axes or axes of movement of the actuator, the sensor and/or the pole tubes are arranged in parallel.

A further simplified production and assembly is realized by a development in which the central axis(s) or movement axis(s) is or are normal to a joint surface of the second assembly group with the first assembly group. The joint surface is preferably flat, which also simplifies sealing of the joint, in particular since a seal, for example an endless seal, is easier to design and manufacture.

In a further development, the coil or coil arrangement has a particularly short and/or fixed connecting section, by which a printed circuit board of the control unit is contacted, particularly directly without further wiring, particularly by means of soldering.

In a further development, the coil or coil arrangement is arranged in a fixed manner in a housing of the second assembly. Preferably, this housing has cooling structures on the outside, in particular in the area of the coil or coil arrangement accommodated, for its recooling. In particular, the housing is designed for free convection with regard to recooling, for example by means of cooling fins or domes as a cooling structure. Such domes extend in particular in an axial extension to the respective central axis of the coil or coil arrangement.

An aluminum alloy is particularly suitable as the material for this housing, and die-casting as the manufacturing process.

A particularly simple structure is given when the printed circuit board is mounted parallel to the joint surface.

In a further development, a housing of the axial piston machine is composed at least in sections of the housings of the two assemblies, as a result of which the design of the axial piston machine is compact.

The housing of the second electronic assembly is designed to be even more compact if it has at least one integrated connector to the outside. In particular, for this purpose, emerging contacts are encapsulated with plastic.

In order to enclose electrical and/or electronic components of the second assembly in a fluid-tight manner, in particular according to the IP class, the housing of the second assembly is filled with casting compound according to a development.

Cumbersome, complex and leak-prone piping or the like is avoided according to a development if a valve body of the pilot valve is slidably received in a wall or a main body of a housing of the first assembly and a fluid connection to the control pressure chamber of at least one Pressure medium channel or a bore is formed in the wall or in the main body.

• 1 eine Axialkolbenmaschine gemäß einem Ausführungsbeispiel in perspektivischer Darstellung,
• 2 die Axialkolbenmaschine gemäß 1 in einem Längsschnitt parallel zur Mittelachse,
• 3 die Axialkolbenmaschine gemäß 2 mit abgehobener Elektronikbaugruppe,
• 4, 5 und 6 die Elektronikbaugruppe gemäß den 1 bis 3 in perspektivischer Ansicht von innen und außen und in einem Querschnitt,
• 7 eine Betätigungsspule eines Elektromagneten der Axialkolbenmaschine in perspektivischer Darstellung und in einem Längsschnitt, und
• 8 einen Stellkolben mit induktivem Wegaufnehmer der Axialkolbenmaschine gemäß den Figuren in einem Längsschnitt.

An exemplary embodiment of an axial piston machine according to the invention is explained in more detail below in eight drawings. Show it:

• 1 an axial piston machine according to an embodiment in a perspective view,
• 2 the axial piston machine according to 1 in a longitudinal section parallel to the central axis,
• 3 the axial piston machine according to 2 with lifted electronics module,
• 4 , 5 and 6 the electronics assembly according to the 1 until 3 in perspective view from inside and outside and in a cross section,
• 7 an actuating coil of an electromagnet of the axial piston machine in a perspective view and in a longitudinal section, and
• 8th an actuating piston with an inductive displacement transducer of the axial piston machine according to the figures in a longitudinal section.

1 shows a hydrostatic axial piston machine 1 configured in a swash plate design. An axial piston machine that is generic in terms of its basic structure is known, for example, from the publication DE 10 2018 214 481 A1 known, so that the description and representation of the basic structure of the present axial piston machine 1 are kept brief and in this regard reference is made to the publication mentioned for the purpose of disclosure.

The axial piston machine 1 is intended to be designed as a hydraulic pump and can be operated as a hydraulic motor when the load is reversed, for example to regenerate hydrostatic pressure medium energy. In the exemplary embodiment shown, the axial piston machine 1 is designed for operation in an open hydraulic circuit with a suction port 2 for connection to a low pressure, for example a tank T, and a working port 4 for connection to a hydraulic consumer. The configuration for the closed hydraulic circuit is possible as an alternative or in addition.

A first assembly 6 of the axial piston machine 1 has a cup-shaped housing section 7, in which, according to the 1 until 3 an engine is accommodated in a rotatably mounted manner, which has a cylinder drum which is non-rotatably connected to a drive shaft and in which hydrostatic working pistons are guided in a linearly movable manner. A hydrostatic working space is delimited by each of these, the working pistons being slidably supported on a pivotable swash plate (not shown).

An electrohydraulic adjusting device 8 with a hydraulic cylinder 10 and a pilot valve 12 supplying this with control pressure medium is provided for pivoting the swash plate and thus for adjusting the displacement volume. The actuating force of the hydraulic cylinder 10 is counteracted by a spring device (not shown) supported on the one hand on the housing section 6 and on the other hand on the swash plate. For further explanations on the basic, generic structure, as already mentioned above, refer to the publication DE 10 2018 214 481 A1 referred.

the 2 and 3 each show a longitudinal section of the axial piston machine 1 spanned by mutually parallel central axes 14, 16 of the hydraulic cylinder 10 and the pilot valve 12. The central axes 14, 16 are according to FIG 1 to the central axis 18 of the axial piston machine 1, so that the housing section 2 is cut obliquely instead of parallel to the central axis 18.

The axial piston machine 1 has according to the 1 until 6 a second assembly 20 with an electronic control unit (ECU) for controlling the pilot valve 12 for adjusting the actuating cylinder 10, and thus for adjusting the displacement volume of the axial piston machine 1.

According to the 2 and 3 For example, an electromagnet with an (excitation) coil 24 and an armature 26 that can move linearly therein is assigned to the pilot valve 12 for electromagnetic actuation of its valve body or slide 22 , the latter being coupled to the valve body 22 . In order to detect a stroke or a position of an actuating piston 28 (of the actuating cylinder 10), this is coupled to an armature 30 which can be moved linearly in a (measuring) coil arrangement 32. The set displacement volume of the axial piston machine 1 can thus be determined via the control unit from the detected position and the kinematics of the engine and its adjustment device.

2 shows the second assembly 20 mounted as a whole on the first assembly 6, in 3 On the other hand, the second assembly 20 is shown lifted off from the first assembly 6 . An interface or interface 34, which separates the assemblies 6, 20, according to 2 , 3 shown dashed. It runs along a joint surface 35 of the first assembly and a joint surface 33 of the second assembly 20. Pole tubes 42, 44 are firmly connected to the first assembly 6 the one into which the armature 26 and the armature 30 are immersed when installed as intended. It is easy to see that the second subassembly 20 can be detachably fastened to the first subassembly 6 as a whole (modular) ( 3 ), or attached ( 2 ) is. 2 and 3 impressively show that the two inductive units 23, 25, each consisting of a coil 24 or coil arrangement 32, pole tube 42, 44 and armature 26, 30, are distributed over the two assemblies 6, 20. The coil 24 and coil arrangement 32 are firmly accommodated in a housing-like base body 36 of the second assembly 20, in each case in a dome 38, 40 extending along the central axis 16, 14. The respective armature 26 , 30 dips into the pole tube 42 , 44 assigned to it and firmly connected to the housing section 7 . With the placement of the second assembly 20, the respective pole tube 42, 44 then dips into the coil 24 or coil arrangement 32 assigned to it, and the units 23, 25 are functionally completed and assembled.

the 4 , 5 show the second assembly 20 in a perspective view, once with an interior view ( 4 ), and once in a transparent representation from the outside ( 5 ). The base body 36 is trough-shaped with a substantially rectangular base area. At each corner of the base body 36 there is a through hole for screwing the second assembly 20 to the first assembly 6.

The base body 36 is trough-shaped on the inside, with a printed circuit board 48 with an integrated processor unit (PCB) being accommodated in a flat section 46 . The dome 38 in which the coil 24 is accommodated extends in a dome section 50 . The dome 38 of the coil arrangement 32 is arranged in a middle section 52 . On its circumference, the base body 36 has a groove in its joining surface 33, in which an endless seal 54 is accommodated. According to 4 and 5 a connector unit 56 is provided on the outside of the base body 36, which makes contact with the printed circuit board 48 on the inside.

6 shows a cross section of the second assembly 20, which is spanned by the central axis 16 of the coil 24 and a vertical axis of the axial piston machine 1. The base body 36 is designed to use free convection for sufficient cooling of the electrics and electronics carried by it. For this purpose, it has cooling structures on the outside, in particular cooling ribs and, in the case of the dome 38, a radially tapered dome extension into which the pole tube 44 dips, as a result of which the armature 26 can perform a maximum stroke. A thermally conductive bed (TIM) 58 is provided on the inside of the flat section 46, with which the printed circuit board 48 is intimately connected, for example by gluing. The base body is made of aluminum alloy using the die-casting process. The two coils 24, 32 are soldered to the printed circuit board 48 after they have been mechanically attached to the base body using screws.

7 shows a perspective view and in the same position a longitudinal section through the coil 24 of the electromagnet of the pilot valve 12. A winding 60 of the coil 24 is encapsulated by an electrical insulation 62, on which a cap-like, magnetic cover 64 is placed. The density of the magnetic field is increased via the magnetic cover 64 .

The cover 64 has a passage 66 into a radially tapered dome extension 68 on the face side, away from the joining surface 33 of the second assembly 20, via which a maximum stroke of the armature 26, in particular beyond the coil 24, is made possible.

In the exemplary embodiment, the electrical insulation 62 of the coil 24 has two diametrically arranged through-holes 70 for fastening the coil 24, through which the screw connection 72 of the coil 24 to the base body 36, as shown in particular 4 emerges on.

The through-holes 70 are formed by sleeves overmoulded with the material of the insulation 62, and they are arranged on projecting shoulders 74, 76 of the insulation 62. In particular, an axial position of the coil 24 can be adjusted via the length of the sleeves 70 .

One 76 of the shoulders 74, 76 carries only the sleeve 70. Two soldering contacts 78 of the coil 24 are also guided through the other 74, which emerge towards the printed circuit board 48 (cf. 4 and 6 ). Solder contacts 78 are stamped and overmolded when shoulder 74 is formed. They enable the direct electrical connection to the printed circuit board 48.

8th shows a detailed structure of the inductive unit 25 which, as already mentioned, is designed as a measuring unit for detecting the position of the actuating piston 28 . For this purpose, the actuating piston 28 is supplemented towards the coil arrangement 32 with a rod element 80 which dips into the pole tube 44 .

The rod element 80 is joined to the actuating piston 28 or is manufactured in one piece with it.

A length of the rod member 80 is designed to be operatively connected to the spool at any possible position of the actuator piston 28 order 32, so that the position can be recorded.

The rod element 80 extends out of an actuating pressure space 82 of the actuating piston 28 .

The control pressure chamber 82 is closed by a screw plug 84 introduced into the housing section 7 and through which the pole tube 44 passes.

A seal of the actuating pressure chamber 82 against a low pressure, in particular against a housing interior 88, is formed by a gap seal 86 of the rod element 80 with the screw plug 84.

In order to completely decouple a seal 90 of the screw plug 84 on the housing section 7 from the actuating pressure, a relief bore 92 is realized from the seat of the screw plug 84 to the housing interior 88 . A low-pressure space delimited by the rod element 80 and the screw plug 84 is fluidly connected to the relief hole 92 via radial bores of the screw plug 84 . In this way, adjusting pressure medium leaking via the gap seal 86 can be discharged directly into the housing interior 88, in particular a tank.

The relief bore 92 can be connected to a tank bore of the pilot valve 12 .

A section of the rod element 80 protruding from the locking screw 84 forms the armature 30 and dips into the pole tube 44 .

The pole tube 44 is supported on an inner collar of the screw plug 84 and is sealed by a seal 94 . Thus, the electrical and electronic components of the second assembly 20 are sealed and protected against the pressure and the pressure medium in the housing interior 88 via the seal 94 and the pole tube 44 .

In this way, electronic components 96 can be positioned directly in the area of the pole tube 44 and the axial piston machine has a compact design with on-board electronics (OBE) and with a sensor system for detecting the swivel angle.

Sensor components can be integrated directly on the circuit board 48 of the control unit, which also enables a compact design of the axial piston machine.

Another sealing point 98 on the outside of the screw plug 84 separates its thread from the control pressure chamber 82 and thereby causes less stress in the area of the thread and less leakage.

The inductive measurement of the position enables a high degree of integration in electronified, hydraulic axial piston machines compared to the state of the art when measuring using the Hall principle. With the concept presented, a more compact design and, depending on the application, a more cost-effective solution has been found than when using a conventional swivel angle sensor. In particular, the skillful distribution of the inductive units 23, 25 to the assemblies 6, 20 and the associated omission of cables and electrical plug connections enables a more cost-effective and more robust concept than the current state of the art with the Hall sensor. By avoiding cabling, the risk of the system failing due to cable breaks or defective plug connections is reduced.

The rod element 80 guided through the locking screw 84 reduces the volume of the actuating pressure chamber 82. This can have a positive effect on the dynamics of the adjustment and the control or regulation of the position of the actuating piston 28. The resulting reduced pressure force on the actuating piston 28 must be taken into account.

An important innovation of the invention is that the functional gap of the inductive units 23, 25, which must be present in each case from the air gap between the relevant coil 24, 32 and the relevant pole tube 42, 44, acts as a module boundary 34. The air gap is used as an assembly interface that allows the electronics to be kept separate from the hydromechanical first assembly 6 of the axial piston machine 1 .

A hydrostatic axial piston machine with a first and a second assembly is disclosed, the second assembly being mountable as a whole on the first assembly. The first assembly has a housing with a cylinder drum mounted rotatably therein, in which working pistons are guided in a linearly movable manner. In addition, it has an adjustment mechanism for the displacement volume with an actuating cylinder, the movable part of which is coupled to a first armature that is accommodated in a first pole tube so that it can move linearly, so that the housing is sealed in a fluid-tight manner in this area, a valve whose control slide is equipped with a second armature is movably coupled, which is accommodated in a linearly movable manner in a second pole tube, so that the housing is closed in a fluid-tight manner in this area, the valve being fluidically connected to the actuating cylinder. the The second assembly has a housing or body, an energizing or actuating coil for the valve which surrounds the second pole tube and which is fixedly received within the latter housing or body, a sensing coil assembly which surrounds the first pole tube and which is fixedly within that housing or Body is accommodated, an electronic control unit which is electrically connected to the actuating coil and the sensing coil assembly and which is firmly housed within this housing or body. This housing / the base body is firmly connected to the first-mentioned housing, in particular screwed.

reference list

1

hydrostatic axial piston machine

2

suction port

4

working connection

6

first assembly

7

housing section

8th

electrohydraulic adjustment device

10

hydraulic cylinder

12

pilot valve

14, 16

central axis

18

central axis

20

second assembly

22

valve body

23

inductive unit

24

Kitchen sink

25

inductive unit

26

anchor

28

actuating piston

30

anchor

32

coil arrangement

33

mating surface

34

interface/interface

35

mating surface

36

body

38, 40

Dom

42, 44

pole tube

46

flat section

48

circuit board

50

cathedral section

52

middle section

54

endless seal

56

connector unit

58

thermal bed

60

winding

62

electrical insulation

64

cover

66

passage

68

dome extension

70

through hole

72

screw connection

74, 76

shoulder

78

solder contact

80

rod element

84

Screw

86

gap seal

88

housing interior

90

poetry

92

relief hole

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102018214481 A1 [0003, 0033, 0036]

Claims (20)

Hydrostatic axial piston machine with a first assembly (6) with a swash plate adjustable in an angle, on which working pistons are supported by cylinder-piston units non-rotatably connected to a drive shaft, and an adjusting piston (28) coupled to the swash plate, from which a control pressure space (82) is limited, which can be charged with control pressure medium via an electromagnetically actuatable pilot valve (12) of the axial piston machine (1) and from which control pressure medium can be released via the pilot valve (12), and with a second assembly (20) with an electronic control unit (ECU) for Control of at least the adjustment, characterized in that the second assembly (20) is detachably attached to the first assembly (6). axial piston machine claim 1 , having at least one inductive unit (23; 25) with components (26, 42, 30, 44; 24, 32) distributed over the assemblies (6; 20). axial piston machine claim 2 , A boundary or interface (34) between the assemblies (6, 20) being determined by a functional gap, in particular an air gap, between the components (42, 24; 44, 32). axial piston machine claim 2 or 3 , wherein the components (26, 42, 30, 44; 24, 32) are assembled or assembled by attaching the second assembly (20) to the first assembly (6) to the, in particular functional, unit (23; 25). Axial piston machine according to one of claims 2 until 4 , wherein the at least one inductive unit (23, 25) is an actuator (23) or a sensor (25), or with two of the inductive units, a first of which is an actuator (23) and a second is a sensor (25). . axial piston machine claim 5 , wherein the actuator (23) is an electromagnet for actuating the pilot valve (12), wherein the sensor (25) is a displacement pickup for detecting a position of the adjusting piston (28). Axial piston machine according to one of claims 2 until 6 , wherein a movable component (26, 30) of the at least one inductive unit (23, 25) of the first assembly (6) and a component (24, 32) fixed to the housing of the at least one inductive unit (23, 25) of the second assembly (20 ) assigned. axial piston machine claim 7 , the movable component being an armature (26, 30) which is coupled to a valve body (22) of the pilot valve (12) or to the adjusting piston (28), the component fixed to the housing being a coil (24) or coil arrangement (32) is. axial piston machine claim 7 or 8th wherein at least one pressure and/or fluid-tight seal (42, 44, 90, 94) is fastened to the first assembly (6) between the movable component (26, 30) and the component (24, 32) fixed to the housing. axial piston machine claim 8 and 9 , wherein the seal has a pole tube (42, 44) that extends, in particular in the shape of a hat, into the coil (24) or coil arrangement (32). Axial piston machine at least after claim 5 and 10 , wherein central axes or movement axes (14, 16) of the actuator (23), the sensor (25) and/or the pole tubes (42, 44) are parallel. axial piston machine claim 11 , wherein the central axes (14, 16) or movement axes are normal to a joint surface (33, 35) of the second assembly (20) with the first assembly (6). axial piston machine claim 12 , wherein the joining surface (33, 35) is flat. Axial piston machine at least after claim 8 , wherein the coil (24) or coil arrangement (32) has a connecting section (78) from which a printed circuit board (48) of the control unit is contacted. Axial piston machine at least after claim 12 and 14 , wherein the printed circuit board (48) is mounted parallel to the joining surface (33, 35). Axial piston machine at least after claim 8 , wherein the coil (24) or coil assembly (32) is fixedly arranged in a housing (36) of the second assembly (20). Axial piston machine according to one of the preceding claims, the housing of which is composed at least in sections of housings (7, 36) of the two assemblies (6, 20). axial piston machine Claim 16 or 17 , wherein the housing (36) of the second assembly has at least one integrated connector (56) to the outside. Axial piston machine according to one of Claims 16 until 18 , Wherein the housing (36) of the second assembly (20) is filled with potting compound, so that electrical and electronic components components of the second assembly (20) are enclosed in a fluid-tight manner, in particular according to the IP class. Axial piston machine according to one of the preceding claims, wherein a valve body (22) of the pilot valve (12) is slidably received in a wall or a main body of a housing (7) of the first assembly (6) and a fluid connection to the control pressure chamber (82) of at least one pressure medium channel (92) or a bore in the wall or in the main body.

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