WO1990001637A1

WO1990001637A1 - Hydraulic axial-piston engine

Info

Publication number: WO1990001637A1
Application number: PCT/DE1989/000527
Authority: WO
Inventors: Eckehart Schulze
Original assignee: Eckehart Schulze
Priority date: 1988-08-12
Filing date: 1989-08-09
Publication date: 1990-02-22
Also published as: EP0428574A1; EP0428574B1; DE58902574D1; DE3827365A1

Abstract

The rotor (18) of an axial piston engine (10) is connected to the engine shaft (16) so as to remain fixed during rotation and during sliding and is supported on the engine housing (91) without play in the axial direction. The cross-sections of control passages (96) alternatively overlap with the control chambers (99) of the engine housing (91), which are put under pressure or relieved of pressure, thus causing the driving pressure chambers (37) of the rotor (18) to be alternately pressurized and depressurized. Said control channels (96) are arranged on a control disk (88), which is linked in a rotationally fixed manner with the driving part (19) of the rotor (18) that delimits the driving pressure chambers (37) but can for compensation sway or be axially shifted relative to said part. Said control disk (88) has a metallic sealing surface (118), inside which the outlet openings (98) of its control channels (96) are situated, and with which it slidingly and sealingly rests against a sealing surface situated on the housing side, inside which the outlet openings (98) of the control chambers (99) are situated. Said control disk is forced to rest against the sealing surface (114), situated on the housing side, by elastic sealing elements (34), which ensure the sealing contact of the driving pressure chambers (37) with the housing chamber containing the rotor (18), whereby said sealing elements (34) are thus strongly pre-loaded in the axial direction.

Description

Hydraulic axial piston motor

The invention relates to a hydraulic axial piston motor as a rotary drive motor for tools or positioning or feed drives on machine tools or processing machines, with a rotor rotatably mounted in a housing and rotatably connected to the output shaft of the motor, the rotor having an axially symmetrical distribution has bores around the axis of rotation, in each of which a piston in the axial direction - parallel to the axis of rotation - is displaceably guided in a pressure-tight manner and forms the axially movable boundary of a drive pressure chamber, through the controllable application of which to the outlet pressure of a pressure supply unit the piston in System with a fixed to the housing, concentric with the axis of rotation cam track can be pushed, which, likewise in a group axially symmetrical with respect to the axis of rotation, but in a smaller multiplicity than that of the bores of the rotor pointing to this and arranged between these projections Has sinks, which adjoin one another with a smooth curvature, form a rolling surface for support balls which are freely rotatably supported at the free ends of the pistons, the pressure medium supply and discharge to and from the drive pressure chambers of the rotor via rotor - 2 -

Control channels on the side and control rooms on the housing side which alternately come into communicating connection and which are grouped around the central axis of the axial piston motor in a symmetry corresponding to the axial symmetry of the cam track in azimuthally equidistant distribution and, seen in the direction of rotation, can be connected alternately to the operating pressure outlet or the tank of the pressure supply unit, and the azimuthal width of a separating wall which is under pressure and which delimits a control chamber which is relieved of pressure towards the tank is equal to the azimuthal width of the rotor-side through-channels with which it is connected Can overlap with the clear cross-sectional area of the control rooms.

Such axial piston motors are known and z. B. in the data sheet RD 14 250 / 2.85 from Mannesmann Rexroth explained in detail.

In the known axial piston motors, the drive part which receives the pistons and, together with them, delimits the drive pressure chambers of the rotor and also the control channels via which the pressure medium is supplied and discharged to and from the drive pressure chambers of the rotor is designed as a one-piece part , which is motionally coupled to the motor shaft via an axial toothing. This drive part lies with an annular surface, within which the control channels have their mouth openings on the housing, in a sliding and metallic sealing manner against an annular counter surface of the motor housing, within which the clear opening cross sections of the control rooms are located, by means of which seen in the circumferential direction, alternative connection to the Pressure output of the pressure supply unit or the pressure control of the pressure-less tank takes place. This drive part is held by the reaction forces resulting from the pressurization of the drive pressure spaces used for the drive in sealing contact of its ring surface with the counter surface of the motor housing. For this it is necessary that the drive part - because of unavoidable manufacturing tolerances of the housing and the drive part itself as well as the motor shaft - must be axially displaceable as a whole, even if only slightly, or must be able to perform wobbling compensating movements, otherwise the operation of the motor with the highest possible efficiency, sliding sealing system of the drive part on the counter surface of the housing could not be maintained. On the one hand, however, this means that in the known axial piston motors a completely play-free, rotationally and displaceably fixed coupling of the arite drive part to the motor shaft is not possible, and, on the other hand, as a result, that the drive part including the pistons which are displaceably guided in it during operation permanently executes vibratory movements, the resonance frequency of which - because of the relatively large total mass of the drive part - is relatively low.

Since axial piston motors of the type mentioned - periodically operating hydraulic motors in general - can only be operated significantly "below" their natural or resonant frequency, the known axial piston motors are at most suitable as so-called slow-speed motors, that is to say with operating speeds of at most 500 rpm, which is unfavorable from the point of view of the ratio of size to useful performance. The object of the invention is therefore to improve an axial piston motor of the type mentioned in such a way that with a simple construction and low wear, operation as a high-speed motor is possible, that is to say operation with at least a motor of the known type with a comparable size four times the maximum speed of the known motor is possible.

This object is achieved according to the invention by the features mentioned in the characterizing part of patent claim 1.

In the design of the rotor of the axial piston motor provided hereafter, in its operation the control disc, which is axially supported on the otherwise play-free rotor and is provided with the control channels, can be excited to oscillate movements. Since the mass of this control disk is small compared to the total rotor mass and the preload of the sealing elements, which hold the control disk in contact with the housing-side sealing surface, it can be chosen to be sufficiently large without difficulty, or in the operation of the engine if the Buffer elements are under the drive pressure coupled into the drive pressure chambers of the motor, it is sufficiently large that the resonance frequency of the possibly still possible vibrations of the control disc is significantly higher than the frequencies of the vibrations which can be resonantly excited in the known axial piston motors, the axial piston motor according to the invention can operate at significantly higher speeds - as a high-speed runner - which, in the associated useful power, which increases in proportion to the speed, is also of considerable advantage with regard to the size for a given power requirement. Since the rotor is "rigidly" coupled to the motor shaft, it occurs ch no wear caused by relative movements of the rotor relative to the shaft, so that the axial piston motor according to the invention, although it can be operated as a high-speed motor, is even distinguished from the known axial piston motor by increased service life.

The features of claims 2 to 7 indicate advantageous designs of the sealing elements, of the rotor, of the control disk of the rotor and of the housing parts of the axial piston motor according to the invention which delimit the control spaces, both from a functional point of view and from the point of view of the inexpensive manufacturability.

The features of claims 8 to 12 provide structurally simple measures for realizing a play-free and low-wear mounting of the motor shaft and the rotor of the axial piston motor according to the invention.

In combination with this, the - known per se - measure according to claim 13 provides the lubricant for the rotor bearing from the pressure medium supply circuit in a simple manner.

The features of claim 14 indicate - using the axial piston motor according to the invention - a hydraulic drive unit which is suitable for a large number of uses and is distinguished by a particularly space-saving overall structure.

Further details and features of the invention emerge from the following description of a special exemplary embodiment with reference to the drawing. Show it: - 6 -

1 shows a hydraulic drive unit with an axial piston motor according to the invention which is controlled by means of an electric motor and a follow-up control valve, in a scaled-up longitudinal sectional illustration,

2 details of the axial piston motor according to FIG. 1, on an enlarged scale,

2a) simplified view representations of control to 2c) elements of the axial piston motor according to FIG. 1 and

3 shows a development of the axial piston motor according to FIG. 1, along the cylinder surface containing the central axes of its drive pistons, to explain its function.

1, to the details of which reference is expressly made, shows a hydraulic axial piston motor according to the invention, designated overall by 10, in the context of a hydraulic drive unit, which in turn is designated overall by 11, which uses the axial piston motor 10 itself and as a control element for it comprises a total of 12 designated electrohydraulic overrun control valve, which works with electrically controlled rotation angle or rotation frequency specification and mechanical rotation angle feedback. To set the angle of rotation, a pulse-controlled stepper motor 13 is provided, whose rotor (not shown for the sake of simplicity) rotates by a defined angle of z. B. experiences 4 °, wherein the stepper motor can be controlled in start-stop mode with a pulse train whose pulse train frequency can be up to 5 kHz.

The follow-up control valve 12 and the stepping motor 13 provided for its control can be assumed to be known in terms of structure and function and are therefore only to be explained below to the extent necessary for understanding the invention.

The axial piston motor 10, the follow-up control valve 12 and the stepper motor 13 are arranged along a common central longitudinal axis 14 of their respective housings, which also marks the axis of rotation of the shaft 16 of the axial piston motor 10 and the control shaft 17 of the stepper motor 13.

The rotor of the axial piston motor 10, designated as a whole by 18, comprises a thick-walled, ring-cylindrical drive part 19 which is designed in the manner of the drum of a drum turret and which is connected to the motor shaft 16 of the axial piston motor 10 in a rotationally fixed and non-displaceable manner. In principle it could be made in one piece with the motor shaft 16, but for manufacturing reasons it is designed as a "separate" structural element of the rotor, which is firmly connected to a control valve-side section 21 of the motor shaft in a manner not shown in detail, which passes through a central bore 22 of the drive part 19 of the rotor 18 and, with a free end section 23 of its length, protrudes from the central bore 22 on the valve side. In the drive part 19 of the rotor 18 a total of eight continuous axial bores 24 are introduced in an axially symmetrical grouping about the central longitudinal axis 14 of the rotor 18, the central bore axes 26 of which are best shown in FIG Reference should be made to the apparent arrangement at azimuthal angular intervals of 45 ° perpendicular to the bore circle 27, the diameter of which corresponds approximately to the mean value between the outside diameter of the drive part 19 and the inside diameter of its central bore 22 and is somewhat larger than that in the special embodiment shown exact mean.

These bores 24 pass on the control valve side into a bore step 28 of slightly larger diameter, which is only slightly extended in the axial direction and which are offset against the somewhat smaller bores 24 by a radial annular shoulder 29.

In the stepped through bores 24, 28, as can best be seen in the illustration in FIG. 1 a), the details of which are also expressly referred to, stepped piston-shaped inserts. These plugs 31 have a cylindrical jacket-shaped step 32, the outer diameter of which is equal to or approximately the same as the diameter d- ^ of the bore 24 of the drive part 19 and an outer diameter larger, ring-flange-shaped piston step 33, ° 'S ^ren outer diameter is slightly smaller than the diameter d2 of the larger bore step 28 of the drive part 19. The peripheral lateral surface 33 'of this ring flange-shaped step 33 has a flat-convex curvature. - 9 -

The plugs 31 are centered by rubber-elastic O-rings 34 and sealed against the drive part 19, these O-rings 34 being axially supported on the one hand on the ring shoulders 29, which - spatially - further bore steps 28 against the bores 24 of the drive part 19 settle and, on the other hand, are supported by a thin washer 35 on the inside of the ring-flange-shaped step 33 of the plug 31, as a result of which they are held in the position shown, in which the inner end faces of the plug 31 are still at a small axial distance e of the annular shoulders 29, which offset the bore stages 28 and 24 against one another. The sealing disk 35 provided as an additional sealing element consists of an elastomer, e.g. B. a polyamide, through this washer of the remaining between the peripheral lateral surface 33 'of the annular flange 33 of the respective plug 31 and the further bore 28 of the drive part 19, relatively narrow annular gap, the radial width is substantially smaller than the radial width the Rin shoulder 39 and z. B. 1/10 of the same, is very well sealable.

Due to the described design of the plug 31 and the arrangement thereof within the bore steps 28 of the drive part 19, a cardanic mobility of the plug 31 is achieved within sufficiently wide limits, which allows the motor 31 to "wobble" required to compensate for manufacturing tolerances and nevertheless ensures a sufficiently pressure-tight limitation of drive pressure spaces 37 of the axial piston motor 10. - 9a -

In each of the - axial - bores 24 of the drive part 19 of the rotor 18, a piston 36 is guided so that it can be moved in a pressure-tight manner, which piston forms the axially movable limitation of one of the drive pressure spaces 37 - 37a to 37h - of the rotor 18, by the alternative pressurization thereof and relief the drive control of the hydraulic motor 10 takes place.

The pistons 36 are axially supported on a housing-fixed, coaxial with the central longitudinal axis 14 of the axial piston motor 10, with respect to this axially symmetrical cam 38, which is shown in the special embodiment shown, in which the rotor 18 with eight drive pistons 36 - 36a to 36h - is equipped, has the shape of a three-pronged "crown", the prongs 39 - 39a, 39b, 39c - are arranged pointing to the drive part 19 of the rotor 18.

3, to the details of which reference is now also made, the prongs 39 of the curved rib 38 which is circular at its base have the shape of flat, isosceles-obtuse-angled triangles, the legs 41 - 41a, 41b and 41c - and 42 - 42a, 42b and 42c - include an obtuse angle β which in practice has a value between 120 ° and 150 °, in the preferred configuration of the axial piston motor 10 a value around 140 °, especially a value of 138 °.

In the azimuthal direction represented by arrow 43 in FIG. 3 and arrow -43 'in FIG. 2c) - 10 -

seen, are formed by the legs 41 and 42 of the prongs 39 or axial projections of the curved rib 38 rising and falling ramps of constant incline, which in the "tips" 44 of the curved rib 38 and in the "valleys" 46 arranged in between of a small angular range, each of which only comprises a few degrees, adjoin one another with a smooth curvature, the radius of curvature, with which a descending flank 42 and a rising flank 41 of two adjacent, axially projecting "crown prongs" 39 of the curve rib 38 in FIG Connect valley areas 46 to one another, which is slightly larger than the ball radius of support balls 47, via which the pistons 36 of the drive part 19 of the rotor 18 engage the cam rib 38.

These support balls 47 are freely rotatable in concave bearing pans 48 of the pistons 36 and can therefore roll on the ramp-shaped running surfaces 41 and 42 of the curved rib 38, as a result of which friction losses are kept very low.

The ascending and descending support or running surface 49 of the curved rib 38 seen in the azimuthal direction (^ direction 43 ') is designed as a flat-concave groove, the radius of curvature of the running surface 49 now being seen in the cutting direction of FIG. 1 is also somewhat larger than the radius of the support balls 47.

In the special embodiment shown, the curved rib 38 is made in one piece with a sleeve-shaped housing part 51 of the motor housing, within which the motor - 11 -

shaft 16 is supported by two axially braced angular ball bearings 52 and 53 free of play. The bearing section 54 of the motor shaft 16, on which the inner rings 56 and 57 of the two angular contact ball bearings 52 and 53 are seated, is separated by a central section 58, the diameter of which is somewhat larger than that of the bearing section 54, against which the drive part 19 of the rotor rotates. and displaceably fixedly connected drive section 21 of the motor shaft 16, the diameter of which in turn is somewhat smaller than that of the central section and in the special embodiment shown is the same as that of the bearing section 54

The inner rings 56 and 57 of the two angular contact ball bearings 52 and 53 are held axially displaceably between the radial step 61 of the motor shaft 16, which sets off the central section 58 against the bearing section 54 of the motor shaft 16, and a snap ring 62 which is inserted into an outer groove 63 of the motor shaft 16 , wherein the inner bearing rings 56 and 57 of the two angular contact ball bearings 52 and 53 with their mutually facing annular end faces lie directly against one another.

In order to be able to brace them against one another, the outer bearing rings 64 and 66 of the angular contact ball bearings 52 and 53 are somewhat "narrower" in the axial direction than the inner bearing rings 56 and 57, in such a way that between the mutually facing ring end faces 67 and 68, a gap 69 with only a small axial gap width remains in the embodiment shown, but this is sufficient to be able to brace the angular contact ball bearings against one another. - 12 -

The outer ring 64 of the inner angular contact ball bearing 52, whose inner bearing ring 56 is supported or can be supported on the radial step 61 of the motor shaft 16, is axially supported on a radially outward-pointing support flange 71 of a slide bearing bush 72, in the central bore 73 thereof the motor shaft 16 with its central section 58 is additionally mounted so that it can rotate. This slide bearing bush 72 is supported with its radially outward-pointing support flange 72 axially on a radially inward-pointing ring flange 74 of the housing part 51 provided for the mounting of the motor shaft 16, with this ring flange 74 of the sleeve-shaped housing part 51 facing the drive part 19 the curve rib 38 is arranged.

The plain bearing bush 72 has a cylinder-jacket-shaped centering extension 76 which passes through the opening which is circular and coaxial with the central axis 14 and which is delimited by the radially inward-pointing flange 74 of the sleeve-shaped housing part 71.

The support flange 71 of the plain bearing bush 72 has a somewhat larger - axial - thickness in its radially outer region 77 than in its central region 78. This difference in thickness is dimensioned in the special embodiment shown so that the annular surface of the thicker, radially outer one Area 77, on which the outer bearing ring 64 of the inner angular contact ball bearing 52 can be axially supported, runs in the plane in which the radial step 61, which separates the central section 58 against the bearing section 54 of the motor shaft 16, also lies there, while that nige plane in which the bearing end face of the - 13 -

Central area 78 of the plain bearing bush 72 is located at a small axial distance from it "within" the area of the central section 58 of the motor shaft 16.

The two angular contact ball bearings 52 and 53 are axially braced against one another by means of a clamping ring 79, which can only be axially supported on the outer, ring-side end face 81 of the outer bearing ring 66 of the outer angular contact ball bearing 53, as seen in the axial direction. To adjust the clamping force with which the two angular contact ball bearings 5 and 53 can be clamped against each other for play-free mounting of the shaft 16 and with this de rotor 18 of the motor 10, axial clamping screws are - in an axially symmetrical distribution about the central longitudinal axis 1 of the motor 82 provided, which are tightened by means of a torque wrench.

The circular central opening 83 of the clamping ring 79 is - by means of a sealing ring 84 firmly connected to the outer, adjoining the bearing section 54 of the motor shaft 16 - free end section 86 of the motor shaft 16 - slidingly - which, as an output shaft with the - not specifically shown - rotating or possibly only pivotally driven part, z. B. a gear or an articulated arm is rotatably coupled.

The plugs 31, which each form the - essentially rotor-fixed - axial delimitation of the drive pressure spaces 37 of the drive part 19 of the rotor 18 have, as can best be seen from FIG. 1 a), central through-holes 87, via which the feed and Discharge - -

of pressure medium to or from the drive pressure chambers 37 follows, through their appropriately controlled pressurization or relief, the axially movable limits of the drive pressure chambers 37 forming pistons 36 undergo axial displacements which result from the fact that the pistons 36 move over the Support balls 47 are axially supported on the cam rib 38, the support balls 47 being able to roll on the running surface 4 of the cam rib 38, are converted into rotational movements of the drive part 19 of the rotor 18 and with it the motor shaft 16.

In order to control the pressurization or relief of the drive pressure chambers 37 of the drive part 19 in accordance with requirements, a first control disk 88 executing the rotational movements of the rotor 18 and in this respect itself forming an element of the rotor 18 and a second control disk 89 are provided, which support the regulator-side support element of the motor housing or stator of the axial piston motor 10, designated overall by 91.

The rotor-side, first control disk 88 is rotatably connected to the rotor 18 by means of a driving pin 92 (FIG. 2b) which is firmly connected to the drum-shaped drive part 19 of the rotor 18 and engages in a driving bore 93 of the first control disk 88 connected. The first control disk 88 has a centering hole 94, through which the controller-side, free end section 23 of the motor shaft 16 passes as a centering piece. The clear diameter d _{2 of} the centering bore 94 of the control disk 88 is larger by a positive minimum tolerance of 0.02 mm than the diameter d of the controller-side section 21 or of the free end section 23 of the motor shaft 16. - 15 -

The first control disk 88 is provided with axial control channels 96, the number and symmetry of the arrangement corresponding to that of the drive pressure chambers 37 and drive pistons 36 of the drive part 19 of the rotor 18.

These control channels 96 have, on the consumer side, that is to say on the side of the control disk 88 facing the stopper 31 of the drive part 19, openings 97 which are arranged coaxially with the central axes 26 of the through bores 87 of the stopper 31 and have the same diameter as these through bores 87.

On the supply side, that is to say on the side facing the housing-fixed, second control disk 89, the control channels 96 have orifices 98, the diameter of which is somewhat smaller than that of the orifice openings 97 on the consumer side and, in the special embodiment shown, the radial inside width w 2a, kidney-shaped control grooves 99 corresponds to the housing-fixed, second control disk 89, which are arranged on its side facing the first control disk 88, in the view of FIG. 2a, to the details of which reference is now also made.

The control channels 96 of the first control disk 88 are realized by mutually merging bore sections of different diameters, the central axes 101 of the bore sections 102, which have the smaller diameter, being arranged along a bore circle 103, the diameter of which is slightly larger than that of the bore approximately circle 27, along which the central axes 26 of the larger bore sections 106 of the diameter Control channels 97 of the first control disk 88 are arranged, the diameter of the smaller bore sections 102 being matched to that of the larger bore sections 106 of the control channels 96 in such a way that the bore sections 102 and 106, seen in the illustration in FIG have the envelope represented by the circle 107, which is also the outer envelope of the kidney-shaped control grooves 99 of the control disk 89 fixed to the housing. Accordingly, the inner envelope, represented by the circle 108, of the smaller diameter bore sections 102 of the control channels 96 of the first control disk 88 also coincides with the inner envelope of the kidney-shaped control grooves 99 of the second control disk 89 fixed to the housing.

The consumer-side orifices 97 of the control channels 96 of the first control disk 88 lie within a flat end face 109 of a flat, first annular rib 111 of the first control disk, which runs perpendicular to the central longitudinal axis 14 of the axial piston motor 10, as shown in FIGS. 1 and la) 88.

The supply-side orifices 98 of the control channels 96 of the first control disk 88 also lie within an end face 112, parallel to the end face 109 of the first annular rib 111, of a second flat annular rib 113, pointing towards the second control disk 89, of the first control disk 88.

Furthermore, the opening cross sections of the kidney-shaped control grooves 99 are within an annular shape - 17 -

End face 114 of a flat annular rib 116, pointing toward the first control disk 88, of the second control disk 89, which is fixed to the housing.

The outer diameters of the flat annular ribs 113 and 116 facing one another of the first control disk 88 and the second control disk 89 have the same value. The same applies, in the special exemplary embodiment shown, with regard to the inner diameter of these two ring ribs 113 and 116.

As can best be seen from the detailed illustration in FIG. 1 a, the stepped piston-shaped plugs 31, which form the one-sided — “rotor-most” - axial boundaries of the drive pressure chambers 37 of the rotor 18 are also included on their side facing the first control disk 88 the central longitudinal axis 26 of their through bores 87 are provided with coaxial ring ribs 117, which have ring-shaped end face faces 118 parallel to the ring face 109 of the first flat ring rib 111 of the first control disk 88 facing them, with which they have a metallic seal on the ring ¬ migen end face 109 of the first control disk 88 - by the elastic preload of the rubber-elastic ring seals 34 - are kept in contact. As a result, the first disk 88 is also held with the end face 112 of its second flat annular rib 113 in a metallic sealing position with the end face 114 of the annular rib 116 of the second control disk 89 fixed to the housing. - -

Just like the diameter d _{z of} the center hole 94 of the first control disk 88 compared to the diameter d of the controller-side section 21 of the motor shaft 16, the clear diameters d- _| _ and d2 of the bore stages 24 and 28, in which the cylindrical jacket-shaped piston stage 32 and the ring-flange-shaped piston stage 33 of the stopper 31 are arranged, have positive tolerances of at least 0.02 mm with respect to them, that is to say the diameter is somewhat larger than the stages mentioned 32 and 33 of the plug 31, so that both this and the first control disk 88 have enough "play" to be able to rest against one another with their ring ribs 117 and 111 or 113 and 116, each with a metallic seal , whereby the ring diameters 34 act as a buffer body, which "axial" manufacturing tolerances of the sealingly abutting parts - the first control disk 88 and the housing-fixed control disk 89 on the one hand and the plug 31 on the first control disk 88 on the other - can compensate.

In principle, the first control disk 88 could be made in one piece with the plugs 31 delimiting the drive pressure spaces 37 of the drive part 19 of the motor 10, but this would be more complex in terms of production technology than the design of the first control disk 88 and the plugs 31 of the rotor 18 described using the special exemplary embodiment. A possible leakage oil flow in this configuration of the control disk 88 and the plug 31, which flows into the rotor via the sealing joint 119, along which the plug 31 and the first control disk 88 bear against one another with the annular surfaces 118 and 109 of their annular ribs 117 and 111 18 surrounding leak oil chamber 121 can, a sufficient elastic - 19 -

Preload the buffer body 34 provided, are easily kept so low that it does not interfere. This leakage oil space is delimited in the radial direction by a tubular housing part 122, which extends between a radial ring flange 123 of the housing-most control disk 89 and a radial ring flange 124 of the sleeve-shaped housing part 51 (FIG. 1) and with this by housing fastening ¬ screws 126 is firmly connected. The tubular housing part 122 is sealed against these housing parts by means of an annular seal 127 and 128, respectively, which are placed in the outer grooves of the control disk 89 fixed to the housing and the sleeve-shaped housing part 51.

The control grooves 99 - 99a to 99f -, which are arranged with the best from FIG. 2a, to the details of which reference is expressly made, are arranged with respect to the central axis 14 of the Axia piston engine 10 6-fold, axially symmetrical grouping, in Circumferential direction, that is to say seen in the azimuthal direction represented by arrow 43 "of FIG. 2a) or arrow 43 of FIG. to the details of which are also expressly referred to, via connection channels 129-129a to 129f - alternately the A-control connection 131 of the overrun control valve 12 or its B-control connection 132 connected, which in turn, depending on the direction of rotation with which the axial piston motor 10 is to be operated, alternatively to the high-pressure (P) connection 133 or the return - (T-) connection 134 of the overrun control valve 12 can be connected, which with the high-pressure outlet or the unpressurized tank is one - not shown for the sake of simplicity - Pressure supply unit are connected. - -

For the follow-up control valve 12, an interpretation is assumed such that when the stepper motor 13, viewed in the direction of arrow 136, is driven in the clockwise direction of rotation, it reaches its functional position I, in which the A control connection 131 of the Follow-up control valve 12 is connected via its flow path 137 to the high-pressure port 33 (P port) and the B control port 132 is connected to the return port 134 of the follow-up control valve 12 via the flow path 138.

If the stepper motor 13 is driven in a counterclockwise direction, the overrun control valve 12 passes into its functional position II, in which the B control connection 132 of the overrun control valve 12 via a flow-through flow path 139 with the high-pressure connection 133 and the A Control connection 131 are connected via a flow path 141 to the return connection 134 of the follow-up control valve 12.

In the illustrated basic position 0 of the follow-up control valve 12, its two control connections 131 and 132 are blocked off from the supply connections 133 and 134.

When the run-on control valve 12 is controlled in its functional position I, the control grooves of the control disk 89 fixed to the housing in the development view of FIG. 3 are designated 99a, 99c and 99e via the flow path 137 of the run-on control valve 12 with its high-pressure connection 133 connected, while the control grooves denoted by 99b, 99d and 99f are connected to the return connection 134 via the flow flow path 138 of the overflow control valve 12. - 21 -

As a result, starting from the position of the rotor 18 within the stator 91 of the axial piston motor 10 shown in FIG. 3, the drive pressure spaces designated 37b, 37d and 37g, which are axially movable by the correspondingly indicated pistons 36b, 36d and 36g are, which - in the illustrated position of the rotor 18 - are axially supported on the coincidentally "rising" sections 41a, 41b and 41c of the cam rib 38 of the stator 91 of the axial piston motor 10, with those at the A control connection 131 of the follow-up control valve 12 - High - output pressure is applied, while those drive pressure chambers 37c, 37e and 37h which are axially movable by the pistons 36c and 36f or 36h and which are located on the correspondingly "inclined" sections 42a or 42b or 42c support the curve rib 38, are relieved of pressure via the flow path 138 of the Nachlau control valve 12 to the pressureless tank of the pressure supply unit, wobe i - in the illustrated special position of the rotor 18 - the two drive pressure chambers 37a and 37e, which are each axially movable by the pistons 36a and 36e, both against the high-pressure supply connection 133 and against the return connection 133 of the follow-up control valve 12 are blocked off.

As a result of the pressurization of the drive pressure chambers 37b, 37d and 37g, which are connected in the functional position I of the follow-up control valve 12 to the high-pressure outlet of the pressure supply unit, the pistons 36b, 36d and 36g which delimit these drive pressure chambers act in the direction thereof central longitudinal axes 26 attacking forces, the amount of which is given by the product P • F - -

, with P the output pressure level of the pressure supply unit and F the effective cross-sectional area of the pistons 36a to 36h of the rotor 18.

From these, directed towards the curved rib 38, onto the pistons. Forces 36b, 36d and 36g result in forces K φ directed in the direction of arrow 142 and acting on the turret-shaped drive part 19, the magnitude of which is given by the relationship

K? tgα

is given, with α being the "pitch angle" which the "rising" sections 41a, 41b and 41c of the curve rib 38 enclose with their base line 40, which, seen in the circumferential direction of the curve rib 38, the envelope of the "valleys "46 forms, in which the sloping sections 42a, 42b and 42c and the rising sections 41a, 41b and 41c of the crown prongs 39a, 39b and 39c of the curved rib 38 adjoin one another with a smooth curvature. 3 in FIG. 3 denotes the - obtuse - angles with which the rising sections 41a, 41b and 41c in the tips 44 of the crown teeth 39a, 39b and 39c pointing towards the drive part 19 of the rotor with a smooth curvature to the falling sections Connect 42a, 42b and 42c of the curve rib 38.

As a result of the force exerted on the drive part 19 of the rotor 18 of the axial piston motor 10 via the pistons 36b, 36d and 36g, the drive part 19 extends in the circumferential direction, that is to say in the azimuthal direction 43 'of FIG. 2c - in the direction of - 23 -

Arrow 136 of FIG. 1 seen clockwise - exerted forces, the drive part 19 of the rotor 18 of the axial piston motor 10 experiences a clockwise rotary movement, which leads to a corresponding, rotational movement of the output shaft 86 of the axial piston motor 10.

Starting from the position of the drive part 19 of the rotor 18 and its pistons 36a to 36h shown in FIG. 3, in which one of the pistons - the piston 36a - assumes and adopts its dead center position linked to the maximum volume of the drive pressure space 37a defined by it further piston - the piston 36e - assumes its dead center position linked to the minimal volume of the drive pressure space 37e defined by it, the aforementioned rotation or displacement of the drive part 19 in the direction of arrow 142 of FIG. 3 initially leads to the piston 36e 3, which had been in the inner dead center position, reaches the rise area 41b of the "middle" prong 39b of the curved rib 38 according to FIG. 3, at the same time, that is to say as soon as the piston disengages from the inner dead center position, the piston 36e limited drive pressure space 37e via the control channel 96e of the control disk 88 of the rotor 18 assigned to it and via the through-channel 87e of the plug 31e axially delimiting the drive pressure chamber 37e comes into communicating connection with the control groove 99c, which is connected to the A-control connection 131 of the follow-up control valve 12 and accordingly in the functional example under consideration under the high output pressure of the follow-up control valve stands. At the same time, the piston 36a previously in its outer dead center position disengages from this position and enters axial support with the falling region 42c of the prong 39c of the cam rib 38, the drive pressure space 37a movably delimited by this piston 36a via the associated control channel 96h of the control disk 88 of the rotor 1 and the through channel 87h of the end plug 31a of this drive pressure space 37a in communicating connection with the control groove 99f of the control disk 89 fixed to the housing connected to the B control connection 132 of the follow-up control valve 12 and thereby relieved of pressure. As soon as the middle piston 36e according to the illustration in FIG. 3 is pressurized, four pistons, namely the pistons 36b, 36d, 36e and 36g, are initially involved in the torque development until the next piston, in the selected example of the explanation, the piston 36d in the valley 46 between the rib sections 42a and 41b it reaches its outer dead center and, as soon as this is the case, is shut off against the control groove 99c of the control disk 89 fixed to the housing, etc.

The azimuthal width ψ ^ of the transverse webs 143 of the ring rib 116 of the second control disk 116 fixed to the housing, measured in the direction of arrow 43 "of FIG. 2a or in the direction of arrow 43 of FIG. 3, which, viewed in the circumferential direction, each has two adjacent ones Distinguish control grooves 99 from each other and the opening cross-sections of the control channels 96, with which they can overlap with the clear cross-sectional areas of the control grooves, are matched to one another in such a way that the drive pressure spaces - as shown in FIG. 3, the drive pressure spaces 37a and 37c, by those Pistons - 36a and 36e - are limited, which are currently in their outer or inner dead center positions, both against the A-control port 131 of the overrun - 25 -

Control valves 99a and 99c connected to the control valve and against the control grooves 99b and 99d connected to the B control connection 132 are blocked, but after a small shift from the dead center positions mentioned, but in communicating connection with the next control grooves 99f following in the direction of rotation or 99c.

In order to achieve an operation of the axial piston motor 10 which is as free from vibrations as possible, the radius of curvature with which rising sections 41 and falling sections 42 of the curved rib 38 connect to one another is somewhat larger than the radius of the piston support balls 47, which are located on the barrel Roll the surface of the curved rib 38, the support balls 47 in the bearing cups 48 of the pistons 36 are slidably mounted. Through-going, axial piston bores 144 open into the bearing troughs 48 of the pistons 36, via which pressure medium is pressed into the bearing pans 48 for lubrication of the support balls. When the axial piston motor 10 is operating in small quantities, pressure medium which always emerges from the bearing pans 48 and which passes into the leak oil chamber 121 is also used for lubricating the motor shaft 16 and for lubricating the angular contact ball bearings 52 and 53. So that a sufficient oil flow from leak oil chamber 121 can get to angular contact ball bearings 52 and 53, bearing section 54 of motor shaft 16, with which it is slidably mounted in slide bearing bushing 72, is indicated by dashed lines in FIG. 1 indicated lubrication grooves 146 provided.

If the stepper motor 13, as seen in the direction of arrow 136, is driven counterclockwise, the overrun control valve 12 reaches its functional position II, with which the direction of rotation of the axial piston motor 10 is linked in the counterclockwise direction.

The following assumptions are made for a rough estimate of the useful power and the torque that can be achieved with the axial piston motor 10:

Cross-sectional area of the pistons 36: 1.5 cm "'

Piston stroke: 1.5 cm

Operating pressure: 100 bar

This data results in a swallowing volume per piston stroke

^• 3 by 2.25 cm. Since each piston performs three strokes per revolution, the displacement volume of a piston per revolution of the engine is 6.75 cm.

Since eight pistons 36 are present, the swallowing volume ^ _j per revolution is 54 cm.

With these values, the torque M that can be achieved with the axial piston motor 10 is first obtained by the relationship:

2π - 27 -

is given, a value of 77 Nm, Δp denoting the pressure difference between the control connections 131 and 132 of the follow-up control valve 12 which essentially corresponds to the operating pressure, and the mechanical-hydraulic efficiency of the axial piston motor 10 for which a Value of 0.9 is assumed.

For the Nutzleitstung P _n , which by the relationship

P _n = ^Q _e ^{* Δ} P '^ t ⁽²⁾

is given, with Q _e denoting the effective swallowing current of the motor and -YJ _t denoting the overall efficiency of the axial piston motor 10, which may have a typical value of 0.85, a value results from the other aforementioned assumptions of 15.3 kW if it is assumed that the motor is operated at 2000 rpm to calculate the effective swallowing current.

The rotational speed of the axial piston motor 10 and thus also its output is regulated by regulating the swallowing volume Q _e by means of the follow-up control valve 12, which according to its structure and function. seen in isolation, can be assumed to be known. The follow-up control valve 12 shown in FIG. B. in DE 37 29 564 AI described in detail, to which extent reference is expressly made.

Such a follow-up control valve works with an electrically controlled setpoint specification of the angle of rotation Ψ of the rotor 18 and mechanical feedback of this angle of rotation, the opening cross section, which is in each case in the alternate - 28 -

tive directions of rotation - clockwise or counterclockwise - of the axial piston motor 10 used flow path 137 and 138 or 139 and 141 varies, that is, increased with increasing tracking error and reduced with decreasing tracking error.

In the special embodiment shown, the Nac running control valve 12 is designed as a 4/3-way slide valve, d assuming that the setpoint and actual value of the rotor angle of rotation are the same, basic position 0 is assumed, in which the control connections 131 and 132 against the supply connections 133 and 134 of the run-on control valve 12 are shut off. The steady-state operation of the engine 10 - constant speed - corresponds to a passage state (I or II) of the follow-up control valve 12 which is linked to a defined flow resistance.

In the drive unit 11 shown in FIG. 1, the central axis 14 simultaneously marks the axis of rotation of the output shaft 17 of the stepping motor 13 and the axial piston motor 10 as well as a (rotation angle) setpoint specification spindle 147 and an actual value feedback spindle 148 .

The setpoint specification spindle 147 is designed as a hollow spindle with an internal thread, which is connected in a rotationally fixed manner to the output shaft 17 of the stepping motor 13, but is arranged so that it can be axially pushed back and forth. For this purpose, the output shaft of the stepping motor 17 is provided with an external axial toothing, with which an axial internal toothing of the spindle end meshes.

The feedback spindle 148 is non-rotatably and non-displaceably connected to the motor shaft 16 and has an external thread - 29 -

in meshing engagement with the internal thread of the setpoint input spindle 147.

The total of 149 slide valve of the Nachlau control valve 12 comprises a total of four valve bodies 151 to 154, by moving them together in the direction of arrow 156 according to FIG. 1 to the left, the follow-up control valve reaches its functional position I and through their common position Displacement in the opposite direction, represented by arrow 157, the overflow control valve 12 reaches its functional position II, the flow cross sections of the flow paths coming in both cases with increasing displacement out of the blocking position of the overflow control valve 12 corresponding to the basic position 0 137 and 138 or 139 and 141 increase steadily, as already mentioned.

The valve bodies 151 to 154 are clamped in pairs between stop rings 158 and 159, through which the setpoint value spindle passes axially, with axial ball bearings 161 and 162, each between one of the stop rings 158 and 159 and a radial one End flange 163 and 164 of the setpoint input spindle 147 are arranged, rotational relative movements of the same with respect to the stop rings 158 and 159 allow such that they perform - axial - displacement movements of the setpoint input spindle 147 with, but do not rotate, but rotatably on the valve bodies 151 to 154 remain supported.

The follow-up control valve 12, which has been explained in summary in terms of its basic structure, operates in the context of the hydraulic drive unit 11 as follows: - -

If the stepper motor 13 with a z. B. a first output 166 of an electronic control unit 167, a sequence of control pulses driven clockwise, the setpoint input spindle 147 also rotating, this leads because of the thread engagement between the setpoint input spindle 147 and the actual value feedback spindle 148 , which initially "remains", for an axial displacement of the setpoint input spindle 147 and with this of the valve slide 149 in the direction of arrow 156 - to the left, that is to say into the functional position I of the follow-up control valve 12 resulting pressurization of the drive pressure chambers 37b, 37d and 37g and pressure relief of the drive pressure chambers 37c, 37f and 37h of the rotor 18 (FIG. 3) of the axial piston 10 is also driven clockwise, the feedback spindle 148 also carrying out this rotary movement. As a result of this rotary movement of the feedback spindle 14, a restoring force acting in the direction of arrow 157 is exerted in a form-fitting manner by its thread engagement with the internal thread of the setpoint specification spindle 147. In the steady state, in which the rotor 18 of the axial piston motor 10 and the output shaft 17 of the stepping motor 13 rotate “at the same speed”, the valve body 159 of the follow-up control valve 12 “remains” in a position that was determined by one with which Given the predetermined engine speed, the value of the effective swallowing volume of the axial piston engine 10 and thus also corresponds to a certain useful output of the same.

The same applies mutatis mutandis in the event that the stepper motor 13 by a z. B. at the second output 168 of the electronic control unit 167 sequence of control pulses in the opposite direction - 31 -

Is driven clockwise, whereby the follower control valve 11 is controlled in its functional position II, in which the axial piston motor 10 rotates counterclockwise.

Instead of an electric motor designed as a stepper motor, which enables a virtually "digital" specification of the speed of the axial piston motor 10, a level-controlled electric motor, e.g. B. a DC motor can be used, especially when it is primarily important that the axial piston motor 10 with a certain minimum useful power - continuously - is driven and the "exact" number of revolutions of the rotor 18 is irrelevant.

Furthermore, it goes without saying that an inventive axial piston motor 10 with a different number of drive pistons 36 and control grooves 99, z. B. seven pistons and six control grooves can be realized.

As far as reference numbers are given in individual drawing figures

Sin, that are not mentioned in the associated description text _/ T should thereby give a reference to the description part in which the reference numerals are used

Terms are defined.

Claims

3 2

Claims

Hydraulic axial piston motor as a rotary drive motor for tools or positioning or feed drives on machine tools or processing machines, with a rotor rotatably mounted in a housing and rotatably connected to the output shaft of the motor, the holes in axially symmetrical distribution about the axis of rotation has, in each of which a piston in the axial direction - parallel to the axis of rotation - is displaceably guided in a pressure-tight manner, which forms the axially movable limitation of a drive pressure chamber, by its controllable application of the outlet pressure of a pressure supply unit, the piston in contact with a housing-fixed arranged, with the axis of rotation concentric cam track can be pushed, which, likewise in a group axially symmetrical with respect to the axis of rotation, but in a smaller multiplicity than that of the bores of the motor, has projections pointing to it and sinks arranged between them, which, with gla tter curvature next to each other, form a rolling surface for support balls, which are freely rotatably supported at the free ends of the pistons, the pressure medium supply and discharge to and from the drive pressure chambers of the rotor via rotor-side control channels and alternately communicating connection with the housing-side Control rooms are located in one of the 33

Axial symmetry of the cam track corresponding symmetry in azimuthally equidistant distribution around the central axis d axial piston motor and, viewed in the direction of rotation, can be alternately connected to the operating pressure outlet or the tank of the pressure supply unit, and the azimuthal width is one under pressure and one control walls relieved from the tank towards each other are equal to the azimuthal width of the rotor-side through-channels with which they can overlap with the clear cross-sectional area of the control rooms,

characterized in that the rotor (18) of the axial piston motor (10) is connected both rotationally and displaceably to its motor shaft (169) and is mounted on the motor housing (91) without play in the axial direction, and in that the control channels (96a to 96h) by their alternating cross-section overlap with pressurized or pressure-relieved control spaces (99a to 99f), the alternating pressurization or relief of the drive pressure spaces (37a to 37f) of the rotor (18) takes place on a control disk (88), which are arranged rotatably coupled to the drive part (19) of the rotor (18) which limits the drive pressure spaces (37a to 37f), with respect to this within a small angular or axial displacement which enables the execution of wobbling or axially shifting compensating movements - Is held movable, this control disc (88) with a metallic sealing surface (112) within which the housing side n orifices (98 of their control channels (96) are located on a housing side 3 4

Sealing surface (114), within which the mouth openings of the housing-side control spaces (99a to 99f) lie, lies in a sliding and sealing manner and by means of sealing elements (34) under elastic prestress, which on the side of the drive part (19) facing the control disk (88) ) mediate the sealing of the drive pressure spaces (97a to 97h) against the housing space (121) containing the rotor (18), which is pushed into contact with the sealing surface (114) on the housing side.

Axial piston motor according to Claim 1, characterized in that the sealing elements (34) which are under elastic pretension are designed as O-rings, each between an annular shoulder (29) of the axial bores (24) of the drive part (19) which form the radial boundaries of the drive pressure spaces (37a to 37h) and a sealing surface of a closing part (31) opposite this, which form the respective one-sided axial boundaries of the drive pressure spaces (31a to 31h) of the rotor (18, 19).

Axial piston motor according to Claim 2, characterized in that the end parts (31) are designed as stepped piston-shaped plugs with central through bores (87), and in that these plugs have a metallic one on their side facing the control disk (88) for contact with the latter Have sealing contact surface (118). 3 5

Axial piston motor according to claim 3, characterized in that the control disk-side sealing surfaces (118) of the plugs (31) are formed by the end faces of annular ribs (117) which surround the control disk-side mouth openings of the through bores (87) of the plugs (31).

Axial piston motor according to claim 4, characterized in that the sealing surface, within which the orifices of the control channels (96) of the control disk (88) facing the plugs (31) of the rotor (18, 19) are arranged, through the free end face (109 ) a flat annular rib (111) of the control disk (88) is formed.

Axial piston motor according to one of the preceding claims, characterized in that the sealing surface (112) with which the control disk (88) slides against the housing-fixed sealing surface (114), within which the cross sections of the control spaces (99) open, and / or the housing fixed sealing surface (114) is formed by the end face (112 or 114) of a flat annular rib (113 or 116) of the control disk (88) or of the housing (89) delimiting the control spaces (99).

Axial piston motor according to one of the preceding claims, characterized in that the housing part (89) delimiting the control chambers (99) in a housing-fixed manner is in turn designed as an annular disk-shaped housing end part of the motor housing (919). 3 6

8. Axial piston motor according to one of the preceding claims, characterized in that two axially braced roller bearings (52 and 53) are provided for play-free mounting of the rotor (18) of the axial piston motor (10).

9. Axial piston motor according to claim 8, characterized in that the bearing section (54) of the motor shaft (16), on which the angular contact bearings (52 and 53) are arranged, between the end section (86) emerging as the output shaft from the housing (91) Motor¬ shaft (16) and the drive part (19) of the rotor (18) carrying drive section (59) of the motor shaft (16) is arranged.

10. Axial piston motor according to claim 9, characterized in that the angular roller bearings (52 and 53) are arranged in a sleeve-shaped housing part (51) which on its side facing the drive part (19) of the rotor (18) has a radially inwardly facing Has flange (74), from which a curved rib (38) extends, which, with its axially projecting and retracting end face facing the drive part (19), forms the curved path on which the pistons (36) of the rotor (18) can be axially supported.

11. Axial piston motor according to claim 10, characterized in that the sleeve-shaped housing part (71) is provided with a radially inwardly facing flange (74) which has a central section (58) - 37 -

surrounds the motor shaft (16) at a radial distance, and that in the sleeve-shaped housing part (71) a plain bearing bush (72) is inserted, in which the shaft (16) with its central section (58) is slidably mounted.

12. Axial piston engine according to claim 11, characterized in that in the plain bearing bushing (72) mounted central portion (58) of the motor shaft (16) is provided with lubricating grooves (146) through which the drive part (19) of the Leakage oil chamber (121) containing the rotor (18), leakage oil for lubrication can also pass into the housing space containing the cross roller bearings (52 and 53).

13. Axial piston motor according to one of the preceding claims, characterized in that the supporting balls (47) of the pistons (36) of the rotor (18, 19), which can be rolled on the cam track, are mounted in pans (48), in which the drive pressure chambers (37) communicating through bores of the pistons (36) open out.

14. Hydraulic drive unit using an axial piston motor according to one of the preceding claims 1 to 13 with a follow-up control valve provided for movement control of the axial piston motor, which operates with an electrically controlled angle of rotation setpoint specification and mechanical angle of rotation actual value feedback, whereby for the Setpoint specification is an axially displaceable spindle which can be driven by means of an electric control motor and one for feedback of the actual value - 58 -

the motor shaft is provided with a rotationally fixed and non-displaceably connected feedback spindle, which mesh with one another via internal and external threads,

characterized in that the output shaft (17) of the electric motor (13) provided for setting the setpoint, the spindle (147) which can be driven therewith, the feedback spindle (148) and the motor shaft (16) of the axial piston motor (10) coaxially along the central longitudinal axis (14) of the axial piston motor (10) are arranged.