EP0428574B1 - Hydraulic axial-piston engine - Google Patents

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

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 rotatably mounted in a housing with the drive shaft of the motor rotatably and displaceably connected, axially play-free, rotor, which is axially symmetrical Distribution around the axis of rotation has bores in which a piston can be displaced in a pressure-tight manner in the axial direction - parallel to the axis of rotation - which forms the axially movable boundary of a drive pressure space, through the controllable application of which to the outlet pressure of a pressure supply unit, the piston in system with a housing-fixed , With the axis of rotation concentric cam track can be urged, which, likewise in a group that is axially symmetrical with respect to the axis of rotation, but with less multiplicity than that of the bores of the motor, indicates projections un d has depressions arranged between them, which, with a smooth curvature adjoining one another, form a rolling surface for support balls which are freely rotatably mounted on the free ends of the pistons, the pressure medium supply and discharge to and from the drive pressure chambers of the rotor via the rotor-side, on a control disk which is connected to the rotor in a rotationally fixed manner and on the housing-side control spaces which alternately come into communicating connection therewith takes place in a symmetry corresponding to the axial symmetry of the cam track in azimuthally equidistant distribution are grouped around the central axis of the 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, the control channels being arranged on a control disk which has a metallic sealing surface within which the housing-side orifices their control channels lie on a housing-side sealing surface, within which the orifices of the housing-side control spaces lie, is held in sliding and sealing engagement, and in order to enable wobbling or axially displacing compensating movements with respect to the rotor within a small angular or axial displacement range End elements provided with central through bores, which are inserted into the bores of the rotor and, via these bores, seal, elastic, prestressed against the housing space containing the rotor elements are axially supported on the rotor, as well as with a metallic sealing surface in turn sealingly against the control disk, is elastically resiliently supported on the rotor.

Such axial piston motors are known from FR-A 1 452 275.

According to a design of the known axial piston motor explained in detail in FR-A 1 452 275, the closure elements are the metal sealing connection of the drive pressure spaces of the individual linear cylinders of the rotor with the control channels of the control disk End elements achieved in the bores mentioned, so that they are not subject to any significant wear, however, in order to keep the end elements in sealing contact with the control disk, additional spring elements - corrugated ring springs - must be provided, which in turn are located in the internal grooves of the cylinder bores of the rotor support the more or less elastic washers axially. A disadvantage is the not inconsiderable technical outlay which is associated with the insertion of internal grooves into the cylinder bores, the arrangement of internal support rings and the spring washers axially supported on these.

FR-A 1 452 275 also mentions the possibility of pressing the end elements against the control disk by means of elastic sealing rings clamped between the end faces of the same and the rotor of the axial piston motor, in which case, however, a centering effect cannot be achieved by the sealing rings and therefore the centering of the end elements must be achieved by a particularly precise adaptation of their shape to the bore cross-sections of the cylinder bores - exact, section-wise spherical shape of their outer lateral surfaces - which in turn is associated with considerable production expenditure and, since in this case the end elements in a sliding system with the Cylinder bore can come, can also be subject to wear.

The last-mentioned design of the known axial piston motor would also have this disadvantage, can come with the cylinder bore, can also be subject to wear.

The last-mentioned design of the known axial piston motor would also have this disadvantage if, instead of rubber-elastic seals, metallic seals which can develop an axial preload, as known in connection with hydraulic motors or pumps by JP-A 6 259 773, were used .

Starting from an axial piston motor of the type mentioned, it is therefore the object of the invention to improve it in such a way that operation as a high-speed motor is possible with a simple construction and low wear.

This object is achieved by the features mentioned in the characterizing part of claim 1.

Due to the design of the bores of the rotor as stepped bores, the end elements as stepped piston-shaped plugs and the arrangement of a prestressed elastic ring seal between an annular shoulder of the cylinder bores and the radial flange of the plugs, this seal also the cylinder jacket-shaped, smaller step of the plug, under tension , encloses, the seal conveys three essential functions, namely on the one hand the sealing of the respective drive pressure space against the housing space containing the rotor, and on the other hand the Pressing the respective closure element onto the control disk and thirdly centering the closure element with respect to the central bore axis, with the favorable consequence that, apart from the good planarity of their metallic sealing surfaces, the plugs otherwise do not require any particularly precise machining and can therefore be produced as simple turned parts which do not require a particularly precise adaptation to the bore diameter, so that relatively large gap widths between the flange-shaped steps of the stopper and these surrounding bore walls are possible, for which particularly favorable minimum values are indicated by the features of claim 2.

It is also expedient if the plugs end at a small distance e from the inner annular shoulder of the cylinder bores, which in any case prevents the plugs from striking the bore walls and minimizing wear.

The features of claims 4 to 7 indicate advantageous designs of the sealing elements of the rotor, the control disk of the rotor and 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 also 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.

• Fig. 1 eine hydraulische Antriebseinheit mit einem mittels eines Elektromotors und eines Nachlauf-Regelventils gesteuerten, erfindungsgemäßen Axialkolbenmotor, in maßstäblicher Längsschnitt-Darstellung,
• Fig. 2 Einzelheiten des Axialkolbenmotors gemäß Fig. 1, in vergrößertem Maßstab,
• Fig. 2a) bis 2c) vereinfachte Ansichtsdarstellungen von Steuer- elementen des Axialkolbenmotors gemäß Fig. 1 und
• Fig. 3 eine Abwicklung des Axialkolbenmotors gemäß Fig. 1, entlang der die zentralen Achsen seiner Antriebskolben enthaltenden Zylinderfläche, zur Erläuterung seiner Funktion.

Further details and features of the invention will become apparent from the following description of a special embodiment with reference to the drawing. Show it:

• 1 shows a hydraulic drive unit with an axial piston motor according to the invention, controlled by means of an electric motor and a follow-up control valve, in a scale longitudinal section illustration,
• 2 details of the axial piston motor according to FIG. 1, on an enlarged scale,
• 2a) to 2c) simplified view representations of control elements of the axial piston motor according to FIGS. 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.

In Fig. 1, to the details of which reference is expressly made, a hydraulic axial piston motor according to the invention, generally designated by 10, is shown in the context of a hydraulic drive unit, which in turn is generally designated by 11, which itself and as a control element for the latter is designated by 12 includes electrohydraulic overrun control valve that 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, the rotor of which - for the sake of simplicity - not shown - when driven with a sequence of electrical pulses per pulse, each rotation 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 stepper 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, designated overall by 18, of the axial piston motor 10 comprises a thick-walled, ring-cylindrical drive part 19 which is designed in the manner of the drum of a drum turret and 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 connected in a manner not shown in detail to a control valve-side section 21 of the motor shaft, which is connected by a central one Bore 22 of the drive part 19 of the rotor 18 passes through and projects out of the central bore 22 on the valve side with a free end section 23 of its length.

In the drive part 19 of the rotor 18 a total of eight through-axis 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. 2 b), to the details of which reference is also expressly made , apparent arrangement in azimuthal angular intervals of 45 ° perpendicular to the bore circle 27, the diameter of which corresponds approximately to the mean value between the outer diameter of the drive part 19 and the inner diameter of its central bore 22 and is somewhat larger than the exact mean value in the special embodiment shown.

On the control valve side, these bores 24 pass 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.

Step-shaped plugs 31 are inserted into the stepped through bores 24, 28, as can best be seen in the illustration in FIG. 1a), the details of which are also expressly referred to. These plugs 31 have a cylinder-shaped step 32, the outer diameter of which is equal to or approximately the same as the diameter d 1 of the bore 24 of the drive part 19 and an outer diameter larger, annular flange-shaped piston step 33, the outer diameter of which is slightly smaller than the diameter d 2 of the larger bore step 28 of the Drive part 19. The peripheral lateral surface 33 'of this ring flange 33 has a flat-convex curvature.

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 separate the - spatially - further bore steps 28 against the bores 24 of the drive part 19, 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 from that of the bore steps 28 and 24 opposing annular shoulders 29 are arranged. The sealing disk 35 provided as an additional sealing element consists of an elastomer, e.g. B. a polyamide, with this washer between the peripheral lateral surface 33 'of the annular flange 33 of the respective plug 31 and the further bore 28 of the drive member 19 remaining, relatively narrow annular gap, the radial width of which is considerably smaller than the radial width of 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 enables the motor 31 to "wobble" to compensate for manufacturing tolerances, and nevertheless ensures a sufficiently pressure-tight limitation of drive pressure spaces 37 of the axial piston motor 10.

In each of the - axial - bores 24 of the drive part 19 of the rotor 18, a piston 36 is guided in a pressure-tight manner, which forms the axially movable limitation of one of the drive pressure spaces 37 - 37a to 37h - of the rotor 18, through 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 in the particular embodiment shown, in which the rotor 18 is equipped with eight drive pistons 36 - 36a to 36h is in the form of a three-pronged "crown", the prongs 39 - 39a, 39b, 39c - are arranged pointing to the drive part 19 of the rotor 18.

Seen in the development view of FIG. 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 limbs 41 - 41a, 41b and 41c - as well as 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 in Fig. 3 by the arrow 43, in Fig. 2c) represented by the arrow 43 ', azimuthal direction 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 slope or inclination, which in the "tips" 44 of the curved rib 38 and in the "valleys" 46 arranged in between of a small angular range, each comprising only a few degrees, connect to 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 the valley regions 46 connect to each other, 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 rotatably mounted 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 seen in the azimuthal direction (φ direction 43 ') ascending and descending support or tread 49 of the curved rib 38 is formed as a flat-concave groove, wherein, now seen in the direction of cut of FIG. 1, the radius of curvature of the tread 49th 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 shaft 16 is mounted free of play by means of two angular ball bearings 52 and 53 braced axially against one another. 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 through 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 is rotationally and displaceably fixed 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 is the same as that of the bearing section 54 in the special embodiment shown.

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 directly abut each other with their mutually facing annular end faces.

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 order to be able to brace them against one another, such that a gap 69 between the facing ring end faces 67 and 68, respectively with only a small axial gap width remains in the illustrated embodiment, which is sufficient to be able to brace the angular contact ball bearings against each other.

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 of which the motor shaft 16 is also supported its central section 58 is additionally rotatably and slidably mounted. This slide bearing bush 72 is supported with its radially outward-pointing support flange 72 axially on a radially inward-facing ring flange 74 of the housing part 51 provided for the mounting of the motor shaft 16, the curved rib on the inside of this ring flange 74 of the sleeve-shaped housing part 51 facing the drive part 19 38 is arranged.

The slide bearing bush 72 has a cylindrical 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 slide 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 region 77 is 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 section 61 of the motor shaft 16 which separates the central section 58 from the bearing section 54 of the motor shaft 16 also lies, while the plane in which the bearing-side ring end face of the Central area 78 of the plain bearing bush 72 is located at a small axial distance from this "within" the area of the central portion 58 of the motor shaft 16.

The axial bracing of the two angular contact ball bearings 52 and 53 against one another takes place by means of a clamping ring 79, which can only be axially supported on the outer, ring 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 52 and 53 can be clamped against each other for play-free mounting of the shaft 16 and with this of the rotor 18 of the motor 10, axial clamping screws 82 are provided in an axially symmetrical distribution about the central longitudinal axis 14 of the motor which are tightened using 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 - the 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 an - essentially rotor-fixed - axial limitation of the drive pressure spaces 37 of the drive part 19 of the rotor 18 have, as can best be seen in FIG. 1 a), central through bores 87, via which the supply and discharge from pressure medium to or from the drive pressure chambers 37, through their appropriately controlled pressurization or relief, the axially movable boundaries of the drive pressure chambers 37 forming piston 36 experience axial displacements, which result from the fact that the pistons 36 via the support balls 47 on the cam rib 38 are supported axially, the support balls 47 being able to roll on the running surface 49 of the curved rib 38, are converted into rotational movements of the drive part 19 of the rotor 18 and with it the motor shaft 16.

To control the pressurization or pressure 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 whole with 91 designated motor housing or stator of the axial piston motor 10 forms.

The rotor-side, first control disk 88 is connected in a rotationally fixed manner to the rotor 18 by means of a driving pin 92 (FIG. 2b) which is fixedly 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. 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 _{z of} the centering hole 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.

The first control disk 88 is provided with axial control channels 96, the number and symmetry of the arrangement of which corresponds 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 plug 31 of the drive part 19, orifices 97 which are arranged coaxially with the central axes 26 of the through bores 87 of the plugs 31 and have the same diameter as these through bores 87.

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

The control channels 96 of the first control disk 88 are realized by 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 circle 27 of which the central axes 26 of the larger diameter sections 106 of the 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 such that the bore sections 102 and 106 seen in the illustration in FIG. 2b, the same outer, through the circle 107 represented envelope, 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 88, which runs at right angles to the central longitudinal axis 14 of the axial piston motor 10, as shown in FIGS. 1 and 1a).

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 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-fixed” - axial boundaries of the drive pressure chambers 37 of the rotor 18, are on their side facing the first control disk 88 with the central longitudinal axis 26 of their through bores 87 are provided with coaxial ring ribs 117, which have ring-shaped end end faces 118 which are parallel to the ring end face 109 of the first flat ring rib 111 of the first control disk 88 facing them and with which they, with a metallic seal on the annular end end face 109 first control disk 88 - are held in contact by the elastic prestressing of the rubber-elastic ring seals 34. As a result, the first disk 88 - with the end face 112 of its second flat annular rib 113 is held in metallic sealing contact 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 centering bore 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 1 and d 2 of the bore stages 24 and 28 in which the cylinder-shaped piston stage 32 and the annular flange-shaped piston stage 33 are Plugs 31 are arranged, with positive tolerances of at least 0.02 mm, that is to say somewhat coarser in diameter than the above-mentioned steps 32 or 33 of the plugs 31, so that both these and the first control disk 88 have sufficient play "in order to be able to contact one another with their ring ribs 117 and 111 or 113 and 116, each with a metallic seal, the ring seals 34 acting as a buffer body, as it were, which" axial "manufacturing tolerances of the parts which lie tightly against one another - the first control disk 88 and the housing-fixed control disk 89 on the one hand and the plug 31 on the first S control disc 88 on the other hand - to be able to compensate.

In principle, the first control disk 88 could be made in one piece with the plugs 31 delimiting the drive pressure chambers 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 leakage oil chamber 121 can pass, a sufficient elastic 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 control disk 89 fixed to the housing and a radial ring flange 124 of the sleeve-shaped housing part 51 (FIG. 1) and is fixedly connected to the latter by means of housing fastening screws 126. The tubular housing part 122 is sealed against these housing parts by means of an annular seal 127 and 128, respectively, which are attached in the outer grooves of the control disk 89 or the sleeve-shaped housing part 51, which are fixed to the housing.

The control grooves 99 - 99a to 99f -, which are arranged with the 6-digit, axially symmetrical grouping with respect to the central axis 14 of the axial piston motor 10, are arranged in the circumferential direction, with the grouping which can be seen best from FIG. 2a, to the details of which express reference is made , that is, seen in the azimuthal direction represented by the arrow 43˝ of FIG. 2 a) or the arrow 43 of FIG. 3, to the details of which are also expressly referred to, via connecting channels 129 - 129a to 129f - alternating connected to the A control connection 131 of the follow-up control valve 12 or its B control connection 132, 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 follow-up 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 stepping 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 connection 33 (P connection) and the B control connection 132 is connected to the return connection 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-through 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 against the supply connections 133 and 134.

If 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 illustration 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 designated 99b, 99d and 99f are connected via the flow flow path 138 of the overflow control valve 12 to the return connection 134 thereof.

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 movably limited by the correspondingly indicated pistons 36b, 36d and 36g, 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 the pending at the A control connection 131 of the follower control valve 12 - high - Output pressure is applied, while those drive pressure spaces 37c, 37e and 37h, which are axially movable by the pistons 36c and 36f and 36h, which are supported on the same "inclined" sections 42a and 42b and 42c of the cam rib 38, over the flow path 138 of the follow-up control valve 12 to the unpressurized tank of the pressure supply unit are depressurized, wherein - in the made 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, are shut off both against the high-pressure supply connection 133 and against the return connection 133 of the follow-up control valve 12.

As a result of the pressurization of the drive pressure chambers 37b, 37d and 37g, which are connected to the high-pressure outlet of the pressure supply unit in the functional position I of the follow-up control valve 12, the pistons 36b, 36d and 36g which delimit these drive pressure chambers move in the direction of their 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 forces directed towards the cam rib 38, acting on the pistons 36b, 36d and 36g, forces K φ acting in the direction of the arrow 142 and acting on the turret-shaped drive part 19 result in the magnitude from the relationship

K φ = P · F · tgα
is given, with α being the "pitch angle" which the "rising" sections 41a, 41b and 41c of the curved rib 38 enclose with their base line 40, which, seen in the circumferential direction of the curved 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 each other 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.

By the piston 36b, 36d and 36g exerted on the drive part 19 of the rotor 18 of the axial piston motor 10, on the drive part 19 in the circumferential direction, that is in the azimuthal direction 43 'of FIG. 2c - in the direction of 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 rotational 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 its dead center position associated with the maximum volume of the drive pressure space 37a defined by it and another piston - The piston 36e - occupies its dead center position associated with the minimal volume of the drive pressure space 37e bounded 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, the had been in the inner dead center position, reached the rise region 41b of the "middle" prong 39b of the cam 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 drive pressure space 37e delimited by this piston 36e the control channel 96e assigned to it of the control disk 88 of the rotor 18 and via the passage Angle 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 is accordingly in the functional example under consideration under the high output pressure of the follow-up control valve. 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 18 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 as shown in FIG. 3 is pressurized, first four pistons, namely the pistons 36b, 36d, 36e and 36g are involved in the torque development until the next piston, in the selected explanatory example, the piston 36d in the Valley 46 between the rib sections 42a and 41b reaches its outer dead center, and, if 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 φ _{b of} the transverse webs 143 of the annular rib 116 of the second control disk 116 fixed to the housing, measured in the direction of the arrow 43 "of FIG. 2a or in the direction of the arrow 43 of FIG. 3, which, viewed in the circumferential direction, each have 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, which 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 follow-up control valve connected control grooves 99a or 99c as well as against the control grooves 99b or 99d connected to the B control connection 132, but after a small shift out of the dead center positions mentioned, but in communicating connection with the next control grooves 99f or following in the direction of rotation 99c arrive.

In order to achieve an operation of the axial piston motor 10 that is as free from vibrations as possible, the radius of curvature with which rising sections 41 and falling sections 42 of the cam rib 38 connect to one another is somewhat larger than the radius of the piston support balls 47, which roll on the running surface of the cam rib 38 can, wherein the support balls 47 are slidably mounted in the bearing pans 48 of the pistons 36. Continuous, 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 lubricating 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 supported in slide bearing bushing 72, is provided with lubricating grooves 146, which are indicated by dashed lines in FIG. 1.

If the stepping 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 cm²
Piston stroke: 1.5 cm
Operating pressure: 100 bar

This data results in a swallowing volume of 2.25 cm³ per piston stroke. Since each piston performs three strokes per revolution, the swallowing volume of one piston per revolution of the engine is 6.75 cm³.

Since there are eight pistons 36, the swallowing volume V _th per revolution is 54 cm 3.

gegeben ist, ein Wert von 77 Nm, wobei mit Δ p die im wesentlichen dem Betriebsdruck entsprechende Druckdifferenz zwischen den Steueranschlüssen 131 und 132 des Nachlauf-Regelventils 12 und mit η_mh der mechanisch-hydraulische Wirkungsgrad des Axialkolbenmotors 10 bezeichnet sind, für den ein Wert von 0,9 angenommen sei.With these values, the torque M that can be achieved with the axial piston motor 10 is given by the relationship: $$\text{M =}\frac{{\text{p · V}}_{\text{th}}}{\text{2π}}{\text{· Η}}_{\text{mh}}$$

is given, a value of 77 Nm, with Δ p 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 with η _mh the mechanical-hydraulic efficiency of the axial piston motor 10, for which a value of 0.9 is assumed.

gegeben ist, wobei in dieser Beziehung mit Q_e der effektive Schluckstrom des Motors und mit η_t der Gesamtwirkungsgrad des Axialkolbenmotors 10 bezeichnet sind, der einen typischen Wert von 0,85 haben möge, ergibt sich mit den weiteren vorgenannten Annahmen ein Wert von 15,3 kW, wenn zur Berechnung des effektiven Schluckstromes davon ausgegangen wird, daß der Motor mit 2000 U/min betrieben wird.For the Nutzleitstung P _n , which by the relationship $${\text{P}}_{\text{n}}{\text{= Q}}_{\text{e}}{\text{· Δ}}_{\text{p}}{\text{· Η}}_{\text{t}}$$

is given, in this connection with Q _e the effective swallowing current of the motor and with η _t the total efficiency of the axial piston motor 10, which may have a typical value of 0.85, results in a value of 15 with the other aforementioned assumptions, 3 kW if it is assumed that the motor is operated at 2000 rpm to calculate the effective swallowing current.

The control of the rotational speed of the axial piston motor 10 and thus also of its output takes place by regulating the swallowing volume Q _e by means of the run-on control valve 12, which can be assumed to be known in terms of structure and function. The overflow control valve 12 shown in FIG. B. in DE 37 29 564 A1 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 φ of the rotor 18 and mechanical feedback of this angle of rotation, the opening cross-section of each of the alternatives being proportional to and in the same direction as the follow-up error Direction of rotation - clockwise or counterclockwise - of the axial piston motor 10 used flow path 137 and 138 or 139 and 141 varies, that is coarsened with increasing tracking error and reduced with decreasing tracking error.

In the special embodiment shown, the overrun control valve 12 is designed as a 4/3-way slide valve, which assumes its basic position 0, in which the setpoint and actual values of the rotor angle of rotation are the same, in which the control connections 131 and 132 against the supply connections 133 and 134 of the follow-up control valve 12 are blocked. 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 (rotational 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 in meshing engagement with the internal thread of the setpoint input spindle 147.

The total of 149 slide valve of the follow-up control valve 12 comprises a total of four valve bodies 151 to 154, by moving them together in the direction of arrow 156, to the left according to FIG. 1, the follow-up control valve reaches its functional position I and by moving them together in the opposite direction, represented by the arrow 157, the overflow control valve 12 reaches its functional position 11, the flow cross sections of the flow paths 137 and 138 in both cases with increasing displacement from the blocking position of the overflow control valve 12 corresponding to the basic position 0 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 specification spindle passes axially, with axial ball bearings 161 and 162, which each between one of the stop rings 158 and 159 and a radial end flange 163 and 164 respectively Setpoint specification spindle 147 are arranged, allow relative rotational movements of the same with respect to stop rings 158 and 159, such that they execute - axial - displacement movements of setpoint specification spindle 147, but do not rotate, but are supported on valve bodies 151 to 154 in a rotationally fixed manner stay.

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

If the stepper motor 13 with a z. B. a first output 166 of an electronic control unit 167 delivered sequence of control pulses clockwise, the setpoint input spindle 147 rotates, so this leads, because of the thread engagement between setpoint input spindle 147 and actual value feedback spindle 148, initially "Stops", for an axial displacement of the setpoint input spindle 147 and with this of the valve spool 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. The resultant pressurization of the drive pressure spaces 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, this 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 148, a restoring force acting in the direction of the 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 corresponds to a specific one, with the predetermined engine speed linked value of the effective swallowing volume of the axial piston motor 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 counterclockwise is driven, whereby the follow-up 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 axial piston motor 10 falling within the scope of the invention also with a different number of drive pistons 36 and control grooves 99, e.g. B. seven pistons and six control grooves can be realized.

Insofar as reference symbols are specified in individual drawing figures that are not mentioned in the associated description text, this is intended to provide a reference to those parts of the description in which the terms with these reference symbols are defined.

Claims (14)

1: Hydraulic axial-piston motor as rotary drive motor for tools or positioning or thrust drives respectively of tool or processing machines, having a rotor, which is play-free and rotatably mounted in a housing and non-rotationally and non-displacably connected to the driveshaft of the motor, and which in axial-symmetrical spacing around the rotary axis is provided with bores, in which a respective piston is pressure-tightly guided in the axial direction parallel to the rotary axis, establishing an axially movable definition of a drive-compression chamber, the controllable loading with the output pressure of a pressure-supply unit pushes the piston into abutment against a curved path, which is fixed relative to the housing and pushed with the curved path which is concentric relative to the rotary axis, which has, also in axial-symmetrical grouping relative to the rotary axis but in lesser multiplicity than those of the engine bores, thereto oriented extensions and ridges thereinbetween, which are adjacent to each other with smooth curvature and form a roll-off surface for support balls which are freely rotatably mounted at the free ends of the pistons, in which respect the pressure-medium feed and removal to or from the drive-compression chambers of the rotor is carried out via control channels, which are attached on the rotor to a control plate, which is non-rotationally connected to the rotor, and control chambers located on the housing, which alternately establish communicating connection thereto, and which control chambers are grouped in symmetry corresponding with the axial symmetry of the curve path in azimuthal equidistant spacing around the central axis of the axial-piston motor and, as seen in the rotary direction, are alternately connectible to the operating-pressure outlet or the tank of the pressure-supply unit, whereby the control channels are arranged on a control plate, which, by means of a metallic sealing surface, which includes the mouth openings of the control channels on the housing, are slidingly and sealingly held in abutment against a sealing surface of the housing which accommodates the mouth openings of the control spaces on the housing, and, in order to permit tumbling or axially displacing compensatory movements relative to the rotor within a small angular or axial displacement range, are elastically supported on the rotor via sealing elements with central through bores, which are inserted into the bores of the rotor and are axially supported on the rotor via these bores against elastic and pretensioned sealing elements which seal the housing space containing the rotor and which seals abut with a metallic sealing surface against the control disc, characterised in that the bores (24, 28), in which the pistons (36) are pressure-tightly displaceable, are stepped bores, the bore steps (24, 28) of which are offset relative to each other by an annular shoulder (29), that the end parts (31) are arranged to be step-piston-shaped plugs, which are inserted into the stepped bores (24, 28) and provided with central through bores (87), having a cylinder-casing-shaped smaller step (32) and a flange-shaped step (33) of larger diameter, whereby the flange-shaped step (33) is arranged in the larger bore step (38) facing towards the control plate (88) and has a diameter which is slightly smaller than the diameter d₂ of the larger bore step (28), and that the elastically pretensioned sealing elements are O-rings (34), which are arranged between the annular flange-shaped step (33) of the plugs (31) and the annular shoulder (29), which offsets the bore steps (28 and 24) relative to each other and centres the plugs (31).

2: Axial-piston motor according to claim 1, characterised in that the diameter d₂ of the larger bore steps (28) is by at least 2/10̸0̸ mm larger than the diameter of the annular flange-shaped step (33) of the plugs (31), and that the outside diameter of the casing-shaped step (32) of the plugs (31) is by at least 2/10̸0̸ mm smaller than the diameter d₁ of the smaller bore step (24).

3: Axial-piston motor according to claim 1 or claim 2, characterised in that the inner end-face surfaces of the plugs (31) are arranged at a small axial distance (e) from the annular shoulder (29) which offsets the bore steps (24 and 28) relative to each other.

4: Axial-piston motor according to claim 3, characterised in that the sealing surfaces (118), located on the control plate, of the plugs (31) are formed by the end surfaces of annular webs (117) which surround the mouth openings, located on the control plate, of the through bores (87) of the plugs (31).

5: Axial-piston motor according to claim 4, characterised in that the sealing surface, within which the mouth openings of the control channels (96) of the control plate (88), which are facing towards the plugs (31) of the rotor (18, 19), are arranged, are formed by the free end surface (10̸9 of a flat annular web (111) of the control plate (88).

6: Axial-piston motor according to one of the above claims, characterised in that the sealing surface (112), with which the control plate (88) slidingly abuts against the sealing surface (114) on the housing, within which the cross-sections of the control spaces (99) terminate, and/or the sealing surface (114) on the housing is formed by the end surface (112 or 114 respectively) of a respective flat circular web (113 or 116 respectively) of the control plate (88) or of the housing part (89) which defines the control spaces (99) on the housing.

7: Axial-piston motor according to one of the above claims, characterised in that the housing part (89), which defines the control spaces (99) on the housing, is itself a circular-plate-shaped housing end part of the motor housing (919).

8: Axial-piston motor according to one of the above claims, characterised in that two axially counter-tensioned angular roller bearings (52 and 53) are provided for play-free mounting of the rotor (18) of the axial-piston motor (10̸).

9: Axial-piston motor according to claim 8, characterised in that the mounting section (54) of the motorshaft (16), on which the angular roller bearings (52 and 53) are arranged, are disposed between the end section (86) of the motorshaft (16), which protrudes from the housing (91) as outputshaft, and the drive section (59) of the motorshaft (10) which supports the drive part (59).

10̸: Axial-piston motor according to claim 9, characterised in that the angular roller bearings (52 and 53) are arranged in a sleeveshaped housing part (51), which has on its side facing towards the drive section (19) of the rotor (18) a radially inward facing flange (74) from which extends a curved web (38) which, with its axially protruding and retracting end surface facing towards the drive section (19), forms the curve path on which the pistons (36) of the rotor (18) are axially supportable.

11: Axial-piston motor according to claim 10, characterised in that the sleeveshaped housing part (71) is provided with a radially inward facing flange (74) which surrounds a central section (58) of the motorshaft (10) at a radial distance, and that into the sleeveshaped housing part (71) is inserted a slidemount bushing (72), in which the shaft (10) is mounted to be slidable with its central section (58).

12: Axial-piston motor according to claim 11, characterised in that the central section (58) of the motorshaft (16), which is mounted in the slidemount bushing (72), is provided with lubricating ridges (146), through which leakage oil for lubrication of the housing space which accommodates the angular roller bearings (52 and 53) can also transfer from the leakage-oil space (121) which includes the drive section (19) of the rotor (18).

13: Axial-piston motor according to one of the above claims, characterised in that support balls (47) of the pistons (36) of the rotor (18, 19), which roll off on the curve path, are mounted in cups (48), into which terminate through-bores of the pistons (30), which communicate with the drive-compression chambers (37).

14: Hydraulic drive unit using an axial-piston motor according to one of the above claims 1 to 13, having a follow-up control valve for movement control of the axial-piston motor, which valve operates by electrically controlled rotary angle nominal value advance and mechanical rotary-angle actual value response, whereby for the purpose of nominal-value advance is provided an axially displaceable spindle, which is driven by an electric control motor, and for the actual-value response is provided a response spindle, which is non-rotationally and non-displacably connected to the motorshaft, and which are mesh via internal and external threads, characterised in that the driveshaft (17) of the electric motor (13) provided for nominal-value advance, a thereby driven spindle (147), a response spindle (148) and the motorshaft (16) of the axial-piston motor (10̸) are arranged coaxially along the central longitudinal axis (14) of the axial-piston motor (10̸).

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