EP2006544B1 - Piston pump with variable eccentricity - Google Patents

Abstract

The pump has displacing units (6) movable from a mantle surface (18) of an eccentric sleeve (17) against fluid pressure, where the displacing units are movable radial to a main axis (16) of the pump. A spring unit (39) acts on the eccentric sleeve in an axial direction, and a pump shaft section (23) is formed as a narrow eccentric pin (24) with an eccentric pin axis (25), which runs to the main axis at an angle of inclination (26). The eccentric sleeve is guided to the eccentric pin and has a cylindrical mantle surface whose ends (20) run parallel to the main axis. An independent claim is also included for a method for driving a fluid driven motor of a hydraulic cylinder or a hydraulic motor.

Description

The invention relates to an eccentric pump, as described in the preamble of claim 1.

Displacement pumps, in particular radial piston pumps are already known from the prior art, in which the delivery volume can be actively influenced by an adjustable eccentricity of an eccentric element of the radial piston pump. From the patent EP 1 090 229 B the same applicant, a radial piston pump is known in which the variable eccentricity is effected by an adjustable adjusting element in the axial direction in the form of an inclined cylinder body. During their operation, the forces exerted by the radial piston on the adjusting element or its axial portion are compensated by an axially acting on the adjusting spring element and thereby arises depending on the system pressure acting on the pump elements a certain axial displacement of the adjusting against the force of Spring elements. Due to the geometry of the adjusting element in the form of an oblique cylindrical body, a lower eccentricity of the adjusting element and thereby a reduced delivery volume of the radial piston pump is effected with increasing system pressure and thereby caused greater axial displacement of the adjusting element. Since the required drive power of such a pump is proportional to the product of delivery volume and system pressure, the drive power and thus the load of a drive motor remains largely constant at different system pressures by such an arrangement and the drive motor can be designed for lower or largely constant loads, thereby the production of such a radial piston pump becomes more economical.

Since the co-operating with the pump piston formed by the lateral surface of the cylinder body sliding surface is oblique to the piston axes acting on the pump piston not only forces in the direction of the piston axes, but also by the axial force components caused transverse forces, in addition to the rotation of the eccentric shaft in its direction of action switch back and forth. These constantly changing shear forces, the pistons of the pump elements are exposed to high loads, causing them either wear out quickly or must be designed consuming and expensive adapted to these loads.

The object of the invention is to provide a positive displacement pump, which has largely constant power requirement with variable system pressures, so to speak is self-regulating and yet can be equipped with simple running, inexpensive pump elements without being over-stressed.

The object of the invention is achieved by the features of the characterizing part of claim 1, according to which the eccentric sleeve bearing pump shaft portion is formed as an oblique eccentric pin with a main axis of the pump shaft extending in a helix angle eccentric pin axis and guided on the eccentric eccentric sleeve has a cylindrical outer surface whose Generating parallel to the main axis.

Due to the oblique eccentric pin is the variable eccentricity of the eccentric sleeve, and thus causes the variable delivery volume of the pump elements; through the cylindrical surface, whose generatrices extend parallel to the main axis of the pump shaft, axial force components are exerted on the eccentric sleeve at the contact point between the pump piston and the lateral surface with respect to the eccentric sleeve only in the form of frictional forces during an axial displacement of the eccentric sleeve on the eccentric pin. The transverse forces acting on the pump piston are thereby substantially lower than in the prior art and largely negligible, whereby simply constructed and thus inexpensive pump elements can be used in such a positive displacement pump, without these being subject to excessive stresses and thereby caused wear.

By the helix angle of the eccentric pin acts on the rotating with the driven pump shaft eccentric sleeve in addition to the force exerted by the spring force and a centrifugal force that wants to drive the eccentric sleeve in the direction of greater eccentricity and therefore supports the spring force. Only in the position in which the center of gravity of the eccentric sleeve comes to lie exactly in the main axis of the pump shaft, the centrifugal force and caused by this force component disappears in the direction of increasing eccentricity. Depending on the position of the eccentric pin axis with respect to the main axis of the pump shaft and the adjustment path for the eccentric sleeve which is possible on the eccentric pin axis, such an eccentric pump can therefore adjust the delivery volume automatically and in dependence adjust automatically from the applied system pressure, whereby a largely constant level of performance of the pump drive is given. The relative position of the eccentric pin axis with respect to the main axis of the pump shaft can also be skewed when cooperating with the eccentric hole in the eccentric sleeve extends so that the generatrix of the outer surface of the eccentric sleeve parallel to the main axis of the pump shaft.

For the design and manufacture of such eccentric pump, it is advantageous if the eccentric pin axis intersects the main axis. Furthermore, even if a central axis of the lateral surface intersects the eccentric pin axis. As a result, simple geometrical relationships are achieved and the influences of the geometry on the dynamic behavior during operation can be estimated more easily.

Although the eccentric pin can have any cross-section which is constant over its length, it is advantageous and simpler for manufacture if the lateral surface of the eccentric pin is designed as a circular cylinder surface with the eccentric pin axis as a circular cylinder axis.

The spring element acting axially on the eccentric sleeve on the pump shaft section is advantageously formed by a compression spring or tension spring which is supported on the pump shaft. Such spring elements are readily available in a wide range and can thus be easily adapted by the choice of the spring rate of the spring element, the dynamic behavior of the eccentric sleeve. It is possible that a spring element is provided which surrounds the eccentric pin concentric, and is guided on this; It is also possible that a plurality of spring elements are provided which engage distributed on the eccentric sleeve on a pitch circle outside of the eccentric pin.

In order to be able to predetermine or rule out certain operating states of the eccentric pump, it is advantageous if the axial displaceability of the eccentric sleeve on the eccentric pin is limited at least in one direction by a stop element and thus a starting position or starting position is defined. A travel limit of the eccentric sleeve on the eccentric pin can be done for example by the shape of the pump shaft, ie in which the pump shaft itself forms a stop element. Likewise, the adjustment can be limited by a pump housing, further, the adjustment can also be adjustable, in which the stop element is designed in the form of a set screw.

An advantageous operating behavior of the eccentric pump is achieved when the eccentric sleeve is biased in the starting position at low pressure level in the pump elements by the spring element against the stop element. In the starting position at low back pressure can be predetermined by the initial position eccentricity and thus a certain delivery volume of the eccentric pump, for example, for idling operation of the eccentric pump when the consumer side there is no increased pressure requirement. The starting position can be assigned both a maximum delivery volume and a minimum delivery volume, which depends on the purpose of the eccentric pump.

If the lateral surface of the eccentric sleeve in the starting position has a maximum eccentricity with respect to the main axis, the delivery volume is at idle at low pressure level in the pumping elements maximum and regulates as described above with increasing system pressure in the direction of smaller displacement, whereby the drive power of the eccentric pump remains largely constant. Alternatively, it would also be possible that the eccentric sleeve has a minimal eccentricity in the starting position, and the movement of the eccentric sleeve in the direction of increasing eccentricity is effected by the centrifugal force acting on the eccentric sleeve.

If the spring rate of the spring element is selected so that upon displacement of the eccentric sleeve from the initial position, the increase in the spring force exerted by the spring force is greater than the decrease in the axial component, acting on the eccentric centrifugal force, a stable operating behavior of the eccentric pump is ensured and it can be prevented at an occurring consumer-side pressure increase, that the delivery volume of the eccentric pump is lowered too much.

As advantageous for the operating behavior of the eccentric pump, a helix angle between the main axis and the eccentric pin axis has proven to be from a range with a lower limit of 3 ° and an upper limit of 20 °. At a helix angle of 10 ° results in an advantageous response of the eccentric pump at the consumer side Pressure fluctuations and at the same time a compact size of the eccentric pump.

Since in the case of a circular cylindrical eccentric pin an additional rotation is required, this can be advantageously formed by a parallel to the eccentric pin axis keyway. This can be easily manufactured with proven manufacturing methods and ensures the axial displacement of the eccentric sleeve on the eccentric pin. In the case of a non-circular eccentric pin, for example, with a square cross-section or a polygonal cross-section, the rotation can be omitted, however, the production of the eccentric and cooperating bore in the eccentric sleeve is again consuming.

In an embodiment of the eccentric pump with pumping elements in only one working plane, that is, with only one cylinder star, the eccentric pin can be mounted in an easy-mounting manner at one end of the pump shaft. This makes it possible that both the eccentric sleeve and the pump shaft with the eccentric pin can each be made in one piece and do not have to be composed.

If the eccentric pin is arranged on a circular-cylindrical crank arm of the crankshaft, in particular on a concentric crank axis to the main axis, provides the end face of the circular cylindrical crank arm sufficient surface for supporting the spring elements and for attaching stop elements to limit the axial adjustment of the eccentric sleeve. Furthermore, such a crank arm forms a relatively large flywheel, which is advantageous for the synchronization of such eccentric pump.

In order to reduce wear-promoting sliding movements between the lateral surface of the eccentric sleeve and the displacement elements of the pump elements as much as possible, it is advantageous if the eccentric sleeve has a cylindrical roller bearing whose outer ring forms the lateral surface. As a result, only slight sliding movements occur in the axial adjustment of the eccentric sleeve and by the translational eccentric movement of the lateral surface in the form of the outer ring in the tangential direction. The outer ring of the rolling bearing has a width which is greater than the axial displacement of the eccentric sleeve. Since only very low frictional forces are effective in the axial direction, needle bearings can also be readily installed.

To supply multiple consumers, the eccentric pump can also be designed so that along the pump shaft a plurality of eccentric, in particular rotationally symmetrical with respect to the main axis are arranged and each eccentric pin own group of pump elements, in particular a fixed, several pump elements comprehensive cylinder star is assigned. The pressure lines of the pump elements in each case one cylinder star are combined in each case to a common high pressure port which is used to supply a consumer. Due to the multiple eccentric and cylinder stars are several separate high-pressure connections for multiple consumers available, with the delivery volumes of the individual cylinder stars can each independently adapt to the operating condition of the respective consumer. Thus, a common drive motor for several consumers is also claimed very evenly.

For simultaneous supply of several consumers, the eccentric pump can also be designed so that at least two pump shafts are arranged on the frame at least one eccentric, each associated with its own group of pump elements, parallel to each other and are driven by a common drive device. Between the at least two parallel pump shafts, a drive connection can be produced by simple means, for example a traction mechanism, in particular a toothed belt drive, and only one drive motor is required, which is subjected to very uniform stress due to the pump characteristic.

In order to ensure a low-wear operation of an eccentric pump, it is advantageous if the frame is designed as a housing and the pump elements are arranged in the housing containing a lubricant reservoir, and the pump shaft passes through the housing sealed. The lubricant can be introduced by the movements of the pump shaft to the wear-prone contact points and in particular at the same time form the pressure medium to be pumped by the pump elements. The pump elements can therefore suck directly from the pressure medium supply, which is also lubricant supply, within the housing.

The pump elements of the eccentric pump advantageously have spring elements, which are the displacement elements biasing radially in the direction of the main axis against the lateral surface of the eccentric sleeve. The displacement elements in the form of piston elements or membrane elements can thereby perform the suction of pressure medium in the displacements of the pump elements automatically, without that tensile forces must be exerted by the eccentric sleeve on the displacement elements. This results in a simple construction of the eccentric pump.

In order to prevent a pressure medium return flow to the suction side during the working cycle of the pump elements, suction valves, in particular plate seat valves, are arranged between the displacements in the pump elements and a pressure medium supply. Likewise advantageously arranged between the displacements in the pump elements and a high-pressure port of the eccentric pressure valves, in particular plate seat valves, which during the intake stroke, a backflow of pressure medium from the high pressure side is prevented in the displacements.

Alternatively, the control of the pump elements, i. the pressure medium inlet or the pressure medium discharge into or out of the displacements of the pump elements by means of a slide control, which may be useful at lower operating speeds of an eccentric pump.

In order to achieve the highest operating pressures of such an eccentric pump, it can be designed in particular in the form of a radial piston pump, in which the displacement elements are designed as pump pistons guided in pump cylinders. With such a design operating pressures of over 500 bar, for example, 700 bar, can be easily generated.

The invention further relates to a recovery device comprising a hydraulic system and a mountain scissors or a mountain spreader driven by the latter, characterized in that the hydraulic system comprises an eccentric pump according to the invention. Hydraulic consumers, such as Bergescheren or Bergespreizer, are characterized by the fact that they require on the one hand with unloaded tools fast movements and thus large volume flows, but on the other hand require very high operating pressures from the intervention of the tools, in which a fast tool movement and thus high volume flows Not more are needed. By means of an eccentric pump according to the invention as a hydraulic drive for such a recovery device, the drive motor for the eccentric pump can be optimally utilized in all working states, and thus a more cost-effective drive motor can be used.

The invention further relates to a method for driving a fluid-operated motor, such as a hydraulic cylinder or a hydraulic motor, by means of a pressure medium flow, which is characterized in that the pressure medium flow is provided by an eccentric pump according to the invention. Due to the self-regulating operation of the eccentric pump whose drive motor is in all operating conditions in each case in the range of the optimal operating point and optimum performance.

The invention will be explained in more detail below with reference to the embodiments illustrated in the drawings.

Fig. 1

eine Schnittdarstellung einer erfindungsgemäßen Exzenterpumpe in Form einer Radialkolbenpumpe;

Fig.2

eine Ansicht der Exzenterpumpe gemäß Fig. 4 in Richtung der Pumpenwellenachse;

Fig. 3a

eine Darstellung der in einem ersten Betriebszustand auf die Exzenterhülse wirkenden Kräfte;

Fig. 3b

eine Darstellung der in einem zweiten Betriebszustand auf die Exzenterhülse wirkenden Kräfte;

Fig. 4

einen Schnitt durch eine weitere Ausführungsform einer erfindungsgemäßen Exzenterpumpe in Form einer Radialkolbenpumpe;

Fig. 5

ein Bergegerät mit einer erfindungsgemäßen Exzenterpumpe.

Each shows in a simplified, schematic representation:

Fig. 1

a sectional view of an eccentric pump according to the invention in the form of a radial piston pump;

Fig.2

a view of the eccentric pump according to Fig. 4 in the direction of the pump shaft axis;

Fig. 3a

an illustration of the forces acting on the eccentric sleeve in a first operating state forces;

Fig. 3b

an illustration of the force acting on the eccentric sleeve in a second operating state forces;

Fig. 4

a section through a further embodiment of an eccentric pump according to the invention in the form of a radial piston pump;

Fig. 5

a recovery device with an eccentric pump according to the invention.

By way of introduction, it should be noted that in the differently described embodiments the same parts are provided with the same reference numerals or the same component names, the revelations contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or the same component names transmitted. Also, the position information selected in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and these are mutatis mutandis to transfer to a new position to the new situation. Furthermore, individual features or combinations of features from the illustrated and described, different embodiments may represent for themselves, inventive or inventive solutions.

All statements on ranges of values in the description of the present invention should be understood to include any and all sub-ranges thereof, e.g. the indication 1 to 10 should be understood to include all sub-ranges, starting from the lower limit 1 and the upper limit 10, i. all subregions begin with a lower limit of 1 or greater and end at an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1 or 5.5 to 10.

In the Fig. 1 and 2 is exemplified the structure and operation of an inventive eccentric pump 1 in the form of external radial piston pump 2 shown. This essentially comprises a pump shaft 3, which can also be referred to as eccentric shaft 4. This acts in a rotation on peripheral to the eccentric shaft 4 arranged pump elements 5, 5 ', in the displacement elements 6, 6', in the form of pump piston 7, 7 ', displacements 8, 8', periodically reduce and enlarge. In each work cycle of a displacement element 6 while pressure fluid or hydraulic fluid via a suction line 9, 9 'sucked by a pressure medium supply 10 by increasing the displacement 8 and delivered by reducing the displacement 8 via a pressure line 11 to a high-pressure port 12; from a consumer, such. B. a fluid operating engine in the form of a hydraulic cylinder; a hydraulic motor or the like is supplied. The control of the pressure medium flow through the pump elements 5, 5 'takes place with the aid of suction valves 13, 13' and pressure valves 14, 14 'which control the flow direction of the pressure medium from and to the displacements 8, 8'. The suction valves 13 and the pressure valves 14 may for example be designed as a disk seat valves or else be formed by other valve types.

The pump shaft 3 and the pump elements 5; 5 'are stationary with respect to a frame 15 mounted, which is formed for example as a housing. The term frame 15 is not related to the type in this context; but on the kinematic function as a reference system, relative to which the pump shaft 3 and displacement elements 6; 6 'of the pump elements 5; 5 'move. The pump shaft 3 is of an in Fig. 1 Driven drive device, not shown, and executes a rotation about a main axis 16 during operation. The periodic actuation of the displacement elements 6; 6 'takes place by an eccentric sleeve 17; whose lateral surface 18 eccentrically rotates about the main axis 16. The lateral surface 18 of the eccentric sleeve 17 has in the illustrated embodiment, the shape of a circular cylindrical surface 19, whose generatrix 20 are parallel to the main axis 16, whereby a central axis 21 of the circular cylindrical surface 19 extends parallel to the main axis 16. The distance between the central axis 21 and the main axis 16 results in an eccentricity 22 of the eccentric sleeve 17 with respect to the main axis 16 and also corresponds to half the stroke of the displacement elements. 6

In the eccentric pump 1 according to the invention, the eccentricity 22 is variable, for which the eccentric sleeve 17 is mounted axially displaceably on a pump shaft portion 23 which is formed as an eccentric pin 24 whose eccentric pin axis 25 has a helix angle 26 with respect to the main axis 16. This helix angle 26 is in the illustrated embodiment about 10 ° C, but may be preferably selected from a range with a lower limit of 3 ° C and an upper limit of 20 ° C. By existing between the eccentric pin axis 25 and the main axis 16 helix angle 26 causes an axial displacement of the eccentric sleeve 17 on the eccentric pin 24, a change in the eccentricity 22, ie, the distance between the central axis 21 of the lateral surface 18 and the major axis 16 is changed by the axial Displacement of the eccentric sleeve 17. To transmit the drive torque is between the eccentric pin 24 and the eccentric sleeve 17, a rotation 27, in the illustrated embodiment in the form of a feather key 28 is formed. Alternatively, any type of anti-rotation 27 may be formed, which allows the axial movement of the eccentric sleeve 17 along the eccentric pin 24, for example a deviating from the circular cross-sectional area 29 of the eccentric 24 and a rotatably cooperating recess or bore 30 in the eccentric sleeve 17th The cross section of the eccentric pin 24 For this purpose, it can be designed, for example, as a splined shaft profile or as a polygonal profile.

In the illustrated embodiment, the eccentric pin 24 is formed as a circular cylindrical portion 31, the circular cylinder axis 32 forms the eccentric pin axis 25. Alternatively, the eccentric pin 24 may also have angular, for example, square cross-section.

Also, the lateral surface 18 of the eccentric sleeve 17 may alternatively have a deviating from the circular cross-section of the illustrated embodiment, for example, be oval or have flats, the cross-sectional shape to achieve a desired characteristic of the eccentric pump 1 can be used.

The displacement elements 6 in the form of pump piston 7 are guided in pump cylinders 33 and are pressed by piston springs 34 against the lateral surface 18 of the eccentric sleeve 17 or at least in the direction of the main axis 16. The piston springs 34 are chosen so that the intake stroke of the pump elements 5 is performed automatically by the displacement elements 6. As an alternative to the pump piston 7, membrane elements can also be used as displacement elements 6, 6 '. Instead of the use of piston springs 34 for the pump piston 7 or generally of spring elements for the displacement elements 6, the displacement elements 6 can perform the suction stroke by pulling forces when an articulated, suitable for transmitting tensile forces connection between displacement elements 6 and eccentric sleeve 17 is provided. The eccentric sleeve 17 may be provided with an outer sleeve, which executes only the translational eccentric movement but not the rotational movement.

The axial displacement of the eccentric sleeve 17 on the eccentric pin 24 is in Fig. 1 bounded on the left side by a first stop element 35 and to the right by a second stop element 36, wherein as a stop element 35, 36 each have a screw member 37 is inserted, which is used on the crank webs 38 of the pump shaft 3. The crank webs 38 have in the illustrated embodiment, the shape of disc-shaped circular cylinder sections.

Between the eccentric sleeve 17 and the in Fig. 1 to the right of it arranged crank arm 38, a spring element 39 is arranged in the form of a compression spring 40, which on the eccentric sleeve 17th exerts a spring force in the axial direction. The spring element 39 is oriented as shown parallel to the eccentric pin axis 25. Since the spring element 39 is formed in the illustrated embodiment as a compression spring 40, the spring force acts on the eccentric sleeve 17 to the left and the eccentric sleeve 17, when the forces exerted by the pump piston 7 forces are low, pressed to the left against the first stop member 35, whereby a Home position or home position is defined.

In operation of the eccentric pump 1 acting on the eccentric sleeve 17 neglecting frictional forces - the force exerted by the pump piston 7 radial piston forces exerted by the spring element 39 axial spring force, caused by the eccentricity of the center of gravity of the eccentric sleeve 17 with respect to the main axis 16 centrifugal force in the radial direction and a force acting between eccentric pin 24 and eccentric sleeve 17, with respect to the eccentric pin axis 25 radial contact force.

The interaction of the force acting on the eccentric sleeve 17 forces and the function of the eccentric pump 1 will be described below with reference to the Fig. 3a and 3b explained.

Fig. 3a shows the detail of an eccentric pump 1 according to the invention, in which the eccentric sleeve 17 is pressed by means of the spring element 39 in the form of the compression spring 40 against the left stop element 35 and thereby assumes a starting position 41. In the starting position 41, the eccentricity 22 between the central axis 21 of the eccentric sleeve 17 and the main axis 16 of the pump shaft 3 corresponds to a maximum eccentricity 42, wherein the maximum stroke of the displacement elements 6, 6 'in the form of the pump piston 7, 7' and thereby the maximum Delivery volume of the eccentric pump 1 is given.

1. 1. eine resultierende Kolbenkraft 43, die direkt proportional zum Systemdruck an den Hochdruckanschlüssen 12, 12' ist. Die von den Kolbenfedern 34, 34' verursachten Kräfte können in diesem Zusammenhang vernachlässigt werden, da sie sich zum Großteil gegenseitig aufheben;
2. 2. eine zwischen dem Exzenterzapfen 24 und der Bohrung 30 der Exzenterhülse 17 übertragene Kontaktkraft 44, die etwa rechtwinklig auf die Exzenterzapfenachse 25 orientiert ist;
3. 3. eine vereinfacht im Schwerpunkt 45 der Exzenterhülse 17 angreifende Fliehkraft 46, die etwa rechtwinklig zur Mittelachse 21 der Exzenterhülse 17 orientiert ist; und
4. 4. eine vom Federelement 39 ausgeübte Federkraft 47, die parallel zur Exzenterzapfenachse 25 orientiert ist.

In consequence, the operating state of the eccentric pump 1 is considered, in which the contact force between the eccentric sleeve 17 and the left stop element 35 disappears and the eccentric sleeve 17 is immediately before an axial displacement on the eccentric pin 24 to the right. Neglecting friction forces act on the eccentric sleeve 17 simplifies the following forces:

1. 1. a resulting piston force 43, which is directly proportional to the system pressure at the high pressure ports 12, 12 '. The forces caused by the piston springs 34, 34 'can be neglected in this context, since they largely cancel each other out;
2. 2. a transmitted between the eccentric pin 24 and the bore 30 of the eccentric sleeve 17 contact force 44 which is oriented approximately at right angles to the eccentric pin axis 25;
3. 3. a simplified in the center of gravity 45 of the eccentric sleeve 17 engaging centrifugal force 46, which is oriented approximately at right angles to the central axis 21 of the eccentric sleeve 17; and
4. 4. a force exerted by the spring element 39 spring force 47, which is oriented parallel to the eccentric pin axis 25.

In this operating condition, the component of the piston force 43 acting axially with respect to the eccentric pin axis 25 is compensated by the oppositely acting axial components of the centrifugal force 46 and the spring force 47. The corresponding force polygon is shown in FIG Fig. 3a additionally shown. If the system pressure applied to the high-pressure connections 12, 12 'remains unchanged in this operating state, the forces acting on the eccentric sleeve 17 are in equilibrium and the eccentric sleeve 17 will continue to rotate in the initial position 41 shown.

If now an increase in pressure at the high pressure ports 12, 12 'is evident that thereby the resulting piston force 43, which acts on the lateral surface 18 of the eccentric sleeve 17 increases and the. With respect to the eccentric pin axis 25 axial component of the piston force 43, a displacement of the eccentric sleeve 17th causes to the right until the increase of the axial component of the piston force 43 is compensated by an increase of the spring force 47 caused by the axial displacement and sets a new equilibrium state with respect to the starting position 41 shifted to the right eccentric sleeve 17.

By this displacement of the eccentric sleeve 17 along the oblique eccentric pin 24th reduces the eccentricity 22 and thus the stroke of the pump piston 7 whereby the delivery volume of the eccentric pump 1 at constant assumed input speed decreases relative to the delivery volume in the starting position 41 of the eccentric 17. In the described new equilibrium position is compared to the starting position 41, of the Eccentric pump 1 to be supplied system pressure higher, but also the flow rate lower, making the required for the eccentric 1 drive power remains largely constant, since this is proportional to the product of system pressure and flow and cancel each other's changes. An increase in the system pressure at the high pressure ports 12 thus causes a displacement of the eccentric sleeve 17 in the direction of lower eccentricity 22 in the illustrated embodiment to the right and in turn causes a reduction of the system pressure 12 at the high pressure ports 12 a displacement of the eccentric sleeve 17 in the direction of increasing eccentricity ie in Theoretically, an infinitely increasing pressure at the high pressure ports 12 due to the ever increasing piston force 43 would cause a displacement of the eccentric sleeve 17 so far to the right until the eccentricity 22 disappears and the flow of the Eccentric pump 1 goes to zero. Since such an operating state is undesirable in practice, the displacement of the eccentric sleeve on the eccentric pin 24 is limited by a second stop member 36 to the right.

In Fig. 3b an operating state of an eccentric pump 1 is shown, in which the eccentric sleeve 17 just occupies the end position 48 of its maximum displacement along the eccentric pin 24 and comes into contact with the right, second stop element 36. In this operating state act on the eccentric sleeve 17 in turn, the resulting piston force 43, which is substantially higher in this operating condition, as in the initial state 41; Furthermore, the correspondingly larger contact force 44 between the eccentric pin 24 and the bore 30 in the eccentric sleeve 17; Further reduced by the reduced eccentricity 22 centrifugal force 46 and the increased spring force 47, which just balances the axial components of the piston force 43 and the centrifugal force 47. The interaction of the forces is in turn simplified in a separate force polygon.

In this end position 48, the eccentricity 22 between the central axis 21 of the lateral surface 18 of the eccentric sleeve 17 and the main axis 16 of the pump shaft 3 corresponds to a minimum eccentricity 49, which also determines the minimum delivery volume per revolution of the eccentric pump 1.

The operating behavior of such eccentric pump 1 can thus be influenced in many areas, for example by the choice of the helix angle 26, the position and size of the adjustment of the eccentric 17 on the eccentric 24, the spring characteristic and bias of the spring element 39, the maximum eccentricity 42 and minimal eccentricity 49.

Fig. 4 shows a detail of a section through a further embodiment of an eccentric pump 1 according to the invention, in which the frame 15 is formed as a housing 50, the pump shaft 3 is guided in the housing interior 51 and at one end 52 of the pump shaft 3, the eccentric sleeve 17 axially displaceable on the end 52 of the pump shaft forming, flying eccentric pin 24 is mounted axially displaceable. Fig. 4 shows the eccentric sleeve 17 in the starting position 41, in which this is biased by a plurality of compression springs 40 against an end 52 of the eccentric pin 24 fixed end plate 53. The outside of the housing 50 lying part of the pump shaft 3 has a shaft bore 54 with a keyway 55, whereby the pump shaft can be easily connected to a drive motor, not shown. The pump shaft 3 is mounted by means of rolling bearings 56 in the form of radial ball bearings 57 in the housing 50 and the housing interior 51 sealed by shaft seals 58 from the environment.

On the inside of the housing 50, a plurality of pump elements 6 are fixed on a pitch circle relative to the main axis 16 of the pump shaft 3, which have radially displaceable displacement elements 6 in the form of pump piston 7. The operation of the pump elements 5 has already been based on Fig. 1 described and will not be repeated at this point.

In order to reduce the wear caused by the sliding between the lateral surface 18 of the eccentric sleeve 17 and the pump piston 7, the eccentric sleeve 17 has a cylindrical roller bearing 59 whose outer ring 60 forms the lateral surface 18 of the eccentric sleeve. By this rotatable roller bearing of the outer ring 60 of this does not perform as the eccentric sleeve 17 is an eccentric rotation with respect to the main axis 16 but performs when the rolling friction between Outer ring and inner ring is neglected a circular translation with respect to the main axis 16, wherein the diameter of this circular motion is twice the eccentricity 22. The anti-rotation 27 between the eccentric sleeve 17 and the eccentric pin 24 is again formed by a keyway 28.

The leading away from the displacements 8 in the pump elements 5 pressure lines 11 are formed by corresponding holes 61 and are combined to form a common high pressure port for supplying a consumer, while the suction lines 9 end in the housing interior 51, in which there is a sufficient pressure medium supply, whereby the housing 50 fulfills the function of a tank in an open hydraulic circuit. As in Fig. 4 As can be seen, the suction line 9 for a pump element 5 arranged above the liquid level comprises a suction tube 62 which is guided below the liquid level 63.

The functioning of in Fig. 4 shown eccentric 1 corresponds to the basis of the Fig. 3a and Fig. 3b described operation and will not be described in detail to avoid repetition. The pump elements 5 may be arranged on a pitch circle with respect to the main axis 16 and in order to achieve the lowest possible pressure fluctuations at the high pressure port 12, merged into a common port and distributed uniformly over the circumference of the pitch circle. Depending on the size of the pump elements 5, for example, 4 to 9 pump elements 5 may be assigned to an eccentric sleeve 17 and form a so-called cylinder star 64 by their star-shaped arrangement.

Fig. 5 shows as an example of the use of an eccentric pump 1 according to the invention a recovery device 65, comprising a Bergeschere 66 or a Bergespreizer and a hydraulic system 67 with the eccentric pump 1 according to the invention and a hydraulic control 68 for controlling the flow of fluid to or from the Bergeschere 66. The Bergeschere 66 includes a fluid operated motor 69 in the form of a hydraulic cylinder 70 which converts the flow of hydraulic fluid into movements of the recovery tools. The provision of the pressure medium flow is effected by an eccentric pump 1, in which the pump shaft 3 has a plurality of, in the illustrated embodiment, three eccentric pins 24, each of which a plurality of pump elements 5 comprehensive cylinder star 64 is assigned. The pressure lines 11 of the pump elements 5 each of a cylinder star 64 are combined to form a common high-pressure port 12. The three cylinder stars 64 thus provide three high-pressure connections, one of which is connected to the consumer in the form of the mountain shear 66 by the hydraulic control 68 and two additional high-pressure connections 12 ', 12 "are available for additional consumers 5 are connected by suction pipes 62 to the pressure medium supply 71 contained in the housing 50. To protect the eccentric pump 1 from damaging pressure peaks, the hydraulic system comprises a pressure limiting valve 72. The drive of the pump shaft 3 is effected by a drive device 73, which is indicated only symbolically, for example in the form of a the electric motor.

In Fig. 4 is still shown the possibility of driving by means of a drive device 73 driven pump shaft 3 by means of a toothed belt drive 74 one or more further pump shafts, not shown, whereby a plurality of eccentric pump units can be operated with only one drive motor and separate consumers for several hydraulic circuits are available.

The embodiments show possible embodiments of the eccentric pump 1, wherein it should be noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but also various combinations of the individual embodiments are possible with each other and this possibility of variation due to the teaching of technical action the subject invention is within the skill of those skilled in the art. So are all conceivable embodiments, which are possible by combinations of individual details of the illustrated and described embodiments, of the scope of protection.

For the sake of order, it should finally be pointed out that in order to better understand the design of the eccentric pump, these or their components have been shown partly out of scale and / or enlarged and / or reduced in size.

Above all, the individual in the Fig. 1, 2 . 3a, 3b ; 4 ; 5 shown embodiments form the subject of independent solutions according to the invention. The relevant objects and solutions according to the invention can be found in the detailed descriptions of these figures.

REFERENCE NUMBERS

1

Eccentric pump

2

Radial piston pump

3

pump shaft

4

eccentric shaft

5

pump element

6

displacement element

7

pump pistons

8th

capacity

9

suction

10

Pressure fluid supply

11

pressure line

12

High pressure port

13

suction

14

pressure valve

15

frame

16

main axis

17

eccentric

18

lateral surface

19

Circular cylindrical surface

20

generating

21

central axis

22

eccentricity

23

Pump shaft section

24

eccentric

25

eccentric pin

26

helix angle

27

twist

28

Key Connection

29

Cross sectional area

30

drilling

31

Circular cylindrical section

32

Circular cylinder axis

33

pump cylinder

34

piston spring

35

stop element

36

stop element

37

screw element

38

crank web

39

spring element

40

compression spring

41

starting position

42

Maximalexzentrizität

43

piston force

44

contact force

45

main emphasis

46

centrifugal

47

spring force

48

end position

49

Minimalexzentrizität

50

casing

51

housing interior

52

The End

53

end disk

54

shaft bore

55

keyway

56

roller bearing

57

Radial ball bearings

58

shaft seal

59

roller bearing

60

outer ring

61

drilling

62

suction tube

63

liquid Level

64

cylinder radial

65

recovery equipment

66

mountains scissors

67

hydraulic system

68

hydraulic control

69

engine

70

hydraulic cylinders

71

Pressure fluid supply

72

Pressure relief valve

73

driving device

74

toothed belt drive

Claims (21)

1. Eccentric pump (1) comprising a frame (15), a pump shaft (3) which can be driven by means of a driving device (73) and is mounted to be rotatable about a main axis (16) that is stationary relative to the frame (15), an eccentric sleeve (17) which is mounted in an axially movable manner on a pump shaft section (23), an anti-rotation element (27) which is effective between the pump shaft section (23) and eccentric sleeve (17), several pump elements (5) which are stationary relative to the frame (15) and are provided with displacement elements (6) that can be moved in a radial direction relative to the main axis (16) and act on a fluid contained in swept volumes (8) of the pump elements (5), and are moved against a fluid pressure by an external surface (18) of the eccentric sleeve (17), and at least one spring element (39) provided in the form of a compression spring (40) or tension spring supported on the pump shaft (3) which acts on the eccentric sleeve (17) in an axial direction, and the axial displacement of the eccentric sleeve (17) against the force of the spring element (39) is caused by the forces expended by the displacement elements (6) on the eccentric sleeve (17), and the eccentric sleeve (17) is pretensioned in the start position (41) by the spring element (39) against a stop element (35), and the external surface (18) of the eccentric sleeve (17) in the start position (41) has a maximum eccentricity (42) with respect to the main axis (16), characterised in that the pump shaft section (23) is designed as an inclined eccentric pin (24) that has an eccentric pin axis (25) which extends at an oblique angle (26) from the main axis (16), and the eccentric sleeve (17) guided on the eccentric pin (24) has a cylindrical external surface (18), the generatrices (20) of which extend parallel to the main axis (16), and the at least one spring element (39) is oriented parallel to the eccentric pin axis (25).
2. Eccentric pump (1) as claimed in claim 1, characterised in that the eccentric pin axis (25) intersects the main axis (16).
3. Eccentric pump (1) as claimed in claim 1 or 2, characterised in that a central axis (21) of the external surface (18) intersects the eccentric pin axis (25).
4. Eccentric pump (1) as claimed in one of claims 1 to 3, characterised in that the eccentric pin (24) is designed as a circular cylinder section (31) with the eccentric pin axis (25) as a circular cylinder axis (32).
5. Eccentric pump (1) as claimed in one of claims 1 to 4, characterised in that the spring detent of the spring element (39) is selected so that on displacing the eccentric sleeve (17) from the start position (41), the increase in the spring force (47) exerted by the spring element (39) is greater than the reduction of the axial component of centrifugal force (46) acting on the eccentric sleeve (17).
6. Eccentric pump (1) as claimed in one of claims 1 to 5, characterised in that the angle of inclination (26) between the main axis (16) and eccentric pin axis (25) is selected from a range with a lower limit of 3° and an upper limit of 20°.
7. Eccentric pump (1) as claimed in one of claims 1 to 6, characterised in that the anti-rotation element (27) is formed by a featherkey connection (28) running parallel to the eccentric pin axis (25).
8. Eccentric pump (1) as claimed in one of claims 1 to 7, characterised in that eccentric pin (24) is arranged to overhang on one end (52) of the pump shaft (3).
9. Eccentric pump (1) as claimed in one of claims 1 to 8, characterised in that eccentric pin (24) is arranged on a circular cylinder crank cheek (38) of the pump shaft (3).
10. Eccentric pump (1) as claimed in one of claims 1 to 9, characterised in that the eccentric sleeve (17) comprises a cylindrical roller bearing (59), the external ring (60) of which forms the external surface (18).
11. Eccentric pump (1) as claimed in one of claims 1 to 10, characterised in that along the pump shaft (3) several eccentric pins (24) are arranged, in particular rotationally symmetrically with respect to the main axis (16), and each eccentric pin (24) is assigned its own group of pump elements (5), in particular a fixed cylinder star (64) comprising several pump elements (5).
12. Eccentric pump (1) as claimed in one of claims 1 to 11, characterised in that on the frame (15) at least two pump shafts (3), each with at least one eccentric pin (24), to which respectively a separate group of pump elements (5) is assigned, are arranged parallel to one another and can be driven by means of a common drive device (73).
13. Eccentric pump (1) as claimed in one of claims 1 to 12, characterised in that the frame (15) is designed as a housing (50), and the pump elements (5) are arranged in the housing (50) containing a lubricant supply and the pump shaft (3) passes through the housing (50) in a sealed manner.
14. Eccentric pump (1) as claimed in claim 13, characterised in that the lubricant supply is formed by the pressure medium to be conveyed.
15. Eccentric pump (1) as claimed in one of claims 1 to 14, characterised in that the pump elements (5) comprise spring elements, for example piston springs (34), which pretension the displacement elements (6) radially in the direction of the main axis (16) against the external surface (18) of the eccentric sleeve (17).
16. Eccentric pump (1) as claimed in one of claims 1 to 15, characterised in that between the displacement spaces (8) in the pump elements (5) and a pressure medium supply (10) suction valves (13), in particular disc bearing valves, are arranged.
17. Eccentric pump (1) as claimed in one of claims I to 16, characterised in that between the displacement spaces (8) in the pump elements (5) and a high-pressure connection (12) of the eccentric pump (1) pressure valves (14), in particular disc bearing valves, are arranged.
18. Eccentric pump (1) as claimed in one of claims 1 to 16, characterised in that the pressure medium inflow or the pressure medium outflow is controlled in or out of the displacement spaces (8) of the pump elements (5) by means of a gate control.
19. Eccentric pump (1) as claimed in one of claims 1 to 18, characterised in that the displacement elements (6) are designed as pump pistons (7) guided in pump cylinders (33).
20. Method for driving a fluid-driven motor (69), such as a hydraulic cylinder (70) or hydraulic motor by means of a pressure medium flow, characterised in that the pressure medium flow is provided by an eccentric pump (1) as claimed in one of claims 1 to 19.
21. Salvage device (65), comprising a hydraulic system (67) and salvage cutters (66) driven by the latter or a salvage spreader, characterised in that the hydraulic system (67) comprises an eccentric pump (1) as claimed in one of claims 1 to 19.

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