EP3749857A1

EP3749857A1 - Swash plate-type axial piston pump

Info

Publication number: EP3749857A1
Application number: EP19715863.7A
Authority: EP
Inventors: Manuel KRONPASS
Original assignee: Hydac Drive Center GmbH
Current assignee: Hydac Drive Center GmbH
Priority date: 2018-04-19
Filing date: 2019-03-29
Publication date: 2020-12-16
Anticipated expiration: 2039-03-29
Also published as: CA3096965A1; JP7167182B2; AU2019256414A1; WO2019201574A1; CN111989485A; DE102018003207A1; US20210115909A1; US11725639B2; EP3749857B1; JP2021520470A

Abstract

The invention relates to a swash plate-type axial piston pump, in particular for hydraulic systems, comprising a cylinder drum (3) which is rotated about a rotational axis (7) in a pump housing (1) and in which pistons (9) are arranged in an axially movable manner, the piston actuation ends that can be accessed from outside the cylinder drum (3) being supported at least indirectly on a swash plate (15), wherein the swash plate can be pivoted into a desired inclination angle relative to the rotational axis (7) by means of an adjustment device (21) in order to adjust the stroke of the piston (9) and thus the fluid system pressure generated thereby, and the adjustment device has at least one pivot lever (23) which can be deflected in at least one direction and restored by means of an adjustment drive and which has a respective actuation piston (35) in at least one hydraulically actuatable actuation cylinder (31, 43), said actuation piston engaging on an attachment point (29) of the pivot lever (23) at one end. The invention is characterized in that the at least one actuation piston (35, 47) has a guide surface (73) at the end opposite the attachment point (29), said guide surface being a single-piece part of the actuation piston (35, 47) and contacting a paired guide surface (33, 45) of the actuation cylinder (31, 43), and at least one adjustment means (75, 70, 59) is provided which aligns the respective position of each guide surface (73; 33, 45) relative to each other.

Description

Axial piston pump in swashplate design

The invention relates to an axial piston pump in swash plate design, in particular for hydraulic systems, with a rotatably driven in a pump housing about a rotational axis cylinder drum, are arranged axially movable in the piston, which are at least indirectly supported with its drum outside the cylinder accessible operating end of a swash plate, the to adjust the stroke of the piston and thus of the fluid system pressure generated by the desired tilt angle relative to the axis of rotation by means of an adjusting device is pivotable, which has at least one pivot lever, the deflection by means of a Stelltrie in at least one direction and is resettable and the Weil in at least one hydraulically actuated actuating cylinder each case has an actuating piston which engages at one end to an on steering point of the pivot lever.

Axial piston pumps in swash plate design are state of the art. They find widespread use for the pressure medium supply of consumers such as working cylinders, hydraulic motors and the like. Axial piston pumps of the type mentioned in the introduction, in which the swashplate is adjustable in its inclination with respect to the axis of rotation, are distinguished from likewise known axial piston pumps with a fixed swashplate by a better energy balance during operation. While pumps with a fixed swashplate are used as fixed displacement pump with given drive speed always promote a constant volume flow of the fluid, even if no energy is required by pressure-medium-actuated units and therefore the idle flow resistances in the hydraulic circuit must be overcome, for which drive energy is expended, which provides no useful energy is by the adjustment of the slant disc tilt the delivery volume Zero adjustable and the need for drive energy can be minimized. An axial piston pump of the aforementioned type is disclosed in the document WO 2014/187512 A1. The preparation of the known axial piston pumps of this type is costly, because for the adjusting device with the geared connection, which converts the line arbewegung of the respective actuating piston of the at least one fixed actuating cylinder in a pivoting movement of the slant disc, a considerable design effort is required.

In view of this problem, the invention has the object to provide an axial piston pump available, the adjustment of the position adjustment of the swash plate is characterized in comparatively simp cherem structure by a high level of reliability.

According to the invention this object is achieved by an axial piston pump having the features of claim 1 in its entirety.

According to the characterizing part of claim 1, a we sentliche peculiarity of the invention is that the at least one Actuate supply piston at its end remote from the articulation point has a guide surface which is integrally part of the actuating piston and in contact with an associated guide surface of the actuating cylinder, and that at least one compensating means is present, which aligns the Führungsflä chen in their respective position to each other. By provided in the invention He compensation device, the mutual Lageaus direction of piston-side guide surfaces and cylinder-side guide causes effect surfaces, the actuator can be realized with only a single pivotal point between the pivot lever and the actuating piston. In order to keep the piston of the actuating cylinder in the adjustment movements, at de nen the pivot lever to a cylinder axis of the actuating cylinder transverse pivoting movement, free from constraining forces, in the mentioned known solution between the piston and Kol rod of the actuating piston, a ball joint is formed. Thanks to the presence of the compensating means, in the invention, this articulated joint is eliminated, so that the actuating piston with its piston rod can be formed in one piece by a rotating part. In addition to the simplification achieved thereby and reduction of the manufacturing costs are reduced by eliminating the ball joint located in the piston and the frictional forces and the hysteresis. The compensating means may be formed at least partially from a convex th outer contour of at least one of the guide surfaces and / or a fe edend yielding seal assembly at the free end of at least one respective actuating piston and / or a compression spring assembly and / or a lubricant supply.

In particularly advantageous embodiments, two actuating pistons are provided, both of which have at least one of the compensating means. With particular advantage, the arrangement may be such that a Be tätigungskolben is connected with its free end face to a system pressure and the other actuating piston with its free end to a control pressure side, which are part of the actuator for the adjustment device. The lubricant supply can a longitudinal channel by one of the actuator should be actuation piston, which is preferably assigned to the system pressure side, as well as a further channel in the pivot point of the pivot lever aufwei sen. Advantageously, in this case a throttle on the free end face of the actuator should account for the input of the longitudinal channel.

In particularly advantageous embodiments, the respective actuating piston, adjacent to its end face, has a sealing zone formed by at least one piston ring and then a guide zone which forms the convex guide surface which forms the compensating means by abutment with the guide surface of the actuating cylinder. wherein the guide zone is followed by a reduced diameter portion forming the transition to the piston rod of the actuating piston.

In advantageous embodiments, the articulation point is formed by a Ku gelgelenk with a ball formed at the free end of the pivot lever ball and a ball socket on the respective actuating piston, wherein the spring assembly ball and each ball socket force-fitting holding each other in conditioning. This allows the entire pedestal to be designed without backlash.

The arrangement can be made with advantage such that the Federanord voltage simultaneously biasing the swash plate in the maximum Pumpenförde tion corresponding pivot position. Through this Doppelfunk tion of the spring assembly of the actuating cylinder need not be designed as dop peltwirkender cylinder for the generation of actuating movements in both directions, but it can be a single-acting actuator should be provided tion cylinder, the only one actuating movement from the pivot position for maximum pumping support to lower För the volume, down to zero promotion out causes. In particularly advantageous embodiments, the second Actuate supply cylinder with common, perpendicular to the axis of rotation cylinder axis of the first actuating cylinder is arranged opposite, wherein the actuating piston of the second actuating cylinder is hydraulically movable against movement of the piston of the first actuating cylinder, wherein a second compensating means between the second Betätigungszy cylinder and the piston rod is formed with its a guide surface forming a spherically shaped guide surface of the piston of the second Betätigungszylin DERS and wherein the end of the piston rod of the second Actuate supply cylinder on the actuating part of the swash plate a second Kugelge steering is formed.

In a particularly advantageous manner, the spring assembly may comprise a compression spring which biases the piston rod of the second actuating piston for movement, the extension of the actuating piston of the two th actuating cylinder and the retraction of the actuating piston of the first actuating cylinder and thus the pivoting of the pivot lever from the axis-parallel direction Direction to the position of the maximum pump delivery corresponds.

With regard to the operation of the adjustment, the arrangement can be made with advantage so that the first actuating cylinder with a STEU erdruck for adjusting the pump delivery and the second Actuate supply cylinder are subjected to the prevailing system pressure.

As a result, the adjustment is set in the absence of system pressure, ie at standstill of the pump, by the force of the compression spring to the maximum promotion. When operating the pump with resulting Sys temdruck the setting for maximum promotion remains so th long until the force generated by the control pressure in the first actuating cylinder generated by the system pressure in the second actuating cylinder Piston force, plus the spring force exceeds, after which, depending on the control pressure, the swash plate is pivoted zurückge to lower flow. For operation with a control pressure limited pressure levels before the acted upon by the control pressure piston surface of the piston of the first actuating cylinder is selected to be greater than the acted upon by the system pressure piston surface of the piston of the second Betätigungszylin DERS. Below, the invention with reference to an embodiment shown in the drawing is explained in detail ,

Show it:

1 shows a longitudinal section of an axial piston pump in Schrägscheib benart type according to the prior art;

Fig. 2 shows a comparison with Figure 1 rotated by 90 ° drawn longitudinal section of the axial piston pump according to the prior art; Fig. 3 is a side view of the embodiment of the inventive axial piston pump, wherein the adjusting device is shown in section;

Fig. 4 is a representation corresponding to FIG. 3, wherein the adjustment device is shown in the operating state corresponding to the maximum pumping pumping;

Fig. 5 shows a comparison with FIGS. 3 and 4 enlarged and canceled GE recorded representation, wherein the adjusting device in the the zero feed corresponding operating state is Darge presents;

Fig. 6 is a separate view of the left in Fig. 5 Actuate supply piston of the embodiment of the invention;

Fig. 7 is a longitudinal section of the illustration of Fig. 6;

Fig. 8 in comparison with Figure 7 about 50-fold enlarged view of the designated in Figure 7 with X area.

Fig. 9 is a side view of a separation point having Kol benringes of the embodiment; and FIG. 10 shows the region of the separation point designated by Y in FIG. 9 approximately 50 times larger than in FIG. 9.

In the figures, of which Figs. 1 and 2, an axial piston pump according to the prior art and Fig. 3 to 10 show an embodiment of the inven tion, a pump housing is designated 1, in which a Zylin dertrommel 3 by means of a drive shaft 5 to a Rotary shaft 7 is rotatable. As best of the one axial piston pump of the prior tech technology facing Fig. 1 and 2 can be seen, are based in the Zylindertrom mel 3, axially movable piston 9 located at their upper ends sliding shoes 1 1 on the sliding surface 1 3 a swash plate 15 off. This is on its side facing away from the sliding surface 1 3 on a circular arc-shaped swash plate bearing 1 7 on the pump housing 1 so movably guided, that the swash plate 1 5 about a pivot axis is pivotally, which, perpendicular to the axis of rotation 7, in the plane of the sliding surface 1 3 of the swash plate 1 5 and thus to the plane of FIG. 1, 3 and 4 is perpendicular. By means of an adjusting device designated as a whole by 21, the swashplate 15 is arranged about this pivot axis between the pivoted settings shown in FIGS. 1 and 4, which correspond to the maximum delivery rate of the pump, and those shown in FIGS. 2, 3 and 5 Settings pivotable to zero promotion, in which case the plane of the sliding surface 1 3, based on the vertical course of the axis of rotation 7, is in the horizontal, so that no stroke of the Kol ben 9 takes place during the rotation of the cylinder Cylmer 3.

As the swash plate 1 5 associated operating part has the

Adjustment 21 to a pivot lever 23 which is attached to the bevel slide be 1 5 and the side of the swash plate 1 5 and the cylinder drum 3 extends. The pivot lever 23 is pivotally mounted on the housing 1 by means of a pivot pin 9 (see FIG. At its lower free end, the pivot lever 23 has a pivot point 29, to act on the Stellglie of the adjusting device 21 to move the pivot lever 23 in the plane of Fig. 1 and 3 to 5 and thus the slant disc 1 5 about its pivot axis to pivot.

The adjusting device 21 has, as shown in FIGS. 3 to 5 show a first actuator should actuator 31 with a cylinder axis 32 defining cylinder bushing 33, in which an actuating piston 35 is guided. The piston 35 is formed by a one-piece with its piston rod 37 rotary member and has at its free end a ball socket 39, which forms a ball joint when resting on the pivot point forming ball head 29 of the pivot lever 23. The first actuating cylinder 31 opposite and lying with this on the common cylinder axis 32, the Verstellein device 21, a second actuating cylinder 43 with a cylinder liner 45 on. In this a second actuating piston 47 is guided, which, like the first actuating piston 35, together with its piston rod 49 is formed by a one-piece rotary member. Like the first actuating piston 35, the second actuating piston 47 at the free end of its piston rod 49, a ball socket 51, which is under contact with the ball head 29 of the

Swing lever 23 forms a second ball joint. The pressurized piston surface 53 of the first piston 35 is larger than the pressurized piston surface 55 of the second actuating piston 47. Between the Zylin derbuchse 45 of the second actuating cylinder 43 and a spring plate 57 which is formed by a radially projecting collar of the piston rod 49 of the second actuating piston 47, is a compression spring 59 is clamped, which biases the adjusting device 21 in the shown in Fig. 4, the maxima len pump delivery corresponding setting and also keeps the ball joint 29 formed on the pivot lever 23 ball joints clearance.

In order to keep the actuating piston 35 and 37 free of constraining forces in the A adjusting movements in which the ball head 29 of the pivot lever 23 with vertical movement component slightly removed from the Zylin derachse 32, a compensation means is provided in the invention, which in the state of Technology provided for this, in the respective Actuate supply piston located additional ball joint replaced. In the present embodiment of the invention, the compensating means Füh approximately surfaces on the respective actuating piston 35, 47, which is formed integrally with its Kol rod 37 and 49, and by a guide surface on the associated actuating cylinder 31, 43, more precisely, through the cylinder liner 33 and 45, respectively. In the embodiment shown, for example, a special outer contour of the respective actuating piston 35, 47 is provided as a guide surface forming part of the compensating means. The relevant shaping is tert erläu with reference to FIGS. 6 to 8, the separate representations of the einstü with its piston rod 49 second actuating piston 47 included. This in these figures, and in particular in Fig. 8, for the smaller actuating piston 47 gezeig te circumferential profile fully corresponds to the circumferential profile of the size ren actuating piston 35th

6 and 7 show the actuating piston 47 with preinstalled compression spring 59, which is supported on the one hand on the fixed spring plate 57 of the piston rod 49 and at the other end on a circular cylindrical outer surface 61 of the piston rod 49 movable spring plate, which is at one composed of two ring halves 63 and 65 together set Federteller. In the shown in Fig. 6 and 7, relaxed state of the compression spring 59 is the split spring plate 63, 65 at a stu fe 67 of the piston rod 49 at. The design of the outer contour of the Actuate supply pistons 35 and 47, which allows a limited deflection movement of the axis of the piston rods 37, 49 from the cylinder axis 32 as part of the compensating means is shown only in detail for the example of the smaller piston 47 in Fig. 8. As shown, in the vicinity of the front Kol benfläche 55 a sealing zone 69 is formed of a piston ring package 70, which consists of three identically formed piston rings 71, one of which in Figs. 9 and 10 is shown in more detail. At the side facing away from the piston surface 55 side closes (see Fig. 8) to the piston rings 71 a Füh approximately zone 73 at. This is formed from a peripheral portion 75 which forms the respective piston-side guide surface and has a slight crowned curvature, which is chosen such that the piston 47 is guided even with clotting ger axis deviation in the respective cylinder liner 33, 45, which forms the cylinder-side guide surface , The section 75 in turn followed by a recessed in the outer periphery portion 77 (FIG. 8), which forms the transition to the outer diameter further verrin siege peripheral portions of the piston rod 49.

FIGS. 9 and 10 show the construction of the piston rings 71. In FIG. 10, the open area of the respective piston area designated by Y in FIG. 9 is shown. ring 71 shown in more detail. As shown, this area is toothed such that the piston ring 71 is elastically yielding, because at the transition region of its ring ends 80 free spaces 79 are present, within which the two ring ends 80, as indicated by directional arrows 81, can move against each other while on a separation point 83 slide against each other, which forms a sealing surface. For the supply of lubricant to the ball head 29 formed with the ball sockets 39 and 51 ball joints in the piston 49 acted upon by the system pressure in the Kol rod 49 through a lubricant bore 85 is formed, starting from a lying on the piston surface 55 throttle body 87, to Ball socket 51 leads and continues from there via a bore 89 in the ball head 29 to the ball socket 39 of the larger piston 35.

As mentioned, the pressure chamber 91 of the actuating cylinder 31 (FIGS. 3 and 5) is controllable with the control pressure which actuates the adjusting device 21, while the pressure chamber 93 of the actuating cylinder 43 (FIG. 4) can be acted upon by the system pressure. The Fig. 4 shows the setting for maximum delivery capacity in the absence of control pressure in the pressure chamber 91 of the larger actuating piston 35. By acting in the pressure chamber 93 of the small ren actuating piston 47 system pressure and the force of the pressure spring 59 extending over the split spring plate 63, 65 on the cylinder sleeve 45 is supported, the pistons 35 and 47 are shifted in the drawing to the right and the pivot lever 23 is swung in the Stel development shown in Fig. 4. To adjust the adjustment 21 to lower delivery power, the pressure chamber 91 of the actuating cylinder 31, a corresponding control pressure is supplied. Once this exceeds the combined force resulting from the system pressure in the pressure chamber 93 of the smaller piston 47 and the force of the compression spring 59, the pistons 35, 47 move to the left in the drawing, the delivery capacity can be reduced to zero flow rate is shown in Figs. 3 and 5, wherein the split spring plate 63, 65 on the cylindrical portion 61 of the piston rod 49 has moved and moved away from the step 67, wherein the compression spring 59 is compressed. Due to the action of the compression spring 59, even when the pump is at a standstill and therefore the system pressure is absent, the adjustment device is set to the maximum delivery rate, which is shown in FIG. 4.

Claims

Patent claims

1 . Axial piston pump in swash plate design, especially for

Hydraulic systems, with a in a pump housing (1) about an axis of rotation (7) rotatably drivable cylinder drum (3) in the piston (9) are arranged axially movable, with their au ßerhalb the cylinder drum (3) accessible operating end on a swash plate Supported (1 5) at least indirectly, which is pivotable to a position of the stroke of the piston (9) and thus of this prod th fluid system pressure in desired inclination angle relative to the axis of rotation (7) by means of an adjusting device (21), at least one Pivoting lever (23) which by means of an actuating drive in at least one direction and deflectable back and is adjustable in at least one hydraulically actuated loading actuating cylinder (31, 43) each having an actuating piston (35) has, at one end to a Anlenkstelle (29) of the Schwenkhe lever (23) engages, characterized in that the at least one actuating piston (35, 47) at its the pivot point (2 9) abge turned end has a guide surface (73) which is integrally part of the actuating piston (35, 47) and in abutment with a arrange arrange guide surface (33, 45) of the actuating cylinder (31, 43), and that at least one compensating means ( 75, 70, 59) is present, the guide surfaces (73; 33, 45) aligns in their respective position to each other.

2. Axialkolbenpumpe according to claim 1, characterized in that the compensating means at least partially

a convex outer contour (75) at least one of

Guide surfaces (73) and / or a resilient sealing arrangement (70) at the free end of at least one respective actuating piston (35, 47) and / or

a compression spring arrangement (59) and / or

a lubricant supply (85, 87, 89)

is formed.

3. Axial piston pump according to claim 1 or 2, characterized in that two actuating pistons (35, 47) are provided, both of which have at least one of the compensating means.

4. Axial piston pump according to one of the above-mentioned che Ansprü, characterized in that an actuating piston (47) with its free end face (55) connected to a system pressure and the other actuating piston (35) with its free end face (53) connected to a control erdruckseite which are part of the actuator for the adjusting device (21).

5. Axial piston pump according to one of the aforementioned Ansprü surface, characterized in that the lubricant supply ei NEN longitudinal channel (85) through one of the actuating piston (47), which is preferably assigned to the system pressure side, and a white direct channel (89) in the articulation point ( 29) of the pivot lever (23).

6. Axial piston pump according to one of the above-mentioned che Ansprü, characterized in that the respective actuating piston (35, 47), adjacent to its end face (53, 55), by at least one piston ring (71) formed sealing zone (69) and at this subsequently has a guide zone (73) which forms the one convex guide surface (75) which forms the compensating means by abutment against the guide surface (33, 45) of the actuating cylinder (31, 43). Det, and that adjoins the guide zone (73) has a reduced diameter portion (77) which forms the transition to the piston rod (37, 49) of the actuating piston (35, 47).

7. Axial piston pump according to one of the above che Ansprü, characterized in that the articulation point by a Ku gelgelenk with a at the free end of the pivot lever (23) gebil Deten ball head (29) and a ball socket (39, 51) on the respective actuating piston (35 , 47) is formed, and that the Federanord voltage (59) ball head (29) and respective ball socket (39, 51) holds by force in abutment with each other.

8. Axial piston pump according to one of the above-mentioned che Ansprü, characterized in that the spring arrangement (59) biases the swash plate (1 5) corre sponding to the maximum pumping promotion swivel position.

9. Axial piston pump according to one of the above-mentioned che Ansprü, characterized in that the pivot lever (23) since Lich the swash plate (15) and the cylinder drum (3) at a position on zero pump delivery parallel to the axis of rotation (7) he stretches and at its free end the ball joint (29, 39, 51) has.

10. Axialkolbenpumpe surface according to one of the above che Ansprü, characterized in that the second actuating cylinder (43) with common, to the rotation axis (7) vertical cylinder axis (32) the first actuating cylinder (31) opposite, that the actuating piston (47) of the second Actuating cylinder (43) hyd raulisch against the movement of the piston (35) of the first Actuate supply cylinder (31) is movable, that a second compensating means between the second actuating cylinder (43) and the piston rod (49) with a convex guide surface (75 ) Denden guide zone (73) of the piston (47) of the second Actuate supply cylinder (43) is formed and that the end of the piston rod (49) of the second actuating cylinder (43) on the actuating part (23) of the swash plate (15) has a second ball joint (29, 51).

1 1 .Axialkolbenpumpe surface according to one of the above che Ansprü, characterized in that the spring arrangement comprises a compression spring (59) which biases the piston rod (49) of the second Actuate supply piston (43) for the movement, the extension of the actuating piston ( 47) of the second actuating cylinder (43) and the retraction of the actuating piston (35) of the first Actuate supply cylinder (31) and thus corresponds to the pivoting of the pivot lever (23) from the axis-parallel direction in the direction of the position of the maximum pump delivery.

12. Axialkolbenpumpe surface according to one of the above che Ansprü, characterized in that the control pressure beauf beatable end face (53) of the piston (35) of the first actuating cylinder (31) is selected to be greater than the system pressure beauf beatable piston surface (55) of the Piston (47) of the second Actuate supply cylinder (43).

1 3. Axialkolbenpumpe according to any one of the preceding claims,

characterized in that the respective actuating piston (35, 47), adjacent to its end face (53, 55), has a sealing zone (69) formed by at least one piston ring (71) formed from a piston ring assembly (70) consists of at least two, preferably three, identically formed piston rings (71).

14. Axial piston pump according to one of the preceding claims,

characterized in that the respective actuating piston (35, 47), adjacent to its end face (53, 55), has a sealing zone (69) formed by at least one piston ring (71) passing through formed at the transition region of its ring ends (80) free spaces (79) is elastically yielding, within which the two ring ends (80) can move against each other.