EP0953111B1 - Axial piston machine with damping element for the inclined or wobble plate - Google Patents

Description

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

Such an axial piston machine is e.g. known from DE 34 28 591 A1. At this Axial piston machines are several in a rotating cylinder block in a known manner Cylinder bores are formed in which pistons are movably guided. The pistons are supported by sliding shoes on a non-rotating swashplate. The inclination the swash plate, which determines the displacement of the axial piston machine adjustable by means of a hydraulic adjusting piston by turning the swash plate by one Swivel axis is pivotable within a certain angular range. When swiveling back of the swash plate from the stroke position towards the zero stroke position the signal pressure attacking the hydraulic control piston increases and the swash plate pivots back until it hits the zero stroke position on a stop surface reached. The movement of the swash plate is however relatively uncontrolled, so that the swash plate hard when the zero stroke position is reached on the stop surface strikes. This is undesirable as this will wear the stop and the Swashplate increased and also a mechanical shock load on the entire Axial piston machine leads.

DE 44 40 452 A1 describes an axial piston machine in a swashplate design in which two separate for the variation of the inclination of the swash plate Hydraulic cylinders are provided. One of the hydraulic cylinders serves the purpose Swinging out the swash plate and the second hydraulic cylinder Swing the swashplate back. The swashplate is used in this solution guided throughout the entire movement, but the second requires Hydraulic cylinder a comparatively large design effort, which can be found in relative high manufacturing costs. There is also a separate hydraulic control of the two hydraulic cylinders necessary.

The present invention is therefore based on the object of an axial piston machine in swashplate or swashplate construction so that the movement when swashing the swashplate or swashplate not suddenly, but done continuously.

The object is in connection with the characterizing features of claim 1 solved with the generic features.

The invention is based on the finding that by providing an inclined or swash plate attacking damping element swiveling back the inclined or swashplate can be checked. The damping piston is in one Damping cylinder arranged movably, which via a throttle element and a Check valve arranged parallel to the throttle element with a pressure fluid reservoir connected is. The check valve ensures an unthrottled inflow of the pressure fluid from the pressure fluid reservoir into the damping cylinder and prevented an unthrottled outflow of the pressure fluid from the damping cylinder below Bypassing the throttle element.

Claims 2 to 12 contain advantageous developments of the invention.

According to claim 2 or 3, the return spring, the damping piston act that this pressure fluid from the pressure fluid reservoir via the Check valve and, if necessary, the throttle element as soon as the damping piston is in Direction of an increase in the volume of the damping cylinder is freely movable. This ensures that the damping cylinder is instantly filled with pressurized fluid is refilled and thus the swiveling movement of the swashplate or swashplate immediately follows. The pressure medium reservoir can be a leakage fluid collecting space according to claim 4 be in the vicinity of the damping element, the leakage fluid collecting space usually through the housing interior of the axial piston machine is formed.

The swash plate or swash plate can be a first according to claim 5 Swivel position with a larger angle of inclination and a second swivel position have a smaller angle of inclination and between these two Be swiveling back and forth. The axial piston machine can also be designed according to claim 6 in swash plate construction, wherein Damping element according to claim 7 in the swash plate or accordingly Claim 9 in a stationary counterpart opposite the swash plate can be arranged. The return spring holds the damping piston on the Swash plate according to claim 10 or on the stationary counterpart according to claim 8 on surcharge.

The swash plate can also according to claim 11 on the side facing away from the piston Side have a first and a second stop surface, each having a stop for form the first and second swivel positions of the swash plate.

According to claim 12, it is particularly advantageous to the point at which the Damping piston attacks the swash plate, so opposite the cylinder block axis to offset that the resulting force, which results from that of the damping piston the swashplate force exerted by the pivoting device during the Swing on the swashplate and the force exerted by the piston on the Force applied swashplate, attacks in a center of gravity that is on the cylinder block axis. This way they become unbalanced Bearing forces avoided and levering of the bearing prevented.

Fig. 1

einen auszugsweisen, axialen Schnitt durch ein erstes Ausführungsbeispiel der erfindungsgemäß weitergebildeten Axialkolbenmaschine in einer ersten Schwenkstellung der Schrägscheibe;

Fig. 2

das in Fig. 1 dargestellte erste Ausführungsbeispiel der erfindungsgemäß weitergebildeten Axialkolbenmaschine in einer zweiten Schwenkstellung der Schrägscheibe;

Fig. 3

eine schematische Darstellung der Wirkungsweise des Dämpfungselements;

Fig. 4A

die Kräfteverteilung an dem in Fig. 1 dargestellten Ausführungsbeispiel der erfindungsgemäß weitergebildeten Axialkolbenmaschine;

Fig. 4B

eine Seitenansicht der Darstellung nach Fig. 4A;

Fig. 4C

eine Aufsicht auf die Darstellung entsprechend Fig. 4A;

Fig. 5

einen auszugsweise, axialen Schnitt durch ein zweites Ausführungsbeispiel der erfindungsgemäß weitergebildeten Axialkolbenmaschine in einer zweiten Schwenkstellung der Schrägscheibe;

Fig. 6

das in Fig. 5 dargestellte zweite Ausführungsbeispiel der erfindungsgemäß weitergebildeten Axialkolbenmaschine in einer zweiten Schwenkstellung der Schrägscheibe.

The invention is described below with reference to preferred embodiments with reference to the drawing. The drawing shows:

Fig. 1

an excerpt, axial section through a first embodiment of the axial piston machine further developed according to the invention in a first swivel position of the swash plate;

Fig. 2

the first embodiment shown in Figure 1 of the axial piston machine according to the invention in a second swivel position of the swash plate;

Fig. 3

a schematic representation of the operation of the damping element;

Figure 4A

the distribution of forces in the embodiment of the axial piston machine shown in FIG. 1;

Figure 4B

a side view of the illustration of FIG. 4A;

Figure 4C

a plan view of the representation corresponding to FIG. 4A;

Fig. 5

a partial, axial section through a second embodiment of the axial piston machine further developed according to the invention in a second swivel position of the swash plate;

Fig. 6

5 shows the second exemplary embodiment of the axial piston machine further developed according to the invention in a second swivel position of the swash plate.

1 and 2 show an axial longitudinal section through an only partially shown, Axial piston machine 1 developed according to the invention. The in FIG. 1 and FIG. 2 Axial piston machine 1 shown by way of example is designed in a swashplate design and comprises a cylinder block 2, in which several, evenly on a pitch circle Distributed cylinder bores 3, 4 are provided. In the cylinder bores 3, 4 pistons 5, 6 are arranged movably. The cylinder bores 3, 4 are over Connection channels 7, 8 with the kidney-shaped control openings 9, 10 of a stationary Control disc 11 connected. The cylinder block 2 rotates about the cylinder block axis 12, see above that the cylinder bores 3, 4 cyclically with one at the control opening 9 connected, not shown low pressure line and one at the control opening 10 connected, not shown high pressure line can be connected. The pistons 5, 6 are formed into spherical heads 13, 14 at the ends facing away from the control disk 11, the sliding shoes 17, 18 assigned by the pistons 5, 6 in spherical bearings 15, 16 are stored. The pistons 5, 6 are designed as hollow pistons and each have one Piston recess 19, 20 on. The piston recesses 19, 20 are over Connecting channels 21, 22 of the pistons 5, 6 and further via connecting channels 23, 24 of the Sliding shoes 17, 18 for hydrostatic relief with on the sliding shoes 17, 18 provided pressure pockets connected.

The pistons 5, 6 are supported by the sliding shoes 17, 18 on a sliding surface 26 Swashplate 25 from. The swash plate 25 is pivotable about a pivot axis 27 mounted and has a first stop surface 28 on the side facing away from the pistons 5, 6 and a second stop surface 29. If the swash plate, as shown in Fig. 1, is in contact with a stationary counterpart 30 on its first stop surface 28 Swash plate or its sliding surface 26 with a first, relatively large angle of inclination inclined with respect to the cylinder block axis 12. If the swash plate, as in Fig. 2 shown, however, at its second stop surface 29 on the stationary counterpart 30 is present, the swash plate or its sliding surface 26 is opposite the cylinder block axis 12 with a second, smaller than the first angle of inclination Inclination angle inclined to the cylinder block axis 12. The inclination of the Swash plate 25 is therefore in the embodiment between two discrete Swivel positions by means of a swivel device which is only indicated schematically 31 can be swung back and forth. The pivot device 31 can e.g. one hydraulic act upon actuating piston which is non-positively on the swash plate 25 attacks.

According to the invention, the damping piston 40 also engages on the swash plate 25 generally indicated at 41 damping element. 1 and 2 The exemplary embodiment shown is the damping element 41 in the swash plate 25 integrated. The damping piston 40 is in one in the exemplary embodiment of FIGS. 1 and 2 provided in the swash plate 25 provided damping cylinder 42 movable. The Damping cylinder 42 is designed as a blind bore on the second stop surface 29 of the swash plate 25 opens out. The damping piston 40 is also by means of a in the damping cylinder 42 arranged return spring 43 on the stationary Counterpart 30 brought to the plant. The stationary counterpart 30 can e.g. act as a housing end plate. The damping cylinder 42 is over a Check valve 44 and an inlet channel 45 with which the swash plate 25 and Cylinder block 2 surrounding housing interior 46 connected as a leakage fluid collection space serves and is filled accordingly with leakage fluid. The damping cylinder 42 is also via a throttle element 47 with the housing interior 46 Axial piston machine 1 connected. The throttle element 47 is shown in FIG Embodiment designed as a bore with a relatively small cross section. The Inlet channel 45 and check valve 44 are thus parallel to throttle element 47 arranged.

The damping element 41 according to the invention works as follows:

If the swash plate 25 due to a relief of the pivoting device 31 from the 2 shown second pivot position in the direction of that shown in Fig. 1 pivoted toward the first pivot position, the damping piston 40 is by means of Return spring 43 held on the stationary counterpart 30 in contact. Doing so Pressure fluid via the inlet channel 45 and the open check valve 44 and in parallel Via the throttle element 47 from the housing interior 46 filled with leakage fluid sucked in. The damping cylinder 42 is filled via the inlet channel 45 and the check valve 44 so quickly that the damping piston 40 on the stationary Counterpart 30 is kept in constant investment.

Conversely, if the swash plate 25 due to exposure to the Swivel device 31 from the first swivel position shown in FIG Fig. 2 shown pivoted pivot position, that closes Check valve 44 from the inlet channel 45 and that in the damping cylinder 42nd located pressure fluid can only from the throttle element 47 Discharge damping cylinder 42. The desired damping is achieved and it is prevented that the swiveling movement of the swash plate 25 occurs suddenly and the stop surface 29 strikes hard on the stationary counterpart 30. The latter would to a relatively quick wear of the swash plate 25 and the stationary Guide counterpart 30. In addition, the entire axial piston machine 1 would Swinging movement is subjected to a shock load, which is undesirable.

Due to the damping element 41 provided according to the invention, the Swiveling process therefore slightly delayed and a continuous, not abrupt Swiveling movement of the swash plate 25 achieved. This also ensures Damping element 41 according to the invention in the second shown in Fig. 1 Pivotal position and during the pivoting of the first shown in Fig. 1 A certain pivot position in the second pivot position shown in FIG. 2 Support of the section of FIG. 1 located above the pivot axis 27 Swash plate 25 so that the loads to which the swash plate 25 is exposed can be advantageously reduced by the training according to the invention.

3 illustrates the mode of operation of the damping element 41 according to the invention based on a hydraulic equivalent circuit diagram. Elements already described are included Identical reference numerals designated to facilitate the assignment. How already described, the suction of the pressure fluid takes place from a pressure fluid reservoir 48, which e.g. the housing interior 46 can be via the inlet channel 45 and that arranged between the inlet channel 45 and the damping cylinder 42 Check valve 44. This is parallel to the check valve 44 and the inlet channel 45 Throttle element 47 arranged, which when the check valve 44 is closed throttled outflow of the pressure fluid from the pressure fluid cylinder 42 into the Pressure fluid reservoir 48 provides.

4A to 4C illustrate the distribution of forces on the invention further developed axial piston machine 1 corresponding to that already shown in FIGS. 1 and 2 explained embodiment. 4A shows one corresponding to FIG. 1 Representation, while Fig. 4B is a side view looking towards the piston 5, 6 shows the side of the swash plate 25 facing away and FIG 4A shows the arrangement shown.

As can be seen from FIGS. 4A to 4C, on the swash plate 25 during the adjustment thereof the force component F _V exerted by the swiveling device 31, the bearing force F _{L / R} exerted on the mounting of the swiveling axis 27, caused by the two in the exemplary embodiment existing damping pistons 40a and 40b each acting force F _DR and the force F _KL exerted by the pistons 5, 6 in the opposite direction. It is particularly advantageous if the point of action at which the damping piston 40b or 40a acting on the right or left acts on the swash plate 25 is so offset relative to the cylinder block axis that the resulting force, which results from the corresponding damping pistons 40b and 40a, respectively, on the swash plate 25, the force F _DR , the force F _V exerted by the swivel device 31 on the swash plate 25 during the swiveling process and the force F _KL exerted by the pistons 5, 6 on the swash plate 25, in attacks a center of gravity (S), which is located on the cylinder block axis 12. This results in a symmetrical distribution of the bearing forces acting on the mounting of the cylinder block 2 and moments of deviation are prevented. In this way, levering out the mounting of the cylinder block 2 is counteracted. A triangle of forces corresponding to FIG. 4B could also be drawn for the left-hand damping piston 40a, which is omitted for reasons of simplification.

5 and 6 show an axial longitudinal section through a second embodiment an axial piston machine 1 developed according to the invention. Already described Elements are provided with the same reference numerals, so that there is a Repetitive description in this regard is unnecessary.

The embodiment shown in FIGS. 5 and 6 differs from that in 1 and 2 embodiment shown in that the inventive Damping element 41 not in the swash plate 25, but on that of the swash plate 25 opposite stationary counterpart 30, e.g. in a housing end plate, is arranged. The damping element 41 essentially has the already based on Fig. 1 described structure. The damping piston 40 is in the damping cylinder 42 is movably arranged and is acted upon by the return spring 43 so that the Damping piston 40 on the swash plate 25, preferably on the second Stop surface 29 is present. The suction of the pressure fluid from the interior of the housing 46 takes place via the inlet channel 49 and the check valve opened in the suction phase 44. When the swash plate 25 from the first pivot position shown in Fig. 5 in the second pivot position shown in Fig. 6 is pivoted, the pressure fluid about this also in this embodiment as a bore with a small diameter trained throttle element 47 and the adjoining outlet channel 48 the damping cylinder 42 pushed out, whereby the intended damping of the Movement of the swash plate 25 and the support of the swash plate 25 during the Pivoting results.

The invention is not restricted to the exemplary embodiments shown. How mentioned at the beginning, the present invention can also be used in axial piston machines Swashplate construction are used. The damping arrangement can also be arranged at any other place, provided that it is guaranteed that the Damping piston 40 in a suitable manner on the swash plate 25 or Swashplate attacks. Furthermore, additional damping elements in the area of First stop surface 28 may be provided to a for the other pivoting direction to ensure adequate cushioning.

Claims (12)

1. Axial piston machine (1) with a cylinder block (2), in which cylinder bores (3, 4) are provided, in which pistons (5, 6) are displaceably guided, which in order to execute a lifting movement are supported against an inclined or wobble plate (25), and with a pivoting device (31) for changing the inclination of the inclined or wobble plate (25) by pivoting said plate about a pivot axis (27), characterised by at least one damping element (41) with a damping piston (40), which acts upon the inclined or wobble plate (25) and is displaceably arranged in a damping cylinder (42), which is connected via a throttle element (47) and a non-return valve (44) arranged parallel to the throttle element (47) to a pressure fluid reservoir (48), the non-return valve (44) allowing for the unthrottled supply of the pressure fluid from the pressure fluid reservoir (48) into the damping cylinder (42) and preventing the unthrottled outflow of the pressure fluid from the damping cylinder (42) bypassing the throttle element (47).
2. Axial piston machine according to claim 1, characterised in that a restoring spring (43) acts upon the damping piston (40) in such a manner that the damping piston draws further pressure fluid from the pressure fluid reservoir (48) via the non-return valve (44) as soon as the damping piston (40) is freely movable in the direction of an increase in volume of the damping cylinder (42).
3. Axial piston machine according to claim 2, characterised in that further pressure fluid is additionally drawn via the throttle element (47).
4. Axial piston machine according to one of claims 1 to 3, characterised in that the pressure fluid reservoir (48) is a leakage fluid collecting chamber, more particularly the housing interior (46) of the axial piston machine (1).
5. Axial piston machine according to one of claims 1 to 4, characterised in that the inclined or wobble plate (25) can be pivoted back and forth by means of a pivoting device (31) between a first pivot position (Fig. 1, Fig. 5) corresponding to a larger angle of inclination and a second pivot position (Fig. 2, Fig. 6) corresponding to a smaller angle of inclination, the damping element (41) damping the pivoting movement during the pivoting of the inclined or wobble plate (25) from the first into the second pivot position as a result of the throttled outflow of the pressure fluid from the damping cylinder (42).
6. Axial piston machine according to one of claims 1 to 5, characterised in that the axial piston machine (1) is designed with an inclined plate construction and the pistons (5, 6), which are arranged in the cylinder bores (3, 4) of the cylinder block (2) rotating about the cylinder block axis (12), are supported against a stationary inclined plate (25).
7. Axial piston machine according to claim 6, characterised in that the damping element (41) is arranged in or on the inclined plate (25).
8. Axial piston machine according to claim 7, characterised in that, by means of the restoring spring (43), the damping piston (40) is held in abutment against a stationary counter element (30) opposing the inclined plate (25).
9. Axial piston machine according to claim 6, characterised in that the damping element (41) is arranged in or on a stationary counter element (30) opposing the inclined plate (25).
10. Axial piston machine according to claim 9, characterised in that the damping piston (40) is held in abutment against the inclined plate (25) by means of the restoring spring (43).
11. Axial piston machine according to claim 5 and one of claims 6 to 10, characterised in that, on its side facing away from the pistons (5, 6), the inclined plate (25) comprises a first (28) and a second (29) abutment surface, and during abutment against the first abutment surface (28) the inclined plate adopts the first pivot position (Fig. 1, Fig. 5) with the larger angle of inclination and during abutment against the second abutment surface (29) it adopts the second pivot position (Fig. 2, Fig. 6) with the smaller angle of inclination.
12. Axial piston machine according to one of claims 6 to 11, characterised in that the point of application, at which the or each damping piston (40a; 40b) acts upon the inclined plate (25), is offset relative to the cylinder block axis (12) in such a manner that the resulting force, which is composed of the force (F_DR) exerted by the damping piston (40a; 40b) upon the inclined plate (25), the force (F_V) exerted by the pivoting device (31) upon the inclined plate (25) during the pivoting procedure and the force (F_KL) exerted by the pistons (5, 6) upon the inclined plate (25), acts at a centre of gravity of the forces (S) which is located on the cylinder block axis (12).

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