Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
  • F04B1/122—Details or component parts, e.g. valves, sealings or lubrication means
  • F04B1/124—Pistons
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
  • F01B3/00—Reciprocating-piston machines or engines with cylinder axes coaxial with, or parallel or inclined to, main shaft axis
  • F01B3/0082—Details
  • F01B3/0085—Pistons

Definitions

• the invention relates to a piston according to the preamble of claim 1.
• pistons are to be used in axial piston machines which, in general, serve to convert pressure energy into rotational energy or vice versa, that is to say can be used either as pumps or hydraulic motors.
• the principle of an axial piston machine is that the pistons can move axially back and forth in cylinders, and the size of the displacement space delimited by the piston in the cylinder can be changed as a result.
• the hydraulic medium is conveyed by changing this volume; when used as a motor, this volume is changed cyclically by the inflow of hydraulic medium and, as a result, causes the engine to rotate.
• the cylinders with the pistons axially displaceable therein are arranged in a circle and parallel to one another in a rotatably mounted piston drum.
• One end of each of the pistons protrudes into the cylinder space, while the other end is usually spherical and lies in a suitably designed, pan-shaped bearing.
• the pistons are supported by a pan-shaped bearing on a level slide, which is part of the cradle. This disc can be inclined relative to the axis of rotation of the piston drum, so that from a
• the swash plate circulate, but also be radially displaceable.
• a hold-down device is provided, from which the following forces have to be overcome:
• pistons for axial piston machines are known in which the piston crown is drilled out as shown above, but then, in order to avoid the dead volume, was closed and sealed again by a cover Reducing the
• Friction required through hole from the piston crown to the opposite end of the piston or the relief pressure fields are attached.
• Another known solution in which the pistons were drilled centrally but in a ring, so that material for introducing said through-bore was present in the axis of symmetry of the piston
• the object of the invention is therefore to create pistons with a through bore from the piston crown to the opposite piston end and with the smallest possible dead volume, which have the lowest possible mass and are easy to manufacture.
• Such a weakened, central region of a piston can, if simple manufacture is in the foreground, be formed with a constant cross-section, especially if the bending forces acting on it are not very different over the axial length of the central region, in which case, of course, the Cross-section must be dimensioned according to the greatest bending load occurring.
• the mass reduction is to be further optimized while accepting a somewhat more complex manufacture of the piston
• the piston cross section in the axial course of the central region is changed in accordance with the bending loads occurring at every point, so that there is a constant deflection over the piston course.
• a further reduction in the mass of the piston is made possible by turning the two edge regions, in which the piston rests against the cylinder wall, from the central region, which has the advantage that the remaining lateral surfaces on the cylinder wall, which have a load-bearing capacity Lubricating film and a sufficient sealing length must not be reduced.
• FIG. 1 shows a cross section through an axial piston machine with pistons according to the invention
• Fig. 3 is a partially cut piston with different cross-section in the central area
• FIG. 4 shows a piston similar to FIG. 3 with the end regions turned behind.
• Fig. 5 shows a partially cut piston with concentrically arranged longitudinal bores in plan and elevation.
• axial piston machine which is located in a cup-shaped housing 2, which is closed with a cover 1.
• The. both parts are screwed together via the tie rod 5 with the aid of the nuts 21.
• Slides in the pump operation, via the shaft • 19 driven axial piston machine essentially consists of coaxially about the shaft 19 rotatably disposed piston drum 12 on the plate one side on the Verteiler ⁇ 14 and protrude into the on the other side of the piston 13
• the end of the pistons 13 protruding from the piston drum 12 is spherical and is mounted in the sliding shoes 16 provided with a corresponding inner contour.
• the sliding shoes 16 are slidably supported on the fixed swash plate 17 in order to be able to maintain the elliptical orbit around the shaft 19 due to the inclined position of the swash plate 17 relative to the shaft 19.
• the swash plate 17, against which the sliding shoes 16 are pressed with the aid of a hold-down device 15, is arranged on a cradle 18, which with its semi-cylindrical outer contour is pivotable in a corresponding recess in the bearing body 10.
• the piston 13 used in the axial piston machine of FIG. 1 is shown in more detail in FIG. 2.
• the piston 13 has an outer contour in the front area 3 and rear area 4, which corresponds to the inner contour of the cylinder and slides along it. In the central region 6, however, the cross-section of the piston 13 is significantly smaller, namely over the entire axial length of the central region.
• the front region 3 is of the ball-shaped head 7 of the piston 13, which is rotatably mounted in a recess of the sliding shoe ent speaking '16th
• pockets 8 are formed on the underside of the sliding shoe, which serve as relief pressure fields when the pressure is applied accordingly.
• the necessary pressure supply takes place via the bore 9 in the slide shoe 16 and the further bore 11 in the piston 13 from the compression chamber. inside the cylinder. Since the bore 11 advantageously lies in the longitudinal axis of the piston 13, its function is restricted by the cross-sectional constriction in the. middle region 6 of the piston 13 is not affected.
• FIG. 3 Another embodiment of the piston 13 according to the invention is shown in FIG. 3.
• the central region 6 of the piston has. 13 does not have a constant cross-section, but the cross-section of the piston increases towards the front end, corresponding to the increasing bending load, which results in a uniform deflection in the longitudinal direction over the central region 6 of the piston 13.
• Piston 13 shown 3 can in mass savings are still being optimized on the piston that der.'vordere region 3 and "the rear portion 4 of the piston are behind 13 rotates from the middle section 6, without the remaining lateral surfaces, with which the piston 13 abuts the cylinder wall to further reduce, as shown in Fig. 4.
• the use of such pistons is particularly advantageous in the case of short-stroke axial piston machines, since in this case only relatively small bending forces act on the pistons due to the overall short overall length of the pistons 13, and the axial length of the front region 3 of the piston 13 is all the less can be selected, the smaller the stroke of the piston, if a complete disengagement of the lateral surface of the front area 3 with the cylinder wall is to be avoided.
• a piston is shown, the mass of which was reduced without accepting a dead volume in that bores 22 were made concentrically about the longitudinal axis of the piston in the piston head, so that enough material remained in the center of the piston to introduce the bore 11 therein . So that the cavities of the bores 22 do not act as a dead volume during operation of the axial piston machine, they are closed and sealed on the piston head by covers 23, which are fastened, for example, by brazing in the piston.
• covers 23 are fastened, for example, by brazing in the piston.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Reciprocating Pumps (AREA)
• Compressors, Vaccum Pumps And Other Relevant Systems (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6288964

Family Applications (1)

Country Status (3)

Cited By (1)

Families Citing this family (4)

Citations (5)

Family Cites Families (1)

• 1985
  • 1985-12-19 DE DE19853545137 patent/DE3545137A1/de active Granted
• 1986
  • 1986-12-12 EP EP87900123A patent/EP0252105B1/de not_active Expired - Lifetime
  • 1986-12-12 DE DE8787900123T patent/DE3678287D1/de not_active Expired - Fee Related
  • 1986-12-12 WO PCT/EP1986/000741 patent/WO1987003926A1/de active IP Right Grant

Patent Citations (5)

Also Published As

Similar Documents

Legal Events