• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A piston (1) of a hydraulic piston machine is described, the piston (1) having a hole (2) surrounded by a wall (3) and an insert (4) arranged in the hole (2). This type of piston is used to have a piston machine with high efficiency at low cost. For this, at least two flexible rings (12, 13) are arranged between the insert (4) and the wall (3). (Machine-translation by Google Translate, not legally binding)
    公开号:ES2826125A1
    申请号:ES202030891
    申请日:2020-08-28
    公开日:2021-05-17
    发明作者:Andersen Stig Kildegaard；Iversen Frank Holm；Sveinn Porarinsson
    申请人:Danfoss AS；
    IPC主号:
    专利说明:

    [0002] Piston of a hydraulic machine and hydraulic piston machine
    [0004] The present invention relates to a piston of a hydraulic piston machine, the piston having a hole surrounded by a wall and an insert arranged in the hole.
    [0006] Furthermore, the invention relates to a hydraulic piston machine.
    [0008] A piston engine is a positive displacement machine and can be, for example, in the form of an axial piston engine.
    [0010] Such a machine is used, for example, to pump a liquid such as water. Although water is generally considered to be an incompressible fluid, in fact, it is slightly compressible. The compressibility of the water decreases the efficiency of the machine.
    [0012] In order to reduce the negative effects of liquid compressibility, the insert is used to reduce capacity loss due to liquid-filled dead volume. This increases energy efficiency and allows the machine to operate at higher pressures and speeds.
    [0014] However, it is difficult to fix the insert reliably in the bore of the piston. It is known to use an insert of a polymeric material that is pressed into the gap. However, such an assembly step carries the risk of a deformation of the piston. Therefore, it is necessary to produce the insert with high precision to obtain small tolerances. This increases the costs of the hydraulic piston machine.
    [0016] The object underlying the invention is to have a piston machine with high efficiency at low costs.
    [0018] This object is solved with a piston as described at the beginning in that at least two flexible rings are arranged between the insert and the wall.
    [0020] Flexible rings can deform during insertion of the insert into the gap. After insertion of the insert into the gap, the flexible rings secure the insert in the piston thus defining a position of the insert in the hollow that can be maintained even against the forces that can be produced by centrifugal forces during the higher working speeds of the piston. Such centrifugal forces can occur, for example, when the piston is arranged in a cylindrical drum of an axial piston machine.
    [0022] In one embodiment of the invention the two rings are located on either side of a center of mass of the insert. The two flexible rings prevent an inclination of the insert in the recess and consequently prevent wear of the insert.
    [0024] In one embodiment of the invention, a first ring ensures an axial position of the insert in the piston and a second ring ensures a radial position of the insert in the bore only. Thus, overdetermination of the position is avoided.
    [0026] In one embodiment of the invention the first ring is located adjacent an open end of the gap. This makes it easier to mount the insert in the hole. The first ring has to be moved only a small distance in the gap.
    [0028] In one embodiment of the invention the first ring is arranged in an inner groove in the wall and in an outer groove in the insert. The first ring locks the insert in the hole.
    [0030] In one embodiment of the invention the second ring rests against a bottom of the gap. The bottom forms an end stop for the movement of the second ring. Therefore, the position of the second ring is reliably determined.
    [0032] In one embodiment of the invention, the insert comprises a conical section near an end remote from the open end of the gap and the second flexible ring is disposed around a conical section. Therefore, the insert can be centered with respect to the second ring and therefore can be centered with respect to the piston axis.
    [0034] In one embodiment of the invention a space is formed between the insert and the wall. Space has two advantages. It prevents a contact between the insert and the wall of the hole and consequently prevents wear of the insert or wall that could result in movement of the insert relative to the wall. In addition, the space allows a flow of fluid along the piston wall that can be used to cool the piston.
    [0035] In one embodiment of the invention at least the first ring comprises at least one thin section having a radial magnitude smaller than the largest radial magnitude of the ring. The thin section allows the liquid to pass the first ring and enter the gap. When the second ring also comprises a thin section, the liquid is allowed to pass the second ring.
    [0037] In one embodiment of the invention the ring comprises a series of blocks separated by thin sections. The ring is made up of a succession of blocks and thin sections. Therefore, a series of fluid passages are envisaged passing through the first ring.
    [0039] In one embodiment of the invention the blocks are equidistant spaced. When the blocks are evenly distributed around the circumference of the insert they ensure an even distribution of fluid flow in the space between the insert and the piston and minimize shape defects in the roundness of the piston caused by pressing the insert into the bore. The ring ensures that the insert is precisely centered within the piston.
    [0041] In one embodiment of the invention the thin sections have an axial extension less than the axial extension of the blocks. The thin sections form a kind of spring that allows deformation of the ring when the insert is inserted into the hole. Furthermore, they increase a section of a flow path beyond the ring, in particular in the second ring, when it rests against the bottom of the hole.
    [0043] In one embodiment of the invention the first ring and the second ring have the same shape. This facilitates the assembly of the piston and the insert. There is no need to be careful about the shape of the ring in the respective position at both ends of the insert.
    [0045] In one embodiment of the invention the insert is made of a fiber reinforced plastic or ceramic material. A ceramic material can be produced with a low mass and almost no compressibility. The same happens with fiber-reinforced plastic material, in particular fiber-reinforced polymer, such as PEEK (Polyetheretherketone).
    [0047] The invention relates to a hydraulic piston machine having a piston as described above.
    [0049] The invention will now be described in more detail with reference to the drawing, in which: Fig. 1 shows a longitudinal section of a piston according to the line AA of Fig. 2,
    [0051] Fig. 2 shows a top view of the piston,
    [0053] Fig. 3 shows a flexible ring in perspective view,
    [0055] Fig. 4 shows a top view of the ring, and
    [0057] Fig. 5 shows a side view of the ring.
    [0059] Fig. 1 shows a sectional view of a piston 1 of a hydraulic piston machine. The piston 1 comprises a gap 2 surrounded by a wall 3. An insert 4 is arranged in the gap 2.
    [0061] The insert 4 is made of a ceramic material or other light and rigid material that cannot be compressed. Said material can be a fiber-reinforced plastic material, in particular a fiber-reinforced polymer, such as PEEK (Polyetheretherketone).
    [0063] The recess 2 comprises an open end 5 through which the insert 4 can be mounted in the recess 2. Furthermore, the recess 2 comprises a bottom 6 at the opposite end. The bottom 6 is basically closed except for a channel 7 through which liquid can flow to reach a hydrostatic bearing face 8 of a sliding shoe 9. The sliding shoe 9 is mounted on a ball 10 of the piston, as known in the technique. During operation, the sliding shoe 9 bears against an angled inclined plate and is held against the angled inclined plate by a retaining plate (not shown).
    [0065] A space 11 is formed between the insert 4 and the wall 3.
    [0067] The insert 4 is fixed in the recess 2 by means of a first flexible ring 12 and a second flexible ring 13. The first flexible ring 12 is arranged in an inner groove 14 in the wall 3 and in an outer groove 15 of the insert 4. The inner slot 14 and the outer slot 15 are located adjacent to the open end 5 of the gap 2.
    [0068] The insert 4 comprises a conical section 16 at or near the end remote from the open end of the gap 2. The second flexible ring 13 is arranged around the conical section 16 and abuts against the bottom 6.
    [0070] The first flexible ring 12 ensures an axial position of the insert 4 in the piston 1 and at the same time ensures a radial position of the insert 4 in the gap 2. The first flexible ring 12 centers the insert 4 with respect to the piston 1 near the open end 5 of gap 2.
    [0072] The second flexible ring 13 ensures only a radial position of the insert 4 in the gap 2. The two flexible rings 12, 13 are arranged with a certain distance from each other along the longitudinal extension of the insert 4. More precisely, they are arranged at both sides of a center of mass of the insert 4. Therefore, they prevent an inclination of the insert 4 with respect to the wall 3.
    [0074] Figs. 3 to 5 show the first flexible ring 12. In a preferred embodiment of the invention, the second flexible ring 13 has the same shape.
    [0076] The ring 12 is not closed, but open in the circumferential direction, that is, it comprises a clearance 17 in the circumferential direction. In an embodiment not shown, the ring 12 may be closed in the circumferential direction.
    [0078] Ring 12 comprises a number of blocks 18 that are uniformly distributed in the circumferential direction. In other words, the blocks 18 are equally spaced. This is true for blocks 18 on both sides of clearance 17.
    [0080] Two adjacent blocks 18 are connected by means of a thin section 19. The thin section 19 comprises (Fig. 4) a radial extension 20 that is smaller than a radial extension 21 of the blocks 18 that is the largest radial extension of the ring 12.
    [0082] Furthermore, the thin sections 19 have an axial extension 22 that is smaller than an axial extension 23 of the blocks 18.
    [0084] Such a construction has the following effect. Due to the smaller radial extension 20 of the thin sections 19 a fluid passage is formed through which the fluid can enter the space 11 between the insert 4 and the wall 3 and can flow past the ring 13 towards the hydrostatic bearing 8. In addition, the thin sections 19 allow a deformation of the ring 12 that is necessary to mount the insert 4 together with the rings 12, 13 in gap 2.
    [0086] When the insert 4 is assembled by pressing it into the gap 2, the rings 12, 13 are plastically deformed by an amount that varies slightly depending on the production tolerances of the piston and insert 4. The first ring 12 flows into the inner groove 14 of wall 3, so that the axial position of insert 4 within gap 2 is locked and well defined. The main function of the second ring 13 is to center the insert 4 inside the piston 1.
    [0088] The combination of the second flexible ring 13 in the bottom 6 of the gap 2 and the conical section 16 of the insert 4 ensures good centering of the tip of the insert 4 even if the production tolerances for the piston 1 and the insert 4 cause significant variations in the axial clearance between the tip of the insert 4 and the bottom 6 of the gap 2 in the piston 1.
    [0090] Therefore, the two ends of the insert 4 are locked against radial movements within the piston 1. Otherwise, the inertial forces acting on the insert 4 during high speed operation can cause the insert 4 to make small movements. within the piston 1 which can eventually lead to wear, the formation of damage, and even the insert 4 becoming dislodged over time.
    [0092] The space 11 allows a flow of fluid that helps to cool the piston 1, so that the piston 1 does not overheat. If piston 1 overheats, it can get stuck in the cylinder due to excessive thermal expansion of the piston. The first ring 12 (and the second ring 13 as well) allow fluid to pass in the assembled state.
    [0094] Rings 12, 13 further ensure that insert 4 is precisely centered within gap 2 to ensure uniform size of gap 11 and uniform fluid flow and cooling in gap 11. Since blocks 18 of rings 12, 13 are equidistant, ensure a uniform distribution of fluid flow in space 11 and minimize shape defects in the roundness of the piston caused by pressing the insert 4 into the piston.
    [0096] The piston 1, more precisely the wall 3 of the piston is made of a material of high resistance that can withstand the loads on the piston. It is a material with good tribological properties to guarantee low friction losses and low wear of the piston and the components with which it interacts. Lastly, the piston material must be compatible with the piston engine fluid. This will often lead to the piston being made of metal with a high density. Hole 2 reduces the mass.
    [0098] The insert 4 reduces the compressibility in the volume in which the piston moves by filling a significant fraction of the dead volume with a material with bulk moduli higher than the fluid, but with a lower density than the material of the wall 3 and others. parts of the piston 1. The material of the insert 4 must be compatible with the fluid, but does not need to have the strength and tribological properties of the material of the rest of the piston 1. The use of the two flexible rings 12, 13 helps to reduce the requirements for the strength of the material of the insert 4 because the space 11 between the insert 4 and the wall 3 allows the insert 4 to remain straight even if the wall 3 itself is deformed by external loads. This allows the use of materials for the insert 4 with very high stiffness, but low strengths, such as for lightweight ceramic extensions or fiber-reinforced polymer, such as PEEK (Polyetheretherketone), without risk of bending loads being transferred from piston to insert 4.
    权利要求:
    Claims (15)
    [1]
    1. Piston (1) of a hydraulic piston machine, the piston (1) having a hole (2) surrounded by a wall (3) and an insert (4) arranged in the hole (2), characterized in that at least Two flexible rings (12, 13) are arranged between the insert (4) and the wall (3).
    [2]
    Piston according to claim 1, characterized in that the two rings (12, 13) are located on both sides of a center of mass of the insert (4).
    [3]
    Piston according to claim 1 or 2, characterized in that a first ring (12) ensures an axial position of the insert (4) in the piston (1) and a second ring (13) ensures a radial position of the insert (4) in hole (2) only.
    [4]
    Piston according to claim 3, characterized in that the first ring (12) is located adjacent to an open end (5) of the hole (2).
    [5]
    Piston according to claim 4, characterized in that the first ring (12) is arranged in an inner groove (14) in the wall (3) and in an outer groove (15) in the insert (4).
    [6]
    Piston according to any one of claims 1 to 5, characterized in that the second ring (13) rests against a bottom (6) of the hole (2).
    [7]
    Piston according to any one of claims 1 to 6, characterized in that the insert (4) comprises a conical section (16) near an end remote from the open end (5) of the gap (2) and the second flexible ring (13 ) is arranged around the conical section (16).
    [8]
    Piston according to any one of claims 1 to 7, characterized in that a space (11) is formed between the insert (4) and the wall (3).
    [9]
    Piston according to claims 1 to 8, characterized in that at least the first ring (13) comprises at least one thin section (19) with a radial extension (20) less than the largest radial extension (21) of the ring ( 12).
    [10]
    Piston according to claim 9, characterized in that the ring (12) comprises a series of blocks (18) separated by thin sections (19).
    [11]
    Piston according to claim 10, characterized in that the blocks (18) are equally spaced.
    [12]
    Piston according to claim 10 or 11, characterized in that the thin sections (19) have an axial extension (22) less than the axial extension (23) of the blocks (18).
    [13]
    Piston according to any one of claims 1 to 12, characterized in that the first ring (12) and the second ring (13) have the same shape.
    [14]
    Piston according to any one of claims 1 to 13, characterized in that the insert (4) is made of a ceramic material or fiber-reinforced plastic.
    [15]
    Hydraulic piston machine comprising a piston (1) according to any one of claims 1 to 14.
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    同族专利:
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    US20210148342A1|2021-05-20|
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    GB1332183A|1969-10-09|1973-10-03|Tokico Ltd|Vehicle suspension unit|
    US3747479A|1972-01-28|1973-07-24|Ici Ltd|Piston assembly|
    US4009645A|1975-11-03|1977-03-01|Gerhart Engineering And Machine Company|Piston pump|
    US5080202A|1989-05-11|1992-01-14|Bendix Altecna S.P.A.|Wheel cylinder|
    US6325181B1|1999-07-30|2001-12-04|Kelsey-Hayes Company|Piston assembly for use in a wheel cylinder of a drum brake assembly|
    US3915071A|1972-07-28|1975-10-28|Linde Ag|Piston for hydrostatic machines|
    CA985959A|1972-12-21|1976-03-23|Caterpillar Tractor Co.|Piston for hydraulic translating unit|
    US3999468A|1972-12-21|1976-12-28|Caterpillar Tractor Co.|Piston for hydraulic translating unit|
    US3986439A|1974-11-25|1976-10-19|Deere & Company|Piston and slipper arrangement for hydraulic pump or motor|
    DE3732648C2|1987-09-28|1989-10-19|Brueninghaus Hydraulik Gmbh, 7240 Horb, De|
    US5564903A|1993-11-23|1996-10-15|Alliedsignal Inc.|In-line ram air turbine power system|
    法律状态:
    2021-05-17| BA2A| Patent application published|Ref document number: 2826125 Country of ref document: ES Kind code of ref document: A1 Effective date: 20210517 |
    优先权:
    申请号 | 申请日 | 专利标题
    DE102019130843.7A|DE102019130843A1|2019-11-15|2019-11-15|Piston of a hydraulic piston machine and hydraulic piston machine|
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