DE7212013U - Piston with a bearing surface arranged on one side for receiving a force transmission element - Google Patents

Description

PATB HTAKWA I.T WE WOOD SIFL ·. IN O. R. ECM SBURU "Ft ATTO LSKR-8ΪΒΛΒ8 * 1 * niumn- a SUf * W.

N. 231

Augsburg, March 24, 1972

National Research Development Corporation, Kingsgate House, 66-7h Victoria Street, London, S.W.l, England

Piston with a bearing surface arranged on one side for receiving a force transmission element

The innovation relates to a piston with a one-sided Storage area for receiving a power transmission element and includes in particular, but not exclusively, Ball or cylinder pistons for use in hydro-

static pumps or motors that perform rotary or linear movements.

In the case of hydrostatic machines, the mechanical power output (in the case of a motor) or the input mechanical performance (in the case of a ■ · pump) more of a function the pressure (and thus the potential energy) of the working fluid, as its speed (and thus the kinetic Energy).

In known hydrostatic piston machines, the pistons are each designed as balls, each in a A fine fit slide in a cylinder bore to which the working fluid, e.g. oil, is fed and from which she is expelled. The balls work, so to speak, as cam followers and lie on a guide profile track that moves relative to the cylinders in which the spherical pistons slide back and forth.

If the ball pistons move slowly to and fro, the oil that seeps past the ball can be considerable except for a considerable amount Part of the total amount flowing into the cylinder will increase. Because the ball rotates freely in the cylinder must be able to function as a cam follower is

It is not possible to reduce the seepage of the oil through a pressure seal attached to the ball.

It has already been proposed to provide an auxiliary piston to reduce the leakage flow on the ball, which is essentially designed as a rigid disc and fitted with a sliding fit in the cylinder bore of the spherical piston is and dar has a seat for the ball. It has proven difficult with such an arrangement to keep the friction between disk and ball small.

The aim of the innovation is to achieve the objective of reducing the friction between the piston body in such a piston and to reduce the ball and to seal the cylinder effectively.

In terms of solving this problem, a piston is provided with a bearing surface arranged on one side on the piston body according to the invention characterized in that the piston body contains an insert made of low-friction material, which in said bearing surface is formed into a bearing shell for a power transmission element, and that devices for secure attachment of the insert in the piston body are available.

The insert is preferably made in the piston body by correspondingly shaping the insert and / or the bearing surface securely attached, the shape of the insert and / or the shape of the bearing surface are chosen so that the Insert is firmly locked in the piston body by the support of the bearing surface.

The piston body preferably has a groove or bore on the bearing surface, the one made of low-friction Material existing insert into this groove or protrudes through this hole. The use and / or the groove or the bore are shaped so that the insert is thereby secured in the piston body that it protrudes into this groove or through this hole.

As another possibility or in addition to this, projections from the bearing surface can also serve for fastening protrude into the insert.

The insert preferably protrudes into a bore in the piston body which extends from the bearing surface to one of the latter

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remote front side is enough. The insert may have a flange extending over at least part of the End face of the piston body extends. The part of the insert extending through said bore can be a Have through hole, which from said end face of the piston body to the surface of the in the The bearing shell lying on the bearing surface is sufficient and allows the bearing shell to be lubricated during operation.

In terms of the further solution to the object of the innovation, the piston body has a bore from the bearing surface up to the named end face remote from the bearing surface or up to the side wall of the piston body, said insert extending through said bore and on the periphery of said face or on the side wall of the piston body forms a sealing ring which engages the inner surface of the bore, in which the piston is fitted during operation.

As a result, this bore can either be axially through the piston body up to the aforesaid, remote from the bearing surface End face or at right angles to the piston body axis and the seal in an annular groove in the Be arranged cylinder wall.

Preferably, said insert consists of a single part, which is in place in said

Drilling or recessing, for example by injection molding, is shaped.

As another option, if the piston body has a bore from the bearing surface to the end face remote from the bearing surface, the insert a part formed into a bearing shell, a pin reaching through the bore and one on the plane surface of the Piston body arranged fastening part exist, wherein at least two of the aforementioned xeiie produced separately and will be assembled after the pin has been pushed through the hole.

The pin can be made as one part together with the bearing shell and the fastening part can then be welded to the pin. In contrast, the insert in the piston body can also be fitted with a screw cap,

§ other fasteners with screw threads, one

Spring washer or other mechanical fastening means to be attached to the pin and so the bearing shell part hold in the piston body. As another option, you can the insert is attached to the piston body with an adhesive

7212C13-3.8.72

or the pin can be deformed by heat or pressure or in some other way and so the insert in the

Such an arrangement can also be designed in such a way that the piston body surrounding the bearing surface is shaped in such a way is that the holds the power transmission element for which the bearing shell is intended during operation. The storage area surrounding piston body can be flanged over the power transmission element so that it does this during operation Force transmission element holds.

In this way, a piston ¹ " ^{1 can} be manufactured in such a way that an insert made of low-friction material is inserted into a piston body which has a bearing surface on its end face and a bore from this bearing surface to the other end face of the piston body consists of a bearing shell part, which is fitted into the seat and serves as a bearing shell for a cam follower, and a pin which protrudes through the bore, the pin being held at the end remote from the bearing shell so that the insert sits firmly in the piston body .

Another way to attach the insert

in the piston body consists in forming the pin so that it acts as a bracket with which the bearing shell part in the Can engage the piston body.

It may be appropriate to provide more than one bore and / or recess in the piston body in order to insert the insert. In some cases it can be advantageous to provide a large number of axially parallel bores, which are from the bearing surface to the flange of the insert, which a: .. the end face of the piston body remote from the seat surface is applied. If the insert is manufactured by injection molding and this fills such a large number of through holes off, then the shrinking away of the insert is reduced, which can otherwise lead to the insert detaches from the storage area.

Said insert is preferably made from Künste KoT f, where it is expedient to use polytetrafluoroethylene, nylon, or an acetal material such as "DeIrin" or "Kemeial" .

The power transmission element lying in the bearing shell mentioned during operation can be designed as a ball, for example in the case of a hydrostatic spherical piston machine, or as a roller .

Some preferred shapes of the piston after the innovation are described below with reference to the accompanying drawings described. Show it:

Fig. 1 is a longitudinal section of a ball

piston according to the innovation for a hydrostatic machine,

Figs. 2, 3

and 4 each a longitudinal section of

different spatial shapes ^ it shown in Fig. 1 Piston,

FIGS. 5 and 6 each show a longitudinal section of

Three-dimensional shapes which are similar to the piston shown in FIG are, the piston body having one or more grooves instead of a bore having.

7 and 8 are longitudinal sections of three-dimensional shapes of the one shown in FIG Piston, with the insert

forms one or two piston seals in the piston body,

9a and 9b show a longitudinal and a corresponding cross section of a Kolbtis similar to that in FrIg. shown spatial shape, the however, has several bores in the piston body, and

Figures 10 and 10a

and FIGS. 11 to 15 show further three-dimensional shapes of a

Pistons according to the innovation.

In Fig. 1, a piston for hydrostatic spherical piston pumps or motors is shown. The piston 11 consists of a piston body 12 which has a bearing surface on one end face and an axial bore I ¹ I which penetrates the piston body from the bearing surface 13 to its other end face. The bearing surface 13 is shaped so that it can receive a spherical force transmission element 15. An insert 16, which forms a bearing shell for the ball 15, rests on the bearing surface 13. In operation, the piston 11 moves back and forth in a cylinder bore 17 under the guidance of a guide profile track 18 on which

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the ball 15 rests. In the case of hydrostatic machines, this is Bore 17 is filled with a working fluid, e.g. oil.

The insert 16 is preferably made of plastic and its friction on metal is much less than that of the piston body 12, which, like the ball, is expediently made of metal. The insert 16 protrudes through the hole I ^ and fills a groove 19 in the of the end face of the piston body remote from the bearing surface 13 the end. The diameter of the groove 19 is larger than that Diameter of the bore I ^, so that the insert 16 mechanically is held in its position in the piston body 12. The insert 16 has a lubrication hole 20 which axially between the bearing surface 16 and the end face of the piston body remote from this bearing surface.

In the three-dimensional shapes shown in FIGS. 1 to 9, the insert 16 is expediently in place in FIG the piston body 12 is poured in, the mold partly from the piston body 12 itself and from additional mold parts for forming the bearing shell 13 and, if necessary, the end face of the insert remote from the bearing shell Gebi! let will. Preferably, a low-friction one is used for injection molding Plastic, such as Folytetrafluoroethylene, is used.

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FIGS. 2, 3 and H show modified three-dimensional shapes of the piston shown in FIG. 1. In the three-dimensional shape shown in FIG. 2, the diameter of the piston body is only slightly larger than the diameter of the ball 15 in order to keep the stresses between the ball and the guide profile track as small as possible. According to the three-dimensional shape shown in FIG. 3, the ball 15 is inserted into the piston body in such a way that it is retained by the insert 16 - in the uniform shown in FIG. K , the end of the piston body 12 encloses the bearing surface 13 and is above the ball beaded to hold it in place.

5 and 6 show modified forms of the piston shown in FIG. 1, which instead of the bore I ¹ * have a groove 21 and 22, respectively. The groove 21 or is shaped in such a way that the insert is held in the piston body 12 as a result.

Fig. 7 shows a further three-dimensional shape of the piston shown in Fig. 1, in which the insert 16 the whole Covered end face of the piston body remote from the bearing surface 13, with only the lubrication hole 20 remaining. At the end face of the piston body remote from the bearing surface 13, the insert 16 stands radially over the circumference 23 Piston body and thus forms a seal on the wall of the cylinder bore 17

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In Fig. 8 a further three-dimensional shape is shown, which has a piston ring 24 as the main seal, which is formed by the insert 16, which is formed by radial bores protrudes in the piston body 12 and is shaped on the circumference to form a ring, and in which a second seal by the on of the bearing surface 13 remote end face of the piston is formed on the circumference over this protruding insert.

9a and 9b show a longitudinal and a cross section of a further three-dimensional shape of the piston shown in FIG. 1, in which the piston body 12 has a plurality of axially parallel bores Ih.

If the insert 16 is produced by injection molding, the plastic may shrink to a small extent and lead to the insert becoming detached from the bearing surface 13 of the piston. To prevent this, several holes I ¹ I are drilled into the piston body from the spherical bearing surface 13. As a result of the shrinkage of the plastic in these bores I ¹ J, the insert 16 is tensioned against the spherical bearing surface 13 of the piston.

Referring now to FIG. 10, a piston constructed similarly to the piston shown in FIG. 1 will now be described which is not used, however, by injection molding,

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but is used in a different way. The insert consists of two originally separate parts, namely from a storage axis part 23 with a pin 2 * 5 and from a flange 25 · The insert is assembled by inserting the bearing shell part 23 with the pin 24 through the Bore 14 and in the flange located in the groove 19 pressed and the flange 25 is welded to the pin 24 will.

The grooves 27 and the pin 26 in the piston body or in the bearing shell part 23 prevent the insert from rotating.

Compared to the injection molding process described above, this arrangement has a number under certain circumstances of advantages:

The metal pistons do not need to be inserted into the injection molding machine, which means that the Greatly reduce the cost of injection molded parts.

The dimensional deviations when contracting the plastic can be taken into account, so that a good fit of the insert in the piston body is achieved.

The pistons can be cold-formed, whereby the same

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early the grooves can be made. ^{The bores I 2} J required in the three-dimensional shape shown in FIG. 9a are expensive to manufacture.

FIGS. 11 to 15 show three-dimensional shapes of the piston shown in FIG. 10, the same parts with the same in each case Reference numbers are provided.

In the three-dimensional shape shown in FIG. 11, the pin 24 has a screw thread and is fitted with a nut 29 attached. According to Fig. 12, the pin 24 is by a resilient Terminal 30 secured, and according to Fig. 13, the end 31 of the pin 24 remote from the bearing shell 13 is under heat or Deformed pressure.

In the piston shown in Fig. 14, the free end of the pin 24 is shaped into a resilient head 32, which when Pressing into the bore 14 is compressed and expands again in the groove 19, so that he the insert holds on in its position.

According to FIG. 15, the insert 16 is fastened in the piston body 12 with adhesive 33.

Although it has been described on the basis of examples,

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As the insert is held in its position by providing a bore or a groove in the bearing surface of the piston body, it appears more favorable if the bearing surface of the piston body ύ is provided with a roughening or the like, which protrudes into the insert made of low-friction material and thus the fastening of the insert in the piston body is improved.

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Claims (22)

Protection claims: 1. Piston with a bearing surface arranged on one side for receiving a force transmission element, characterized in that that the piston body (12) contains an insert (16) made of low-friction material, which in said Bearing surface (13) to a bearing shell for a power transmission element is shaped, and that there are devices for securely fastening the insert in the piston body. 2. Piston according to claim 1, characterized in that the insert (16) in the piston body (12) by the shape of the insert and / or the bearing surface (13) is attached. 3. Piston according to claim 1 or 2, characterized in that the piston body (12) on the bearing surface (13) has a groove (21, 22) or a bore (I ² O, and that the insert (16 ) protrudes into or through this recess or bore, the insert and / or the recess or bore being shaped so that the insert is secured in the piston body by protruding into or through this recess or bore. 4. Piston according to one of claims 1 to 3, characterized - 17 - characterized in that the piston body has a bore (1 * 0 a_fv.eist, which extends from the bearing surface (13) to the end face of the piston body remote from this bearing surface extends, and that the insert (16) rvigt through this bore. 5. Piston according to one of claims 1 to 4, characterized characterized in that said insert (16) has a flange which is remote from the bearing surface (13) The end face of the piston body (12) is at least partially covered. 6. Kolbei. according to claim k or 5, characterized in that the part of the insert (16) protruding through said bore (1 * 0) has a through bore (20) which extends from said end face of the piston body (12) to the surface of the insert The bearing shell formed is sufficient and enables this bearing shell to be lubricated during operation. 7. Piston according to one of claims ¹ I to 6, characterized in that said insert (l6) is formed on the circumference of said end face of the Kolher.körpers (12) to form a sealing ring (23) which is attached to the inner surface of a bore ( 17), into which the piston is fitted during operation. - 18 - 7212Ü13-3.8.72 8. Piston according to one of claims 1 to 6, characterized in that the piston body (12) has one of the bearing surface (13) to the side wall of the piston body leading opening and that the insert (16) extends through said opening and on The circumference of said side wall of the piston body forms a sealing ring (2 ¹ I) which rests on the inner surface of a bore (17) into which the piston is fitted during operation. 9. Piston according to one of claims 1 to 8, characterized in that said insert (16) consists of a only part consists which is injection molded in place into said bearing surface (13). 10. Piston according to one of claims 4 to 8, characterized characterized in that the insert (16) consists of a part (23) formed into a bearing shell, a pin (24) which passes through the hole (1 * 1) protrudes, and one on the face mentioned of the piston body (12) arranged fastening part (25), wherein at least two of said parts as separate items are made and assembled after the pin has been inserted into said hole is. - 19 - 11. Piston according to claim 10, characterized in that the pin (2 ¹ O and the bearing shell part (23) are made as a single part and dafi »the fastening part (25) is welded onto the pin, 12. Piston according to claim 10 or 11, characterized in that the two said items are screwed together are attached to each other. 13. Piston according to claim 10 or 11, characterized in that the two said individual parts by a resilient Disc (30) are held together. 14. Piston according to claim 10 or 11, characterized in that the two individual parts mentioned by deformation are joined together under heat or pressure. 15. Piston according to one of claims 1 to 14, thereby characterized in that the insert (16) is attached to the piston body (12) with an adhesive. 16. Piston according to claim 9, characterized in that the piston body (12) has a plurality of bores (I ¹ O, which from the bearing surface (13) to that thereof - 20 = remote end face of the piston body, and that the insert extends through this bore and at the end is formed into a splash, which rests against the end face of the piston body, and that the bores are used to to reduce the consequences of insert shrinkage when the insert is injection molded in place into the piston body is. 17. Piston according to one of claims 1 to δ, characterized in that for fastening the insert (16) in the Piston body (12) of the pin (24) to a resilient head (32) which is locked with respect to the piston body. 18. Piston according to one of Claims 1 to 17, characterized by projections which are used for enabling and which protrude from the bearing surface (13) into the insert. 19. Piston according to one of claims 1 to l8 _3, characterized in that said insert 6l6) is made of plastic. 20. Piston according to one of claims 1 to 19, characterized characterized in that said insert (16) is made of polytetrafluoroethylene, nylon or an acetal material. - 21 - 21.? Iolben according to one of claims 1 to 20, characterized characterized in that the part of the piston body (12) surrounding the bearing surface (13) is shaped so that it in operation the power transmission element holds which sits in this storage area. 22. Piston according to claim 21, characterized in that that the part of the piston body (12) surrounding the bearing surface (13) is above said force transmission element is umöraelt in such a way that it is in operation this Kraftübortragungselement holds on. 23 · Piston according to one of Claims 1 to 22, characterized in that this piston is connected to a force transmission element which is designed as a ball or a roller is. - 22 - 7212β13-3. · .7ί