JP2876480B2 - Axial piston machine piston - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention is formed as a hollow body having a recess in an axial direction. And a piston applied to an axial piston machine, such as an axial piston pump, provided with at least two radially extending annular shoulders which engage with the light metal solidified by casting into the recess.

(Prior Art and Problems to be Solved by the Invention) A piston of this kind is described and exemplified in U.S. Pat. No. 3,187,644. In a known construction, the annular shoulder comprises a sloped side which engages the cast light material. Due to the sloped sides, the light material must be selected to balance the contraction movement of the hollow body and the light material and to maintain the abutment of each sloped surface of the hollow body against each sloped side of the light material. Must. Thus, although the hollow body is engaged with the light material, a firm connection is not ensured. Accordingly, in known embodiments, the light material is provided with means for preventing rotation of the molded fit to prevent the light material from detaching from the piston.

An object of the present invention is to improve the fixation of a lightweight metal to a hollow body while ensuring a simple configuration of a piston of an axial piston machine such as an axial piston pump.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a vehicle, wherein an annular shoulder extends in a direction substantially perpendicular to an axial direction of a piston, and a lightweight metal pinches the annular shoulder by shrinking and forcibly engages the annular shoulder. In order to achieve this object, the present invention provides a hollow body piston having an opening in the front end surface which is the working surface of the piston and having a recess in the axial direction of the piston. Is filled with a lightweight metal that has been cast and solidified, and the annular peripheral wall forming the concave portion has at least two axially spaced apart extending in the direction perpendicular to the piston axis and defining the annular peripheral wall. In a piston having annular shoulder surfaces, the annular shoulder surfaces comprise side walls of at least two spaced annular grooves, and the axially intermediate portion of the cast and solidified lightweight metal has at least two annular annular portions. Groove ring The cast and solidified lightweight metal is located in a region that covers the annular shoulder surface and covers the annular peripheral wall defined by the annular shoulder surface, and the cast, solidified light metal is axially opposed to the annular shoulder surface during cooling. In the direction and forcedly fixed to the annular shoulder surface.

In this case, it is preferable that a passage extends through the piston and the lightweight metal in the axial direction, and opens in a front end surface of the piston and a bearing surface of the piston head opposite to the front end surface. Both may be constituted by a sleeve embedded in the lightweight metal in the region of the lightweight metal.

In this case, the end of the sleeve facing the piston head side is accommodated in a hole in the piston, and the outer surface of the sleeve has at least one shoulder surface in contact with the lightweight metal. A narrow portion is provided in the sleeve, preferably a filter is provided at an end of the sleeve, wherein the sleeve has at least one narrow portion formed by a reduced portion in the sleeve and a slit-shaped filter; And the slit filter is formed at an end of the sleeve, and this end protrudes from the front end surface of the piston. Further, the shoulder is preferably formed by a narrow portion in the sleeve.

(Operation) In the configuration according to the present invention, the annular shoulder surface extends in a direction orthogonal to the axial direction of the piston, and the lightweight metal is forcibly fixedly connected to the annular shoulder surface. It is not harmful that the cast and solidified light metal shrinks radially when it cools, and the axial shrinkage of the light metal can be fully exploited and the tightening produces the desired connection. No additional means for locking against rotation are required, for example an additional shoulder running in the axial direction.

Within the scope of the present invention, the position of the annular shoulder can be shifted to a position perpendicular to the axial direction of the piston as long as the following requirements are fulfilled. As long as the difference between the axial contraction of the piston material and the light metal is greater than its radial contraction, i.e., greater than the radial distance of the light metal shoulder from its corresponding annular shoulder, the deviation is there is no problem. When this requirement is fulfilled, the lightweight metal firmly tightens against the two or more annular shoulders.

Suitable light metals are all metals which are light and strong and whose expansion coefficient is not significantly less than the expansion coefficient of the material of the piston. This means that light metals having the same coefficient of expansion as the piston material can also be applied if the desired tightening at the shoulder is achieved, but this will result in a large temperature drop during casting. And therefore a greater shrinkage occurs in the lightweight metal compared to the shrinkage of the piston material. However, it is preferred that a lightweight metal having a larger coefficient of expansion than that of the piston material be used. In particular, aluminum, magnesium,
Alternatively, alloys of these metals are suitable.

It is known from German Offenlegungsschrift 23,63,941 to provide an annular shoulder with a gap on the inner wall of the piston for holding light material to be cast in place on the piston. Is formed by an annular groove and serves to accommodate an internal retaining ring or circular clip for holding the light material in place. Therefore, this arrangement requires additional securing means or circular clips.
Furthermore, the fasteners made in this way are not exactly immovable, since the circular clip moves to some extent in the annular groove.

The solution according to the invention is to make the shoulder surface a closed annular shape. In another embodiment of the invention, the piston is provided with its axial passage to create a hydraulic bearing for the piston head. This passage is preferably formed by a sleeve embedded in a lightweight metal. A particular feature of the embodiment is a simple and practicable structure, which also allows for inexpensive manufacture. The embodiment according to claim 5 makes it possible to fix the sleeve in the position to be cast in a simple manner. The embodiments according to claims 6 to 10 make it possible to form a constriction or a filter in the axial passage in a simple manner.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments shown in the drawings.

The piston, generally designated by the reference numeral 1, has a sac-shaped recess 2, which is open on the front end face 3, ie on the working surface of the piston 1. The recess 2 is a cylinder in this embodiment, and is filled with a lightweight metal 4 inserted by casting, die casting, or forging. In order to securely fix the lightweight metal 4 to the concave portion 2, a plurality of (four in this embodiment) annular grooves 5 are formed on the annular peripheral wall forming the concave portion 2 with a gap in the axial direction of the piston 1. An annular shoulder surface 6 is provided on the peripheral wall at least spaced apart from each other and runs in a direction perpendicular to the piston shaft 7 of the piston 1. As the lightweight metal, aluminum, magnesium or an alloy of these metals can be used. Since the annular shoulder surface 6 is provided so as to run in a direction substantially perpendicular to the piston shaft 7, the lightweight metal 4 cast or injected into the recess is cooled.
Automatically and firmly tension against the annular shoulders 6 of each of the annular grooves 5 facing away from each other. This is clearly shown in FIG. 2 and shows the detail indicated by X in FIG. 1 on an enlarged scale.

Due to the large temperature drop of the light metal 4 when cast into the piston 1 at the standard temperature, the opposing light metal shoulder surfaces 8 may be attached to the piston, especially if the light metal has a larger coefficient of expansion than the material of the piston. The first annular shoulder surface 6 is tightened. This tightening force is shown by an arrow and is indicated by S.

In this embodiment, the piston 1 is made of steel. In particular, in the case of a lightweight metal having a coefficient of expansion greater than the material of the piston, the piston 1 and the lightweight metal 4
Results in both radial and axial contraction. In this embodiment, the contraction of the lightweight metal 4 in the axial direction results in the desired clamping force S. Radial shrinkage of the lightweight metal 4 does not affect the tightening force S, so that no damage occurs.

Securing the lightweight metal 4 to the piston 1 according to the invention results in the axial molded-fit connection and the radial forced-lock (friction-lock) connection. The lightweight metal does not sag under the load expected when the piston 1 is in operation, and therefore does not create additional noise or functional problems.

The distance a shown in FIG. 2 is between the shoulders of the light metal in the direction away from each other and the shoulders of the pistons facing each other and between the inner and outer walls of the cylinder, In the present embodiment, this is a minute clearance generated when the expansion coefficient of the lightweight metal is larger than the expansion coefficient of the material of the piston. This clearance is exaggerated in the drawing, but is actually quite small.

In this embodiment, the piston 1 has a spherical piston head 11 at the end opposite to its front end face 3, which is mounted in a corresponding spherical bearing recess 12 provided in a so-called slipper 13. When the piston 1 is used in an axial piston machine in which several pistons are arranged in a pitch circle, the slipper 13 has its slip surface 14 away from the piston 1 for driving the piston. As a result, the piston 1 comes into direct contact with the drive disk when the piston 1 is used in an oblique shaft machine.

In order to create a hydraulic bearing for the piston head 11 (or also for the slipper 13), an axial passage 15 is provided in the piston 1 and which
And open at the spherical bearing surface 16 of the piston head 11, the hydraulic pressure can be transmitted through this axial passage to the piston head bearing indicated generally by the numeral 17, or the slipper 13 can pass through another passage 18 of the slipper 13. Slip surface 14
Can be transmitted to

In this embodiment, the passage 15 is formed by a circular sleeve 19 embedded in the lightweight metal 4 in the axial direction of the piston. In this embodiment, the end of the sleeve 19 opposite to the front end face 3 protrudes from a lightweight metal. That is, this end of the sleeve 19, designated by the reference numeral 21,
Is inserted into a socket or hole 22 extending in the axial direction from the end of the socket. Preferably, it is a stepped hole as included here. That is, the cross-sectional area 23 inside the sleeve 19 is the same as the cross-section of the cross section of the passage 15 passing through the piston head 11. This configuration allows the sleeve 19 to be inserted and held in place in the piston 1 before inserting the lightweight metal 4 and therefore does not require additional support of the sleeve 19 during casting of the lightweight metal.

The sleeve 19 is provided with a narrow portion 24, preferably formed by squeezing so as to partially reduce the cross section. For this squeezing, another shoulder surface 25, the waist, is formed on the sleeve 19, and the shoulder surface 25 is embedded in a lightweight metal, thereby fixing the sleeve 19 in the axial direction.

The sleeve 19 preferably has another narrow section in the form of a slit filter 26 formed at the end of the front end face portion 3 in a slit-shaped cross section by reducing both sides of the sleeve 19. In this embodiment, the sleeve 19 protrudes from the front end face 3 of the piston 1 by an amount of c, and
Is formed at the free end protruding outward of the sleeve 19.
FIG. 3 is a right side view of the slit filter 26 and the sleeve 19.
Is shown.

In particular, when the above-mentioned slit filter is provided, it is advantageous to arrange the narrow portion 24 at a large distance d from the front end face 3 or from the slit filter 26, preferably close to the end 21 thereof.

The embodiment according to FIG. 4 is essentially different from the embodiment described above in that the shoulder 6 of the piston 1 is formed by a thread-shaped helical groove 27 and an annular groove 5.1. It is provided at the end of the lightweight metal 4 opposite to the front end face 3 of the piston 1. In this embodiment, economical manufacture is possible and the light metal may be provided with means to prevent rotation of the molded fit so as to prevent the light metal from being unwound in the axial direction. Furthermore, the embodiment according to FIG. 4 does not have the features of the sleeve 19, only a simple passage 15 in the form of a hole.

[Brief description of the drawings]

FIG. 1 is an axial sectional view of a piston formed according to the present invention, FIG. 2 is a detailed view of a configuration according to the present invention, FIG. 3 is a detailed view of a filter according to the present invention, and FIG. FIG. 4 is an axial sectional view of a further embodiment of the piston according to the invention. 1 ... piston, 2 ... recess, 3 ... front end face, 4 ... lightweight metal, 5, 5.1 ... annular groove, 6 ... annular shoulder, 7 ...
Piston shaft, 11 ... piston head, 15 ... passage, 16 ...
... Spherical bearing surface, 19 ... Sleeve, 22 ... Socket, 24 ...
… Nozzle, 25 …… Shoulder surface, 26 …… Filter slit, 27
…… helical groove

Continuation of the front page (72) Inventor Even Peknik Federal Republic of Germany Day 7270 Nagorto Albert-Kraig-Strase 23 (56) References JP-A-51-75202 (JP, A) JP-A-57-144349 (JP, A) JP-A-62-215166 (JP, A) JP-A-49-54902 (JP, A) JP-B-47-37843 (JP, B1) JP-B-43-18921 (JP, Y1) US Patent 3,187,644 (US, A) U.S. Pat. No. 3,633,467 (US, A) West German Patent Application No. 2363641 (DE, A1) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16J 1/00-10/04 F03C 1/00- 5/02 F04B 1/00-7/06 F04B 39/00-39/16 B22D 19/00

Claims (10)

(57) [Claims] 1. A hollow piston having an opening in a front end face (3) which is a working surface of a piston (1) and having a recess (2) in the axial direction of the piston. The annular peripheral wall, which is filled with the solidified light metal (4) and forms the concave portion (2), extends in the direction perpendicular to the piston shaft (7) and has an axial interval defining the annular peripheral wall. A piston having at least two annular shoulder surfaces formed therein, said annular shoulder surfaces comprising side walls of at least two spaced annular grooves, said cast and solidified. The axial middle portion of the light metal is at least 2
The cast and solidified lightweight metal (4) is located in a region that covers the annular shoulders of the two annular grooves and that covers the annular peripheral wall defined by the annular shoulders of each annular groove. A piston for an axial piston machine, wherein the piston is contracted in the axial direction opposite to the annular shoulder surface and is forcibly fixed to the annular shoulder surface. 2. A passage (15) extending through said piston (1) and said lightweight metal (4) in said axial direction, said front end face (3) and a piston opposite said front end face (3). The piston of an axial piston machine according to claim 1, characterized in that it opens into a bearing surface (16) of the head (11). 3. The method according to claim 2, wherein the passage comprises, at least in the region of the light metal, a sleeve embedded in the light metal. Axial piston machine piston. 4. The axial piston according to claim 3, wherein the end of the sleeve facing the piston head is accommodated in a bore in the piston. Mechanical piston. 5. Axial according to claim 3, wherein the outer surface of the sleeve (19) has at least one shoulder (25) in contact with the lightweight metal (4). Piston of piston machine. 6. A piston according to claim 5, wherein the shoulder (25) is formed by a narrow portion in the sleeve (19). 7. The piston of an axial piston machine according to claim 3, wherein a constriction (24) is provided in the sleeve (19). 8. A filter (2) is attached to the end of the sleeve (19).
The piston of an axial piston machine according to claim 3, characterized in that the piston has (6). 9. A method according to claim 3, wherein said sleeve has at least one narrow portion formed by a reduced portion in said sleeve and a slit filter. The piston of the axial piston machine described. 10. The sleeve-shaped filter (26) is formed at the end of a sleeve (19), the end of which is formed by a piston (1).
The piston of an axial piston machine according to claim 3, characterized in that it protrudes from a front end face (3) of the piston.