Arrangement for the supply of pressure medium to a hydraulic or pneumatic cylinder

The supply of pressure medium to hydraulic or pneumatic cylinders is usually carried out by means of pressure medium lines which are connected to the heads of the cylinders by means of standardized connection threads. This method of supplying pressure medium requires a minimum wall thickness of the casing of the cylinder in the connection region. In order to permit secure attachment of the pressure medium lines even when the minimum thickness which is necessary for the use of the standardized connection thread is not present, the outside of the casing of the cylinder is flattened in the vicinity of the exit point of a duct provided for the supply of pressure medium. A connection plate which is provided with ducts for the pressure medium is secured to the flattened part of the casing, and the connection plate is provided with a port for a pressure medium line. This arrangement for the supply of pressure medium is suitable in particular for cylinders of small size whose casings have only a small wall thickness or in which the pressure medium lines are to be conducted near to the casing of the cylinder.

FIELD AND BACKGROUND OF THE INVENTION
 The invention relates to an arrangement for the supply of pressure medium
 to a hydraulic or pneumatic cylinder. In hydraulic and pneumatic
 cylinders, the supply of pressure medium is usually carried out by means
 of pressure medium lines which are connected to the heads of the
 cylinders. In the vicinity of the heads of the cylinder, there is usually
 a sufficient wall thickness for receiving standardized connection threads
 for pressure medium lines. Such a cylinder for hydraulic pressure medium
 is represented, for example, in the company document RD/E/F 17 032/08.98
 "Hydrozylinder/Hydraulic Cylinder/Verin Hydraulique--Type CDT3/CGT3" from
 Mannesmann Rexroth AG, in particular on pages 1/42, 40/42 and 41/42. The
 axes of the connection threads are perpendicular to the longitudinal
 direction of the cylinder. If the pressure medium lines are to be arranged
 parallel to the longitudinal direction of the cylinder, angular elements
 are necessary for the reversal of direction. Because of the minimum radii
 which have to be complied with here, it is difficult, if not even
 impossible, to conduct the pressure medium lines along right next to the
 casing of the cylinder. There is a further problem in hydraulic and
 pneumatic cylinders of small size. In them, the wall thickness of the
 casing is so small that it is no longer sufficient for standardized
 connection threads. Secure attachment of the pressure medium lines is not
 necessary in these cases.
 SUMMARY OF THE INVENTION
 The invention is based on the object of providing an arrangement for a
 reliable supply of pressure medium even in cylinders of a small size in
 which the wall thickness of the casing is not sufficient for standardized
 connection threads for the attachment of the pressure medium lines.
 The arrangement according to the invention makes it possible to conduct the
 pressure medium lines right next to the casing of the cylinder. The
 flattening of the casing of the cylinder which is provided for the bearing
 of the connection plate can be manufactured easily.
 The detachable connection between the casing of the cylinder and the
 connection plate makes it possible firstly to attach the pressure medium
 line to the connection plate and only afterward to screw the connection
 plate (with the pressure medium line attached to it) to the casing of the
 cylinder. Given a rectangular base surface of the bearing region it is
 possible to arrange the connection plate in two positions which are turned
 through 180.degree.. Given a square base surface of the bearing region of
 the connection plate in conjunction with the four screws which are
 arranged in the corners of the square base surface it is possible to
 arrange the connection plate rotated in each case through 90.degree. where
 necessary. The direction of flow of the pressure medium is already
 deflected in the connection plate by means of ducts which are arranged
 perpendicularly to one another. Thus, external angular elements between
 the cylinder and the pressure medium lines are dispensed with. Two
 pressure medium lines can be conducted one next to the other if the
 connection plate projects beyond a rectangular base surface on one side,
 and the connection for the pressure medium line is arranged on that part
 of the connection plate which projects beyond the rectangular base
 surface, in such a way that the port for the pressure medium line is
 arranged perpendicularly with respect to the longitudinal direction of the
 connection plate. By virtue of this measure, the port for the pressure
 medium line is arranged parallel to the longitudinal direction of the
 cylinder. If the port for the pressure medium line is embodied as a
 connection nipple, the pressure medium line can be attached to the
 connection nipple by means of a press-fit connection. Such a connection
 requires little space. There is sufficient space available for the tool
 required for the press-fit connection if the pressure medium line is
 already attached before the screwing of the connection plate to the casing
 of the cylinder. In order to simplify the fabrication of the connection
 plates provided with the connection nipple in comparison with a one-piece
 embodiment, the connection plate and the connection nipple are fabricated
 separately and both parts are held together by a screwed connection. In
 order to increase the mechanical strength of the screwed connection--in
 particular in the case of small wall thickness'--part of the connection
 nipple is embodied as a cylindrical bolt, guided through a bolt in the
 connection plate and secured by means of a screwed connection which is
 supported on two side faces, one opposite the other, of the connection
 plate. This embodiment makes it possible to mount the connection nipple on
 both sides of the connection plate as desired. A chamfer in the connection
 plate in the vicinity of the outlet opening of the hole serves as an
 abutment and antitwist protection for the connection nipple.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 Identical components are provided with identical reference symbols.
 FIGS. 1 and 2 show two different views of a hydraulic cylinder 10. FIG. 1
 shows the plan view, FIG. 2 shows the front view. The casing of the
 hydraulic cylinder 10 is provided with the reference symbol 11. The supply
 of pressure medium to the hydraulic cylinder 10 is carried out via a first
 connection plate 12 into a first chamber of the hydraulic cylinder 10 and
 via a second connection plate 13 into a second chamber of the hydraulic
 cylinder 10. The connection plates 12 and 13 are secured to the casing 11
 of the hydraulic cylinder 10 with, in each case, four screws 14 to 17 and
 18 to 21. 22 and 23 designate two eyelets, the eyelet 22 of which is
 connected to the piston rod 24, and the eyelet 23 is connected to the
 casing 11 of the hydraulic cylinder 10.
 In the vicinities in which a duct for the supply of pressure medium to a
 chamber of the hydraulic cylinder 10 emerges from the casing 11, the
 casing 11 is flattened. In FIG. 3, which shows a section along the line
 A--A (cf. FIG. 1), the duct which is provided for the supply of pressure
 medium is provided with the reference symbol 26. The associated flattened
 portion of the casing 11 is provided with the reference symbol 27. The
 flattened portion has a square base surface. The connection plate 12 rests
 on the flattened portion 27. A sealing ring 28 is arranged between the
 casing 11 and the connection plate 12. The connection plate 12 is provided
 with ducts 30, 31 and 32. They connect the duct 26 to a connection nipple
 33 which is arranged as an extension of the duct 32. The connection plate
 12 projects beyond the square base surface on the one side. The duct 32 is
 located in the part of the connection plate 12 which projects beyond the
 square base surface of the flattened portion. It is arranged
 perpendicularly with respect to the duct 31 running in the longitudinal
 direction of the connection plate 12, and runs parallel to the
 longitudinal axis of the hydraulic cylinder 10. The connection nipple 33
 is integrated into the connection plate 12. It serves as a port for a
 flexible hydraulic line (not illustrated in the figures). As FIGS. 1 and 2
 show, the connection nipple 33 is arranged as closely as possible to the
 casing 11 of the hydraulic cylinder 10. So that sufficient space is
 nevertheless available for the tool which is necessary for pressing the
 hydraulic line with the connection nipple 33, the connection plate 12 is
 separated from the casing 11 of the hydraulic cylinder 10 by releasing the
 screws 14 to 17 for the attachment of the hydraulic line to the connection
 nipple 33.
 FIG. 4 shows, in a section along the line B--B (cf. FIG. 1), the attachment
 of the connection plate 12 to the casing 11. The screws 15 and 16 which
 are visible in the section are secured in a region of the casing 11 in
 which the thickness of the material of the casing 11 is greater than in
 the vicinity of the duct 26. In addition, the force with which the
 connection plate 12 is secured to the casing 11 is distributed between
 four screws.
 The connection plate 13 is basically of the same design as the connection
 plate 12. However, the connection plate 13 does not project beyond the
 square base surface of the bearing region. A connection nipple 34 is
 integrated into the connection plate 13. It is arranged between the screws
 19 and 20. By virtue of the lateral offset of the connection nipples 33
 and 34, the hydraulic lines which are secured to them can be laid directly
 one next to the other. This is desired in particular if the hydraulic
 lines are to be conducted near to the casing 11 of the hydraulic cylinder
 10 when the spatial conditions are restricted.
 The square base surface of the bearing region of the connection plates 12
 and 13, in connection with the arrangement of the screws 14 to 17 and 18
 to 21 in the corners of the square base surface, makes it possible to
 mount the connection plates 12 and 13 rotated in increments of 90.degree.,
 and also to exchange the connection plates 12 and 13 with one another
 where necessary.
 When the hydraulic cylinder 10 is replaced, only the screws 14 to 21 need
 to be released. The connection plates 12 and 13 which are connected to the
 hydraulic lines can then be removed from the casing 11, and the connection
 plates 12 and 13 can be connected to the new hydraulic cylinder.
 In the case of the connection plates 12 and 13 which are illustrated in
 FIGS. 1 to 4, the connection nipple 33 is integrated into the connection
 plate 12, and the connection nipple 34 is integrated into the connection
 plate 13. The connection plate and connection nipple are therefore each
 fabricated from one piece. Such connection plates require a large
 expenditure in terms of fabrication equipment. FIGS. 5 to 7 show a
 two-part connection unit 40 which can be fabricated more cost-effectively
 than a single-part connection plate. The two-part connection unit 40 is
 composed of a connection plate 41 and a connection nipple 42. As in the
 case of the connection plate 12, the connection plate 41 projects beyond
 the square base surface of the bearing region.
 FIG. 5 shows, in the manner of an exploded view under the connection plate
 41, the connection nipple 42, once in a partially sectional view and once
 in a plan view. The connection plate 41 is--like the connection plate
 12--provided with ducts 30 and 31 for the pressure medium. The duct 31
 opens into a hole 43. The other outlet opening of the duct 31 out of the
 connection plate 41 is closed off by a pressed-in ball 44. The connection
 nipple 42 is divided into four regions 45 to 48. The region 45 is embodied
 as a cylindrical bolt 49. The cylindrical bolt 49 is provided with ducts
 50 and 51. The duct 50 is aligned with the duct 31 in the connection plate
 41. The outlet opening of the duct 50 is provided with the reference
 numeral 52. The duct 51 extends from the region 46, which serves to
 receive the hose receptacle, via the region 47 and into the region 45 and
 opens into the duct 50 there. The cylindrical bolt 49 is provided on both
 sides of the outlet opening 52 with, in each case, one annular groove 53
 and 54. The annular grooves 53 and 54 serve to receive sealing rings 55
 and 56, respectively. As illustrated in FIG. 7, the sealing rings 55 and
 56 are arranged between the cylindrical bolt 49 and the wall of the hole
 43 and prevent pressure medium from emerging from the gap between the
 cylindrical bolt 49 and the hole 43. The region 47 of the connection
 nipple 42 is embodied as an abutment for the connection nipple 42 against
 a side wall of the connection plate 41. It engages in the mounted state in
 a first chamfer 57 of the connection plate 41 in the vicinity of the one
 outlet opening of the hole 43. The connection nipple 42 has a square cross
 section in the region 47. However, it is also possible to use a
 rectangular cross section instead of the square cross section. Owing to
 the square cross section, the region 47 acts as an antitwist protection
 for the connection nipple 42. This measure ensures that the ducts 31 and
 50 are connected to one another. The cylindrical bolt 49 is provided with
 a threaded bolt 58 on the side facing away from the region 47. As
 illustrated in FIGS. 6 and 7, the threaded bolt 58 is provided in the
 mounted state with a washer 59 and a nut 60. The washer 59 has the same
 cross section as the region 47. It engages in a second chamfer 61 of the
 connection plate 41. Since the chamfers 57 and 61 are of the same size,
 the connection nipple 42 can be introduced into the hole 43 from both
 sides. In conjunction with the symmetrical design of the connection plate
 42, which ensures that the ducts 31 and 50 are aligned, it is thus
 possible to realize a hose connection either from one side or from the
 other side.
 FIG. 6 shows a plan view of the assembled connection unit 40, in which the
 connection nipple 42 is inserted into the hole 43 of the connection plate
 41.
 FIG. 7 also shows a plan view of the assembled connection unit 40, the
 connection nipple 42 and the surrounding region of the connection plate 42
 being represented in partially sectional form. This figure shows in
 particular the sealing rings 55 and 56.
 In the case of the connection unit 40 illustrated in FIGS. 5 to 7, the hose
 connection is effected--as in the case of the single-part connection
 plate--outside the square base surface of the flattened portion of the
 casing 11. However, it is also possible to embody the connection unit in
 such a way that the connection nipple is arranged--as in the case of the
 connection plate 13--within the square base surface (that is between the
 attachment screws 19 and 20).