EP0717199A1 - Flat-type fluid cylinder - Google Patents

Abstract

The piston (15) and driven rod (22) are axially spaced apart and connected by an intermediate connecting rod (16). A partition (12) inside the interior (3) of the housing is axially spaced apart from the open end (6) of the housing on which the driven rod protrudes. The partition is axially positioned between the piston and the driven rod and is penetrated axially by the connecting rod. The partition divides the lengthwise section of the interior between the piston and open housing end into a second operating chamber (33) positioned on the side facing the piston, and a guide chamber (14) positioned on the side facing the piston. The second operating chamber has an opening (35) for the inflow or outflow of pressurised fluid. The guide chamber receives that part of the driven rod inside the interior.

Description

The invention relates to a working cylinder in a flat design, with a cylinder housing having an at least substantially rectangular cross-sectional contour on the outside, which also defines an at least substantially rectangular cross-sectional contour in the receiving space, in which a complementarily contoured, axially movable piston is arranged, which is arranged with a An open housing end face is connected to the output rod which protrudes from the receiving space, the longitudinal section located within the receiving space is contoured complementarily to the receiving space and is axially movably guided by the peripheral wall of the receiving space, the longitudinal portion of the receiving space lying on the axial side of the piston opposite the output rod forms a first working space which communicates with a connection opening for supplying and / or discharging a fluid pressure medium.

Such cylinders sold by the applicant under the name EZH are characterized by their particularly flat design, which results from the rectangular contour of the cylinder housing, the piston and the output rod. The linear guide function and pneumatic drive function are combined in a compact manner in this working cylinder. Thanks to the anti-rotation drive rod, the working cylinder can be used in many applications where high accuracy is required.

In the known working cylinder, the extension stroke of the output rod is caused by the fluid pressure medium supplied to the first working space, which is expediently compressed air. If the first work area is vented, a mechanical spring arrangement acting on the piston ensures the return to the starting position. However, this spring arrangement integrated in the working cylinder limits the maximum possible stroke for conceptual reasons and leads to a certain length of the working cylinder that cannot be undercut. In addition, the restoring force is not variable, since it is fixed by the spring arrangement.

It is the object of the present invention to create a compact, flat-design working cylinder of the type mentioned at the outset, which enables longer strokes and more variable actuating forces.

To solve this problem it is provided that the piston and the output rod are arranged at an axial distance from one another and are coupled in motion via an intermediate connecting rod, the cross-section of which is smaller than that of the piston and the guided longitudinal section of the output rod, that within the receiving space, with an axial distance the open housing end face, on which the output rod protrudes, a space-divider element is fixed in a sealed manner, which is located axially between the piston and the output rod and is axially penetrated by the connecting rod, and in that the space-divider element connects the piston and the open housing Longitudinal portion of the receiving space lying axially divided into a second working space located on the side facing the piston and a guide space facing the open housing front side, the second working space having a connection opening for supply and / or he communicates the discharge of fluidic pressure medium and the guide space receives the longitudinal section of the output rod that is located within the receiving space.

In this way, there is a working cylinder which enables an extreme flat construction and can be actuated fluidically in a double-acting manner, so that a mechanical spring arrangement which takes up a lot of space can be dispensed with. The Fluid loading of the piston, which is possible on both sides, allows variable actuating forces to be achieved by simply changing the applied pressure conditions. Nevertheless, with this arrangement, good guidance and transverse support of the output rod is maintained, which runs in the guide space having a relatively large cross-sectional area, which is defined by the space divider element in the receiving space.

Advantageous developments of the invention emerge from the subclaims.

The space divider element expediently serves as a stroke limiting element for the jointly movable unit consisting of the piston, the connecting rod and the driven rod. Depending on the stroke direction, either the piston or the output rod runs onto the space divider element at the stroke end, which thus has a stop function. To dampen the impact, the relevant end faces of the room divider element can be provided with a buffer. However, the two front end parts of the space divider element itself preferably form the relevant buffers, in that the space divider element is expediently designed as a plastic part as a whole, which has a certain elastic flexibility.

In a preferred embodiment, the space divider element forms a combined stop and sealing part, preferably made of elastomer material. In this case, it seals the second working space from the guide space by being in sealing contact with the peripheral wall of the receiving space and with the outer periphery of the connecting rod.

The supply and discharge of the pressure medium into and out of the second work space is expediently carried out via a fluid channel running in the space divider element, which in particular opens at the end and can be formed at least in part by a particularly annular longitudinal gap which surrounds the connecting rod.

In favor of a low-wear displacement guide of the output rod, it has also proven to be expedient to produce this output rod from plastic material, wherein the cylinder housing can consist of metal, for example of aluminum material.

Fig. 1

eine erste Bauform des erfindungsgemäßen Arbeitszylinders, teilweise im Längsschnitt gemäß Schnittlinie I-I aus Fig. 2,

Fig. 2

einen Querschnitt durch den Arbeitszylinder aus Fig. 1 gemäß Schnittlinie II-II,

Fig. 3

einen Querschnitt durch den Arbeitszylinder aus Fig. 1 gemäß Schnittlinie III-III und

Fig. 4

eine weitere Bauform des Arbeitszylinders, wiederum teilweise im Längsschnitt analog der Schnittlinie I-I aus Fig. 2.

The invention is explained in more detail below with reference to the accompanying drawing. In this show:

Fig. 1

2 a first design of the working cylinder according to the invention, partly in longitudinal section according to section line II from FIG. 2,

Fig. 2

2 shows a cross section through the working cylinder from FIG. 1 according to section line II-II,

Fig. 3

a cross section through the working cylinder of FIG. 1 according to section line III-III and

Fig. 4

a further design of the working cylinder, again partly in longitudinal section analogous to section line II from FIG. 2.

The working cylinder shown in Fig. 1 to 3 has a particularly flat design in that it has an overall cuboid-like outer shape, the rectangular cross section of which is selected so that it has a large long side compared to the narrow side, the extension of which in the exemplary embodiment is at least twice as large like the one on the narrow side. This makes it possible to put several of these working cylinders in a packet-like manner with their long sides, the center-to-center distance of cylinders lying side by side being reduced by around 40% compared to round-piston cylinders with the same piston area.

The working cylinder has a cylinder housing 1 which has a rectangular cross-sectional contour on the outside with rounded corners. It has one Circumferential wall 2, which forms the radial boundary of a receiving space 3 formed in the cylinder housing 1. At one end, which is on the left in FIG. 1, this receiving space 3 is closed by an end wall 4 which is preferably connected in one piece to the peripheral wall 2. This carries a mounting eye 5 for fixing the working cylinder on a component, not shown.

At the opposite other end, on the right in FIG. 1, the cylinder housing 1 is open. Said end is referred to as the open housing end face 6.

The receiving space 3 has a continuously constant cross-sectional contour over its entire axial length, starting from the end wall 4 up to its opening 7 on the open housing end face 6. In the present case, this is at least substantially rectangular, in that two longer straight longitudinal sides 8, 8 'are parallel and at a distance from one another and the two narrow sides 9, 9' are rounded, in particular in a semicircular shape. In the figures it should be borne in mind that in practice the working cylinder can have a very small size, the longitudinal dimensions of the cross section e.g. 6.5 mm and the transverse dimensions e.g. 1.5 mm.

Sits inside the receiving space 3, at a greater distance to the open housing end face 6, a space divider element 12. According to the example, it is located approximately in the middle of the entire axial length of the receiving space 3. It divides the receiving space 3 into a cylinder space 13 facing the end wall 4 and a guide space 14 opening out towards the open housing end face 6 .

In the cylinder space 13, a piston 15 that is contoured and axially movable is complementary. This sits firmly on a connecting rod 16, which extends coaxially to the receiving space 3 and passes through a central, axially continuous opening 17 of the space divider element 12. Its outer end 18 protruding into the guide space 14 is fixed to an output rod 22 which is plate-shaped in the exemplary embodiment and is axially displaceably mounted in the guide space 14 and projects with an actuating section 23 at the opening 7 beyond the cylinder housing 1. A component (not shown) to be moved can be fixed on the actuating section 23.

While the cylinder housing 1 expediently consists of metal, for example aluminum material, the exemplary output rod 22 is a plastic part. In the fully retracted position in the guide space 14 (FIG. 1), the driven rod 22 lies with its inner end on the facing end portion 24 of the room divider element 12. The entire length of the output rod 22 lying within the guide space 14 has a cross-sectional contour that is complementary to the guide space 14. This expediently extends over the entire length of the output rod 22.

The output rod 22 and the connecting rod 16 could in principle be made in one piece. In order to simplify the assembly, however, a separate configuration is provided in the present case, the connecting rod 16 being fixed to the output rod 22 by means of a connecting device 25. According to FIG. 1, the output rod 22 has a blind hole-like recess 26 on the end face facing the room divider element 12, into which the connecting rod projects with its outer end 18. A connecting pin 25 'is provided here as the connecting device 25, which extends through the end 18 and is fixed at the end in two opposite boundary walls of the recess 26 on the output rod 22.

The connection is preferably such that there is a degree of freedom of rotation between the output rod 22 and the connecting rod 16 with respect to the longitudinal axis of the bolt 25 ′, so that no tension can occur.

For reasons of compactness, the connecting rod 16 in the exemplary embodiment of FIGS. 1 to 3 is a flat component which has an essentially rectangular cross-sectional contour, the narrow edges being rounded. The main axes of all previously mentioned rectangular-like components coincide.

The piston 15 of the exemplary embodiment is seated on the inner end 27 of the connecting rod 16 facing the end wall 4. It is expedient for there to be a cohesive connection. The piston 15 can be a plastic part which is directly molded onto the connecting rod 16 by injection molding, so that additional fastening devices are not necessary. In the area of its outer circumference, the piston 15 carries a circumferential sealing ring 28, which is expediently held in a circumferential groove of the piston 15 and rests on the inside against the circumferential wall 2 of the cylinder housing 1.

The piston 15, the connecting rod 16 and the driven part 22 form an at least axially fixed unit which can be moved axially with respect to the cylinder housing 1.

The piston 15 divides the cylinder space 13 into a first and a second work space 32, 33. The frontal boundary of the first work space 32 forms the end wall 4, that of the second work space 33 forms the space divider element 12. Each work space 32, 33 communicates with its own connection opening 34, 35, via which compressed air or another fluid pressure medium can be supplied or removed as required. The resulting pressurization of the piston 15 results in an axial movement of the same, which, depending on the stroke direction, causes an extension movement or an insertion movement of the output rod 22 with reference to the guide space 14.

The extension stroke of the output rod 22 is limited by the space divider element 12. This forms a stroke limit stop for the piston 15, which at the end of its extension movement runs onto the associated end portion 24 ′ of the space divider element 12. The arrangement is such that the output rod 22 always protrudes a bit into the guide space 14 in the maximum extended position and is thereby supported in the transverse direction.

The axial clear distance between the piston 15 and the output rod 22, reduced by the axial length of the space divider element 12, results in the maximum possible stroke of the output rod 22. The cross-sectional area of the connecting rod 16 is smaller than that of the piston 15 or the output rod 22. Its cross-sectional length and its cross-sectional width is smaller than the corresponding dimensions of the receiving space 3, so that there is a space on all sides between the connecting rod 16 and the peripheral wall 2 is present.

In the present case, the space divider element 12 is a separate component with respect to the cylinder housing 1, which is fixed in the interior of the receiving space 3 in the manner of an intermediate wall with a seal to the peripheral wall 2. The fluid-tight seal prevents pressure medium from escaping from the adjacent second working space 33. Furthermore, there is a sealing contact between the space divider element 12 and the connecting rod 16, so that fluid leakage is also ruled out in the area of the opening 17.

Separate sealing elements could in principle be provided for sealing. In order to achieve the minimum size already indicated above, it is recommended, however, to provide appropriate one-piece sealing means directly on the room divider element 12, as is the case with the exemplary embodiment.

Here, the room divider element 12 has on the outer circumference a circumferential outer sealing projection 36 which rests on the inside against the peripheral wall 2. Furthermore, inside the opening 17 there is a circumferential inner sealing projection 37, which is also integrally formed on the space divider element 12 and coaxially surrounds the connecting rod 16 under sealing contact. The sealing projections 36, 37 can be designed in the manner of sealing lips which have a certain inclined course, with their free end facing the second working space 33 to be sealed. Moreover, it is advantageous if the space divider element 12 has at least one bearing section 38, which is contoured complementarily to the receiving space 3, on the outer circumference in addition to the outer sealing projection 36 and serves for transverse fixing of the space divider element 12 and via which the space divider element 12 fits snugly in the receiving space 3. Said bearing section 38 extends in the exemplary embodiment according to FIG. 1 over only a partial length of the space divider element 12.

For the axially immobile fixation of the room divider element 12 in the receiving space 3, a fastening device 39 is used in the exemplary embodiment, which also brings about a form-fitting fixation with respect to the cylinder housing 1. This has the advantage that the space divider element 12 does not move axially despite the hard impact of the piston rod 15 and the output rod 22. In case of exemplary inexpensive embodiment of the fastening device 39 comprises two transverse pins designed as dowel pins, which penetrate the space dividing element 12 at preferably diametrically opposite locations and are fixed in position in the peripheral wall 2 with their end regions, not shown in detail. For assembly, the room divider element 12 is pushed into the receiving space 3 until corresponding transverse openings in the room divider element 12 are aligned with transverse holes in the peripheral wall 2, so that the spring pins then only have to be pressed in.

In order to achieve a certain impact damping, the two front end parts 24, 24 'of the space divider element 12 consist of material with rubber-elastic properties, preferably of elastomer material. These front end parts 24, 24 ′ can be designed as annular, self-contained axial projections that surround the connecting rod 16.

The space divider element 12 is preferably made entirely of plastic material with the properties described, so that it can be a single component in integrally molded outer and inner sealing means 36, 37, in which the stroke limiting function and the sealing function are combined. Such a room divider element 12 can be manufactured inexpensively by injection molding.

The two first and second connection openings 34, 35 mentioned are provided in the exemplary embodiment on connection pieces 42, 43 which are fastened to the cylinder housing 1. The end wall 4 has a central recess 44 which is open to the first working space 32 and in the circumferential region of which a transverse bore 45 which is open to the outside of the cylinder housing 1 is provided. In the latter, the first connection piece 42 is inserted with a pin-like end section 46. There can be a press and / or adhesive connection, as well as a screw connection. A channel 47 passing through the first connection piece 42 opens into the recess 44 on the inside and ends with the first connection opening 34 on the outside.

The first connection piece 42 is preferably designed as a plug nipple, onto which a pressure medium line can be plugged, via which the fluid pressure medium is supplied and discharged.

The second connection opening 35 is provided on the appropriately designed second connection piece 43. Its inner end section 46 'passes through a transverse bore 45' of the peripheral wall 2 provided in the peripheral region of the space divider element 12 and projects into an aligned manner subsequent transverse recess 48 of the room divider element 12 into it. The latter is open radially on the inside towards the opening 17. There, it communicates with a longitudinally extending fluid channel 52, which opens out into the second working space 33 at the front end portion 24 ′. The fluid channel is preferably formed by a longitudinal gap 53 which is located radially between the connecting rod 16 and the wall of the opening 17 surrounding it. In the exemplary embodiment, this longitudinal gap 53 extends over the entire circumference of the connecting rod 16. The mentioned inner sealing projection 37 is located in the area of the opening 17 lying between the opening of the transverse recess 48 and the front end portion 24.

On the end wall 4 there is no need to attach a shock-absorbing buffer. The arrangement is such that the output rod 22 runs onto the space divider element 12 before the piston 15 strikes the end wall 4.

The embodiment according to FIG. 4 is essentially identical to that of FIGS. 1 to 3, so that the above description applies accordingly. The only differences are in the structural design of the room divider element 12 and the connecting rod 16 and the connecting device 25. In order to improve the flow of fluid, a groove-like longitudinal recess 54 is introduced into the wall of the opening 17 surrounding the connecting rod 16, into which the transverse recess 48 opens, and which causes an increase in the available flow cross section of the associated fluid channel 52.

Furthermore, in this embodiment, the connecting rod 16 is fixed to the output rod 22 via a threaded connection. Its outer end 18 is provided with an external thread 25 ″, which is screwed into a complementary internal thread of the recess 26. In this case, the connecting rod 16 expediently has a circular cross section over its entire length.

Claims (17)

Working cylinder in a flat design, with a cylinder housing (1) which has an at least substantially rectangular cross-sectional contour on the outside and which also defines a receiving space (3) which also has an at least substantially rectangular cross-sectional contour, in which a complementarily contoured, axially movable piston (15) is arranged which is connected to an output rod (22) protruding from the receiving space (3) on an open housing end face (6), the longitudinal section of which is located within the receiving space (3) and is contoured complementarily to the receiving space (3) and from the peripheral wall ( 2) of the receiving space (3) is guided so as to be axially movable, the longitudinal section of the receiving space (3) lying on the axial side of the piston (15) opposite the output rod (22) forming a first working space (32), which with a connection opening (34) communicates for the supply and / or discharge of a fluid pressure medium, thereby g marks, that the piston (15) and the output rod (22) are arranged at an axial distance from one another and are coupled in motion via an intermediate connecting rod (16), the cross-section of which is smaller than that of the piston (15) and the guided length section of the output rod (22), that Within the receiving space (3), at an axial distance from the open housing end face (6), on which the output rod (22) protrudes, a space divider element (12) is fixed in a sealed manner, which is located axially between the piston (15) and the output rod (22) is located and axially penetrated by the connecting rod (16) and that the space divider element (12) axially extends into the longitudinal section of the receiving space (3) between the piston (15) and the open housing end face (6) the second working space (33) facing the piston (15) and a guide space (14) facing the open housing end face (6), the second ar beitsraum (33) communicates with a connection opening (35) for supplying and / or discharging fluidic pressure medium and the guide space (14) accommodates the longitudinal section of the output rod (22) located within the receiving space (3). Working cylinder according to claim 1, characterized in that the connecting rod (16) at least in has a substantially rectangular cross-sectional contour. Working cylinder according to claim 1 or 2, characterized in that the space divider element (12) acts as a stroke limiting element, on which the piston (15) and / or the output rod (22) runs to limit the retracting or extending stroke. Working cylinder according to one of claims 1 to 3, characterized in that the space divider element (13) is a plastic part, preferably an elastomer part. Working cylinder according to claim 4, characterized in that at least one circumferential outer sealing projection (36) is formed on the outer circumference of the space divider element (12) and bears against the peripheral wall (2) of the receiving space (3). Working cylinder according to claim 4 or 5, characterized in that the opening (17) of the space divider element (12) penetrated by the connecting rod (16) is associated with at least one inner sealing projection (37) formed on the space divider element and which is circumferential on the outer circumference of the connecting rod (16) is present. Working cylinder according to claim 6, characterized in that the inner sealing projection (37) is within the opening (17). Working cylinder according to one of claims 1 to 7, characterized in that the space divider element (13) is inserted into the receiving space (3) and is fixed in place by at least one transverse pin (39) anchored in the end of the cylinder housing (1). Working cylinder according to one of claims 1 to 8, characterized in that the fluidic connection between the second working space (33) and the associated connection opening (35) takes place via a fluid channel (52) running in the space dividing element (12), which on the second Working space (33) facing end face of the room divider element (12) opens out. Working cylinder according to claim 9, characterized in that at least a portion of the fluid channel (52) is formed by a longitudinal gap (53) formed between the connecting rod (16) and the wall of the opening (17) surrounding it. Working cylinder according to one of claims 1 to 10, characterized in that the connection opening (35) assigned to the second working space (33) is connected to one Connection piece (43) is provided, which passes through the peripheral wall (2) of the receiving space (3) and protrudes with an end section (46) into a transverse recess (48) of the space divider element (12). Working cylinder according to one of claims 1 to 11, characterized in that the output rod (22) and the connecting rod (16) are designed as separate components fastened to one another by means of a connecting device (25, 25 ', 25' '). Working cylinder according to claim 12, characterized in that the connecting rod (16) protrudes into an end recess (26) of the output rod (22) and is fixed therein. Working cylinder according to one of claims 1 to 13, characterized in that the output rod (22) is a plastic part which is in particular plate-like. Working cylinder according to one of claims 1 to 14, characterized in that the piston (15) is a plastic part which is fixed on the piston rod (16) by a casting process. Working cylinder according to one of claims 1 to 15, characterized in that the narrow sides of at least part of said, at least substantially rectangularly contoured components are rounded. Working cylinder according to claim 16, characterized in that the at least substantially rectangularly contoured components have a cross-section with parallel straight longitudinal sides (8, 8 ') and semicircularly contoured narrow sides (9, 9').

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