A CYLINDER DEVICE

Abstract: A cylinder unit has a cylinder portion (1) in which a piston provided with a piston rod (3) is reciprocally movable under the influence of a pressure medium which is supplied to the cylinder portion (1). In order to provide reliable guiding, also in the direction of rotation, to that object which is to be displaced by means of cylinder units, it applies that the piston rod (3) is, in its end, secured in a connecting piece (2) which is also provided with a number of guide rods (4, 5) in spaced-apart relationship about and parallel to the piston rod (3). The guide rods (4, 5) are slidably accommodated in corresponding guides in the cylinder portion (1) and suitably the connecting piece (2) and the cylinder portion (1) have a common cross-sectional configuration which includes outer, planar defining surfaces (12-14) with longitudinal undercut grooves (15-18).

Description: A CYLINDER DEVICE TECHNICAL FIELD The present invention relates to a cylinder unit with a cylinder portion in which a piston provided with a piston rod is reciprocally movable under the influence of a pressure medium supplied to the cylinder portion. The present invention also relates to a section-bar for producing a cylinder unit. BACKGROUND ART Cylinder units of the type mentioned by way of introduction are pre¬ viously known in many different variations and for many different fields of application. The cylinder portion proper may often be pro¬ vided with an anchorage flange, anchorage eye or the like for se- curing the cylinder portion, while the piston rod may be provided with an eye, threading or corresponding means for securing that part which is to be reciprocated by means of the cylinder unit. Prior art conventional cylinder units require extra auxiliary equip- ment in order that the object which is to be reciprocated by means of the cylinder unit can be reliably guided transversely of its di¬ rection of displacement and also in the direction of rotation with the direction of displacement as centre axis. For example, use has been made of various types of guides in which, for instance, rollers have catered for low-frictional guiding. Common to all of these prior art arrangements is a considerable space requirement and, in addition, such prior art arrangements suf¬ fer from drawbacks in respect of convenient anchorage of both the cylinder portion and that part which is to be reciprocated. OBJECTS OF THE INVENTION The object of the present invention is to realise a cylinder unit of the type mentioned by way of introduction, the cylinder unit being designed in such a manner as to offer both the possibility of reci¬ procal motion and total guiding of the object which is reciprocated, i.e. transversely of the direction of displacement and in the di¬ rection of rotation about the longitudinal direction of the piston rod. The present invention also has for its object to realise a cylinder unit which is easy to mount and which permits simple an¬ chorage and adjustment of both the cylinder portion and the object which is to be displaced. The present invention further has for its object to realise a cylinder unit which is both simple and econ¬ omical in manufacture, with varying stroke lengths, and which is otherwise designed in an extremely versatile manner. The present invention yet further has for its object to realise a section-bar which is intended for producing a cylinder unit. SOLUTION The objects forming the basis of the present invention will be attained if the cylinder unit is characterised in that the piston rod is, in its end facing away from the cylinder portion, secured in a connecting piece; that a number of guide members are secured in the connecting piece in spaced-apart relationship from the piston rod and directed parallel therewith; and that the guide members are slidingly accommodated in corresponding guide apertures in the cylinder portion. One preferred embodiment of the present invention is suitably characterised in that both the cylinder portion and the connecting piece are of the same cross-sectional configuration transversely of the longitudinal axis of the cylinder portion; and that the cross- sectional configuration includes planar outer defining surfaces in which longitudinal undercut grooves are provided. As a result of these constructional features, there will be attained • an extremely simple anchorage of both the cylinder portion proper and of the fittings and details which the connecting piece is intended to carry. A section-bar which is suitable for the production of the cylinder unit according to the invention is characterised by a centrally dis- posed, longitudinal and circular-cylindrical bore, and a number of additional bores which are disposed in spaced-apart relationship from this central bore and are parallel with and preferably equi¬ distant from the central bore, the section-bar having outer defining surfaces which are approximately planar. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS The nature of the present invention and its aspects will be more readily understood from the following brief description of the accompanying Drawings, and discussion relating thereto. In the accompanying Drawings: Fig. 1 shows a cylinder unit designed according to the present invention; and Fig. 2 is a cross-section through that section-bar from which the cylinder unit is produced. DESCRIPTION OF PREFERRED EMBODIMENT It will be apparent from Fig. 1 that the cylinder unit essentially comprises a cylinder portion 1 which has a longitudinal internal bore (not shown) in which is accommodated a piston which is reci ¬ procally displaceable. The piston is disposed on one end of a piston rod 3 -which, at its opposite end, is secured in a connecting piece 2. In the connecting piece 2, there are fixedly disposed a number of guide members which, in the preferred embodiment, are suitably de¬ signed as circular-cylindrical rods. The guide members, or guide rods, 4 and 5 extend into the cylinder portion 1 in corresponding bores therein, there being suitably provided, at the ends of the bores 6 and 7, respectively, appropriate slide bushings which reduce friction, prevent the penetration of dirt and in addition provide an accurate guiding between the guide members and the cylinder portion. Naturally, the guide bushings may possibly extend con- tinually throughout the entire cylinder portion from the one end 6 to the opposite end 7. The cylinder portion 1 is further provided with conventional gaskets for the piston rod 3, these gaskets being, of course, designed in dependance upon the type of working medium with which the cylinder portion is intended to work. The design of the piston of the piston rod 3 in the cylinder portion and the gaskets of the piston may cor¬ respondingly be considered as conventional. For the supply and evacuation of pressure medium, the cylinder portion is provided with connection ports 8 and 9 so that pressure medium may optionally be led in on one or the other side of the piston in the cylinder portion. In the embodiment shown on the Drawing, the cylinder portion 1 may be considered as immobile, while the connecting piece 2 is reci¬ procally movable according to the double-headed arrow A. In order to obtain as exact- guiding as possible for the connecting piece.2, the length of the guide members 4 and 5 is selected such that the distal ends 10 and 11 of the guide members are always located outside the distal end surface of the cylinder portion irrespective of the working position of the connecting piece 2. In such situations when the guiding function, as a result of the connecting piece 2 being fully protracted, may possibly be somewhat impaired, it is naturally also conceivable that the distal ends 10 and 11 of the guide rods 4 and 5 be made shorter, such that, when the connecting piece is fully protracted, they are located inside the cylinder portion 1. However, according to the present invention, the connecting piece 2 could - just as well as the cylinder portion 1 - be considered as the fixed and immobile unit, in which event the cylinder portion 1 proper would, in this alternative, move reciprocally along the guide rods 4 and 5. According to the invention, it is possible to design the guide rods 4 and 5 so as to be hollow, such that pressure fluid or other medium may be led along these (acting as conduits) up to the connecting piece 2 to be used or consumed there, for instance for operating a device secured on the connecting piece 2, for lubrication pur¬ poses, coolant purposes or any other appropriate purpose. In order to facilitate assembly and fine-adjustment of the cylinder unit according to the present invention, both the cylinder portion and the connecting piece are produced of bar material with substan¬ tially planar surfaces 12, 13 and 14 which are mutually at right angles. For example, the cylinder portion and the connecting piece may be quadratic or rectangular in cross-section, in which event the corners need not, naturally, be sharp but may be rounded. To facilitate anchorage and mounting of the cylinder unit, the planar surfaces 12 - 14 are provided with longitudinal, undercut grooves 15 which are intended for the securement of different details and fittings. Preferably, these grooves may be T-grooves. 1 In the alternative with an approximately quadratic cross-section of the cylinder portion 1 and the connecting piece 2, it is appropriate to employ four guide members, one at each corner of the cross- section. In such instance, the guide members are placed so that their distance in to the centre axis of the cylinder portion will be substantially equal and, in addition, the guide members are distri¬ buted uniformly about the centre axis in the circumferential di¬ rection. In one example with a quadratic contour for the cylinder portion, the guide members, thus, lie at the corners of the cross- section and consequently have a centre distribution of 90°. As was intimated above, the cylinder unit according to the present invention is produced using a section-bar as the point of departure. One example of such a section-bar is shown in Fig. 2. It will be apparent from this Drawing figure that the section-bar is of approximately quadratic cross-section with gently rounded corners, each longitudal side being provided with the above- mentioned T-grooves 16 - 18. These three T-grooves are provided with arched bottom surfaces 19 so that greater space will thereby be created for, for instance, the head of a screw or bolt. On the other hand, the groove 15 - i.e. the groove where the connection ports 8 and 9 are placed - is provided with a planar bottom surface 20 in order to facilitate sealing of the connection ports 8 and 9. Centrally in the cross-section according to Fig. 2, there is dis¬ posed a longitudinal, circular-cylindrical bore 21 which, in the finished cylinder unit, will constitute the cylinder bore proper. Furthermore, there are disposed at each corner of the cross-section additional bores 22 in the form of guide bores for accommodating the guide members 4 and 5 and possibly guide bushings for these. Suitably, all of the additional bores 22 are placed in such a manner that they are equidistant from the centre line in the bore 21. More¬ over, the additional bores 22 should be placed uniformly distributed circumferentially about the centre line of the bore 21 so that these additional bores have the same cone angle in the circumferential direction. DESCRIPTION OF ALTERNATIVE EMBODIMENTS In the foregoing, it has been assumed that the cylinder unit is to be designed using an approximately quadratic section-bar as the point of departure. This is not necessary according to the present invention, it being possible instead for the section-bar to be rec- tangular, triangular or have any other appropriate cross-sectional configuration. In one alternative with a rectangular section-bar, it is conceivable that this section-bar be of a cross-section which could correspond approximately to two section-bars according to Fig. 2 placed adjac¬ ent one another. Such a double, rectangular cylinder portion may have two individually operating pistons, for which reason two sep¬ arate connecting pieces are also provided in this case. Naturally, these two pistons may also work against a single connecting piece common to both pistons. In one alternative employing a triangular section-bar, the guide members 4 and 5 are suitably disposed one in each corner of the cylinder portion at as great a distance as possible from the central cylinder bore 21. The Drawing illustrates the employment of one T-groove each on the planar surface of the cylinder portion. Naturally, it is possible to employ, instead of one T-groove, two such grooves on each surface or at least on some of the planar surfaces. Nor is it necessary according to the present invention that the section-bar, and thereby the cylinder portion, have external planar surfaces, it being conceivable in certain cases that a circular outer contour is more appropriate. Also in this case, longitudinal preferably T-shaped grooves can advantageously be employed for securing and adjusting the cylinder unit. As yet a further variation, mention might be made that the guide members 4 and 5 may be fixedly mounted in the cylinder portion 1, while the connecting piece 2 is slidable along the guide members and is possibly provided with slide bushings. According to the present invention, the cylinder unit may also be double-sided so that the distal ends 10 and 11 of the guide members 4 and 5 are also provided with a connecting piece. In this embodi¬ ment, the piston rod 3 can, but need not, be a through rod so that it extends from connecting piece to connecting piece. The present invention could be further modified within the scope of the appended Claims.

Claims: CLAIMS 1. A cylinder unit with a cylinder portion (1) in which a piston provided with a piston rod (3) is reciprocally movable under the in¬ fluence of a pressure medium supplied to the cylinder portion, char¬ acterised in that the piston rod (3) is, in its end facing away from the cylinder portion (1), secured in a connecting piece (2); that a number of guide members (4, 5) are secured in the connecting piece in spaced-apart relationship from the piston rod (3) and directed parallel therewith; and that the guide members are slidably accom¬ modated in corresponding guide apertures in the .cylinder portion. 2. The cylinder unit as claimed in claim 1, characterised in that both the cylinder portion (1) and the connecting piece (2) have the same cross-sectional configuration transversely of the longitudinal axis of the cylinder portion; and that the cross-sectional con- figuration includes planar, outer defining surfaces (12-14) in which longitudinal, undercut grooves (15-18) are provided. 3. The cylinder unit as claimed in claim 1 or 2, characterised in that the longitudinal cylinder bore (21) in the cylinder portion (1) in which the piston is reciprocally movable is disposed centrally in the cylinder portion; and that the guide apertures are disposed con¬ centrically about the centre axis of the cylinder bore, preferably with the same angle distribution. 4. A section-bar for producing a cylinder unit, characterised by a centrally disposed, longitudinal and circular-cylindrical bore (21), a number of additional bores (22) disposed in spaced-apart re¬ lationship from the central bore, parallel with the central bore and preferably disposed equidisant therefrom, the section-bar having outer defining surfaces (12-14) which are approximately planar. 5. The section-bar as claimed in claim 4, characterised in that the approximately planar surfaces (12-14) are approximately at right angles to one another and are provided with undercut, longitudinal grooves (15-18), preferably so-called T-grooves.

Inventors: FASTH KENNETH, FASTH, KENNETH
Applicants: FASTH KENNETH, FASTH, KENNETH
Application year: 1988
Main classification: F16J7
IPC codes: F15B15, F16J10