DE7819942U1 - Hydraulic cylinders, in particular for controlling a workpiece chuck for machine tools - Google Patents

Description

TER sea.möller. STEINMEISTER ... _: , ··, ···: LSi! Precision Industrielle T

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- 6 DESCRIPTION

The invention relates to an annular hydraulic cylinder, in particular for controlling a workpiece chuck for machine tools according to the preamble of the main claim.

In FR-PS No. 72.12621 () of the applicant, an annular hydraulic cylinder is described, which has a rotatable hydraulic connection, the axis of which through a tubular extension of the "bottom of the annular Cylinder is formed. Two main lines open into the two chambers of the cylinder. In the main lines the hydraulic connection is switched on. This is followed by a one-way flap valve. An auxiliary line leading to the Control of the opening of the flap valve is used, connects the flap valve with the other main line upstream their own flap valve. Facilities are provided through which the inlets of the two main lines alternately connected to a pressurized fluid source and a pressurized fluid container at atmospheric pressure can be. This known hydraulic cylinder offers a very high level of operational reliability. When in the position in which the workpiece is clamped by the chuck of the machine tool, the corresponding main line does not accept any further hydraulic fluid under pressure because a malfunction of any kind has occurred, the one-way flap valve that is switched on in this main line maintains the pressure in the corresponding chamber of the cylinder upright, so that an unintentional loosening of the workpiece, which could have all the more dangerous consequences, the faster it is turned, it turns off.

The described hydraulic cylinder of the applicant's FR-PS Incidentally includes Saimmler for hydraulic pressure fluid, which offer the advantage that it is only necessary the hydraulic cylinder closes under the increased control pressure

supply when the cylinder can perform a clamping or releasing operation while a reduced supply pressure outside of these switching times is sufficient. Because of this, they are relatively complex and expensive feeding equipment required.

In addition, in the known hydraulic cylinder, the two one-way flap valves and their control elements are shown in FIG Axial bores of the tubular extension of the cylinder base are arranged. This tubular approach must therefore have a sufficient radial wall thickness, so that at a certain diameter of the central opening of the annular piston a lower limit for the inner diameter of the fixed part of the rotatable hydraulic connection is set. This latter limit has proven to be particularly troublesome in the case of annular ones Hydraulic cylinders for controlling the chucks of machine tools that operate at high speeds will.

The invention is aimed at overcoming the aforementioned disadvantages of the hydraulic cylinder of FR-PS ISIr. 72.12621 () directed.

The hydraulic cylinder of the generic term according to the invention is characterized in that the two one-way flap valves are provided in bores in the cylinder base are, which is firmly connected to the tubular extension of the cylinder.

This design allows the strength of the tubular extension of the cylinder, which is the axis of the rotary connector forms to reduce and thus also to reduce the inner diameter of the fixed part of the Drehanschlusseis. This is particularly advantageous in the case of a hydraulic clamping device or a hydraulic cylinder, for controlling the chuck of a tool machine

TER MEER .MÜLLER ■ STBNMEISTEFj ■ ■ ;! _. -.— j . j ± Bf _ec i _s i _on industrial

Machine is provided that runs at high speeds. On the other hand, the hydraulic cylinder according to the invention, since it is not provided with collectors for receiving the hydraulic pressure fluid, with the help of simpler and less expensive organs are supplied with fluid.

In particular when used for machine tools that run at high speeds, it is useful to use the to balance the rotatable cylinder as much as possible and the moving parts of the one-way flap valves to withdraw as much as possible from the effect of centrifugal force. For this reason there is a Preferred embodiment of the invention is that the holes serving to accommodate the two flap valves are arranged on both sides of the central opening of the annular piston, with their axes preferably run perpendicular to a common longitudinal center plane of the cylinder.

The features of the invention described above provide the The advantage that the functional reliability of the machine tool is ensured by loosening the chuck is excluded during the rotation and machining of the workpiece, even in the event of any malfunctions the supply of hydraulic fluid to the cylinder to operate the chuck. The invention is concerned with The rest with an additional design that ensures the safety of the machine in the start-up phase will. In this embodiment, the tubular sleeve carrying the piston of the annular cylinder is above the rotatable one Hydraulic connection is also extended and at its end with a washer or a ring made of ferromagnetic Material provided. Two magnetic transmitters are attached outside the cylinder and scan the respective end positions the disc or the ring and thus the position of the piston. These end positions correspond respectively clamping and releasing the workpiece

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- 9 through the chuck.

When the start of the machine tool depends on the signal that one of the two magnetic sensors delivers when the piston of the hydraulic cylinder is in is in the position that corresponds to the clamping of the workpiece by the chuck, any risk is excluded, that the machine starts without the tool being clamped.

10

The application of the hydraulic cylinder according to the invention is not to the control of the chuck for workpieces limited to machine tools. The hydraulic cylinder can, for example, also be used to control the drive of the Drilling tool of a drilling machine, especially with vertical holes when searching for oil or when drilling in can be used in any direction in mining or in stone bridges. It can also be used for Control, for example, the circuit of a transmission gear and in general in all cases where an axial force is to be exerted on a rotating, solid or hollow shaft.

In the following, preferred exemplary embodiments of the invention are explained in more detail with reference to the accompanying drawings.

Fig. 1 shows an embodiment of the Er

finding in longitudinal section;

Figure 2 is a section along the line

II-II in Fig. 1;

Fig. 3 shows a section along the line III-III in Fig. 1; 35

FIG. 4 is a schematic diagram of FIG

Circuit of the hydraulic cylinder of Figures 1 to 3.

IS ■ ■ »1 S ·« S

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The ring-shaped hydraulic cylinder according to the invention, which is shown in the aeichcvsig, essentially comprises a cylinder body 1, a first cylinder base 1a _# which can be fastened to the end of a hollow spindle (not shown) which is connected to the machine tool via screws which are inserted into threaded bores 2 (Fig. 1) intervene, and a second cylinder base 1b, which has a tubular extension 3 on the side facing away from the cylinder body 1, the inner diameter of which corresponds exactly to that _a 10 of coaxial central openings of the two cylinder bases 1a and i'b . According to the invention has

ι the tubular extension 3 of the cylinder base Ib a radial

I strength on that small in relation to the inside diameter

{ is. An annular piston 4, which is on a tubular

I 15 sleeve is attached is freely movable within ei-I ner tight chamber through the cylinder body 1 and the

I cylinder bottoms 1a and 1b is limited. The piston below

! * divides the chamber into two compartments A and B, which are tight

i separated from one another by an annular seal 6

I 20, which is inserted into an annular circumferential groove of the piston 4 %. The tubular sleeve 5 has an outer

} diameter that is slightly smaller than the

\ ' knife of the openings in the cylinder bottoms 1a and 1b and { the annular extension 3 is in which the piston is free

; 25 is slidable. The sleeve follows the displacements of the ν annular piston 4, so that on a not shown

Organ exercised a train to the left or right in FIG. 1; will. One end of this organ, not shown, is both

, for example in an internal thread 5a at the right end of the sleeve

I 30 se 5 screwed in, while the other end of this organ \ is attached to a chuck, not shown, of a machine tool.

'works. When the annular piston 4 and the sleeve 5 their

■ take the right end position shown in Fig. 1, be

<the chuck of the machine tool is in a position

35 in which it releases the workpiece while the workpiece is clamped when the lines 4 and 5 are in their left end position take in. Annular seals 6a and 6b, the

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in grooves in the interior of the openings in the cylinder base 1a and the extension 3 are inserted, effect the chambers A and B of the cylinder chamber.

¥ and the approach 3 are inserted, cause a seal ί

The angular locking of the annular piston 4 with respect to the cylinder body 1 and its cylinder bottoms takes place with the aid of a pin 7, one end of which extends perpendicularly from the annular piston 4 and on this is attached and the other end is freely displaceable in a bore 8 in the cylinder bottom 1a.

The tubular extension 3 of the cylinder base 1b forms the axis of a rotatable hydraulic connection, the fixed part 9 of which is annular and has an inner diameter that is only slightly larger than the outer diameter of the tubular extension 3. The cylindrical inner surface of the ring 9 has four annular grooves. In the middle area, grooves a and b are provided, which are connected via channels such as channel 11a through ring 9 to fixed tubes 10a (FIG. 1) and 10b (not shown). Which lie in the vicinity of the ends of the fixed ring 9 and of roller bearings 12a and 12b _# between the ends of the ring and the tubular projection 3 _f are two collection grooves c and d, whose function will be explained later.

The arrangement of the ring-shaped hydraulic cylinder and the circumferential Hydraulic connection including stationary ring 9 is housed inside a sealed housing 13, which has an outlet line 13a in the lower region .

The cylinder base 1b of the hydraulic cylinder, to which the tubular extension 3 is firmly connected, has an axial one Strength, which allows the inclusion of two one-way flap valves in suitable holes. In the case of the preferred embodiment are these bores

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15a, 15b, which serve to accommodate the flap valves 14a, 14b, are arranged on both sides of a central opening Ob in the cylinder base 1b symmetrically with respect to its axis C (FIG. 2). The axes Aa and Ab of the bores run perpendicular to a common center plane of the hydraulic cylinder, which is indicated by the line P in FIG. Due to this * ^a Jiordnung the two valve bodies 16a and 16b (FIG. 2) of the two flap valves 14a and 14b of the centrifugal force are freely displaceable in the bores 15a and 15b withdrawn from the particular effect when the hydraulic cylinder with a fast rotating machine tool is connected and the cylinder of the hydraulic cylinder is fully in equilibrium.

15th

In the embodiment described, the chambers of the two one-way flap valves are also cylindrical, like the bores 15a and 15b, in which the chambers are formed and by plugs 17a and 18b to the Ends are sealed. The valve bodies 16a and 16b are essentially cylindrical and have a Length which is slightly less than the length of the corresponding chamber, so that each valve body such as the valve body 16a, zwisehen in the chamber of the bore 15a a first position on the right-hand side, in which the valve body 16a is shown in FIG. 2, and in a second end position on the left, in which the valve body 16b is shown in Fig. 2, displaceable are. The chambers of the two one-way flap valves can also have a prismatic design, provided the valve bodies have a corresponding shape.

The first end of the chambers, shown on the right in FIG. 2, within the bores 15a or 15b of the two flap valves is connected to auxiliary lines that are used to control the opening of the flap valves. In the Embodiment described include these auxiliary lines

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Bores 20a, 20b, which are in a recess of the stopper 18a, 18b open and opposite the corresponding surface the valve body 16a, 16b are open, as well as bores 21a and 21b, which extend in the axial direction and which are formed in the interior of the tubular extension 3 in such a way that that they have a radial bore, not shown, with a narrow space between the tubular extension 3 and the fixed ring 9 at the level of the annular groove b for the bore 21a and at the level of the annular Groove a for the bore 21b are in communication.

In the middle of the chambers 15a and 15b of the two flap valves open via at least one and, for example, three openings main lines 22a and 22b or their upstream section. As shown in Fig. 1, the upstream portion of the main lines is 22a or 22b made by axial bores extending in the tubular extension 3 and with the narrow Gap between parts 3 and 9 in the amount of. annular groove a for the main line 22a and in height the annular groove b for the main line 22b in communication.

The downstream section of the main lines, related on the flap valve, which is designated with 23a and 23b, opens in the middle area of the corresponding chamber in the bores 15a or 15b, namely in annular grooves 24a and 24b, which with respect to the mouths of the upstream sections 22a and 22b on the side of the second end are arranged on the left in Fig. 2 of the chamber. The downstream section 23a of the main line of the corresponding Kläppenventiles 14a consists of a bore 25a, which is in a plane perpendicular to the axis of the annular hydraulic piston extends within the cylinder base 1a, as well as from one or more axial Bores 26a, which are in the wall of the cylinder body 1 and via a lateral branch with the chamber

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mer A of the cylinder cylinder of Fig. 1 are in communication. The downstream section 23b of the main line of the On the other hand, flap valve 14b consists only of an axial bore opening into chamber B of the cylinder chamber.

As can be seen from FIG. 2, the cylinder bodies 16a and 16b have an axial blind bore 27a, 27b which are connected to the second end of the chambers within the bores 15a and 15b on the left in FIG. 2 via suitable nozzles 28a, 28b. Bores 29a and 29b connect the blind bores 27a and 27b of the valve body with the part of the chambers within the bores 15a, 15b in which the current. upward section 22a, 22b of the corresponding main line

tung flows. In the described preferred embodiment. form, the bores 29a, 29b open outside the corresponding

corresponding valve body 16a, 16b in an annular groove 30a, 30b of shallow depth, which is machined into the outer surface of the valve body.
20th

Γ There are two remaining in the circumferential surface of the valve body

In cross-section V-shaped grooves 31a and 31b are incorporated, their axial position within the annular grooves 24a and 24b lies in the walls of the bores 15a and 15b, j 25 provided the valve body 16a and 16b is in a first right end position is for the valve body

s 16a is shown in FIG. At the bottom of this V-shaped nut

th 31a open out several radial bores, which of the

■ go out axial blind hole 27a of the valve body. A

'* "30 ring made of elastic material 32a, 32b, in particular a ring with a circular cross-section, is stretched against the bottom of the grooves 31a, 31b and closes the radial bores in the direction of the blind bores 27a, 27b when there is no pressure difference between this and the grooves 24a , 24b The rings made of elastic material, which act like a sphincter muscle, form a one-way valve with the radial bores of the valve body

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Valve body 16a can be seen, the seal takes place the canter between the annular groove 24a in the lateral Wall of the bore 15a and the two annular grooves 31a is formed in the valve body 16a, according to to the right through a lip seal 33a and to the left through an O-ring 34a. When the valve body reaches its left end position occupy, in which the valve body 16b is in Fig. 2, there is the lip seal 33b at the level of the annular groove 24b, and due to the shape

the side surface of the veritil body 16b beyond the lip seal there is a direct connection between the downstream section 2r, b of the corresponding Main line and the mouths of the upstream section 22b.

15th

In the embodiment described, the tubular sleeve 5, which carries the annular piston 4, is outside of the rotatable hydraulic connection and in particular of the rotatable extension 3, and the end of the sleeve

carries a ring 3a or a disc made of steel, i.

a ferromagnetic material. On the other hand are two magnetic transmitters 35a and 35b (see also Fig. 3) in the outer area of the hydraulic cylinder via angles 36a, 36b attached by the inner wall of a hood

37 are supported in the extension of the housing

is arranged. The axial positions of the two magnetic Encoders 35a and 35b are chosen so that they are respectively the end positions of the ring or the disk 3a and thus of the piston 4 according to a clamping or release

of the workpiece through the chuck. Acquaintances, no Devices shown are used to receive the signals from the magnetic encoder 35a and 35b, by the rotation of the associated machine tool is released or blocked.

The function of the hydraulic cylinder described above will then be explained with reference to FIG. 4

35

TER sea.Möller. STHINMEISTER. ·· £ * <* 'J? R action IKSuiftrielle

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will. Pxg. 4 shows the various lines of the supply system of the two chambers A in simplified form and B of the hydraulic cylinder using the reference numerals of Figures 1 to 3. In Figure 4, P is a hydraulic pressure fluid source, with R a container for hydraulic fluid at atmospheric pressure and with I denotes a known device through which the pipes 10a and 10b, which are the inlets of the channels 11a, 11b of the main lines form ,, with the Druckf luidquelle P and with the container R are to be put in connection.

As has already been stated, it is at the position of the ring-shaped piston 4 at the right end in Fig. 1 released the chuck, not shown, of the machine tool, and the signal at the output of the corresponding magnetic encoder 35b prevents the drive motor from being switched on the machine tool. In this position, the chamber • B of the cylinder chamber is filled with hydraulic pressure fluid, while the chamber A is connected to the container R.

The valve bodies 16a and 16b are de :: two one-way flap valves 14a and 14b assume their second or first end position corresponding to that of Fig. 2 is opposite. When a workpiece is to be machined, a command is sent to the device I according to FIG Container R is connected. In this way, pressure fluid passes through the lines and openings 113,3,223,3Oa and 29a into the axial blind bore 27a of the valve body 16a and from there through the nozzle 28a into the chamber within the bore 15a. The hydraulic pressure fluid acting on the left side of the valve body 16a moves it into its first right end position according to FIG Tube 10b into the container R via the bores and openings 20a, 21a, b, 11b. To-

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the valve body 16b immediately executes the opposite movement into the second left end position, since the Pressurized fluid at the right end of the chamber in bore 15b which enters through the openings and bores 11a, a, 20b, 21b. 5

The two valve bodies 16a and 16b have thus reached the end position shown in FIG. 2, which is initially the The one-way flap valve 14a is closed and then the flap valve 14b is opened. In this position the pressure fluid, which fills the axial bore 27a within the valve body 16a, lifts the elastic rings 32a, since the fluid within chamber A is at atmospheric pressure. The pressurized fluid then occurs enters the chamber A through the lines 25a and 26a and begins the displacement of the annular piston 4 to the left in Fig. 1. The movement of the piston 4 leads to the fact that from the chamber B a part of this filling Hydraulic fluid is pushed out and passes through the pipe 10b into the container R in the following way:

through the downstream section 23b of the main line, the direct connection between the annular groove 24b and the lip seal 33b, which is now on a Height, through the mouth of the section 23b of the main line in the chamber within the bore 15b on the one hand and through the part of this chamber within the bore 15b, at the level of which the annular groove 30b and through the mouths of the upstream section 22b of the main duct into this chamber on the other hand, through the annular groove b and through the channel 11b in the upstream region of the main line.

If under the action of the pressure fluid arriving in the chamber A, the annular piston 4 in the left Has reached the end position and strikes against the cylinder base 1b, the tubular sleeve 5 exercises a to the left in Fig. 1 directed train on the control member of the chuck, not shown. As a result, the

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Chuck is closed-. Because the ring or the washer 3a has reached the level of the magnetic encoder 35a, its output signal controls the activation of the power supply of the drive motor of the machine tool, preferably ensuring that the machine does not start until the chuck is fully clamped.

At the end of the machining of the workpiece, the device I connects the pipe 10b to the pressurized fluid source P, see above that the pressurized fluid moves the flap valve 14b and enters the chamber B while it is still under pressure standing fluid within the chamber A by opening the flap valve 14a under the action of the channels 20a and 21a entering pressurized fluids to atmospheric pressure

is relaxed. The opening of the flap valve 14a. allows the piston 4 to be part of the chamber A delivers pressurized fluid contained through the pipe 10a into the container R. Just before opening the chuck controls the encoder 35b stopping the machine tool.

It should be noted that as soon as the tension of the chuck of the displacement of the piston 4 a certain Opposed resistance, which is sufficient that the fluid pressure in the chamber A the pressure value of the directly from the Pressurized fluid source P accepts fluid supplied, which now fills the axial bore 27a of the valve body 16a, the elastic rings 32a lower again and close the associated one-way valves. It is therefore not indispensable that the pipe 10a with the pressurized fluid source P during the entire machining time of the workpiece is connected without resulting in a risk that the chuck is loosened during processing. As a result, the risk of accidental loosening of the chuck during processing is low, even if if damage to the pressurized fluid source P or the connecting lines occur to the flap valve 14a.

11 Il

TER SEA. MÜLLER. STEINMEISTER

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The embodiment described can be further improved as follows. The outer annular grooves c and d stand via radial channels 38c and 38d, which penetrate the fixed ring 9, with an axial channel 40 in connection, which is also located in the ring 9, preferably in its lower area. A Venturi tube 41 is arranged with its axis essentially perpendicular and connects the channel 40 with the mouth the outlet line 13a of the housing 13. An annular gap 41a is located between the inner wall of the outlet conduit 13a and the outer wall of the venturi tube 41.

In this way, the hydraulic fluid flows through the annular Grooves a and b fills, through the narrow space between the tubular extension 3 and the ring 9 to at the end of this gap. This will lubricate the bearings 12a and 12b * The excess hydraulic fluid collects in the outer collecting grooves c and d, from which it flows through the radial channels 38c and 38d into the axial channel 40 arrives. It then enters the container R which is under atmospheric pressure (FIG. 4), and namely through the Venturi tube 41 and the outlet line 13a of the housing 13. Through this outlet of the hydraulic fluid Part of the air contained in the housing 13 is sucked out through the Venturi tube 41 in the area of the annular gap 41a, so that a slight negative pressure is formed in this, which prevents a haze of the hydraulic f luids, especially oil, due to rapid rotation of the hydraulic cylinder and the movable extension 3 of the rotary joint in the interior of the housing 13 emerges. Because of this negative pressure, a small amount of fresh air enters the interior of the housing 13 through openings provided for this purpose in the upper area. There is therefore a lowering of the mean temperature the individual fixed and rotatable components within the housing 13 ..

. TER sea. Müller. Steinmeister, '·. "·;La.' Prefcisi« «industrial ^/

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The invention is not restricted to the embodiment explained above. In particular, the valve body 16a and 16b of the one-way valves 14a, 14b be carried out in different ways. The number and arrangement of the elastic rings 32a, 32b, which act as sphincters serve can be changed. You can use one or more disposable valves of a known type and similar Effect to be replaced. In addition to or instead of the annular groove 30a on the surface of the valve body 16a may have a corresponding groove in the surface of the bore 15a in the region of the mouth of the upstream Section 22a of the main line may be provided. The valve bodies of the flap valves are general designed so that when through the upstream Section of the main line or through the auxiliary line discharged pressure fluid into the chamber of the flap valve is, the valve body is moved against the stop at the first or 'second end of the chamber, namely in a first end position in which the valve body has at least one one-way flap valve between the two sections the main line closes, or a second end position in which the valve body forms a direct connection between the two sections of the main line manufactures.

25th

Claims (1)

TER MEER - MÜLLER - STEINMEISTER D-8000 Munich 22 D-4800 Bielefeld ^§ '' ■ Triftstrasse 4 Siekerwall 7 JTM / MZ 5342/24
St / ge LA PHECISION INDUSTRIAL 22 avenue de la Republique RUEIL-MALMAISON Hauts-de-Seine France Hydraulic cylinders, in particular for control a workpiece chuck for machine tools PRIORITY: 4th July 1977, France, No. 77.20474 EXPECTATIONS 1. Ring-shaped hydraulic cylinder, especially for controlling the workpiece chuck for machine tools, with a circumferential hydraulic connection, the axis of which through a tubular extension of a cylinder base of the annular cylinder is formed, two main lines opening into two chambers of the cylinder and in which the hydraulic connection and then a one-way flap valve is inserted, which is through a to control the flap valve serving auxiliary line with the other main line upstream of the associated one Flap valve is connected, and with a device TER MEER- MÖLLER. STEINME.STSR »,; , ».» ■; _ "^; p _reeigion alternative and alternating connection of the ?. , Inlets of the two main lines with a hydraulic I see source of pressurized fluid and one under atmospheric pressure ν standing container, characterized in that * 5 that the two Einwsg flap valves (14a, 14b) in Boh stanchions (15a, 15b) are in the cylinder base (1b) of the cylinder, and that the cylinder base (1b) is firmly connected to the tubular extension (3) of the cylinder. ι - 10 2. Hydraulic cylinder according to claim 1, characterized g e k e η n- I draws that the holes (15a, 15b) that the 1 'take up flap valves (14a, 14b), one on both sides $ Central opening (Ob) of the cylinder (1,1b) are arranged, §; and that their axes are particularly perpendicular to a s 15 common longitudinal median plane of the cylinder. ] '3. Hydraulic cylinder according to claim 1 or 2, characterized ; characterized in that the flap valves (14a, i 14b) a cylindrical or prismatic chamber (15a, 15b) • 20 comprise, in the valve body (16a, 16b) essentially <the same shape can be moved freely, and that one end j of the auxiliary line (20a, 21a, 20b, 21b) for controlling the valve ; opening opens at one end of the chamber so that the flow j upstream and downstream sections (22a, 22b, 23a, *: 25 '23b) of the main line in the middle area of the chambers (15a, j 3 5b) at a first point and at a number of two- I th points open between the first point and I lie at the first end of the chamber, and that the valve bodies I per (16a, 16b) are designed in such a way that when j '30 pressurized fluid through the upstream section (22a, 22b) ^{1 of} the main line or the auxiliary line (20a, 21a, 20b, 21b) ; into the chamber of the flap valve the valve body (16a, I 16b) against the first or second end of the chamber ] ben, namely in a first end position in which the 35 valve body at least one one-way valve (32a, 32b) in the switches on both sections of the main line, and a second end position in which the valve body has a direct TER sea. Müller. Steinmeister, "·;<".'"/.^" ^ Qjsion Industrial _J 1 Establishes a connection between the two sections of the main line. 4. Hydraulic cylinder according to claim 3, characterized in that g e - indicates that the valve body (16a, 16b) of the flap valves (14a, 14b) are essentially axial Has a blind hole (27a, 27b) with your second end the chamber, preferably via a nozzle (28a, 28b) in connection that at least one bore for Connection of the blind bore (27a, 27b) of the valve body with the region of the chamber of the valve body is provided is in which the upstream portion (22a, 22b) of Main line opens out that the one-way valve (32a, 32b) is switched into a branch of the blind hole, the in the downstream section (23a, 23b) of the main line opens when the valve body is in its first end position, and that the lateral surface of the The valve body is shaped such that in the second end position of the valve body there is a direct connection the first and second points of the chamber. 5. A hydraulic cylinder according to claim 4, characterized g e kennze ichnet that the lateral surface of the valve body (IDa ₇ IDb) of the Kiappenventile ring = shaped seals (33a, 33b, 34a, 34b) on either side of the mouth of the branches of the blind bores (27a, 27b ), -in which the one-way valve (32a, 32b) is switched on « 6. Hydraulic cylinder according to one of claims 4 and 5, characterized in that a recess, in particular an annular groove (31a, 31b) on the surface of the valve bodies (16a, 16b) of the flap valves (14a, 14b) at the level of the mouth of the junction the blind bore (27a, 27b) of the valve body is provided is, in which the one-way valve (32a, 32b) is inserted, and / or that in the lateral surface of the chamber (15a, TER sea - MÜLLER. STEINMEISTE «···; . ··. ••• jLa'TPretiision Industrial I · ■ · It · ··· 15b) of the flap valve at the mouth of the downstream section (23a, 23b) of the main line a groove (24a, 24b) is provided. 7. Hydraulic cylinder according to one of claims 4 to 6, characterized in that the one-way valve (32a; 32b) essentially a ring made of elastic Comprises material which is clamped in an annular groove (31a, 31b), preferably with a V-cross section, which groove is provided in the surface of the valve body of the flap valve, and that several at the bottom of the groove radial branches of the blind bore (27a, 27b) of the valve body open. 8. Hydraulic cylinder according to one of claims 1 to 7, characterized in that the tubular sleeve (5) which carries the piston (4) of the cylinder (1,1a, 1b) extends into the interior of the rotatable hydraulic connection (9) is that the sleeve carries a disk or ring (3a) made of ferromagnetic material at its end, and that magnetic sensors (35a, 35b) are provided outside the cylinder for scanning the respective extreme positions of the disk and the ring and thus the piston _f which extreme positions correspond to the clamping and releasing of the workpiece in the chuck. 9. Hydraulic cylinder according to one of claims 1 to 8, in which the rotatable hydraulic connection has an outlet for delivering hydraulic fluid to an outlet conduit provided housing, characterized in that that the hydraulic connection collecting devices (c, d) for receiving excess hydraulic fluid, in particular in the form of annular grooves, which in the fixed part (9) of the hydraulic connection, in particular are incorporated at both ends in the vicinity of corresponding bearings (12a, 12b), and that in the TER sea. Müller. STEiNMEiSTpR, ···; , ··. '"Ia · Ρϊβο1β1οη Industrial ^ Line for delivering the hydraulic fluid to the outlet line (13a), a Venturi tube (41) is inserted, which is arranged in such a way that it generates a negative pressure in the housing (3).
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