Hydraulic control and drive units

Abstract

The invention relates to a hydraulic control device, in particular for a casting machine, and a drive unit provided with such a hydraulic control device, wherein the control device has a hydraulic cylinder to which a control block is assigned. The position of the piston of the hydraulic cylinder is detected by means of a position sensor, which, according to the invention, is accommodated at a distance from the inflow region of the hydraulic cylinder or of the control block.

Description

Technical Field

[0001] The invention relates to a hydraulic control device and a drive unit provided with the control device. Background Art

[0002] The drive unit can be used, for example, to drive a casting piston of a casting unit of a casting machine, for example a die-casting machine, a thixomolding machine or an injection molding machine.

[0003] The basic structure of such a drive unit for a die-casting machine is described, for example, in the documents DE 102017220836 A1 and DE 102017220832 A1, both of which are from the present applicant. The drive unit thus has a casting cylinder for a casting unit of a die-casting machine, which is designed as a differential cylinder. The piston rod of the differential cylinder drives a casting piston, through which the corresponding molding material can be injected into the cavity of the mold. The pressure chamber of the differential cylinder can be used to introduce three casting phases, namely: pre-filling / advancing (Vorschieben)

[0004] - injection / pressing, and

[0005] - Reseal / pressure build-up

[0006] And be connected with high pressure storage or low pressure storage or material box through the hydraulic circuit with proportionally adjustable reversing valve and switch valve.These three casting stages are described in detail in the prior art mentioned at the beginning, so no further explanation is needed.

[0007] In a compact solution, the hydraulic circuit with the switching valves and, if necessary, the pressure accumulator is integrated into a control block which can be placed on the differential cylinder. However, the control block can also be arranged separately from the casting cylinder.

[0008] In the compact solution, the casting cylinder and the control block together form a cylinder chamber and an inflow chamber defined by the piston. The stroke of the piston is detected by a position sensor, which in conventional solutions is fixed to the bottom of the inflow chamber and extends with a sensor rod into a sensor recess, which extends into the piston rod of the piston. This sensor rod cooperates with a position magnet arranged on the piston. For example, a pressure connection loaded with high pressure for compression in a die-casting machine leads to this piston-side inflow chamber, and the high pressure can be in the range of more than 400 bar, for example. The pressure chamber on the piston rod side of the hydraulic cylinder is connected to the material box here, so that extremely rapid force build-up is achieved. Due to the resulting high pressure medium inflow force, the sensor can bend or deform, so that the function of the hydraulic control device is particularly hampered by the measurement accuracy when detecting the piston position. Summary of the invention

[0009] In contrast, the object of the present invention is to provide a hydraulic control device and a drive unit provided with the hydraulic control device, wherein a proper function is ensured even at high pressures.

[0010] This object is achieved with respect to the hydraulic control device by a support which supports the position sensor offset relative to the cylinder chamber and / or relative to the piston in the transition region between the inflow chamber and the cylinder chamber and with respect to the drive unit by a control device according to the invention.

[0011] Advantageous extended design schemes of the present invention include but are not limited to: the bracket has a holding tube, which is supported on the control block side and is held and preferably partially surrounds the position sensor by the end section on the piston side of the holding tube; it has a supporting ring device, and the holding tube and / or the position sensor are supported in the cylinder chamber or in the cylinder housing by the supporting ring device; wherein the supporting ring device has at least one notch, preferably multiple notches, for conveying pressure medium; wherein the sensor base carrying the sensor rod is preferably pre-tensioned relative to the radial shoulder in the area of ​​the supporting ring device by clamping in the holding tube; wherein the sensor rod is surrounded by a sleeve, and the sleeve is placed on the holding tube; wherein the sensor rod or sleeve is radially supported or guided in the piston or piston rod; wherein the sleeve The end section of the tube removed from the retaining tube is closed with an end piece, which radially supports the sensor rod; wherein the opening of the sensor recess on the cylinder chamber side is widened toward the cylinder chamber by a funnel-shaped widening; wherein a position magnet is held in the area of ​​the funnel-shaped widening, which is penetrated by the sensor rod; wherein an annular gap is constructed between the sensor rod and the circumferential wall of the sensor recess, the annular gap being designed so that during operation, even under high pressure medium loads, no contact occurs between the sensor rod or the sleeve and the circumferential wall of the sensor recess; wherein a sensor cable of the position sensor leads through the retaining tube to the control block; wherein the hydraulic cylinder is a differential cylinder and the sensor recess extends into the piston rod of the piston.

[0012] The hydraulic control device according to the invention has a hydraulic cylinder, in particular a casting cylinder, on which a hydraulic control block is preferably placed, via which the pressure medium connection of the hydraulic cylinder to a high-pressure accumulator or a low-pressure accumulator or a tank is controlled.

[0013] The hydraulic cylinder has a piston which is guided in a cylinder housing and partially delimits a piston-side cylinder chamber, to which an inflow chamber adjoins or which is formed with an inflow chamber section. A pressure medium connection opens into this inflow chamber.

[0014] In order to detect the piston position, the control device is designed with a position sensor, which is supported in the area of ​​the cylinder chamber and extends into the sensor recess of the piston with a sensor rod. According to the present invention, the sensor rod is not fixed on the bottom of the inflow chamber as in the conventional solution, but is fixed on a bracket, which supports the sensor offset from the piston or offset from the transition area between the cylinder chamber and the inflow chamber / inflow chamber section. The bracket preferably extends roughly along the extension of the sensor rod or the position sensor. The bracket is positioned in this way so that the sensor is no longer directly in the inflow area of ​​the pressure medium, for example, in the inflow chamber on the control block side, and the bracket is correspondingly loaded by the pressure medium inflow force and the sensor is not loaded by the pressure medium inflow force. However, this can be designed in a simple way so that this bracket can withstand the inflow force even at high pressure. The sensor is then preferably supported in the transition area from the control block side part of the cylinder chamber or the inflow chamber to its own cylinder housing, for example, the cylinder tube, in which the pressure medium force is much smaller than in the inflow area and in the flow area of ​​the sensor connected to the transition area, so that the problem mentioned at the beginning does not occur with the deformation of the sensor.

[0015] The terms "cylinder chamber" and "inflow chamber" can be interpreted relatively broadly, wherein the inflow chamber or inflow chamber section can also be formed by a corresponding design of the cylinder chamber, which extends, for example, into the control block. The region of the piston-side pressure chamber extending into the control block is referred to as the inflow chamber / inflow chamber section in the following embodiments.

[0016] By axially offsetting the sensor toward the piston / cylinder chamber, a shorter sensor can be used than in conventional solutions, in which the sensor is supported on the bottom of the cylinder chamber or inflow chamber, preferably on a control block, wherein the sensor rod then penetrates the inflow chamber without overlapping the piston and is thus subjected to pressure. The support can be dimensioned stably in a simple manner so that it cannot deform. Even possible deformations of the support do not affect the measurement quality of the sensor.

[0017] In a particularly preferred solution, the support is preferably designed as a holding tube, which is supported on the control block side and holds the sensor at its piston-side end section. This end section preferably partially surrounds the sensor. The holding tube then serves both as a support and as a protective tube, by which the sensor is partially covered, so that the sensor is not directly acted upon by pressure medium in this area.

[0018] The support of the sensor can be further improved if the holding tube and / or the sensor are supported radially in the region of the cylinder chamber or of the cylinder housing by a support ring arrangement.

[0019] In this embodiment, the pressure medium connection to the sensor recess of the piston can be realized by means of a recess / recess in the support ring arrangement, by means of which the pressure medium flow is stabilized.

[0020] According to an advantageous development of the invention, a sensor base of the sensor carrying the sensor rod is prestressed against the supporting shoulder, preferably in the region of the supporting ring device by means of a clamping device in the holding tube.

[0021] The risk of damage to the sensor can be further reduced if the sensor rod is surrounded by a sleeve which is placed onto the holding tube, so that the entire sensor is enclosed and thus protected.

[0022] According to one embodiment, the sensor rod (in the case of a position sensor without an associated sleeve) or the sleeve is radially supported / guided in the piston or in the case of a differential cylinder in the piston rod by means of suitable supports / guides.

[0023] It is particularly preferred here if the end section of the sleeve removed from the holding tube is closed with an end piece which supports the sensor rod in radial direction and thus completes the relative positioning of the sensor within the sleeve in a defined manner.

[0024] However, the sleeve can in principle also remain open in the region of the end section, so that pressure medium can flow from the end section into the sleeve and / or the retaining tube, but this region is not subjected to the inflow forces explained at the outset.

[0025] The pressure medium flow into the sensor recess is optimized if the cylinder-chamber-side access opening of the sensor recess widens in an approximately funnel-shaped manner toward the cylinder chamber.

[0026] In order to ensure the inflow and outflow of pressure medium even under unfavorable operating conditions, in one embodiment of the present invention, an annular gap is constructed between the sensor rod and the circumferential wall of the sensor recess or between the sheath of the sensor rod and the circumferential wall of the sensor recess, and the annular gap is designed in such a way that during operation, even under high pressure medium loads, no contact occurs between the circumferential wall and the sensor rod / sleeve.

[0027] When the retaining tube is also configured as a cable bushing for the sensor cable, the signal transmission and current supply of the sensor are particularly simple. The sensor cable extending through the cylinder chamber and the inflow chamber to the control block is sealed tightly against the pressure medium by this expansion scheme.

[0028] In a particularly preferred embodiment, the hydraulic cylinder is designed as a differential cylinder, wherein the sensor recess extends into the piston rod of the piston.

[0029] According to the previous embodiments, the solution according to the invention with a position sensor spaced apart from the inflow region was explained using a hydraulic control device as an example. In principle, it is also conceivable that this solution is generally used when the sensor is loaded with external forces, for example, by mechanical vibrations or by eddies present in the liquid / gas flow, and then the support of the sensor is guided out of this interfering region in order to avoid interaction with the sensor.

[0030] In the above-described embodiment, the position sensor is clamped / encapsulated by means of a tubular structure. Of course, other structures may also be used for clamping / covering.

[0031] In a simple embodiment, instead of a two-part protective device with a retaining tube and a sleeve, a single retaining / protective tube can be used, which is radially guided in the area of ​​the control block and / or the cylinder chamber on the one hand and in the area of ​​the piston or the piston rod on the other hand. Of course, it is also possible for the retaining tube and / or the sleeve to be of multi-part design.

[0032] The support of the holding tube or of a corresponding structural element in the control block can also be realized in a variety of ways and is not restricted to the specific embodiment described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Preferred exemplary embodiments of the invention are explained in more detail below with reference to schematic diagrams.

[0034] Figure 1 A schematic diagram of a casting unit of a die casting machine is shown;

[0035] Figure 2 The control button is shown Figure 1 The circuit diagram of the drive unit of the die-casting unit;

[0036] Figure 3 A sectional view of a hydraulic control device according to the invention is shown with a hydraulic cylinder forming a casting cylinder, which is placed on a hydraulic control block;

[0037] Figure 4 Shows the Figure 3 A detailed view of the area of ​​the control device on the control block side;

[0038] Figure 5 A detailed view showing the transition area between the control block and the hydraulic cylinder;

[0039] Figure 6 Shows the Figure 3 a detailed view of a piston rod-side end section of a control device; and

[0040] Figure 7 Shows Figure 6Details of B. DETAILED DESCRIPTION

[0041] exist Figure 1 The basic structure of the die casting machine is shown in FIG. In this patent application, only some structural elements of the die casting machine that are essential for understanding the present invention are explained. For further details, reference can be made to the literature mentioned at the beginning.

[0042] according to Figure 1 The die-casting machine has a drive unit with a control device 1, which has a casting cylinder, hereinafter referred to as a hydraulic cylinder 2, which can be controlled by means of hydraulic circuits arranged in a control block 4. In the illustrated embodiment, the control block 4 is placed on the hydraulic cylinder 2 in a compact construction via a terminal block 6. This hydraulic cylinder is also designed as a differential cylinder with a cylinder housing 8, in which a piston 10 with a piston rod 12 is guided. The piston 10 defines a cylinder chamber 14 on the bottom side of the piston. The annular surface of the piston 10 and the piston rod 12 define an annular chamber 16 of the cylinder housing 8. The piston rod 12 is led out of the cylinder housing 8 at the end and drives a casting piston 18, which is guided in a shot bushing 20 and defines a shot chamber 22 together with the shot bushing. A filling opening or inlet 24 for the molten or viscous molding material to be processed leads into this shot bushing. The injection bushing 20 is placed on a mold 26 with two mold halves 28, 30 that can be separated from each other. The two mold halves form a cavity 32, into which the molding material can be moved / injected by moving the casting piston 18 through the casting channel 34. The cavity 32 is designed according to the shape of the workpiece to be produced. The two mold halves 28, 30 can be designed with corresponding cores in order to form the inner contour.

[0043] As mentioned above, the hydraulic control elements for actuating the hydraulic cylinder 2 and thus for driving the casting piston 18 are essentially accommodated in the control block 4. Figure 1 In the embodiment shown, the control block 4 is placed on the hydraulic cylinder 2. However, it is also possible in principle to arrange the control block 4 at a distance from the hydraulic cylinder 2 and to establish a pressure medium connection via a line or a channel. However, according to the invention, the compact solution shown with the control block 4 placed on the hydraulic cylinder 2 is preferred.

[0044] Figure 2 The hydraulic circuit diagram of the control device 1 is shown in a greatly simplified form. The hydraulic cylinder 2 described above and the hydraulic components required for the actuation, which are accommodated in the control housing 4, are shown.

[0045] The control device 1 thus has a high-pressure reservoir HD and a low-pressure reservoir ND, both of which can be charged by a variable pump 36. A 2 / 2-way valve 36 is arranged in the line to the low-pressure reservoir ND, by means of which a pressure medium connection to the low-pressure reservoir ND is opened or closed. A proportionally adjustable directional valve 38 is assigned to the high-pressure reservoir HD, by means of which the opening cross section to / of the high-pressure reservoir HD can be proportionally adjusted. The outputs of the two valves 36, 38 are connected to a pressure line 40, which is in pressure medium connection with the cylinder chamber 14, so that the cylinder chamber 14 can be connected to the high-pressure reservoir HD or the low-pressure reservoir ND, depending on the actuation of the directional valve 36 or the proportionally adjustable directional valve 38.

[0046] Furthermore, a connecting line branches off from the pressure line 40, in which a proportionally adjustable connecting valve 42 is arranged. This connecting line 44 is connected to the annular chamber 14 and to a tank line 46. In the latter, a likewise proportionally adjustable tank valve 48 is arranged, which controls the pressure medium connection to the tank T. Both the proportionally adjustable connecting valve 42 and the proportionally adjustable tank valve 48 are designed as two-way valves. All the aforementioned valve assemblies are controlled by a common control unit (not shown) of the die-casting machine. Further details of the hydraulic control of the die-casting machine according to the invention are known from the literature mentioned at the beginning.

[0047] exist Figure 3 , a cross section of a specific embodiment of a hydraulic control device 1 according to the invention is shown. This hydraulic control device is used, for example, as a drive unit for a casting piston 18 of a die-casting machine, wherein a hydraulic control block 4 is placed on a hydraulic cylinder 2. The aforementioned valves and control / regulating devices provided for controlling the pressure medium input and pressure medium output are accommodated in this hydraulic control block. In the illustrated embodiment, the control block 4 is designed in a flat plate construction, wherein the cylinder housing 8 of the hydraulic cylinder 2, which is designed with a cylinder tube 50, is placed on an end-side terminal block 6 by means of a cylinder flange 52.

[0048] An inflow chamber 54 is formed in the control block 4, into which a pressure medium connection 56 opens, through which pressure medium, for example pressure medium loaded with high pressure (420 bar), can flow in or out. The inflow chamber 54 is transformed into the cylinder chamber 14, which is opened at the pressure medium connection 56. Figure 11 is bounded to the left by the piston 10 in the illustration. In the retracted position of the piston 10 shown, the volume of the cylinder chamber 14 is minimal. The piston rod 12 and the cylinder tube 50 define an annular chamber 16, which can be connected to a tank or to the cylinder chamber 14 via a further pressure medium connection 60 and the control block part 62 shown. The end section of the cylinder tube 50 removed from the control block 4 is closed by means of a multi-part end flange 64, which is penetrated by the end section of the piston rod 12. In the region of this end flange 64, the guide and sealing elements of the hydraulic cylinder 2 are arranged, but the details of the guide and sealing elements are not important for the present application. In the illustrated embodiment, the end flange 64 is clamped to the support flange 66 by a longitudinal strut (not shown), which is itself fastened to the cylinder tube 50. Between the support flange 66 and the end flange 64, a connecting socket 68 extending in the extension of the cylinder tube 50 is arranged, in which the above-mentioned pressure medium connection 60 is constructed and the control block part 62 is placed on the connecting socket. The control block part is connected to the control block 4 via the shown line 70. In the region of the connecting socket 68 the above-mentioned guide and sealing element 72 is accommodated.

[0049] To actuate the cast piston 18 , in a first phase, for example for advancing the piston 10 with the piston rod 12 , the two pressure medium connections 56 , 60 are connected to the low-pressure accumulator ND via the switching valve 36 and the connecting valve 42 , so that the piston 10 is extended due to the area difference.

[0050] In the subsequent injection phase, the annular chamber 14 is connected to the tank T via the pressure medium connection 60 and the tank valve 48 and the connecting valve 42 is blocked, so that the piston 10 is extended at a higher speed.

[0051] Immediately following the compression, the pressure medium connection 56 is connected to the high pressure reservoir HD (up to 400 bar), wherein the tank valve 48 remains open, so that the pressure for compressing the molding material is built up in a short time. The displacement speed of the piston 10 and thus the casting piston 18 can be produced by correspondingly adjusting the opening cross sections of the proportionally adjustable valves 38, 42, 48, so that the aforementioned phases, i.e., starting, injection and pressure build-up, can be adjusted independently of each other and the mold can be filled in an optimal manner, so that highly complex workpieces can also be produced.

[0052] During these phases, the directional valve accommodated in the control block 4 (62) is also actuated depending on the position of the piston 10 and the piston rod 12. This position is detected by a position sensor 74, which, as will be explained in more detail below, is supported in the control block 4 by means of a holding tube 76 and is inserted with a sensor rod 78 into a sensor recess 80 in the piston 10 and the piston rod 12.

[0053] Further details are available via Figures 2 to 5 Explanation.

[0054] Figure 4 Shows Figure 3 The part of the holding tube 76 is shown. This holding tube is supported on the control block 4, wherein a receptacle 82 is constructed therein, into which the end section of the holding tube 76 is inserted. The part of the holding tube 76 that protrudes from the receptacle 82 passes through the inflow chamber 54 and extends into the area of ​​the cylinder chamber 14, which together with the inflow chamber 54 forms a pressure chamber. In the transition area between the inflow chamber 54 and the cylinder chamber 14, the position sensor 74 is inserted into the end section of the holding tube 76 with a sensor base 84. The elements of the position sensor 74 required for transmitting signals and supplying energy are arranged in this sensor base. The signal and energy connection to the control block 4 is carried out via a sensor cable 86, which extends through the holding tube 76 to the control block 4 and is therefore reliably sealed from the pressure medium. The sensor rod 78 is placed on the sensor base 84 and, as will be explained in more detail below, is covered from the pressure medium by means of a sleeve 88. This sleeve 88 is also inserted into the holding tube 76 in a sealing manner. Figure 4 In the end section shown.

[0055] exist Figure 4 In the illustrated embodiment, the holding tube 76 has a radial shoulder 90 in the region of the sensor-side end section, on which the sleeve 88 is supported at one end and the sensor base 84 is supported at the other end. The sensor base is held on this radial shoulder 90 by a clamping tube 92, which is inserted into the holding tube 76. The tensioning is done here by a clamping ring 94, which is screwed into the holding tube 76 and presses the sensor base 84 against the radial shoulder 90 via the clamping tube 92. The position of the holding tube 76 in the receptacle 82 is fixed by a nut 96, which presses the holding tube 76 with the shoulder 98 against the support ring 100, thereby fixing the holding tube 76 in position in the axial direction.

[0056] according to Figure 5 ( Figure 3 Detail A), this support ring 100 is part of a support ring arrangement 102, to which an intermediate ring 104 also belongs, in which a channel section 106 is formed which widens toward the support ring 100. The support ring 100 is arranged according to Figure 5 It is designed as a perforated disk with a plurality of recesses / openings 108 which form a pressure medium connection between the inflow chamber 54 and the cylinder chamber 58. The support ring device 102 is supported on one hand on a support shoulder 110 in the control block 4 and on the other hand on a radial surface 112 of the cylinder tube 50.

[0057] according to Figure 5As shown in the figure, the sensor recess 80 is designed with a funnel-shaped widening portion 114 in the access area to the cylinder chamber 14, which makes the flow of pressure medium from the cylinder chamber 14 or from the inflow chamber 54 into the sensor recess 80 be uniform in cooperation with the likewise funnel-shaped channel section 106 and the notch 108.

[0058] An annular position magnet 116 of the position sensor 74 is held on the piston 10 in the region of the funnel-shaped widening 114 and is penetrated by the sensor rod 78 .

[0059] Figure 6 The end section of the hydraulic cylinder 2 removed from the control block 4 is shown. As explained above, a pressure medium connection 60 is formed in this area to the annular chamber 16. A section of the control block part 62 can also be seen in this figure. As explained above, the cylinder tube 50 is closed by means of an end flange 64 or an end flange arrangement, which is penetrated by the piston rod 12 in a sealing manner. The sealing and guide element 72 of the piston rod 12 mentioned at the beginning is also arranged in this area. The sensor recess 80 ends in this area, wherein the sensor rod 78 extends into this area accordingly in the retracted position of the piston rod 12. This end section ends at Figure 6 and 7 Marked as detail B in the figure.

[0060] Especially by Figure 7 It can be seen that the end section of the sleeve 88 is closed by means of an end piece 118. This end piece can be screwed onto the end section of the sleeve 88, for example, and is designed with a conical cap 120, which further optimizes the flow around it.

[0061] In the end section of the end piece 118 removed from the cap 120, a blind hole 122 is formed, into which the end section of the sensor rod 78 is inserted with little play or with a press fit. The end piece 118 is inserted into the sleeve 88 with a precise fit in this area, so that the sensor rod 78 is supported radially in the sleeve 88.

[0062] The outer diameter of the sleeve 88 and the inner diameter of the sensor recess 80 are matched to one another in such a way that an annular gap 124 is produced with a gap width S which is large enough to avoid contact between the sleeve 88 and the piston rod or the circumferential wall of the sensor recess 80 even under unfavorable pressure and flow conditions and thus the sensor rod 78 always runs at a distance from this circumferential wall. This gap width S also facilitates the inflow and outflow of pressure medium during the extension and retraction of the piston rod 12.

[0063] Even if sleeve 88 can possibly be omitted, it is advantageous to provide the gap width S described above between the circumferential wall of sensor recess 80 and sensor rod 78 in this case.

[0064] A hydraulic control device, in particular for a casting machine, and a drive unit provided with such a hydraulic control device are disclosed, wherein the control device has a hydraulic cylinder to which a control block is assigned. The position of the piston of the hydraulic cylinder is detected by means of a position sensor, which is accommodated according to the invention at a distance from the inflow region of the hydraulic cylinder or of the control block.

Claims

1. A hydraulic control device, comprising a hydraulic cylinder (2), a hydraulic control block (4) being placed on the hydraulic cylinder, wherein: The hydraulic cylinder (2) has a piston (10) which partially defines a cylinder chamber (14), the cylinder chamber being adjacent to an inflow chamber (54) of a control block (4), wherein a pressure medium connection (56) opens into the inflow chamber or the cylinder chamber (14); and having a position sensor (74) for detecting the position of the piston; and having a sensor rod (78) which extends into a sensor recess (80) of the piston (10), characterized by a bracket which supports the position sensor (74) in a transition area between the inflow chamber (54) and the cylinder chamber (14) in an offset manner relative to the cylinder chamber (14) and / or relative to the piston (10).

2. The control device according to claim 1, wherein: The support has a holding tube (76) which is supported on the control block side and holds the position sensor (74) via its piston-side end section.

3. The control device according to claim 2, comprising a support ring device (102), by which the holding tube (76) and / or the position sensor (74) are supported in the cylinder chamber (14) or in the cylinder housing (8).

4. The control device according to claim 3, wherein: The support ring device (102) has at least one recess (108) for supplying a pressure medium.

5. The control device according to any one of claims 2 to 4, wherein: The sensor base (84) carrying the sensor rod (78) is prestressed against a radial shoulder (90) by clamping in the holding tube (76).

6. The control device according to any one of claims 2 to 4, wherein: The sensor rod (78) is surrounded by a sleeve (88) which is placed onto the holding tube (76).

7. The control device according to claim 6, wherein: The sensor rod (78) or the sleeve (88) is supported or guided radially in the piston (10) or the piston rod (12).

8. The control device according to claim 6, wherein: The end section of the sleeve (88) removed from the holding tube (76) is closed with an end piece (118) which supports the sensor rod (78) in radial direction.

9. The control device according to any one of claims 2 to 4, wherein: The opening of the sensor recess (80) on the cylinder chamber side is widened toward the cylinder chamber (14) by a funnel-shaped widening portion (114).

10. The control device according to claim 9, wherein: A position magnet (116) is held in the region of the funnel-shaped widening (114) and is penetrated by the sensor rod (78).

11. The control device according to claim 6, wherein: An annular gap (124) is formed between the sensor rod (78) and the circumferential wall of the sensor recess (80), which is designed in such a way that during operation, even under high pressure medium loads, no contact occurs between the sensor rod (78) or the sleeve (88) and the circumferential wall of the sensor recess (80).

12. The control device according to any one of claims 2 to 4, wherein: A sensor cable (86) of the position sensor (74) passes through the retaining tube (76) and leads to the control block (4).

13. A control device according to any one of the preceding claims 1 to 4, wherein: The hydraulic cylinder (2) is a differential cylinder and the sensor recess (80) extends into the piston rod (12) of the piston (10).

14. The control device according to claim 2, wherein: The position sensor (74) is partially enclosed by a piston-side end section of the holding tube.

15. The control device according to claim 4, wherein: The support ring device (102) has a plurality of openings (108) for conveying a pressure medium.

16. A control device according to any one of claims 3 or 4, wherein: A sensor base (84) carrying a sensor rod (78) is prestressed against a radial shoulder (90) in the region of the support ring device (102) by clamping in the holding tube (76).

17. A drive unit for a casting unit having a control device according to any one of the preceding claims 1 to 16.

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