EP1255046B1 - Fluid pressure cylinder, especially for use in the food industry - Google Patents

Description

The invention relates to a pressure medium cylinder, in particular for use in the Food industry, with a cylinder tube, the end with a cylinder bottom as well a cylinder cover is closed and in which a piston is longitudinally displaceable is housed, from which coaxially a piston rod emanating from the cylinder cover sealed penetrates, wherein the cylinder tube, a sensor for detecting the piston position is provided, which is longitudinally slidably mounted along the Zyhnderrohres.

A generic pressure cylinder comes from the catalog "Know-How in Pneumatics" Rexroth Mecmann GmbH (Print No. 00010 006 01, page 1.235). Of the Pressure medium cylinder consists essentially of a cylinder tube with internal Piston and piston rod, at the end of a cylinder bottom and a cylinder cover over outside along the cylinder tube extending tie rods is attached. The tie rods serve Here also the attachment of a sensor, which for detecting the position of the is used within the cylinder tube extending piston. The so determinable Piston position value is usually a parent control unit for controlling the Actuation of the pressure cylinder provided. Due to the exposed Arrangement of the sensor outside the cylinder tube may be undesirable Dirt accumulations in this area come. Furthermore, the sensor is not here sufficiently protected against external forces, so that it leads to an adjustment of Position of the sensor and thus can lead to a faulty position determination. in the In extreme cases, the sensor as a result of the exposed attachment outside of the cylinder tube also be exposed to destruction.

In order to solve these problems, DE 197 167 36 A1 proposes the sensor to accommodate within a groove-like recess along the cylinder tube and the outwardly open groove-like recess by means of a to the outer contour of the Cylinder barrel adapted cover to close. Although this solution allows one dirt-proof housing of a sensor on a cylinder tube; nevertheless hereby no safe moisture protection can be ensured because moisture through the Area of engagement of the cover on the cylinder tube in the groove-like recess can get. Furthermore, in the case of an extreme external force here Danger that the cover is released from the cylinder tube, so that the groove-like recess completely open with the sensor.

Furthermore, it is generally known, one on the cylinder tube of a pressure cylinder to be provided sensor by a complete encapsulation of dirt and To protect against moisture. However, such encapsulation requires consuming, on the sensor and the cylinder tube constructively matched separate box-like Capsule, which adversely the required number of components for the pressure cylinder increase. Since such capsule means usually on the outer contour of the pressure cylinder protrude, thereby fouling accumulations are favored.

DE 199 25 600 A1 discloses a generic pressure medium cylinder. This is designed as a lightweight hydraulic cylinder and has a cylinder tube in composite construction on. Here are longitudinal through holes are introduced, which for Implementation of tie rods for screwing the cylinder base and the Cylinder covers can be used. It is also possible these through holes to use for the accommodation of sensors. The multipart cylinder tube consists of a inner liner made of a non-magnetic material and a outer jacket tube, wherein in the area between liner and jacket tube doppelT-shaped Plungers are provided to form the individual through holes. The disadvantage of this solution is that the positioning of in the through holes accommodated sensors from the outside is not recognizable, so that their adjustment right elaborate appears: In addition, the assembly of the multipart appears Cylinder tube here because of the many individual component, in particular the many pressure pieces quite expensive.

It is therefore the object of the present invention to provide an easily assembled Pressure medium cylinder to create a reliable dirt and moisture protected Attachment of an externally visible sensor for detecting the piston position guaranteed.

The invention is based on a pressure medium cylinder according to the preamble of Claim 1 solved in conjunction with its characterizing features. The The following dependent claims give advantageous developments of the invention again.

The invention includes the technical teaching that with the piston co-operating cylinder tube of the pressure medium cylinder consists of a metal and of a separate outer tube made of a transparent material, which with at least a closed longitudinal channel within the wall for housing of the sensor.

Thus, the present invention uses a two-part construction of the Cylinder barrel range. First, a cylinder tube is used, which only the task has, with the inner piston of the pressure cylinder co. This cylinder tube is for this purpose form pressure stable and is therefore made of metal. The function of recording sensors is determined by the Cylinder tube, however, not executed. For this there is separate over the cylinder tube pushed transparent outer tube used. The outer tube serves as one of the dirt and moisture protected Accommodating the sensor and therefore does not need to be pressure stable. On the other hand will determined by the outer tube, the outer contour of the pressure medium cylinder, so that this one smooth, level, rancid surface receives, at which no dirt accumulate and can fix. Since the sensor is completely surrounded by the channel, moisture can do not get to the sensor. For sealing are only the frontal To close the outlet openings of the channel. This is preferably done by the Cylinder cover or bottom. By the solution according to the invention, the sensor is also completely protected against contact, so that an unwanted adjustment as a result of a disturbing external force is avoided.

According to a measure improving the invention, however, the sensor can be moved along the Channels are moved for adjustment by along the channel an axial Gearing is formed, which corresponds to the locking means formed on the sensor interacts. The teeth can, for example, by introducing a Tapped hole can be formed in the channel. Preferably, the toothing However, in the manner of an axially along the channel and extending part of the Cross-sectional profile of the channel-forming toothing section made. Of the Gear section may be a separate rack or the like, which in a corresponding groove-like recess along the channel positively inserted and insofar as is herein held. As an alternative to the gearing, it is also conceivable to slidably mounting the sensor along the channel to provide a magnetic tape, the cooperates with magnetic means on the sensor. Thus, the magnetic tape be designed, for example, permanently magnetic and the sensor at least partially Steel or vice versa.

According to a further measure improving the invention, the channel is in Cross-section seen from a sensor section for sliding attachment of the sensor and a parallel cable section for accommodating one of the sensor outgoing sensor cable. Due to the parallel arrangement of both channel sections and their unique function assignment may be an adjustment of the sensor within the channel unhindered by the arrangement of the outgoing sensor cable, as the sensor cable U-shaped running in the channel can be accommodated.

In order to fix the sensor secured against rotation within the sensor section, so that a unique positioning of the sensor relative to the internal piston can be achieved can, is according to a further improvement of the invention measure proposed that the sensor section seen in cross-section one of a circular shape has different profile shape, which with a corresponding profile shape of the sensor cooperates accordingly. Due to the positive connection that occurs in this case simply twisting the sensor within the sensor portion of the channel avoided.

Preferably, cooperating with the toothing of the channel locking means of the Sensors in a simple manner as one end of a sensor arranged on the spring portion trained lug executed. The latch reaches so spring loaded in the Toothing for engagement. The spring portion can, for example, as a spring plate or as Spiral spring or be formed in another suitable manner. Preferably, the Loosen this locking connection a fixed to the locking lug arranged steel flag provided, about what by means of a suitable adjusting magnet from the outside a Return movement of the locking lug against the spring force exerted by the spring portion is possible. The adjusting magnet is to be regarded as a special tool, which alone authorized persons can be made available to an unwanted adjustment of the Sensor position excluded by unauthorized persons.

Advantageously, the cooperating with the piston cylinder tube annular profile and consists of a metal, preferably aluminum. By This measure can be by using a commercially available semi-finished the cylinder tube manufactured in a simple way by cutting to length. By appropriate dimensioning of Wall thickness is the cylinder tube to the design requirements in terms of Pressure stability customizable. In contrast, there is the pushed over the cylinder tube Outer tube preferably made of a transparent material, such as acrylic glass. Thus, optionally located on the sensor LEDs are as well as the position the sensor relative to the channel from the outside recognizable. Furthermore, by the transparent version of the outer tube, the adjustment of the sensor within the channel facilitated.

The outer tube can advantageously with a substantially square outer Cross section are provided, wherein the channel to accommodate the sensor in this case along of the opposite the inner circular cross-section of the outer tube reinforced Wandungsseckbereichs runs. The remaining Wandungseckbereiche can for Arrangement of further sensors in corresponding channels or for through holes for Accommodation of tie rods are used. The tie rods are here to attach the Cylinder cover and cylinder bottom provided on the cylinder tube. By such Use of the wall corner areas can be the outer dimensions of the Pressure medium cylinder are kept minimal.

Further measures improving the invention will be described below together with the Description of a preferred embodiment of the invention with reference to the figures shown in more detail.

Fig. 1

eine schematische Explosionsdarstellung von Gehäuseteilen eines erfindungsgemäß ausgebildeten Druckmittelzylinders,

Fig. 2

einen Querschnitt durch den Bereich des Zylinderrohres des Druckmittelzylinders,

Fig. 3

einen Längsschnitt als Detailansicht im Schnitt A-A gemäß Fig. 2, und

Fig. 4

eine perspektivische Ansicht eines Sensors zur Detektion der Kolbenstellung des Druckmittelzylinders.

It shows.

Fig. 1

a schematic exploded view of housing parts of an inventively designed pressure cylinder,

Fig. 2

a cross section through the region of the cylinder tube of the pressure cylinder,

Fig. 3

a longitudinal section as a detail view in section AA of FIG. 2, and

Fig. 4

a perspective view of a sensor for detecting the piston position of the pressure cylinder.

The pressure medium cylinder consists of FIG. 1 essentially of a circular ring profiled cylinder tube 1 made of aluminum, which is made of a transparent plastic existing outer tube 2 is surrounded. Within the cylinder tube 1 is a - not here further shown - housed piston with piston rod longitudinally displaceable. The Piston rod is sealed by a arranged on one end of the cylinder tube 1 Cylinder cover 3 out. The opposite end of the cylinder tube 1 is provided with a Cylinder bottom 4 closed. The cylinder cover 3 and the cylinder bottom 4 are on Cylinder tube 1 by means of two tie rods 5a and 5b attached. The tie rods 5a and 5b are as Threaded rods formed, which fastening on the end screwed nuts allow the cylinder cover 3 and the cylinder bottom 4 on the cylinder tube 1. The Tie rods 5a and 5b in this case extend along the cylinder tube 1 within associated, arranged in the outer tube 2 through holes 6a and 6b.

Parallel to the two through holes 6a and 6b for the tie rods 5a and 5b are in Outer tube two channels 7a and 7b for accommodating sensors 8 are provided. This here Exemplary dargestclltc sensor 8 is used to detect the piston position of the Pressure medium cylinder A sensor cable 9 leaving the sensor 8 is replaced by the Cylinder cover 3 or the cylinder bottom 4 or the wall of the outer tube 2 to the outside led to the connection to a - not shown here - control unit enable. The outer tube 2 has a square outer cross section, the adapted accordingly to the shape of the cylinder cover and the cylinder base is to give the pressure fluid cylinder a smooth outer contour.

According to Fig. 2, the channel 7 for accommodating the sensor 8 has a two-part profile shape on, on the one hand from a sensor section 10 for displaceable placement of the Sensor 8 and the other from a parallel thereto extending cable section 11 to Housing the sensor 8 outgoing sensor cable 9 consists. The sensor section 10 is seen in cross-section profiled so that due to an appropriately trained Profiling the sensor 8 a rotation of the sensor 8 within the Sensor section 10 is enabled. The sensor 8 is within the sensor portion 10 of Channel 7 via a rack 12 fixable, which in a corresponding groove-like Recess along the sensor portion 10 is inserted.

The fixation of the sensor 8 within the channel 7 takes place according to FIG. 3 via the sensor 8 trained locking means, which with the teeth of the running along the channel 7 Rack 12 interact. After releasing the resilient locking means is an adjustment the sensor 8 within the channel 7 possible to assemble or adjust.

Referring to FIG. 4, this is done via a sensor 8 formed on the Spring section 13, which has a locking lug 14 at the end. Neighboring and stationary to Latch 14 run the latching means in a steel flag 15. The locking means consist in This embodiment of spring steel. The steel flag 15 serves a - not shown here - outer Verstellmagneten as a kind of magnet armature to a Return movement of the locking lug 14 from the toothing for the purpose of adjusting the Allow sensors 8 within the channel.

The invention is not limited to the preferred one described above Embodiment. On the contrary, it is also possible to make modifications to this, which despite another constructive embodiment also of the scope of the following Claims can make use of. In particular, the invention is not limited to the Fixation of the sensor within the closed channel by with a toothing cooperating locking means. These are also suitable by others, a shift the sensor enabling fixer replaceable.

LIST OF REFERENCE NUMBERS

1

cylinder tube

2

outer tube

3

cylinder cover

4

cylinder base

5

tie rods

6

Through Hole

7

channel

8th

sensor

9

sensor cable

10

sensor section

11

cable section

12

rack

13

spring section

14

locking lug

15

steel flags

Claims (14)

1. A pressure cylinder, in particular for use in the food industry, with a cylinder tube (1), which is closed off by a cylinder bottom (4) and a cylinder top (3) and in which a piston is slidably arranged in a longitudinal direction, from which a piston rod extends coaxially, which passes through the cylinder top (3) in a sealed manner, wherein at the cylinder tube (1), a sensor (8) attached to be slidable along the cylinder tube (1) is provided for detecting the piston position, wherein the cylinder tube (1) cooperating with the piston is surrounded by a separate outer tube (2) which is equipped with at least one closed channel (7) extending within the wall in a longitudinal direction to accommodate the sensor (8),
   characterised in that the cylinder tube (1) cooperating with the piston is of a metal while the outer tube (2) slipped over the cylinder tube (1) is of a transparent material to make it possible for the position of the sensor (8) to be readily seen relative to the channel (7).
2. The pressure cylinder according to claim 1,
   characterised in that the outer tube (2) slipped over the cylinder tube (1) is of acrylic glass.
3. The pressure cylinder according to claim 1,
   characterised in that the cylinder tube (1) cooperating with the piston has a circular profile.
4. The pressure cylinder according to claim 1,
   characterised in that for displaceably attaching the sensor (8) along the channel (7) an axial toothing is formed which cooperates with engagement means formed on the sensor (8).
5. The pressure cylinder according to claim 4,
   characterised in that the toothing is formed by introducing a threaded bore in the channel (7).
6. The pressure cylinder according to claim 4,
   characterised in that the toothing is in the manner of a toothing section extending axially along the channel (7) and forms part of the cross-sectional profile of the channel (7).
7. The pressure cylinder according to claim 6,
   characterised in that the toothing section is a separate rack (12) which is inserted into a corresponding groove-like recess along the channel (7) in a positive engagement.
8. The pressure cylinder according to claim 1,
   characterised in that, for the displaceable attachment of the sensor (8) along the channel (7), a magnetic strip extends which cooperates with magnetic means on the sensor (8).
9. The pressure cylinder according to claim 1,
   characterised in that the channel (7), as seen in cross section, consists of a sensor section (10) for the displaceable attachment of the sensor (8) in a parallel cable section (11) to accommodate a sensor cable (9) coupled to the sensor (8).
10. The pressure cylinder according to claim 9,
    characterised in that the sensor section (10), as seen in cross section, has a profile form departing from the circular, which cooperates with a corresponding profile form of the sensor (8) in order to avoid rotating the sensor (8) within the sensor section (10) of the channel (7).
11. The pressure cylinder according to claim 4,
    characterised in that the engagement means consist of an engagement protrusion (14) formed on an end face of a spring section (13) on said sensor (8), which snaps into engagement with said toothing.
12. The pressure cylinder according to claim 11,
    characterised in that to release said snap engagement, a steel tab (15) fixed with respect to the area of the engagement protrusion (14) is arranged, wherein said steel tab (15) is used to move said engagement protrusion (14) from the outside, by means of an adjustment magnet, back against the spring force applied by said spring section (13).
13. The pressure cylinder according to claim 1,
    characterised in that the outer tube (2) has an essentially square cross section, wherein said channel (7) extends along the wall corner portion of the outer tube (2), which is thicker than the circular cross section.
14. The pressure cylinder according to claim 11,
    characterised in that precisely two opposite channels (7a, 7b) are provided to accommodate sensors (8), and two through bores (6a, 6b) are provided, also arranged opposite each other in the remaining two wall corner portions, to accommodate tie rods (5a, 5b) which attach the cylinder top (3) and the cylinder bottom (4) on said cylinder tube (1).

Images