JPS62246434A - Connector for assembly tool such as clipper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a coupling device for an assembly tool such as a clipper or the like according to the generic concept of claim 1.

The object of the invention is to adapt a device of the above-mentioned type with regard to the assembly tool and its correct coordination of operation, which is simple and
The object is to have a structure that is stable in use and a compact and unified structure.

(Means for Solving the Problems) The above problems are solved by the configuration described in the characterizing part of claim 1. Advantageous developments are described in the implementation section.

(Effects of the Invention) With such a configuration, the above-mentioned device with high practical value can be obtained. One of these is inter alia the provision of several assembly tools in the central position of the e-bod arm.

The change of the assembly tool takes place in a programmed plunger-specific control sequence, ie without a return stroke to the magazine. Due to the rotationally symmetrical configuration of the turret, only a fraction of a second is lost. Coupling with the robot arm is done quickly, safely and stably. For this purpose, the turret support has an insertion opening for the robot arm. The spatial distribution is also optimal due to the axis of rotation of the turret being located at an acute angle to the plug-in opening. An adjustment motor extends into the turret rotation axis for exerting a rotational movement. Each angular position is specified by a turret locking device. A particularly advantageous coupling of the assembly tool with the load and the lever is achieved in that the assembly tool receptacle, which is brought into the respective working position, is located coaxially with respect to the plug-in opening. During the course of the turret movement, the other assembly tool receptacles also come into corresponding axially coincident positions in this way. A correspondingly advantageous design of the parts forming the relatively rotatable turret allows for a correctly compact construction. Correspondingly,
A low specific weight of the device can also be obtained. In this connection, a preferred configuration is made possible by the insertion opening, the axis of rotation of the turret and the axis of the entire assembly tool receptacle intersecting at one point. This intersection point is reasonably the turret center. The "rear head" is clearly link-shaped to extend the life of the drive and support elements. On the other hand, the visual representation of mutually adjacent receptacles is omitted. An advantageous configuration is provided by a slipping clutch in front of the end face of the turret. This prevents excessive stress. Furthermore, it is advantageous for a code disk for detecting the turret position to be arranged in the region of the rotary joint between the turret support and the turret. The whole cooperates with the program plunger computer. The turret locking device is specifically formed by a pressure-medium-controlled locking pin, which is seated on the turret support and extends beyond the rotary joint into the code disk. Reading of the code desk is carried out by a proximity sensor which cooperates with the iron core and conveys a controlled position in the form of a feedback to the monitoring point. Furthermore, the turret rotation axis occupies a position of 45 degrees with respect to the insertion opening.

This allows a good distribution of the driven and held means onto a relatively small support. The working medium, for example compressed air, is supplied to the area of the plug-in opening via a central pressure medium supply. Free supply lines are thereby omitted. The gripper and tool drive are provided on the turret support and are carried out by at least two plungers operable by pressure medium, located at an acute angle and symmetrically to the insertion opening axis and crosswise on the turret side, and on the rotary joint side thereof. In each rotational position of the turret, the receiving opening is located coaxially with the entry chamber of the turret, which entry chamber communicates with an assembly tool receptacle formed as a bayonet opening. Furthermore, it is proposed according to the invention that the point of intersection of the intersecting plungers is located on an extension of the insertion opening axis. This also results in a similarly calculated drive and operating situation for all assembly tools controlled via the intersection point, since the turret rotation axis crosses the center of the entry chamber. The intersection point is located below the turret rotation axis. The assumed plane of the plunger axis intersects this axis of rotation.

Overall, such a device as a robot/multifunctional hand is optimally distributed spatially and, in particular, a very compact construction is ensured.

A program-controlled tool, such as a gripper, can be moved to the desired position with a loss time of a fraction of a second due to the rotationally symmetrical structure of the turret, with the robot arm insertion opening axis and the assembly tool receptacle. Due to the coaxiality of , a linear force course exists. This can lead to costly damage, especially in the event of a fault with minimal control times. It is therefore reasonable to keep the multifunctional hand of the robot highly sensitive, i.e. to design the device in such a way that its safety in use is increased and in particular it reacts immediately in the event of a failure, such as an unprogrammed load. For this purpose, it is proposed that the turret is guided longitudinally movably on the robot arm in the direction of the insertion opening axis with the formation of a free path.

Use and safety are enhanced due to such a configuration.

The free path located in the direction of direct force application allows a displacement in the event of a shock on the gripper side that differs from the program. This actually takes place brakingly. Sensitive tools are thus protected. The relative movement between the turret and the robot arm is exploited more safely in such a way that the free travel path acting rationally between the turret support and the robot arm is detected electrically. The pulses obtained in this way are used via the control device for immediate shutdown of the device and are interrupted (also for new commands). The configuration for avoiding this Grob-Crash is achieved by taking structural considerations into account, in which the longitudinal guide section is formed by a bush on the turret support side and a shaft guided coaxially therewith. It is carried out by Similarly, in order to achieve a transferable rotational fixation in the event of a globe-crushing action, the invention provides that the shaft has a plurality of longitudinal grooves on its outer surface, the longitudinal grooves cooperating with the radially inwardly directed balls of the bushing. Suggest that you do. Therefore, when the turret is pushed in a direction that increases rotational torque, the ball elastically deflects. The identified position is immediately adjusted accurately again upon removal of the obstruction. Since the longitudinal grooves are provided with the same angular pitch, it is possible to provide the turret support with different angular reference positions. Another advantageous configuration consists in the weight compensation for the turret rotation axis and the turret support, which device is constituted by a piston-cylinder device. For example, with a turret weight of 1.5 Kg, the pneumatic counterpressure will result in, for example, 0.5 kg.
It is provided that a load of 5 kg only needs to be overcome. The turret is therefore also highly sensitive. In particular, the weight compensation device is constructed in that a piston-cylinder arrangement is fixed to the robot arm by means of a piston rod oriented in the direction of the insertion opening axis, and the cylinder is formed in the turret. For the installation of the pneumatic pressure cylinder, it is advantageous if the piston rod intersects the axial duct for supplying the pressure medium for the piston-cylinder arrangement. In this case, the supply is preferably realized and modified via a supply duct in the arm. Regarding the detection of the relative movement between the turret support and the robot arm, this is done in such a way that the free path is detected by the detection device and fed to the control device of the arm. The detection device is preferably designed as an inductive or capacitive travel sensor and is formed by a sensor located in the travel of the piston. In certain cases, an adapted sensor is selected. As already explained above, the gripper and the tool drive are mounted on the turret support and carried out by two plungers operable by a pressure medium, oriented at an acute angle and symmetrically to the insertion opening axis and crossed on the turret side. be done. One plunger controls a gripper, and the plunger, also referred to as a pusher, controls, for example, a pressing body or a pressing finger. The roles of these parts will be explained in detail in the examples. Furthermore, it is advantageous for at least one of the plungers to be equipped with a plunger position recognition device. The plunger position recognition device is formed by the use of an induction coil, which contains a longitudinally movable iron core connected to the plunger.

Such devices operate with high sensitivity. Recognition is 1/10
It is on the order of ms+. The synchronization for obtaining the signal is such that in the event of incomplete execution of the programmed full stroke, the setting function is stopped or a new command is issued.

(Example) (Configuration) A device seated on the arm end of a robot arm having a plurality of joints has a turret support 2 with a turret rotatably provided thereon.

For fixing the arm end 1, a turret support 2 is provided.
has a cylindrical insertion opening 5 in the area of the connecting tube 4 attached to it. Due to the longitudinal slit 6, which takes into account the partial length of the connecting tube, a type of chuck is obtained. In the area of the vertical slit, there are parallel and radially outwardly facing grooves 7.
is inserted, and the jaw can be tightened with a reduced opening width by means of a screw 8 passing through it laterally. The insertion opening is designed as a blind hole.

The turret support 2 is centrally hollow or perforated. A corresponding cylindrical extractor 9 is connected to the adjusting motor 1
Contains 0. Here, electric variable speed motors are considered. According to FIG. 2, the electric variable speed motor has a bushing 11.
Inserted therein, the bushing forms a ring flange 12 at the opposite end, but not quite reaching the bottom of the extraction part 9. The bushing 11 is fixed to the turret 2 by a retaining screw 13 passing through them.

Driven shaft 1 of adjusting motor 10 facing towards turret 3
4 passes through the opening in the center of the bottom of the bush-like bush 11.

The driven shaft 14 is removably coupled to the intermediate shaft 15. The intermediate shaft is connected via a joint 16 to a shaft 17 of a coaxially connected slip clutch 18. slip clutch 18
is located in front of the flat end face 3' of the turret 3 and extends its end into a concentric recess 19 of the turret 3.

The sliding clamp 18 can be adjusted to a desired braking state by means of a grip 20.

According to FIG. 5, the coolet 3, which has a number of receptacles 21 for assembly tools, etc. (not shown), is rotated into the respective working positions by means of an adjusting motor 10 which is inserted into a withdrawal part, which will not be described in detail.

Then each drive is fixed in the proper working position.

In order to maintain the working position of the assembly tool accommodating portion 21 as space-wise as possible, the insertion opening axis x-x has a tip angle α4 with respect to the turret rotation axis y-y (Fig. 1).
Extends 5".

The assembly tool accommodating parts 21 are located at the same angular distance from each other when viewed in the rotational direction. Six such housing sections 21 are provided in the turret 3. The six facets are evident from FIG.

As can be seen in FIG. 2, the extension of the assembly tool receptacle axis zz on the support side likewise forms an acute angle with respect to the turret rotation axis y-y. Here again, the angle β is 45@. Overall, an axial relationship is created in which the extensions of the insertion opening axis y-y, the turret rotation axis X-X, and the assembly tool storage axis z-z intersect at a common point P. This point is actually the center of the robot head 3.

The result is thus that each of the six assembly tool receptacles 21 is located in a coaxial position with respect to the turret rotation axis x--x and thus its extension.

The normal operating position is determined by the assembly tool or by a similarly operated plunger 24,25. The plunger is actuated by a pressure medium and has a shape that passes through the turret support 2 and narrows at an acute angle in the direction of the turret 3. The part of the support 2 which forms the insertion opening 5 is located in the angular interior. Near the apex, the drive and intermediate axes 14.15 intersect. Again, the position chosen at an acute angle to the plug-in opening axis x--x results from FIG. In contrast, the angular planes or inclined positions intersect at an angle α. Since the point P is cut in a plane, the plunger 2 is expanded on the extension of the insertion opening axis x-x.
4.25 is located, but spatially clearly below the horizontally oriented turret rotation axis y--y in FIG.

This area of the intersection point pi is also reached by the back of the assembly tool 50, which is shown in detail in FIGS. 5-8. Taking into account the position of the freely projecting heads of the plungers 24, 25 from the turret support 2, which are guided in each case in the area of the plug-in openings of the support 2, the center of the turret 3 is taken out relatively large, so that There is an entry chamber 26 that does not impede the rotational movement of the turret 3. The entry chamber 26 communicates with a receptacle 21 which is designed as a cylindrical insertion cavity for an assembly tool. A radially directed screw 21'' is used for fixing the foot of the assembly tool inserted therein.

Behind the entry chamber 26 extends a central cylindrical bearing cavity 27 (FIG. 2). A likewise cylindrical connecting tube 28 of the turret support 2 enters the bearing hollow from the free end. A retaining ring 30.3 is arranged in pairs between these and on both sides.
A ball bearing ball 29 held in a fixed position by 1 is located. A retaining ring 30 attached to the turret side end is fixed to the support 2 via a retaining screw 32 screwed into the turret support 2. Other outer retaining ring 31
It is designed as a splash ring. The mating thread of the screw ring is located on a collar part 33 of the turret 3 which grips the ball bearing 29 axially at its circumference.

A code disk 34 is placed on the collar 33 and fixed by means not described in detail.

The code disk 34 extends to the periphery of the turret 3.

The code disk extends within the rotary joint between the turret support 2 and the turret 3. The code disk scans each rotational position of the turret.

For this purpose, the code disk cooperates with a proximity switch 35, which is connected via a conductor 36 to a central control point.

The code disk 34 also cooperates with a turret locking device 37. Its component is the lock pin 38. The locking pin is seated in a spring-loaded manner in the locking recess 39. Such a lock recess 39 is attached to each of the six housing portions 21 distributed and arranged on the pyramid polyhedron. The locking pin 39 on the plunger side follows the control and stone 40 on the side opposite the turret 3. Following this is a coil spring 41 on its free piston wood,
This coil spring has a support on its support side at its free end. The release is effected by supplying a pressure medium which biases the turret-side end of the control piston 40, and the next tool is subsequently moved via the adjusting motor 10 into the selected ready position, i.e. in the direction of the plug-in opening axis x- A coaxial position with respect to x is reached.

The control of both plungers 24,25 is likewise effected by pressure medium. The plungers open to the outside for this purpose and form in each case a control piston 42 at the opposite axial end of the turret 3, which pistons pass through a cylindrical bore in the turret support 2. The biasing there is carried out from the opposite side of the turret throat 3 by means of a pressure medium, while the coil spring 43 acts on the return to the basic position. A compressed air connection 44 is seated behind the piston 42, which connection is controlled and supplied via a ring connector, not shown. The pressure medium supply takes place centrally, ie in the area of the plug opening 5. Here is the beginning of a conduit 46 which exits from this plug-in opening 5 and leads to the main connection 45. The arm itself has an internal supply conduit, which is not shown in detail. The connecting member attached to the turret locking device 37 is represented by 46 and is seated on a bracket 47 connected to the support 2. The entire compressed air valve has a four-way plug for the control electrical lead. In front of and within reach of the plunger end on the turret side, there is a working end 51 of the gripper 52 and an assembly tool 5.
The free end 53 of the pressure finger 54 of 0 is located.

The back of gripper 52 is held open by the force of a spring stored in tool 50. A spring, also not shown, urges the pressure finger 54 toward its home position (FIG. 6).

The device is equipped with a damage guard which effects an immediate stop of the robot hand as soon as the turret 3 detects a large resistance. To convert this into displacement or relative motion,
The turret 3 is guided on the robot arm so that it can be moved longitudinally in the direction of the insertion opening axis x-x of the arm 1 with the formation of a free path, and is therefore guided between the turret support 2 and the robot arm l. There is. For example, body K
(FIG. 7) When the vertically descending assembly tool 50 above is brought into contact without being plunged, the turret 3 is displaced accordingly. This is utilized for electrical path measurement in that the free path is detected by the detection device E and fed to the control device of the robot arm 1. Regarding the detection device, such inductive or capacitive methods may be considered. The embodiment is preferably a sensor 56 located in the path of the piston 55. In this sensor, a piston 55 acting as a probe is adjoined by a piston rod 57 pointing in the direction of displacement of the turret 3, the piston wood being fixed to the receptacle of the robot arm 1 formed by the connecting tube 4. In the embodiment, a threaded connection is targeted. In the work preparation position that is clear from Figure 6,
The end surface of the piston on the turret side extends to the upper edge of the sensor 56. As the displacement increases, the sensor surface changes to the piston 55.
Move to the envelope range.

Bush 58 provides movement guidance. Bushu is on special leave 2
is fixed to the back of the For this purpose, the bushing has a ring flange 58° on the support side for a fixing screw 59. To that extent, the bushing 58 is the turret support 2.
It is a functional component of A shaft 60 is guided in the bush 58 coaxially with respect to the end 1 of the robot arm. The shaft is threadedly connected to a forest-like connecting tube 4 which forms a plug-in opening 5 . The pot bottom of the connecting tube 4 has a central through hole 61 in contrast thereto. A stepped portion of the shaft 60 enters through the through-bore, the outer surface of which is provided with a thread for connection with a nut 62. The piston rod 57 has a thread that extends beyond the stepped part of the shaft 60 and is likewise connected to the fixed nand.

The turret end of the shaft 60 further forms an outwardly directed ring-shaped support shoulder 63. The support shoulder portion 63 is the bush 5
The turret support 2 is suspended by grasping the end face of the turret 8 by the edge. The turret support 2 is radially extended for this purpose;
and forming a recess having an axial depth corresponding to the free path between the free edge of the bush and the underside of the forest.

The extraction section is represented by 2°.

On its jacket surface, the shaft 60 has a plurality of longitudinal grooves 64.

In total there are four such angularly equally distributed longitudinal grooves. One ball 65 in each longitudinal groove 64
is involved. Ball bearings are considered here. These are housed in a radial chamber 65° of the bushing 58. These are under the action of a coil spring 66 which presses against the V-notch-shaped surface of the longitudinal groove 64. The spring force is adjustable due to the rear outer spring counter-bearing with the tool gripping point pointing outwards. The ball 65 is displaced under the forced rotation of the turret support 2 on the axis 60;
As a result, unprogrammed loads on the support 2 cannot lead to destruction. Due to the equal angular spacing of the longitudinal grooves 64, the turret support 2 eliminates the bias of the turret 3 brought into several basic positions, so that during the movement the support 2 is removed with a reduction in the free path F. , the turret support 2 is fitted with a weight compensation device V, since the entire weight consisting of the turret 3, assembly tool 50, etc. does not have to be removed - which could lead, for example, to the destruction of the parts to be assembled. be done.

The device is loaded by a piston-cylinder device, the piston 55 already described being also used for this device. The associated cylinder is represented by 68. Here, a forest-like base body is considered, and the base body is attached to the turret support 2 by a screw connection method. The bottom of the pot is piston rod 5
It has 7 outwardly directed central through holes. The seam area is sealed.

The chamber between the piston pressure and the pot bottom has air as pressure medium. The pressure can be precisely adjusted to adapt to different weights when tooling the turret support 2.

The supply of pressure medium for the piston-cylinder arrangement 56,68 is expediently carried out by using a piston rod 57 as a pipe conductor, the supply conductor being centrally perforated;
It also communicates with the pressure chamber via a horizontal duct (not shown).

In addition to the coarse scanning for the implementation of loading/unloading functions or new work commands, a fine scanning is also considered, ie with respect to the plunger 24 acting as the pusher. The plunger plays the role of indicating defective products. A corresponding plunger position recognition device is designated SE. This device works inductively. For this purpose, the shaft leads the piston 42 to an iron core 69 which projects towards the turret side. This core reaches the central cavity of the induction coil 70. The plunger 24 is stroke-wise specified to its maximum travel according to the program steps present. If this path is not carried out completely, or if it is carried out but with different coordinates of the robot arm than programmed, this means that the pressure lift 54 is defective, for example due to incorrect installation.

(Method of action) The present invention will be explained in detail based on FIGS. 6 to 8.

The turret 3 takes out, for example, six electronic components 71 from a magazine (not shown in detail), corresponding to the number of its assembly tools. Each gripper 52 of the assembly tool 50 holds a corresponding component and guides it into the assembly position according to FIG. 7 during a corresponding program. The electronic component 71 has two parallel legs 72 of equal length, so-called bins. The device descends downwards in the direction of a horizontal plate 73, which has through holes 74 arranged in pairs relative to the insert feet 72 in corresponding locations. The insert foot 72 is inserted into the plate on the order of 1/10 (assembly position ■). When this position is reached, the plunger (plunger 2
4) presses the pressing finger 54 downward with a pressure medium. This takes place in the assembly position ■. The gripper jaws can then be unfolded upon opening of the electronic component 71, but the gripper jaws also serve as guides, as already mentioned, and the pressure gripper 54 controls the remaining vertical movement of the electronic component 71. to act. Precisely positioned legs 75 on the back side of the plate 73 act to retain the insert feet 72 on the back side of the plate to prevent ejection of the electronic component 71 via the roof slope (FIG. 7). position ■)
.

On the other hand, in the standard course of the device, if the failure is recognizable, for example in the already positioned body K (Fig. 7, position 1), the turret support 2 is When moving to free path F), the switch 56 immediately interrupts the assembly function. This does not result in damage to the tool or the turret. Plunger 24 does not enter its function.

The corresponding reject function can be obtained from the motion study according to FIG. There, for example, the gripped electronic component 71 is not ready for assembly, since one of the insert feet 72 has moved out of the parallel part; this state exists in position 2. When the turret 3 descends downwards, the plug-in connection described in position (3) reaches the plate 73 (assembly position V). One of the bayonet legs 72 may shift somewhat, but generally does not come into a position comparable to a glove crush, so that the plunger 24 is programmed downwardly. Via the plunger position V2 recognition device SE on the plate side, the gripper 52 pulls out the out-of-order electronic components 71 again and introduces them into the reject-collecting shaft. Other functions are programmed
52 grips a new gripper 52, or simply the next gripper 52 performs a correct installation. Actuation of the plunger 24 in the programmed thrust stroke is also carried out in reaction in which the turret is moved relative to the robot arm differently than under programmed control (
Free process F), whereby the device is stopped or a new work order is issued.

All novel features described in the description and drawings are essential to the invention, even if not stated in the claims.

[Brief explanation of drawings]

Figure 1 schematically shows the turret seated at the end of the robot arm, Figure 2 is a sectional view taken along the line ■-■ in Figure 1, and Figure 3 is a cross-sectional view taken along the line ■-■ in Figure 2. 4 is a view in the direction of arrow A in FIG. 2; FIG. 5 is a partially cutaway view of the device according to the invention seated on the end of a robot arm; FIG. 1 is a sectional view along the line Vl--Vl, and FIG. 7 is the movement state of the mounting process under the normal course and under the fault caused by the dash-dotted line, when the coarse sensor responds with a free path, and FIG. 8 shows the case of a mounting failure, in which the cause of the failure is detected inductively and converted in the auxiliary drive means. Reference numeral 1 in the figure...Robot arm end 2...Turret support 5...Insertion opening 10...Adjustment morph 21...Assembly tool housing section

Claims (20)

[Claims] (1) In a device for connecting an assembly tool such as a clipper to the end of a robot arm, a turret support (2) having an insertion opening (5) at the end of the robot arm (1) is connected to the insertion opening axis (x-x).
At an acute angle (angle α) to A connecting device for an assembly tool such as a clipper, characterized in that the device is positioned coaxially with respect to the insertion opening axis (x-x). (2) An extension of the insertion opening axis (x-x), the turret rotation axis (y-y), and all assembly tool storage axes (z-
z) intersects at a point (P). (3) The device according to claim 1 or 2, wherein the slip clutch (18) is provided in front of the end face (3^1) of the turret (3). (4) Claims 1 to 3, wherein a code disk (34) for detecting the turret position is arranged in the range of the rotary joint between the turret support (2) and the turret (3). Apparatus according to any one of the preceding paragraphs. (5) The turret locking device (37) is seated in the turret support (2) and the cord desk (34) is mounted on the rotary joint.
Pressure medium operated locking pin (38
5. A device according to claim 1, characterized in that it is formed by: (6) In any one of claims 1 to 5, wherein the turret rotation axis (y-y) is at a position of 45° with respect to the insertion opening axis (x-x). The device described. 7. The device according to claim 1, wherein the central pressure medium supply takes place in the area of the bayonet opening (5). (8) At least two plungers (24, 25) is provided,
The receiving opening on the side of the rotary joint is located coaxially in alignment with the entry chamber (26) of the turret (3) in each rotational position of the turret (3), the entry chamber (26) being formed as an opening. 8. The device according to claim 1, wherein the device is connected to an assembly tool receptacle (21). (9) The intersection (P') of both plungers (25, 26) is located on the insertion opening axis (x-x), as described in any one of claims 1 to 8. equipment. (10) The turret (3) is connected to the insertion opening axis (x-x
2. The device according to claim 1, wherein the device is guided by the robot in a longitudinally movable manner with the formation of a free path (F) in the direction of ). (11) Turret support (2) and robot arm (1)
), and there is a free path between the
An apparatus according to claim 10. (12) The extension guide part is connected to the bush on the turret support side (
11. Device according to claim 10, formed by a shaft (60) coaxially guided therein. (13) The shaft (60) has a plurality of vertical grooves (64) on its outer surface.
, and the vertical groove is inwardly preloaded with a bush (5
8) A device according to any one of claims 1 to 12, cooperating with a ball (65) in. (14) Turret (3) and turret support (2)
A weight compensation device is provided for this device (V
11. Device according to claim 10, characterized in that the piston-cylinder arrangement (55, 68) is formed by a piston-cylinder arrangement (55, 68). (15) The piston (55) of the piston/cylinder device (55, 68) is connected to the robot arm (1
), and the cylinder (68) is formed on the turret support (2). (16) The piston rod (57) passes through the axial duct for the supply of pressure medium for the piston-cylinder arrangement (55, 68).
16. The device according to any one of paragraphs 1 to 15. (17) The device according to any one of claims 10 to 16, wherein the free stroke stroke is detected by the detection device (E) and supplied to the control device of the robot arm. . (18) From claim 10, in which the detection device (E) is designed as an inductive or capacitive path measuring device and is formed by a sensor (56) located in the path of the piston (55). 18. The device according to any one of the preceding clauses. (19) At least one of the plungers (24, 25) (
9. The device according to claim 8, wherein 24) comprises a plunger position recognition device (SE). (20) The plunger position recognition device (SE) is formed by an induction coil (70) in which an iron core (69) coupled to the plunger (24) is longitudinally displaceable. Apparatus described in section.