EP0670968A1

EP0670968A1 - Adjusting means for fluid pressure devices

Info

Publication number: EP0670968A1
Application number: EP92904126A
Authority: EP
Inventors: Staffan Hedlund
Original assignee: Rexroth Mecman AB
Current assignee: Rexroth Mecman AB
Priority date: 1991-02-20
Filing date: 1991-12-20
Publication date: 1995-09-13
Anticipated expiration: 2011-12-20
Also published as: SE9100511D0; AU9174491A; DE69129599D1; SE9100511L; SE468176B; DE69129599T2; EP0670968B1; WO1992014934A1

Abstract

The invention concerns a device for setting a piston (11) movement parameter in a piston cylinder aggregate. The setting device comprises two mutually moveable members, namely one reading mark (6) and one indicator member (2), being readable against said reading mark (6). The one of the members is applied to and moveable together with the setting device (1), while the other member is stationary close to the setting device (1). By the two members being mutually adjustable, a distinct initial position for the setting is achieved.

Description

ADJUSTING MEANS FOR FLUID PRESSURE DEVICES

The present invention concerns a means for setting a piston movement parameter in a piston cylinder aggregate, which comprises a setting device being affected by a set screw for fluid flow regulation.

5 \ In previously known fluid pressure devices and particularly in pneumatic piston cylinder aggregates, it is necessary to perform a relatively lengthy procedure to achieve a desired cylinder performance as periodic time, piston speed, accelera-

10 tion etc. In these devices sometimes very time consuming measurings and calculations must be undertaken to estimate e.g. the piston speed. It is therefore a demand for a device which in a simple manner allows the setting of desired piston speed in such an aggregate, allowing easy estimation of the

15 periodic time, acceleration etc. This demand is particularly great in pneumatic piston cylinder aggregates with speed regulation and adjustable stroke end cushioning.

These objects are achieved by a device comprising the features 20 at set forth in claim 1. When in a setting device essentially comprising an indicator member, which is readable against at least one reading mark, one of these members being placed onto the thereto adapted setting device, the two members are mutually adjustable to achieve a distinct initial or zero 25 position for the adjustment and thereafter fixable, possibility of very accurate direct adjustment of a piston movement parameter in a piston cylinder aggregate is achieved, and the effect of the manufacturing tolerance minimized.

30 A considerable advantage with the invention is that simple replaceability with maintained parameter values is allowed. If

^¥ e.g. one of a number of cylinders of a machine brakes down, it is simply replaced with an equal cylinder, the setting means

^* of which is set on the same value as that of the setting means

35 of the broken down cylinder. Hereby very short replacement times with minimized adjustment is achieved. Any smaller deviations due to tolerances are quickly adjusted. By the features of the claims 2-4, the setting possibilities are further simplified. A linear relation between the dis¬ placement of the valve body and the piston speed makes an even distribution of the indicator markings of the indicator member possible, as well as repeatability of the adjustment in turn after turn of the set screw.

By use of any of the further features according to claims 5 or 6, safe and simple indication of the position of the set screw is achieved also after turning of the same more than one turn. Thus great adjustment span is achieved. If a set screw with small pitch is used, the possibilities of achieving accuracy in the adjustment is increased.

The features of claims 7 and 8 define advantageous and simple adjustments of the respective members.

The invention will now be described in greater detail with reference to the appended drawings.

Fig. 1 is a central section through a part of a piston cylinder aggregate with an indicating device according to the invention.

Fig. 2a-2c is an exploded perspective view of the setting device of Fig. 1 with the associated indicator member.

Fig. 3 shows a first embodiment of the invention in a cylinder end plate.

Fig. 4 shows a second embodiment of the invention in a cylinder end plate.

Fig. 1 thus shows an indicator device according to the inven- tion in connection with a cylinder end plate 7. An indicator member comprising an indicator ring 2 is placed onto the outer part of a set screw 1. On its outward surface (not shown) which is directed away from the c^* inder end plate, the indicator ring 2 is provided with indicator markings e.g. in form of numerals (2.1 - 2.5, in Fig. 2a), which are readable against a reading mark in the form of a preferably fixed index (6 in Fig. 3) , e.g. on the cylinder end plate surface, thereby indicating the rotational position of the set screw. A stepped reading ramp 5 is placed onto the cylinder end plate surface radially immediately outside the indicator ring 2. The hight of the steps corresponds to the pitch of the set screw, where- by an indication of the rotational, position of the set screw for an optional number of turns may be obtained by sighting or sensing with a finger.

The piston cylinder aggregate shown in Fig. 1 is a pneumatic cylinder with speed regulation and stroke end cushioning. This device is the subject of the applicant's own application SE-A- 9003578-3. The set screw 1 affects a valve body 12, which co¬ operates with two throttle openings 13, 14 of which the one 13 is arranged in a particular stroke end cushioning channel 21 and the other 14 in the outlet channel 22. Fig. 2a - 2c show the indicator ring 2 in connection with the setting device in an exploaded perspective view, from which it is clear that the throttle openings 13, 14 are essentially rectangular. With this shape a linear relation is obtained between the piston speed and the axial displacement of the valve body 12 and thus the rotational displacement of the set screw 1.

Adjustment for achieving a distinct initial position, here zero position, is obtained as follows: The set screw 1 is screwed into its sleeve 9, until the valve body 12 contacts a stop collar 17, being fixed in the lower part of the sleeve 9. The flow through the throttle openings is now completely closed, and the speed of the piston 11 is zero. The indicator ring 2 is now placed onto the outer part of the set screw, while assuring that the numeral zero appears right in front of the reading index. Finally the indicator ring 2 is fixed, e.g. by tightening a locking screw in a threaded hole adapted for that purpose, in a per se known manner, or by letting an applied glue harden.

Fig. 3 shows a device similar to the one in Fig. 1 whith an indicator member which also in this case comprises an indicator ring 2 being fixed onto the outer part of a set screw 1, in connection with a cylinder end plate 7, in which a valve body 12 being fixedly connected to the set screw l is indicated with dashed lines. On its outward surface the indicator ring 2 is provided with indicator numerals (2.1 -

2.5 in Fig. 2a) from 0 to 4. These numerals here correspond to the speeds 0; 0.1; 0.2; 0.3; 0.4; m/s. The relation between the piston speed and the displacement of a setting device is obtained by simple testing of suitable throttle opening areas. When the relation is linear as above, the indicator numerals are evenly rotationally distributed on the indicator ring. The lines 2.1 - 2.5 are read against the index from the side as well as straight from above.

To be able to read speeds in access of 0.5 m/s, which corresponds to an even turn of the set screw, the scale has been completed with a stepped reading ramp 5, which in this case comprises three steps with grades 0.5; 1.0; l.5 m/s. This value is added to the value of the ring to obtain a true indication of the speed.

Fig. 4 shows a second embodiment of the invention in connec¬ tion with a cylinder end plate 7. Also in this case the indicator member comprises an indicator ring 2 with indicator numerals from 0 - 4 on its outward surface, which are read against an index in the same manner as has been described above. To enable reading of the axial displacement of the set¬ ting device in access of one turn, the indicator ring 2 is further provided with a desired number of annular grooves or similar markings 16 distributed over its axial length, mutual¬ ly spaced apart a distance corresponding to the pitch of the set screw. In the initial position, when the speed of the piston is zero, the setting device is screwed into its inner position, the indicator ring 2 at least with its main part being located within a cylindric recess 15 in the cylinder end plate. When the set screw 1 is then screwed out to partly open the throttle openings of the setting device, the indicator ring 2 will also be displaced axially outwards, whereby the annular grooves 16 or the like markings, will appear in correspondence to one, two or more screw turns out of the recess 15. Reading is simply achieved by sighting against an index applied beside the ring or along the wall of the cylinder end plate or the valve housing.

When the setting device comprises a reading ramp, annular grooves or the like for indicating axial displacement, the adjustment to obtain a distinct initial position may, if desired, be simply completed with axial adjustment in connec¬ tion with the rotational adjustment.

The invention is not limited to the embodiments described above, but only to the scope of the following claims. The set¬ ting device may thus be used in other kinds of piston cylinder aggregates than the shown and does not need to be contained in a cylinder end plate. Nor does the setting device need to comprise a valve body of the kind described in connection with the figures. Also other valve designs may come into question, e.g. needle valves. The indicator member does not necessarily have to be comprised of an indicator ring with outward indicator markings but may e.g. be comprised of a pointer co¬ operating with reading marks in the form of a fixed scale. This may be suitable particularly if the valve is a so called tap valve. The indicator member 2 may be manufactured from a suitable material, e.g. a synthetic material or metal and may be fixed to the set screw in a suitable manner, e.g. by a locking screw radially or axially, by glueing, soldering, stamping, shrinking, jolting or in any other way.

The reading mark(s) may be integral with the reading ramp, which further does not have to bee stepped but may run continuously and possibly with a reading scale applied close to the indicator member. Further the indicator member may be integral with the set screw, the adjustment being achieved by applying/displacing the reading index for calibration against "the zero" of the indicator member. In this case the indicator member may be comprised of a point, a line or the like on the set screw and the reading marks of a scale which is in principle shaped as the indicator ring in Fig. 4a and which is adjustable and then fixable close to the setting device. The reading index may be applied onto the valve housing or the cylinder end plate by casting, punching, painting, stamping or by applying a body by glueing, screwing, soldering or in any other way. In case the reading index as well as the stepped reading ramp are fixed, these members may be made integral with the cylinder end plate/valve housing.

Both of the members may also be adjusted simultaneously, e.g. one axially and the other rotationally.

Finally the invention makes it possible to draw up simply readable tables or diagrams, over cylinder performance as periodic time, acceleration etc as functions of the read value. This considerably increases the competiveness and applicability of products wherein the invention is used.

Claims

C L A I M S

1. Device for setting a piston (11) movement parameter in a piston cylinder aggregate, comprising a setting device for

^* 5 fluid flow regulation which is actuated by a set screw, said setting device comprising two mutually displaceable members, namely at least one reading mark (6) , and one indicator body (2) , which is readable against said reading mark(s) (6) , the one of said members being applied onto and moveable together

10 with the setting device (1) , and the other member being arranged stationary close to the setting device (1) , c h a r a c t e r i z e d in that the two members are mutually adjustable to obtain a distinct initial position for the setting, and fixable after adjustment.

15

2. Device according to claim 1, said set screw (1) being connected to at least one valve body (12) , which in coopera¬ tion with at least one throttle opening (13,14) throttles the outflow of pressure fluid from the piston cylinder aggregate,

20 c h a r a c t e r i z e d in that the throttle opening c*r openings (13,14) are essentially rectangular for obtaining an essentially linear relation between the displacement of the valve body (12) and the p;ston (11) speed.

25 3. Device according to claim 1 or 2, c h a r a c t e r i z¬ e d in that the indicator member (2) is comprised of an indicator ring with indicator markings and that the reading mark is comprised of an index. (6) .

30 4. Device according to claim 3, c h a r a c t e r i z e d in that the indicator markings are applied on the outward sur¬ face of the indicator ring (2) and are comprised of rota¬ tionally distributed indicator numerals (2.1-2.5) .

35 5. Device according to any of the claims 1-4, c h r a c ¬ t e r i z e d in that the reading mark is comprised of a stepped reading ramp, located radially immediately outside the indicator member (2) , the step hight of which corresponding to the pitch of the set screw (1) , the axial displacement of the set screw being readable against the reading ramp.

6. Device according to claim 3 or 4, c h a r a c t e r i z¬ e d in that the indicator ring (2) comprises grooves or markings (16) around its envelope surface, the distance bet¬ ween two adjacent grooves or markings (16) corresponding to the pitch of the set screw (1) , and the axial displacement of the set screw being indicated by said grooves or markings (16) being readable against an index applied beside the ring (2) or a wall of the cylinder end plate (7) or of the valve housing.

7. Device according to any of the claims 1-6, c h a r a c t e r i z e d in that the indicator member (2) is rotationally and/or axially adjustable and thereafter fix¬ able onto the setting device.

8. Device according to any of the claims 1-7, c h a r a c t e r i z e d in that said reading mark(s) (6) is rotationally and/or axially adjustable and thereafter fix¬ able close to the setting device.

9. Device according to any of the claims 1-8, c h a r a c t e r i z e d in that fixation after adjustment is achieved by glueing, screwing, soldering, jolting, stamping shrinking or in any other suitable manner.