US3742609A

US3742609A - Measuring instrument

Info

Publication number: US3742609A
Application number: US00140454A
Authority: US
Inventors: J Jeannet; J Leuba
Original assignee: Tesa SARL
Current assignee: Tesa SARL
Priority date: 1970-05-20
Filing date: 1971-05-05
Publication date: 1973-07-03
Anticipated expiration: 1990-07-03
Also published as: AT300392B; ES202413U; GB1333668A; BR7102577D0; ES202413Y; NL7106804A; CH510865A; FR2089644A5; DE2119504A1

Abstract

A measuring instrument comprising a pole or body portion including a rack recessed in a slot in one edge of the body. The rack is protected by a flexible strip secured at one end to a tensioning spring. A slide block is manually moved along the pole and includes a pinion which meshes with the rack. The flexible strip is diverted around the pinion by two guide pins.

Description

United States Patent [191 Jeannet et al.

[ MEASURING INSTRUMENT [75] Inventors: Jean-PierreJeannet, Lausanne;

Jenn-Pierre Leuba, Renens, both of Switzerland [73] Assignee: Tesa S.A., Renens, Switzerland.

[22] Filed: May 5, 1971 [2]] Appl. No.: 140,454

301 Foreign Application PrlorityData May 20, 1970 Switzerland 7436/70 [52] US. Cl. 33/143 M, 33/125 M, 308/35 [51] Int. Cl. G0lb 5/00 [58] Field of Search 33/143 I, 143 .I,

33/143 K, 143 R, 143 M, 147 T, 147 R, 125 R; 308/35 [56] References Cited UNITED STATES PATENTS 6/1969 Scholl 33/125 M [451 July 3,1973

FOREIGN PATENTS OR APPLICATIONS 466,588 I] 1969 Switzerland 33/ [47 T 1,101,096 3/1961 Germany 308/35 Primary Examiner-William D. Martin, Jr. Attorney-James M. Heilman [5 7] ABSTRACT A measuring instrument comprising a pole or body portion including a rack recessed in a slot in one edge of the body. The rack is protected by a flexible strip secured at one end to a tensioning spring. A slide block is manually moved along the pole and includes a pinion which meshes with the rack. The flexible strip is diverted around the pinion by two guide pins.

14 Cliiims, 2 Drawing Figures Pmmnzmms I915 3.742.609

u x a- JEAN'PIERRE JEANNET JEAN-PIERRE LEUBA INVENTORS AT rORNEY MEASURING INSTRUMENT There are a certain number of measuring instruments such as for example sliding calipers or marking gauges wherein a pole carries a rack which measures with one or more gears controlling the displacements of indicating means, said gears as well as said indicating means being fixed to a slide block which is movable along said pole. These instruments generally permit a very accurate reading, however, this reading is dependent on the good state of the gearing of the rack which can be damaged by shocks or foreign bodies which may be introduced between the teeth and those of the guide gears of the indicating means.

An attempt has been made to eliminate this danger by covering the rack with a rigid profile fixed to the slide block but the protection thus obtained is only relatively effective because as the profile moves with the slide block the gearing of the rack is only completely protected at one of the end positions of the slide block; whereas at all other positions of said slide block the rack remains more or less uncovered. An attempt has also been made to use a flexible strip covering the rack, said strip leaving the slide block to which it is fixed passing along the rack and returning to the slide block via the inside of the pole thus forming a sort of movable loop with the slide block, and whereof the ends are fixed to the slide block whilst its central portion moves within the pole. The protection of the rack thus obtained is good but the system is relatively complicated and costly because it necessitates the provision of a return mechanism in the pole for the retum'of the strip, said return being obtained either by machining the pole or by making the said pole in several portions which are I assembled in sandwich form. Moreover it is necessary for the strip to slide absolutely freely within the pole and its guidance must be very carefully effected if no jamming is to take place. Finally it is necessary to provide an attachment system for the strip to the slide block permitting the strip to be restretched from time to time because if the strip shrinks or expands a little protection is no longer assured, and there is a danger of the strip folding and jamming in the pole.

With the object of removing these disadvantages the present invention has for its object a measuring instrument comprising a pole with a rack meshing with at least one gear controlling the displacements of indicating means, the gearing and indicating means being fixed to a slide block movable along the pole, and a flexible protective strip covering the rack characterized in that the protective strip is fixed to the pole on either side of the ends of the rack and slides in the slide block where it is separate from the rack close to the gear.

The accompanying drawings show as an example one embodiment of the object of the invention.

FIG. 1 is a profile view partially'in cross section;

FIG. 2 is a section along the lines A-Aof FIG. 1.

The measuring instrument shown is a sliding caliper comprising a pole 1 having at one of its ends measuring tips 2. The body of the pole 1 is hollowed out along its lower face by means of a groove 3 wherein is located, in known manner, a rack 4.

On pole 1 is engaged a movable slide block 5 carrying measuring tips 6 and comprising indicating means 7 which are driven by a series of gears 8 meshing with the rack 4. The control of the indicating means 7 can be effected in any appropriate known manner and is not described.

in groove 3 is placed a flexible strip 9 whereof one end has a loop 10 engaged on a pin .11 fixed in one of the endsof groove 3. The otherend of strip 9 is fixed to a tension spring 12 fixed to a pin 13 fixed in the other end of the groove 3. Strip 9 extends over the gearing of rack 4 and its surface opposite to that which is applied to the gearing of rack 4 is located in the plane of the lower face of pole l.

Strip 9 passes into slide block 5 and the

shoulders

14 and 15, which support the latter against the lower face of pole 1, maintain said strip tightly applied against the gearing of rack 4 in the groove 3 of pole 1. Within slide block 5 between

support shoulders

14 and 15 strip 9 passes over two guide pins 16 and 17 arranged close to the gears 8 and intended to separate the strip 9 from rack 4 to give free passage to said gears 8.

Thus on moving slide block 5 along pole 1 the latter slides along the lower face of the pole and consequently along the strip whilst maintaining the latter uniformly applied against the rack except between

shoulders

14 and 15 where said strip is deflected to permit the engagement of the train of gears 8 with the rack 4. The tension spring 12 compensates automatically any variation in the length of the strip and prevents any deformation or folding which could take place accidentally during the displacement of the slide block. The rack is therefore effectively protected by the strip 9 whatever the position of the slide block and the only part of the rack which is not covered by the strip is always inside the slide block and therefore there is no danger of the rack undergoing shocks or damage due to the penetration of dust or foreign bodies between'its gearing and that of the train of gears.

The sliding caliper described is of simple and ecconomic construction because it does not require delicate machining or any special design of the pole or slide block. As the strip is fixed and only runs along the pole surface it is relatively short and there is no need to provide return mechanisms. The attachment of the strip to the ends of the groove containing the rack is simple and its guidance in the slide block only causes slightly deformations which can cause neither fatigue nor rupture. I

The strip 9 can be of metal, for example steel, or of. a non metallic material, such as for example a plastics material.

The guide pins 16 and 17 can be fixed or rotary and it is possible to replace them by any other adequate combination of pins or rollers arranged on the same side or on both sides of the strip or even by a support ramp of appropriate shape.

It is possible to fix the two ends of the strip by means of springs. In addition the springs or springs can be replaced by any other elastic attachment means or be eliminated altogether whereby the strip is then preferably but not necessarily elastic. It is also possible for the two ends of the strip to be attached in a non-elastic manner providing at least one elastic tensioning means thereof which could for example be located in the slide block. v Y

Although the described example is a sliding caliper it is obvious that the measuring instrument according to the invention could also be a marking gauge or any other instrument comprising of a rack engaging with one or more gears controlling the displacements of indicating means, the gears and indicating means being fixed to a slide block which is movable along the pole.

What we claim is:

l. A measuring instrument comprising; a pole for slidably supporting a slide block, said pole formed with a longitudinal slot; a rack positioned within the slot and secured thereto; at least one pinion rotatably mounted on the slide block and meshing with the rack; a flexible protective strip also positioned within the slot with its ends secured to the pole and covering the rack on both sides of the slide block; and deflection means inside the block for moving the flexible strip away from the rack and around the pinion when the slide block is moved along the pole.

2. An instrument according to claim 1 wherein said pole has a rectangular cross section and said slot is formed in one of the edges thereof.

3. An instrument according to claim 1 wherein the flexible strip is secured to the pole on both sides of the ends of the rack.

4. An instrument according to claim 1 wherein said flexible strip is secured to the pole at one end and is connected to a resilient spring at the other end.

5. An instrument according to claim 1 wherein said deflection means inside the block include two support shoulders slidably engaging the edge of the pole adjoining the slot, said shoulders forming a deflection means for the flexible strip.

6. An instrument according to claim 1 wherein at least one guide pin is positioned within the slide block adjacent to the pinion for deflecting the flexible strip around the pinion.

7. An instrument according to claim-1 wherein the deflection of said flexible strip away from the rack occurs only within the slide block thereby providing a protective covering over the rack at all times.

8. An instrument according to claim 1 wherein said resilient means is coupled between one end of the flexible strip and the pole to provide an elastic tension action for automatically compensating for any variation in the length of the strip.

9. A measuring instrument comprising a pole for slidably supporting a slide block, said pole formed with a longitudinal slot; a rack positioned within the slot and secured thereto; at least one pinion rotatably mounted on the slide block and meshing with the rack; a flexible protective strip also positioned within the slot with its ends secured to the pole on both sides of the ends of the rack and covering the rack on both sides of the slide block; resilient means on said strip to subject same to an elastic tension action to automatically compensate for any variation in the length thereof; and deflection means inside the block for moving the strip away from the rack and around the pinion when the slide block is moved along the pole.

10. An instrument according to claim 9 wherein said strip is secured to the pole at one end and is connected to a resilient spring at the other end.

11. An instrument according to claim 9 wherein the strip is connected to a resilient spring at both ends thereof.

12. An instrument according to claim 9 wherein the strip is elastic.

13. An instrument according to claim 9 wherein the strip is subjected to the action of at least one elastic stretching means.

14. An instrument according to claim 13 wherein the elastic stretching means is located in the slide block.

Claims

1. A measuring instrument comprising; a pole for slidably supporting a slide block, said pole formed with a Longitudinal slot; a rack positioned within the slot and secured thereto; at least one pinion rotatably mounted on the slide block and meshing with the rack; a flexible protective strip also positioned within the slot with its ends secured to the pole and covering the rack on both sides of the slide block; and deflection means inside the block for moving the flexible strip away from the rack and around the pinion when the slide block is moved along the pole.

7. An instrument according to claim 1 wherein the deflection of said flexible strip away from the rack occurs only within the slide block thereby providing a protective covering over the rack at all times.

12. An instrument according to claim 9 wherein the strip is elastic.