US3435683A - Manometer - Google Patents

Description

April 1969 B. SPEIDEL ETAL 3,435,683

MANOMETER Filed April 4, 1967 Sheet of 2 B. SPEIDEL ET AL April 1, 1969 MANOME'I'ER Filed April 4, 1967 Sheet 2 f 2 United States Patent O 3,435,683 MANOMETER Blasius Speidel, 244 Hochmeisterstrasse, and Paul Keller, 288 Weilbachstrasse, both of 7455 Jungingen, Germany Filed Apr. 4, 1967, Ser. No. 628,347 Claims priority, application Germany, Apr. 7, 1966, S 103,110 Int. Cl. G01l 7/06 U.S. Cl. 73-410 2 Claims ABSTRACT OF THE DISCLOSURE The improvement in a manometer for preventing a permanent deformation of the main well of the pressure cell by the end of the transmitting lever digging into this wall when the internal pressure in the cell exceeds a certain admissible value, The improvement consists in the provision of at least one fixed stop member which limits the further movement of the cell wall when the pointer of the instrument reaches the highest admissible value on the dial.

Background of the invention The present invention relates to improvements in a manometer, particularly a sphygmomanometer, which essentially consists of a housing with a cup-shaped lower part, a dial ring with a graduated dial on this lower part, a pressure cell mounted within the lower part, a pointer adapted to sweep over the dial, and means for transmitting the movements of a wall of the pressure cell to the pointer which include a `bridge extending over the mentioned wall, a shaft which is rotatably mounted on the bridge and extends parallel to the wall of the pressure cell, and a transmitting lever which is secured to the shaft and projects substantially radially therefrom and engages upon the wall of the pressure cell.

The conventional manometers of this type are designed so that one end of the transmitting lever engages upon the main surface of the pressure cell which usually consists of a cap which is tightly secured along its outer edge to a rigid base plate. The front surface of this cap forms the movable wall or main surface of the pressure cell and is adapted to be temporarily deformed under the pressure at the inside of the cell.

The transmitting lever which engages with one end upon the main surface of the pressure cell then transmits the movements of this surface Via the shaft carrying this lever and via a control lever on this shaft to the elements which are mounted between a lower and an upper plate which together form the bridge, that is, to a segmental rack which is secured to one end of a lever which is pivotable about an axis extending vertically to the bridge, and then from this segmental rack to a pinion which meshes with the rack and is mounted on the shaft Which carries the pointer.

If a manometer of this conventional type is acted upon by an excessive pressure, the lever which carries the seg mental rack will hit against, and will thus be stopped by one of the studs which carry the upper plate of the bridge. consequently, even though the main surface of the pressure cell still presses against it, the transmitting lever can also no longer move and its end will, therefore, press into the main cell surface and permanently deform the same by leaving a substantially point-like depression therein. Aside from this, the transmitting lever as well as some of the other transmitting parts may also be deformed. In any event, the manometer will then no longer indicate correctly the pressure which is to be measured.

3,435,683 Patented Apr. l, 1969 Summary of the invention It is an object of the present invention to provide a manometer of the type as first described which is designed so as to overcome the above-mentioned disadvantages. This object is attained according to the invention by an improved construction of the transmitting elements of the manometer. This improvement consists in providing the bridge with a stop member which has at least one edge surface facing the main wall of the pressure cell and spaced from the latter at such a distance that the cell wall engages -upon this edge surface when the pointer has completed its largest admissible stroke. The stop member is preferably provided with a cutout which is adapted to receive the transmitting lever 'during the movement of this lever and the main cell wall from their neutral position to the position in which the cell wall engages upon the stop member.

More specifically, the stop member may be designed so that its edge forms a narrow elongated surface which may be produced, for example, by making a pair of cuts in the bridge so as to form an intermediate tab which is then bent at a right angle to the bridge in the direction toward the pressure cell. This edge surface should be located at or closely adjacent to the center of the main cell surface.

instead of such a single stop member in the form of a riblike tab, it is also possible according to a modification of the invention to provide a pair of stop members. These stop members project from the bridge and each of them has a surface 'facing the main cell wall. These two surfaces are disposed within the same plane and symrnetrically to the shaft of the transmitting lever and are spaced from each other and from the cell wall so that the latter will engage upon the stop surfaces When the pointer has carried out its largest admissible stroke. One of the stop members is preferably provided with a cutout in the edge facing the other stop member. This cutout is adapted to receive the transmitting lever during the movement from the neural position of this lever and of the cell wall to the position in which the cell wall engages upon the stop members.

The *features and advantages of the present invention will become further apparent from the following detailed description thereof which is to be read With reference to the accompanying drawings, in which- FIGURE 1 shows a front View of the manometer;

FIGURE 2 shows a central cross section of the manometer housing;

FIGURES 3 and 4 respectively show a front view and a side view of the pressure cell and the transmitting elements of the manometer;

FIGURES 5 and 6 show diagrammatically partial cross Sections which are taken along the line III-III of FIG- URE 3 and illustrate a linear stop member for the main cell wall in two different positions of the parts;

FIGURE 7 shows a modification of the stop member as seen in the direction toward the lower side of the bridge; while FIGURE 8 shows a cross section which is taken along the line VIII-VIII of FIGURE 7.

The manometer according to the invention as illustrated in FIGURES l to 6 comprises a housing which consists of a cup-shaped lower part 31 of metal or plastic on which a dial ring 32 is rotatably mounted. This dial ring 32 -has a fiange 34 which engages into the lower part 31 and is prevented from falling oif the latter by being provided on its outer surface with a small peripheral projection 33 which engages into a corresponding annular groove in the lower part 31. The dial ring 32 may be mounted on the lower part 31 of the housing by being pressed thereon until the projection 33 snaps into the annular groove, and the dial ring may thereafter be turned relative to the lower part 31 for adjusting it to the proper position. The dial ring 32 is provided with a dial 35 with a suitable gradnated scale and above the latter with a cover glass 36. For manipulating it more easily, the dial ring 32 is knurled on its outer peripheral surface.

The manometer housing 31, 32 contains a circular metallic pressure cell 1 which consists of a rigid base plate 2 which is provided with a nipple 4, and of a cap 3 of a smaller diameter which is tightly secured along its circular outer edge to base plate 2 and provided in the usual manner with a corrugated deformable main wall surface 3'. Near its outer edge, base plate 2 carries studs 5 Which are riveted thereto at one end and have a tapped *bore in their other end on which a plate 7 is secured by screws 6 so as to be spaced at a uniform distance from base plate 2. On its side facing the main cell-wall surface 3', plate 7 carries small bearing brackets 8 in which a shaft 9 is rotatably mounted so as to extend parallel to the pressure cell 1. To this shaft 9 a curved transmitting lever 10 is secured which extends substantially radially therefrom and engages with its curved part upon the main cellwall surface 3'.

By means of further spacing Studs 5 and screws 6, plate 7 carries another plate 12. The two plates 7 and 12 together with their studs 5 will hereafter be called a bridge. On this bridge a lever 14 is mounted so as to be rotatable about an axis 13 which extends vertically to plates 7 and 12. The free end of this lever 14 carries a segmental rack 15 which meshes with a pinion 16. Lever 14 is actuated by a control arm 11 which engages upon one side of this lever and is secured to and projects radially from shaft 9 and through an aperture 23 in plate 7.

Pinion 16 is secured to an indicator shaft 17 which is rotatably mounted in the two plates 7 and 12 and carries a pointer 18. For resetting the pointer 18 to its zero position, one end of a fine spirally-coiled spring 19 which is concentric to the indicator shaft 17 is secured to the indicator shaft, while the other end of this spring is secured to a stud 5.

Insofar as it has been above described, the manometer is of a known construction.

The improvement in such a manometer consists in accordance with the invention in providing the surface of bridge 7, 12 facing the main cell-wall surface 3' with an at least linear stop surface upon which the main cell-wall surface 3' engages when the air pressure at the inside of the pressure cell 1 reaches an admissible maximum value. This maximum value is therefore dependent upon the distance between the at least linear stop surface and the main cell-wall surface 3'. If the distance of the movement of this surface 3' or the extent to which it may bulge outwardly is limited, this means that the distance of the movement of the transmitting lever 10 will also be limited in accordance with the particular transmission ratio.

For eifecting such a limitation, the invention provides according to FIGURES 1 to 6 that adjacent to the center of the main cell-wall surface 3' one edge of plate 7 is provided with two cuts, and that the tab 7' which is formed between these cuts is bent over toward the main cell-wall surface 3' so as to extend at a right angle thereto and to form a rib which projects from plate 7. This rib 7' is provided with a cutout 7" into which the transmitting lever 10 engages.

The edge of rib 7' which faces the main cell-wall surface 3' forms a linear stop for limiting the movement of this surface. When the main cell-wall surface 3' engages upon the edge of rib 7' and the transmitting lever 10 has passed into the cutout 7" as indicated in FIGURE 6, and therefore cannot be further moved by the surface 3', there is no possibility that this lever or any other parts of the transmitting unit might be permanently deformed. The pressure from the main cell-wall surface 3' is then distributed to an area which is defined by the opposite edge of rib 7'. consequently, the specific counter-pressure acting upon the main cell-wall surface 3' will always be lower than the counter-pressure which is exerted under otherwise equal conditions upon this surface 3' by the transmitting lever 10 of a manometer of the Conventional type in the event that the movement of this lever or any other transmitting elements is blocked.

FIGURES 7 and 8 illustrate a modification of the invention in which the stop for the main cell-wall surface 3' is formed by the surfaces of two stop members 20 which are disposed within the same plane symmetrically to shaft 9 at a suitable distance from the main cell-wall surface 3'. The end of the transmitting lever 10 may enter a cutout 22 which is provided in one of the stop members 20. FIGURE 7 shows two narrow elongated stop members 20 which may consist, for example, of plastic and are located at both sides of shaft 9 and secured to plate 7 by screws 21. In every other respect, the form of construction and principle of operation of the embodiment of the invention as shown in FIGURES 7 and 8 is the same as that described with reference to FIGURES 1 to 6.

Since the engagement of the main cell-wall surface 3' with the two stop members 20 is in this case not linear but by a relatively large surface contact, the specific pressure Which is exerted by the surface 3' against the stop members 20 is still lower than in the embodiment of the invention as shown in FIGURES 1 to 4.

Although our invention has been illustrated and described with reference to the preferred embodiments thereof, we wish to have it understood that it is in no way limited to the details of such em'bodiments but is capable of numerous modifications.

We claim:

1. In a manometer comprising a housing having a cup-shaped lower part, a dial ring mounted on said lower part and having a dial, a pressure cell mounted within said lower part, a pointer adapted to sweep over said dial, and means for transmitting the movements of a wall of said pressure cell to said pointer, said means including a bridge traversing said wall, a shaft rotatably mounted on said bridge and extending parallel to said wall, and a transmitting lever secured to and projecting substantially radially from said shaft and engaging upon said wall, the improvement comprising at least a pair of stop members mounted on said bridge and each having a surface facing said wall, said surfaces being disposed within the same plane and at a distance from each other and symmetrically to said shaft and at such a distance from said wall that said wall will engage upon said surfaces when said pointer has completed its largest admissible stroke, one of said stop members having a cutout in the edge facing the other stop member, said cutout being adapted to receive said transmitting lever during the movement of said lever from the neutral position of said lever and said wall to the position in which said Wall engages upon said stop members.

2. In a manometer comprising a housing having a cup-shaped lower part, a dial ring mounted on said lower part and having a dial, a pressure cell mounted within said lower part, a pointer adapted to sweep over said dial, and means for transmitting the movements of a wall of said pressure cell to said pointer, said means including a bridge traversing said wall, a shaft rotatably mounted on said bridge and extending parallel to said wall, and a transmitting lever secured to and projecting substantially radially from said shaft and engaging upon said wall, the improvement comprising one stop member mounted on said bridge, said stop member having an elongated edge surface facing said wall and spaced at such a distance therefrom that said wall will engage upon said edge surface when said pointer has completed its largest admissible stroke, said stop member having a cutout starting from said edge surface and adapted to receive said transmitting lever during the movement of said lever from the neutral position of said lever and said wall to the position in which said wall engages upon said stop member, said edge surface being located substantially parallel to a diameter of said pressure-cell wall and extending parallel to said shaft, and said cutout facing substantially the center of said pressure-cell wall, in order to provide a line engagement between said edge surface and said Wall.

References Cited UNITED STATES PATENTS l,848,053 3/1932 Bacon 73-410 6/1948 Davis 73 410 3/1953 Eksten 73-410 U.S. Cl. X.R.

Images