DE1206174B - Piston for a precision pressure measuring device designed as a piston balance - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

GOIl

German class: 42 k-10/01

Number:
File number:
Registration date:
Display day:

M58797IXb / 42k
November 6, 1963
December 2, 1965

The known precision pressure measuring devices designed as piston scales cause difficulties when detecting low pressures, for example between zero and 2 kp / cm ² , especially when it comes to achieving accuracies of 1 mm of mercury. In spite of the low-friction mounting of the weight rod in ball bearings, a residual friction remains, so that the weight rod with piston set in rotation comes to a standstill before it is possible to set the measuring marks with a vernier.

It is known that pistons with a larger cross-sectional area can be used to measure low pressures. The weights to be applied will then be greater at the same pressure in the ratio of the piston areas, for example five times as much ^{at 5 instead of 1 cm 2.} This also increases the centrifugal mass that maintains the rotation. The proportion of friction is smaller in relation to the greater weight placed on it, since the rotational friction of the piston in the cylinder is proportional to the piston surface area, i.e. with the diameter, the weight to be placed is synonymous with the flywheel, but proportional to the piston area, i.e. with the square of the diameter takes. One could now use several devices with different piston sizes or one device with interchangeable cylinders and pistons. Both are cumbersome and too complex and not portable for a portable device. _<

To overcome these difficulties, the invention provides a piston balance with two measuring ranges before that the piston consists of two coaxially arranged partial pistons and the larger partial piston designed as a cylinder for the smaller sub-piston and for the transition to the other measuring range is arranged screwable on the device cylinder.

In the lower measuring range, for example below 2 kp / cm ² , according to the invention the larger and +0 the smaller sub-piston act together as one piston of the total piston area of both.

For the measurement in the upper measuring range, the cylinder is designed as a cylinder for the smaller sub-piston larger partial pistons screwed tightly to the device cylinder. The partial piston with the smaller area then acts alone.

So that the weight bar has the same initial weight, for example 1 kg, in both measuring ranges, it is further proposed according to the invention to make the weight plate from two parts, one part of the weight plate being the same as the piston for one designed as a piston scale
Precision pressure measuring device

Applicant:

H. Maihak Aktiengesellschaft,

Hamburg, Semperstr. 38

Named as inventor:

Hans Stuben, moor rain over Uetersen

weight of the screwed larger piston must be. To avoid confusion, is further proposed that the weight plate halves with the size of the associated partial piston area in such a way indicate that when one half of the weight plate is placed, the other half of the weight plate is marked is covered.

In the A b b. 1, E is the pressure vessel of the precision pressure measuring device with the device cylinder C screwed into place. The larger partial piston B ₁ , which also serves as a cylinder for the smaller partial piston B ₂ , slides in this. Both partial pistons act together in this figure as a piston with an area of, for example, 5 cm ² ; the weight _{plate D 1} on the weight bar N is marked accordingly. The screw connection V required for fastening the larger partial piston B ₁ on the device cylinder C is screwed onto the rod N below the weight plate D ₁ .

P ' and O represent, as is known, the upper bearing of the weight rod N in ball bearings, M the measurement mark for the plunger depth, L a stop ring to prevent the plunger from popping out when the pressure is exceeded.

The A b b. 2 shows the arrangement for the higher measuring range with the partial piston B ₁ screwed tightly through the screw connection V on the device cylinder C. The partial piston B ₂ of, for example, 1 cm ² area acts alone. The weight holder half D _{2 of} the weight holder bears the corresponding identification and hides the identification of the weight holder half D ₁ .

Claims (3)

Patent claims: 1. Piston for a precision pressure measuring device designed as a piston balance with two measuring ranges, characterized in that the KoI- "" 509 740/201 ben consists of two coaxially arranged sub-pistons (B ₁ , B ₂ ) and the larger sub-piston (B ₁ ) is designed as a cylinder for the smaller sub-piston (B ₂ ) and can be screwed to the device cylinder (C) for the transition to the other measuring area. 2. Piston according to claim 1, characterized in that the necessary weight compensation during the transition to the other measuring range. Weight bar (N) is carried out by a divided weight plate (D ₁ , D ₂ ) . 3. Piston according to claims 1 and 2, characterized in that the two halves of the weight (D ₁ , D ₂ ) carry an identification for the associated piston part size and that when one half of the weight (D ₂ ) is placed, the identification of the other _{half of the weight (D 1} ) is covered. For this purpose, 1 sheet of drawings