DE102004025006B4 - Measuring volume of hollow body, e.g. motor vehicle air conditioner cooling circuit, by moving feed container until different fluid levels in feed container and fluid reservoir balance - Google Patents

Abstract

The method involves evacuating a hollow space at known outgoing pressure, and letting air in to determine the volume. The admitted air is taken from a feed container (3) connected to a fluid reservoir (4). The feed container is moved until the different fluid levels in the feed container and fluid reservoir (due to removal of air) are balanced. The remaining amount of fluid in the feed container is determined. The volumes of a measuring device that does not belong to the hollow body are taken into account.

Description

The The invention relates to a method for measuring the volume a hollow body, at the standing under a known outlet pressure cavity of the hollow body evacuated and then is determined by air intake of the volume.

For different applications It's kind of common useful or even necessary, the volume of a hollow body, such as for example, a container, to determine with high accuracy. In automotive engineering this applies, for example, to the void volume of an entire refrigeration circuit of an air conditioner or components thereof, such as collectors, heat exchangers, oil separators, Evaporator, compressor.

Basically In the prior art, a number of different procedures known, which allow it with more or less great accuracy the volumes of cavities to investigate.

The DE 35 10 574 A1 describes, for example, a method for determining the volume of space, preferably of subterranean spaces, wherein the volume of the space to be examined filling medium is changed by a sudden and short-term volume decrease, among other things, the resulting from the change in room volume pressure change is used to determine the volume.

The DE 39 19 983 A1 also describes a method for determining the volume of a cavity, in which air is sucked out of the cavity until a predetermined negative pressure is reached, and the cavity is subsequently filled with air while measuring the inflowing air flow. To determine the volume, leakage air is sucked off, inter alia, over a certain period of time.

Also the DE 40 13 373 C1 describes a method for determining the volume of a cavity enclosed by a subject, which is set below a known, atmospheric pressure corresponding outlet pressure, wherein in a reference vessel with a known reference volume, a known reference pressure is set, which differs from the output pressure of the subject, after which the reference vessel is fluidically connected to the subject and a self-adjusting pressure is measured and used for computational determination of the subject volume.

The DE 33 15 238 A1 finally describes a method for measuring the volume of cavities, in which the cavity is evacuated and then the volume is determined by air inlet. The evacuation takes place only up to a certain pressure limit, after which a certain amount of air is recirculated and thereby a pressure increase is generated to a value which is also below said pressure limit and wherein the time is measured in which this pressure change takes place.

all The above-mentioned methods have the disadvantage that the volume determination for Part quite expensive and only by using a correspondingly large apparatus and metrological Effort possible is.

From that Based on the invention, the object is based on another Procedure for measuring the volume of a hollow body show which can be carried out quickly and with the use of fewer aids and still brings out a measurement result of high accuracy.

The inventive solution to see in claim 1. An advantageous development of The invention is claimed in claim 2.

The Invention is described below with reference to the description of the procedure explained in detail. The associated only figure shows schematically the few required for Verfahrendurchführung Equipment. It refers to:

1

container

2

vacuum pump

3

reservoir

4

fluid reservoir

5

measuring Cup

6

manometer

7

stopcock

8th

stopcock

9

management

10

management

11

shutter

12

inlet opening

13.1

liquid level

13.2

liquid level

To determine the void volume of the container 1 the procedure is as follows:
While the reservoir 3 outside the fluid reserver 4 is the one stopcock 7 opened and the other stopcock 8th closed. By vacuum pump 2 will now be over the lines 9 . 10 the container 1 evacuated until a predeterminable pressure, for example 2 hPa, is reached. At the manometer 6 this can be read off. Then also the stopcock 7 closed.

Following this, the reservoir is 3 so in the fluid reservoir 4 immersed in that its lower entrance opening 12 within the fluid reservoir 4 located. Thereafter, the stopcock 8th opened with the result that due to the pressure difference between the under atmospheric pressure fluid reservoir 4 and the evacuated container 1 a certain amount of fluid in the reservoir 3 is pressed.

By moving or lowering the reservoir 3 then have the first different liquid levels 13.1 . 13.2 from storage tank 3 and fluid reservoir 4 be brought to the same height, with the result that even within the container 1 Ambient pressure (atmospheric pressure) prevails.

When this is achieved, the inlet opening becomes 12 closed, the reservoir 3 from the fluid reservoir 4 taken and in the reservoir 3 remaining amount of fluid by means of measuring container 5 exactly determined. For complete emptying of the reservoir 3 It may be necessary to do this by opening the shutter 11 to ventilate. As far as in the further determination of the volume of the container 1 to be considered internal volume of the lines 9 . 10 should not be known, this should still be appropriately determined. This is done analogously as described above, but without the container 1 ,

Out the measured amount of fluid results in the container volume due to the following Relationships:

p:

Umgebungsdruck (Atmosphärendruck) (Pa)

p_E:

Druck nach dem Evakuieren (Pa)

R:

Gaskonstante der Luft (kJ/kg∙K)

T:

Umgebungstemperatur, absolut (K)

V_gem:

gemessene Fluidmenge im Vorratsbehälter 3 (m³)

V_L:

Volumen der Leitungen 9, 10

gesucht ist:

V_B:

Rauminhalt des Behälters 1

Given are:

p:

Ambient pressure (atmospheric pressure) (Pa)

p _E :

Pressure after evacuation (Pa)

R:

Gas constant of the air (kJ / kg ∙ K)

T:

Ambient temperature, absolute (K)

V _{according to} :

measured amount of fluid in the reservoir 3 (m ³ )

V _L :

Volume of pipes 9 . 10

wanted is:

V _B :

Volume of the container 1

After evacuation is in the tank 1 still a small amount of air. This is (1)

After filling with air from the reservoir 3 at ambient pressure, it occupies the volume ΔV. The gas equation is now (2)

Then the volume is ΔV: (3)

With V = V _gem + ΔV the total volume follows (4)

After that, the volume V _{L of} the lines 9 . 10 subtracted from. The volume of the container 1 then results V B = V - V L (5)

Claims (2)

Method for measuring the volume of a hollow body in which evacuated under a known outlet pressure cavity of the hollow body and then determined by air inlet of the volume, characterized by the steps of: - the air is taken from a reservoir ( 3 ) taken with a fluid reservoir ( 4 ), - moving the storage container ( 3 ) until due to the air extraction resulting different liquid levels ( 13.1 . 13.2 ) of storage container ( 3 ) and fluid reservoir ( 4 ) are balanced, - determine the in the reservoir ( 3 ) remaining amount of fluid - do not consider the hollow body ( 1 ) belonging volume contents of a measuring device for carrying out the method. Method according to claim 1, characterized in that the fluid reservoir ( 4 ) under order ambient pressure (atmospheric pressure).