BALANCE HAVING A HOUSING WHICH CAN BE EVACUATED

Abstract

A balance (10) includes an evacuable housing (12) having a bottom (121), side walls (122), and a top (123), and a weighing device (14) arranged in the housing (12) having a load carrier (142), a weighing system (141) and a weighing sensor. The weighing system (141) has a base fixed to the housing and a load receptor connected to the load carrier (142), which load receptor is coupled to the base in a vertically movable manner via a link arrangement articulated to the base on the one hand and is coupled to the weighing sensor fixed to the base in a force-transmitting manner via a lever arrangement on the other hand. A vertical post (124) protrudes from the center of the bottom (121) of the housing (12), wherein the base of the weighing system (141) is fixed on a free end of the post (124).

Claims

1. A balance comprising: an evacuable housing having a bottom, side walls, and a top, and a weighing device arranged in the housing and having a load carrier, a weighing system and a weighing sensor, wherein the weighing system has a base fixed to the housing and a load receptor connected to the load carrier, which load receptor is coupled vertically movably to the base via a link arrangement articulated to the base on the one hand and is coupled force-transmittingly to the weighing sensor fixed to the base via a lever arrangement on the other hand, wherein a vertical post protrudes from a center of the bottom of the housing, and wherein the base of the weighing system is fixed on a free end of the post.

2. The balance according to claim 1, wherein the bottom of the housing is shaped as a circular disk and is surrounded by the side walls in an annular manner.

3. The balance according to claim 1, wherein the bottom and the side walls of the housing are formed in one piece from a common material.

4. The balance according to claim 1, wherein the free end of the post carries a platform which projects beyond an outer circumference of the platform and on which the base of the weighing system is fixed.

5. The balance according to claim 1, wherein the weighing system, at least in a region of the load receptor, projects beyond an outer circumference of the post andif presentbeyond an edge of a platform and the load carrier, which is configured as a pendulum tray, is hinged to the load receptor in a suspended manner below the load receptor.

6. The balance according to claim 5, further comprising a turntable with a test weight magazine concentrically and rotatably mounted to the post.

7. The balance according to claim 1, wherein the side walls of the housing do not or at most by less than a height of the weighing system project beyond the post, and the weighing system is fitted into a corresponding recess in the top of the housing.

8. The balance according to claim 1, wherein the housing is made of thick-walled metal and has an unpainted, polished surface on an outside as well as on an inside of the housing.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0019] FIG. 1: A schematic representation of an exemplary balance according to the invention.

DETAILED DESCRIPTION

[0020] FIG. 1 shows a highly schematized representation of a balance 10 according to the invention. The balance 10 shown comprises an evacuable housing 12 and a weighing device 14 arranged in the housing 12. In the embodiment shown, the balance 10 is fixed on a vibration-isolated foundation 18 via supports 16. The specific mechanism with which the balance 10 is fixed to the foundation 18 and its vibration isolation is not important in the context of the present invention.

[0021] The housing 12 essentially consists of a bottom 121, which can in particular be circular disk-shaped. Side walls 122 rise up around the edge of the bottom 121, which in the embodiment shown are connected to the bottom 121 in one piece and in the same material. The housing 12 is provided with a top 123 in the form of a removable lid, which can be fixed in an airtight manner to the free edges of the side walls 122. This creates a cavity surrounded on all sides by walls, which can also be referred to as a weighing chamber 124.

[0022] The weighing chamber 124 can be evacuated using a conventional evacuation unit not shown in detail here. The skilled person will understand that absolute evacuation is practically impossible and will therefore recognize that evacuation here means the creation of a considerable negative pressure in the weighing chamber relative to the housing environment.

[0023] According to the invention, a vertical post 125 rises from the center of the bottom 121 into the weighing chamber 124. In the embodiment shown, the post 125 is formed in one piece and in the same material as the bottom 121.

[0024] A platform 126 is fixed to the top of the post 125, i.e. to its free end, and projects on one side beyond the outer circumference of the post 125 and into the weighing chamber 124.

[0025] The weighing system 141 of the weighing device 14, in particular its base, is fixed to the platform 126. A load carrier 142 in the form of a pendulum tray is hinged to the load receptor of the weighing system 141, which is not shown separately. In the embodiment shown, the articulated coupling of the load carrier 142 to the load receptor passes through a recess in the platform 126. The load carrier 142 hangs freely suspended next to the post 125 in the weighing chamber 124. A test weight 20 is shown on the pan of the load carrier 124.

[0026] The negative pressure created during the evacuation of the weighing chamber 124 generates considerable forces acting on the walls of the housing 12. These can lead to a temporary, elastic deformation of the housing walls, as shown to a considerably exaggerated extent by the dashed lines in FIG. 1. Particularly in the area of the circular disk-shaped bottom 121, such deformation essentially takes the form of a rotationally symmetrical bulge. This leads to a non-uniform distribution of uplifts and inclinations over the entirety of the bottom, which would lead to distortion of a weighing system fixed flat on the bottom. In the center of the bottom 121, however, this curvature only acts as a vertical lift. Accordingly, the post 125 arranged in the center of the bottom 121 moves in a purely vertical direction. Accordingly, the weighing device 14 fixed on the post 125 is also displaced purely vertically. This vertical displacement is indicated in FIG. 1 by dotted lines. It affects the entire weighing device 14, including its weighing system 141, its load carrier 142 (including test weight 20) and its weighing sensor, which is not shown separately in FIG. 1. All these elements therefore do not move relative to each other during evacuation, so that the deformation of the housing 12 caused by the evacuation has no influence on the measurement result of the weighing device 14.

[0027] In order to minimize the volume of the weighing chamber, in the embodiment shown, the side walls 122 do not extend beyond the upper edge of the weighing system 141. Rather, the top 123 of the housing 12 in the area of the weighing system 141 has a recess 127 corresponding to the shape of the weighing system 141, into which the weighing system 141 projects without contact.

[0028] The embodiments discussed in the detailed description and shown in the figures are only illustrative examples of the present invention. In light of the present disclosure, the person skilled in the art is provided with a wide range of possible variations. In particular, the person skilled in the art may provide further components within the weighing chamber 124. In particular, a test weight magazine and an automated load changing device can be arranged within the weighing chamber 124, for example in the form of a turntable mounted on the post 125. For the sake of clarity, however, these elements are not shown in FIG. 1.

LIST OF REFERENCE SYMBOLS

[0029] 10 balance [0030] 12 bousing [0031] 121 bottom [0032] 122 side wall [0033] 123 top [0034] 124 weighing chamber [0035] 125 post [0036] 126 platform [0037] 127 recess [0038] 14 weighing device [0039] 141 weighing system [0040] 142 load carrier [0041] 16 support [0042] 18 foundation [0043] 20 test weight