Gravimetric measuring instrument with releasable load receiver

• US 8,426,753 B2
• Filed: 07/20/2010
• Issued: 04/23/2013
• Est. Priority Date: 07/23/2009
• Status: Active Grant

• Current Assignee: Mettler Toledo GmbH
• Original Assignee: Mettler-Toledo AG (Mettler-Toledo International Inc.)
• Inventors: Metzger, Andreas, Birrer, Adrian, Kppel, Thomas
• Primary Examiner(s): Gibson, Randy W
• Application Number:
  US12/839,512
• Publication Number:
  US 20110017521A1
• Time in Patent Office: 1,008 Days
• Field of Search: 177/126, 177/238, 177/244, 177/229, 411/411, 411/424, 411/935, 411/935.1
• US Class Current: 177/126
• CPC Class Codes: G01G 21/23 Support or suspension of weighing platforms G01G21/24 takes precedence
• CPC Class Codes: G01G 21/30 Means for preventing contamination by dust

Abstract

A gravimetric measuring instrument that contains a weighing cell having a load-transmitting member. A load receiver can be coupled to the load-transmitting member through a releasable connection. A mechanical stop resides on the load-transmitting member, and a mechanical counter stop resides on the load receiver. By means of an eccentric bolt engaging the load receiver and the load-transmitting member, the mechanical stop can be pressed against the mechanical counter stop, whereby the stop can be clamped tight against the counter stop. With this arrangement, the load receiver can be rigidly but releasably secured to the load-transmitting member.

Claims

1. A gravimetric measuring instrument in the form of a weighing cell having a load-transmitting member adapted for releasable connection to a load receiver, and further comprising:

a mechanical stop residing on the load-transmitting member;

a mechanical counter stop residing on the load receiver; and

an eccentric bolt engaging the load receiver and the load-transmitting member;

wherein rotation of the eccentric bolt causes the mechanical stop to be clamped against the mechanical counter stop, thereby rigidly securing the load receiver to the load-transmitting member.

2. The gravimetric measuring instrument according to claim 1, wherein when the load receiver is in a secured condition, the mechanical stop and the mechanical counter stop lie in a plane that is perpendicular to the direction of the load.

3. The gravimetric measuring instrument according to claim 1, wherein the eccentric bolt has at least one bearing section and at least one eccentric cylinder, said eccentric cylinder arranged with a defined eccentricity relative to the bearing section.

4. The gravimetric measuring instrument according to claim 3, wherein when the load receiver is in a secured condition, a central longitudinal axis of the load-transmitting member and a central longitudinal axis of the bearing section intersect at a right angle.

5. The gravimetric measuring instrument according to claim 3, wherein the load-transmitting member has at least a first bore hole to receive the eccentric cylinder, and the load receiver has at least a second bore hole to receive the bearing section, and wherein the distance between the mechanical counter stop and a central longitudinal axis of the second bore hole is less than the result of subtracting the radius of the first bore hole from the sum of the spacing between the mechanical stop and a central longitudinal axis of the first bore hole, the amount of eccentricity, and the radius of the eccentric cylinder.

6. The gravimetric measuring instrument according to claim 5, wherein when the load receiver is in the secured condition, the effective eccentricity that has been corrected by a leverage ratio, is smaller than the product of the coefficient of friction that exists between the eccentric cylinder and the first bore hole multiplied by the radius of the eccentric cylinder, the leverage ratio depending on the position of the eccentric cylinder within the first bore hole.

7. The gravimetric measuring instrument according to claim 1, wherein the load-transmitting member is comprised of a material of low thermal conductivity.

8. The gravimetric measuring instrument according to claim 1, wherein the material is selected from the group consisting of a polymer and a ceramic material.

9. The gravimetric measuring instrument according to claim 1, wherein the weighing cell and the load receiver are made of an electrically conductive material, and an electrically conductive contact spring is arranged between the weighing cell and the load receiver.

10. The gravimetric measuring instrument according to claim 9, wherein the contact spring is a helical compression spring or a helical tension spring.

11. The gravimetric measuring instrument according to claim 1, wherein the gravimetric measuring instrument includes a housing with a passage, the weighing cell is arranged in the housing, and the load-transmitting member of the weighing cell reaches through said passage.

12. The gravimetric measuring instrument according to claim 11, wherein a contact-free sealing system is arranged between the housing and the load receiver.

13. The gravimetric measuring instrument according to claim 1, wherein the load receiver has a planar surface.

14. The gravimetric measuring instrument according to claim 1, wherein at least one mounting location for the attachment of application-specific devices is provided on the load receiver.

15. The gravimetric measuring instrument according to claim 1, wherein an ejector element is provided to push the eccentric bolt at least partially out of the bore holes during the process of releasing the connection of the load receiver.

16. The gravimetric measuring instrument according to claim 1, wherein the load receiver and the load-transmitting member include positioning elements for the precise alignment of the load receiver and the load-transmitting member in relation to each other.

17. The gravimetric measuring instrument according to claim 1, wherein the mechanical stop is formed on the load-transmitting member.

18. The gravimetric measuring instrument according to claim 1, wherein the mechanical counter stop is formed on the load receiver.

19. A gravimetric measuring instrument in the form of an electrically conductive weighing cell having a load-transmitting member that is comprised of a material of low thermal conductivity and is adapted for releasable connection to an electrically conductive load receiver, the instrument further comprising:

a mechanical stop residing on the load-transmitting member;

a mechanical counter stop residing on the load receiver;

an electrically conductive contact spring arranged between the weighing cell and the load receiver; and

an eccentric bolt engaging the load receiver and the load-transmitting member, the eccentric bolt designed and located such that rotation thereof causes the mechanical stop to be clamped against the mechanical counter stop, thereby rigidly securing the load receiver to the load-transmitting member.

20. The gravimetric measuring instrument according to claim 19, wherein the contact spring is a helical compression spring or a helical tension spring.