Device for measuring loads, especially transient loads

• US 4,102,422 A
• Filed: 04/08/1976
• Issued: 07/25/1978
• Est. Priority Date: 04/08/1975
• Status: Expired due to Term

• Current Assignee: Telub AB
• Original Assignee: Telub AB
• Inventors: Christiansson, Per Lennart
• Primary Examiner(s): Hartary, Joseph W.
• Application Number:
  US05/674,972
• Time in Patent Office: 838 Days
• Field of Search: 177/210 C, 177/133, 317/246, 317/249 R, 317/261, 340/272, 340/200, 361/283, 361/291
• US Class Current: 177/210.00C
• CPC Class Codes: G01G 7/06 by electrostatic action
• CPC Class Codes: G01L 1/142 using capacitors

Abstract

A device comprises for sensing or measuring loads, especially transient loads, such as a load imposed by a wheel of a vehicle driving over the device. The device comprises two electrically conductive plates and an intermediate dielectric and elastomeric or elastic material. In a central plane of the dielectric material a series of threads of steel wire is embedded. Said threads are connected together electrically at one end. At least two spaced capacitor electrodes are constituted by one plate and said threads. The dielectric and elastomeric material is adapted to be engaged by the load and the variation in the capacitance is linearly proportional to the magnitude of the applied load. The two plates are pressed towards each other in order to cause a mechanical preloading of the intermediate material in order to give said linear proportionality.

Claims

1. A variable capacitance device for sensing and measuring loads, especially transient loads, wherein the capacitance varies as a linear function of the loads to be measured, said device comprising:

(a) two conductive plates,

(b) an elastic dielectric layer between said plates,

(c) means encompassing said device for compressing said two conductive plates toward each other and for maintaining pressure on said conductive plates to preload said dielectric layer to cause the capacitance of the device to vary as a linear function of the loads to be measured,

(d) a plurality of conductive threads embedded in said dielectric layer,

(e) a first electrode of the device connected to said threads, and

(f) a second electrode of the device connected to one of said plates.

2. A device according to claim 1, wherein a stiff bond is applied between the plates and the dielectric layer.

3. A device according to claim 1, wherein the threads are oriented in a central plane of the dielectric layer.

4. A device according to claim 1, wherein the threads are further oriented longitudinally in the layer and are equally spaced.

5. A device according to claim 1, wherein compressing means consists of a stretched elastic strip.

6. A device according to claim 1, wherein the breadth of the plates exceeds that of the dielectric layer.

7. A device according to claim 1, wherein the dielectric layer consists of two parts.

8. A device according to claim 7, wherein the two parts are bonded to each other by a flexible bond.

9. A weighing station including a plurality of the devices of claim 1, wherein each device rests upon a road surface and a drive is arranged on both sides of the devices.

10. A weighing station according to claim 9, wherein a plate is covers the devices.