Liquid integrating accelerometer |
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| 申请号 | US3694594D | 申请日 | 1970-12-23 | 公开(公告)号 | US3694594A | 公开(公告)日 | 1972-09-26 |
| 申请人 | BREED DAVID S; | 发明人 | BREED DAVID S; | ||||
| 摘要 | An integrating accelerometer using a liquid which serves both as the sensing mass and the integrator through using the acceleration acting on the mass of the fluid to create a pressure which forces a small portion of the same fluid through a restriction giving rise to either laminar or turbulent duct flow or inertial flow through an orifice or sharp edge slit. | ||||||
| 权利要求 | 1. An integrating accelerometer including a chamber having a portion containing a fluid, a fluid receiving portion, and a restricting passage, positioned between said fluid and said fluid receiving portion, through which a portion of the fluid is adapted to flow; means for permitting the mass of the fluid to be used to sense the acceleration and the volume flow of the fluid through said passage into said fluid receiving portion which volume is a measure of an integral over time of a function of the acceleration; and said fluid containing portion and said passage providing means whereby a major portion of the force induced by the acceleration is used to force the fluid through the restricting passage rather than to substantially move the bulk of the fluid in said fluid containing portion. 2. The invention in accordance with claim 1 wherein means are provided for sensing time integrals of accelerations occurring from more than one direction. 3. The invention in accordance with claim 2 wherein several direction sensitivity is achieved through a substantially two dimensional chamber. 4. The invention in accordance with claim 3 wherein the geometry of the chamber is varied so as to achieve different threshhold acceleration sensing and different particular values and forms of the integral of the acceleration for different directions of acceleration. 5. The invention in accordance with claim 2 wherein the chamber is so shaped as to permit the sensing and integrating of acceleration from a variety of directions having different latituDinal and longitudinal coordinates. 6. The invention in accordance with claim 5 wherein the geometry of the chamber or of the fluid flow passage is varied to permit different acceleration threshold sensing and different particular values and forms of the integral of the acceleration for different directions of acceleration. 7. The invention in accordance with claim 1 wherein a piston and a cylinder is provided and the output of the integrating accelerometer when subject to the proper acceleration stimulus is the motion of a piston in a cylinder. 8. The invention in accordance with claim 7 wherein the clearance between the piston and cylinder serves as a seal to prevent the fluid from flowing past the piston. 9. The invention in accordance with claim 7 wherein a firing pin and aligned primer and means for releasibly latching said firing pin are pro-vided and upon the proper travel of the piston the firing is released and the primer is initiated. 10. The invention in accordance with claim 1 wherein the fluid passage is a tube. 11. The invention in accordance with claim 1 wherein the fluid passage is a sharp edge opening. 12. The invention in accordance with claim 1 wherein the fluid passage is defined by the clearance between two substantially plane surfaces. 13. The invention in accordance with claim 1 wherein the flow passage includes a porous plug. 14. The invention in accordance with claim 1 wherein the passage through which the fluid flows is defined by the clearance between two concentric or offset cylinders. 15. The invention in accordance with claim 14 wherein the cylinders have different thermal expansion coefficients chosen in such a way as to permit compensation for the change in viscosity of the fluid with temperature. 16. The invention in accordance with claim 1 wherein the flow through the passage is laminar flow. 17. The invention in accordance with claim 1 wherein the integrating accelerometer integrates over time the acceleration minus a certain threshhold acceleration. 18. The invention in accordance with claim 1 wherein the flow through the restricting passage is turbulent flow. 19. The invention in accordance with claim 1 wherein the flow through the passage is inertial flow through a sharp edge opening. 20. The invention in accordance with claim 1 wherein the flow through the passage is mixed flow showing both viscous and inertial effects. 21. The invention in accordance with claim 1 wherein the accelerometer measures the integral over time of a power of the acceleration minus a certain bias value, where the power has a value between 0.5 and 1. 22. The invention in accordance with claim 1 wherein the accelerometer measures the integral over time of the square root of the acceleration minus a certain bias value. 23. The invention in accordance with claim 1 wherein means are provided to prevent the integrating accelerometer from operating until a certain threshold or bias acceleration is achieved. 24. The invention in accordance with claim 23 wherein this threshhold or bias acceleration requirement is achieved through imposing a pressure on the fluid downstream of the passage. 25. The invention in accordance with claim 24 wherein the bias pressure is achieved through a spring loaded piston. 26. The invention in accordance with claim 23 wherein the bias acceleration is achieved by utilizing small clearances in the fluid passage and the surface tension properties of the fluid such that the fluid will not flow in the passage until a pressure is achieved in the fluid sufficient to overcome the surface tension. 27. The invention in accordance with claim 1 wherein the fluid is mercury. 28. The invention in accordance with claim 27 wherein the mercury is alloyed to lower the freezing point of the liquid. 29. The invention in accordance with claim 28 where the alloying element is thallium. 30. The invention in accordance with claim 1 wherein the fluid is electrically conductivE. 31. The invention in accordance with claim 30 wherein the fluid bridges a set of contacts at an appropriate value of the integral over time of the appropriate acceleration function. 32. The invention in accordance with claim 31 wherein means are provided to trap the conducting fluid in the area of the contacts to maintain permanent contact closure. 33. The invention in accordance with claim 30 wherein means are provided incorporating the placement of the contacts so as to require different travels of the fluid in the passage for different directions of acceleration. 34. The invention in accordance with claim 1 wherein means are provided to hermetically seal the integrating accelerometer. 35. The invention in accordance with claim 1 wherein means are provided to adapt the device to a vehicle with the device serving as a vehicle crash sensor. 36. The invention in accordance with claim 1 wherein means are provided for a gas to be fed into the volume within the chamber which is vacated by the fluid. 37. The invention in accordance with claim 32 wherein a filter type material is used between the fluid and the gas source which permits the passage of the gas but forbids the passage of the fluid. 38. The invention in accordance with claim 1 wherein a substantial portion of the gas is evacuated from that portion of the accelerometer not containing the fluid. 39. The invention in accordance with claim 25 wherein a return flow tube is provided to return excess fluid from above the piston to the chamber. 40. The invention in accordance with claim 1 wherein a stand pipe is provided to supply fluid to the chamber and to permit the thermal expansion and contraction of the fluid. |
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