Physical quantity detecting apparatus and internal combustion engine control apparatus each utilizing optical fiber

• US 5,693,936 A
• Filed: 04/26/1994
• Issued: 12/02/1997
• Est. Priority Date: 04/27/1993
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Takahashi, Minoru, Kurita, Masahiro, Komachiya, Masahiro, Oho, Shigeru, Shimada, Satoshi, Suzuki, Seiko, Sasayama, Takao
• Primary Examiner(s): ALLEN, STEPHONE B
• Application Number:
  US08/233,749
• Time in Patent Office: 1,316 Days
• Field of Search: 250/231.19, 250/227.14, 250/227.16, 250/227.17, 73/705, 73/715
• US Class Current: 250/227.17
• CPC Class Codes: F02F 11/002 involving cylinder heads
• CPC Class Codes: G01L 23/16 by photoelectric means
• CPC Class Codes: G01L 23/22 for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines

Abstract

A physical quantity detecting apparatus comprises at least one optical fiber, at least one light emitting means for emitting an incident light beam on the optical fiber, at least one light receiving means for detecting an outgoing light beam from the optical fiber, physical quantity applied position information generating means for providing information indicative of a position of a portion at which a physical quantity is applied to the optical fiber, and operation means for receiving signals from the light receiving means and physical quantities applied position information generating means and calculating a change with time in physical quantity at respective positions on the optical fiber.

Claims

1. A physical quantity detecting apparatus utilizing an optical fiber for detecting an operating condition of an engine, comprising:

at least one birefringent optical fiber;

at least one light emitting means for emitting incident light beam on said optical fiber;

at least one light receiving means for detecting the light power of an outgoing light beam from said optical fiber;

physical quantity applying means for bending said optical fiber on the basis of a plurality of physical quantities to be measured so as to change the power of light passing through said optical fiber, wherein said physical quantity applying means is packaged in a member forming part of an engine; and

means for detecting said physical quantity from the light power detected by said light receiving means.

2. A physical quantity detecting apparatus utilizing an optical fiber according to claim 1, wherein said engine member is a gasket.

3. A physical quantity detecting apparatus utilizing an optical fiber according to claim 1, wherein said engine member is an ignition plug.

4. A physical quantity detecting apparatus utilizing an optical fiber according to claim 1, further comprising means for prestressing said optical fiber at least at the location of said physical quantity applying means to preset the level of the power of light detected by said detecting means to a predetermined level in the absence of application of stress to said optical fiber due to said physical quantities.

5. A physical quantity detecting apparatus utilizing an optical fiber according to claim 4, wherein said prestressing means forms part of said physical quantity applying means.

6. A physical quantity detecting apparatus utilizing an optical fiber according to claim 4, wherein said prestressing means forms part of said engine.

21. A physical quantity detecting apparatus according to claim 5 wherein said optical fiber has a tip formed in a reflection surface.

22. A physical quantity detecting apparatus according to claim 21 further comprising light splitting and coupling means, interposed between said light emitting means and said optical fiber, for admitting a reflection beam from said tip to said light receiving means.

7. A physical quantity detecting apparatus utilizing an optical fiber, comprising:

at least one optical fiber;

at least one light emitting means for emitting an incident light beam on said optical fiber;

at least one light receiving means for detecting an outgoing light beam from said optical fiber;

physical quantity applying means for applying stress to said optical fiber on the basis of a plurality of physical quantities to be measured so as to change characteristics of the light passing through said optical fiber;

position information generating means for generating a position reference signal, independent of an output of said light receiving means, concerning positions at which said plurality of physical quantities to be measured are applied to said optical fiber; and

operation means for detecting at least one physical quantity of said plurality of physical quantities on the basis of a detection signal from said light receiving means and the position reference signal from said position information generating means.

8. A physical quantity detecting apparatus according to claim 7 wherein at least part of said optical fiber is a birefringent index optical fiber.

9. A physical quantity detecting apparatus according to claim 8, wherein said birefringent index optical fiber has a cross-sectional structure which causes the distribution of refractive index the fiber to be asymmetrical to the axis thereof.

10. A physical quantity detecting apparatus according to claim 8 wherein said birefringent index optical fiber is a polarization plane conserving optical fiber.

11. A physical quantity detecting apparatus according to claim 7 wherein said optical fiber is a single mode optical fiber.

12. A physical quantity detecting apparatus according to claim 7 wherein said optical fiber is a multi-mode optical fiber.

13. A physical quantity detecting apparatus according to claim 7 further comprising:

means, interposed between said light emitting means and said optical fiber, for performing polarization control of the incident light beam on said optical fiber; and

a polarizer interposed between said optical fiber and said light receiving means.

14. A physical quantity detecting apparatus according to claim 13 wherein

said polarization control means comprises means for providing a plurality of polarized components;

said physical quantity applying means comprises means responsive to at least one of said plurality of physical quantities for changing optical characteristics of each of said plurality of polarized components; and

said polarizer comprises said means for detecting at least said one polarized component of said plurality of polarized components.

15. A physical quantity detecting apparatus according to claim 7 wherein

said light emitting means is a light source for emitting a light beam containing a plurality of polarized components;

said physical quantity applying means comprises means responsive to at least one necessary physical quantity of said plurality of physical quantities to change optical characteristics of at least said one of said plurality of polarized components; and

said light receiving means has means for detecting a polarized component undergoing a change in optical characteristics.

16. A physical quantity detecting apparatus according to claim 7 wherein said physical quantity applying means comprises means for applying said plurality of physical quantities to a plurality of positions on said one optical fiber.

17. A physical quantity detecting apparatus according to claim 16 wherein part of said optical fiber is used as a delay circuit, and said operation means includes means for processing a signal from said light receiving means on a time-division basis.

18. A physical quantity detecting apparatus according to claim 7 having a plurality of optical fibers;

wherein said light emitting means has means for admitting a light beam to each of said plurality of optical fibers;

said physical quantity applying means comprises means for applying at least one physical quantity to each optical fiber; and

said light receiving means has means for detecting light beams from said plurality of optical fibers.

19. A physical quantity detecting apparatus according to claim 18 wherein said light receiving means includes light beam detecting means provided in association with each of said plurality of optical fibers.

20. A physical quantity detecting apparatus according to claim 18 wherein said light admitting means is a beam splitter for splitting a light beam received from one light emitting means.

23. A physical quantity detecting apparatus according to claim 7 wherein said physical quantity is pressure or a quantity to be converted into a pressure.

24. A physical quantity detecting apparatus according to claim 23 wherein said physical quantity applying means has a pressure transmitting medium for transmitting a pressure to said optical fiber.

25. A physical quantity detecting apparatus according to claim 24 wherein said pressure transmitting medium has a diaphragm responsive to pressure to transmit its movement to said optical fiber.

26. A physical quantity detecting apparatus according to claim 25 wherein said pressure transmitting medium further has a working portion for causing movement of said diaphragm on said optical fiber.

27. A physical quantity detecting apparatus according to claim 26 wherein said pressure transmitting medium further has a pressure transmitter for transmitting movement of said diaphragm to said working portion.

28. A physical quantity detecting apparatus according to claim 26 wherein said working portion is provided on one side of said diaphragm opposite to the other side to which a pressure is applied.

29. A physical quantity detecting apparatus according to claim 25 comprising a bending action structure responsive to movement of said diaphragm to provide an action to curve said optical fiber.

30. A physical quantity detecting apparatus according to claim 28 wherein said bending action structure includes,

an optical fiber supporting structure for supporting said optical fiber at two points;

and

a bending stress structure responsive to pressing force exerted by said diaphragm to apply bending stress to said optical fiber between said two supporting points.

31. A physical quantity detecting apparatus according to claim 28 wherein said bending action structure has a two-member structure including:

an optical fiber supporting member for supporting said optical fiber at two points; and

a diaphragm member including said diaphragm for transmitting movement of said diaphragm to said optical fiber between said two support points.

32. A physical quantity detecting apparatus according to claim 31 wherein said two-member structure is unified into an integral structure in the form of a module.

33. A physical quantity detecting apparatus according to claim 32 wherein said optical fiber is cut into sections having a necessary length and each section is mounted, at its ends, with an optical connector.

34. A physical quantity detecting apparatus according to claim 23 wherein said physical quantity applying means has:

a groove for receiving said optical fiber; and

means for applying pressure to said optical fiber positioned in said groove.

35. A physical quantity detecting apparatus according to claim 24 wherein said pressure transmitting medium is formed, at least part thereof, of a thermal conductor and serves as radiation means for radiating heat generated near said optical fiber.

36. A physical quantity detecting apparatus according to claim 23 wherein said physical quantity is an internal pressure in a plurality of cylinders of an internal combustion engine.

37. A physical quantity detecting apparatus according to claim 36 wherein said optical fiber is laid in the vicinity of each of said plurality of cylinders.

38. A physical quantity detecting apparatus according to claim 37 wherein said optical fiber is disposed in a gasket of said engine in the area of said plurality of cylinders.

39. A physical quantity detecting apparatus according to claim 37 wherein said optical fiber is disposed near ignition plugs of said plurality of cylinders.

40. A physical quantity detecting apparatus according to claim 35 wherein said optical fiber is disposed so as to be exposed to the interior of each of said plurality of cylinders.

41. A physical quantity detecting apparatus according to claim 37 wherein said optical fiber is subjected to a predetermined preliminary stress even when said internal combustion engine is in the non-combustion state.

42. A physical quantity detecting apparatus according to claim 26 wherein

said physical quantity applying means has pressure transmitting means for applying pressure to said optical fiber;

and

each of said plurality of cylinders is provided with a pressure sensing portion including a first space for accommodating a pressure receiving portion of said optical fiber and said pressure transmitting means and a second space for admitting internal pressure in a cylinder to said optical fiber and includes internal pressure seal means for sealing a spatial gap between said first and second spaces.

43. A physical quantity detecting apparatus according to claim 42 wherein said internal pressure seal means is made of a material of high thermal conductivity and acts as means for radiating heat generated near said optical fiber.

44. A physical quantity detecting apparatus according to claim 42 wherein said pressure receiving portion of said optical fiber and said pressure transmitting means are assembled into a block with said internal pressure seal means.

45. A physical quantity detecting apparatus according to claim 42 wherein said first and second spaces are formed in a gasket of said cylinders.

46. A physical quantity detecting apparatus according to claim 45 wherein said second space opens to the interior of said cylinder at a semi-circular surface of the cylinder inner surface opposing an exhaust manifold.

47. A physical quantity detecting apparatus according to claim 45 wherein said gasket includes at least one layer stamped for formation of said first and second spaces and said layer and other gasket layers are overlapped with each other to form said first and second spaces.

48. A physical quantity detecting apparatus according to claim 45 wherein a pressure receiving space is in communication with said second space, said pressure transmitting means responsive to pressure in said pressure receiving space and said optical fiber applied with a pressing pressure by said pressure transmitting means are arranged in a direction of thickness of said gasket.

49. A physical quantity detecting apparatus according to claim 42 wherein said first and second spaces are formed in an ignition plug.

50. A physical quantity detecting apparatus according to claim 36 wherein said position information generating means is means for generating position information on the basis of a rotation angle of the crank shaft of said internal combustion engine.

51. A physical quantity detecting apparatus according to claim 36 wherein said position information generating means comprises means for generating position information on the basis of ignition timings of ignition plugs of said plurality of cylinders.

52. A physical quantity detecting apparatus according to claim 7 further comprising conversion means for converting said physical quantity into pressure, wherein said physical quantity applying means comprises means for applying a pressure resulting from conversion by said conversion means to said optical fiber.

53. A physical quantity detecting apparatus according to claim 52 wherein said physical quantity is temperature and said conversion means is means for converting temperature into pressure.

54. A physical quantity detecting apparatus according to claim 53 wherein said conversion means is formed of bimetal member.

55. A physical quantity detecting apparatus according to claim 52 wherein said physical quantity is acceleration and said conversion means is means for converting acceleration into pressure.

56. A physical quantity detecting apparatus utilizing an optical fiber, comprising:

at least one birefringent index optical fiber;

at least one light emitting means for emitting an incident light beam on said optical fiber;

at least one light receiving means for detecting the light power of an outgoing light beam from said optical fiber;

physical quantity applying means for bending said optical fiber on the basis of at least one physical quantity to be measured so as to change the power of light passing through said optical fiber; and

means for detecting said physical quantity on the basis of a detection signal representing light power as received from said light receiving means.

57. An apparatus for controlling an internal combustion engine by detecting cylinder internal pressure through the use of optical fiber, comprising:

a plurality of cylinders;

at least one optical fiber laid in the vicinity of all of the cylinders;

at least one light emitting means for emitting an incident light beam on said optical fiber;

at least one light receiving means for detecting the light power of an outgoing light beam from said optical fiber;

pressure applying means for applying stress to said optical fiber on the basis of an internal pressure of said plurality of cylinders so as to change the power of light passing through said optical fiber; and

operation means for detecting an internal pressure in said plurality of cylinders on the basis of a detection signal representing light power as received from said light receiving means and for calculating at least one ignition timing, fuel amount and air amount for each cylinder on the basis of detected internal pressure in said plurality of cylinders.

58. An internal combustion engine control apparatus according to claim 57 further comprising cylinder information generating means for generating cylinder information concerning one of said plurality of cylinders which applies to said optical fiber a cylinder internal pressure having a distinctive changing point.