Piston rod piston detector, autotensioner and belt tension adjuster

• US 6,666,784 B1
• Filed: 10/05/2000
• Issued: 12/23/2003
• Est. Priority Date: 10/06/1999
• Status: Expired due to Fees

• Current Assignee: NTN Corporation
• Original Assignee: NTN Corporation
• Inventors: Iwamoto, Kenichi, Niki, Motoharu, Koike, Takashi, Inokuchi, Kazuyuki
• Primary Examiner(s): Charles, Marcus
• Application Number:
  US09/679,809
• Time in Patent Office: 1,174 Days
• Field of Search: 324/207.2, 324/207.24, 137/554, 474/109, 474/110, 474/111, 474/107-108, 474/138, 474/135, 474/133, 474/136, 474/102, 310/30, 310/14, 340/686.1, 340/686.3, 340/668
• US Class Current: 474/109
• CPC Class Codes: F01L 1/024 Belt drive
• CPC Class Codes: F01L 2820/045 Valve lift
• CPC Class Codes: F01L 9/20 by electric means
• CPC Class Codes: F15B 15/2861 using magnetic means
• CPC Class Codes: F16H 2007/0806 Compression coil springs
• CPC Class Codes: F16H 2007/081 Torsion springs
• CPC Class Codes: F16H 2007/0812 Fluid pressure
• CPC Class Codes: F16H 2007/0861 comprising means for sensing tensioner position
• CPC Class Codes: F16H 7/0836 of the fluid and restriction type, e.g. dashpot
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01B 7/02 for measuring length, width or thickness G01B7/004, G01B7/12 take precedence
• CPC Class Codes: G01D 5/2013 by a movable ferromagnetic element, e.g. a core G01D5/2033 takes precedence
• CPC Class Codes: G01D 5/2046 by a movable ferromagnetic element, e.g. a core
• CPC Class Codes: Y10T 137/8242 Electrical

Abstract

A piston rod position detecting mechanism is proposed which can detect continuously or in a multiple-point manner that the piston rod position has changed due to increase or decrease in the protruding amount of the piston rod due to aging. The protruding amount from a cylinder end wall is detected by a position detecting mechanism comprising a detecting coil housed in a bobbin provided at the cylinder end, a flange portion formed on the piston rod, and a coil spring. Also, an autotensioner and an electromagnetic valve with such a position detector are proposed. Further, a belt tension adjusting device is provided with a detector for detecting the position of a tension pulley which is pivotable with increase or decrease in the belt tension.

Claims

1. A belt transmission device comprising:

a pulley mounted on a crankshaft;

a pulley mounted on a shaft to be driven;

a belt trained around said pulleys to drive said shaft;

an autotensioner including an engaging member, a cylinder, a pushrod mounted in said cylinder, a tension adjusting spring and a damper mechanism for damping the vibration of the belt through said engaging member; and

a detecting unit for detecting the axial position of said pushrod continuously or at multiple points;

wherein said detecting unit comprises a detecting coil provided at an opening of said cylinder and a flange provided on said pushrod opposite to said detecting coil, to thereby detect any change in the position of said pushrod based on a change in the inductance of said detecting coil with the change in the position of said flange.

2. The belt transmission device as claimed in claim 1 wherein said shaft is a camshaft, said engaging member comprising a tension pulley for tensioning the belt and a pulley arm pivotably supporting said tension pulley, said pushrod of said autotensioner being pressed against said pulley arm.

3. The belt transmission device as claimed in claim 1 wherein said autotensioner comprises a hydraulic autotensioner which utilizes both a gas and a liquid.

4. The belt transmission device as claimed in claim 1 wherein said cylinder has hydraulic oil therein, a piston is slidably mounted in said cylinder to partition said cylinder into a pressure chamber and a reservoir chamber, said pushrod is coupled to said piston so as to move axially with said piston and protrude out of said cylinder, and said tension adjusting spring biases said pushrod in a direction tending to cause said pushrod to protrude out of said cylinder.

5. The belt transmission device as claimed in claim 1 wherein a coil spring is mounted between said flange and said cylinder.

6. The belt transmission device as claimed in claim 1 wherein said flange is formed of a nonmagnetic conductive material.

7. A belt tension adjusting device comprising an inner member supported so as to be pivotable about a fixing bolt passing through an eccentric hole formed in said inner member, a tension pulley rotatably mounted on said inner member, a tension adjusting spring and a hydraulic damper for pivoting said inner member and thus said tension pulley to adjust tension of a belt, and a magnetic sensor for detecting the position of said tension pulley,

wherein said tension adjusting spring is accommodated in said inner member, wherein a magnet is mounted inside said tension adjusting spring so as to move as said tension adjusting spring shrinks and expands, said magnetic sensor being fixed to said inner member to detect the position of said tension pulley.

8. The belt tension adjusting device as claimed in claim 7 wherein said magnet is provided so as to move along a straight line that passes said magnetic sensor, a straight line parallel thereto, or a rotation locus relative to said magnetic sensor, and mounted such that a gap between said magnet and said magnetic sensor changes as the belt stretches.

9. The belt tension adjusting device as claimed in claim 7 wherein said magnetic sensor is a Hall sensor which outputs a linear output or an ON-OFF signal.

10. The belt tension adjusting device as claimed in claim 7 wherein an output signal of said magnetic sensor is sent to a control circuit and a temperature sensor is provided parallel to said magnetic sensor, an output of said temperature sensor being sent to said control circuit for temperature compensation of the output signal of said magnetic sensor.

11. A belt tension adjusting device comprising an inner member supported so as to be pivotable about a fixing bolt passing through an eccentric hole formed in said inner member, a tension pulley rotatably mounted on said inner member, a tension adjusting spring and a hydraulic damper for pivoting said inner member and thus said tension pulley to adjust tension of a belt, and a magnetic sensor for detecting the position of said tension pulley,

wherein said tension adjusting spring is accommodated in said inner member, wherein two magnets having different polarities are mounted inside said tension adjusting spring so as to move as said tension adjusting spring shrinks and expands, said magnetic sensor being fixed to said inner member to detect the position of said tension pulley.

12. The belt tension adjusting device as claimed in claim 11 wherein said magnetic sensor is a Hall sensor which outputs a linear output or an ON-OFF signal.

13. The belt tension adjusting device as claimed in claim 11 wherein an output signal of said magnetic sensor is sent to a control circuit and a temperature sensor is provided parallel to said magnetic sensor, an output of said temperature sensor being sent to said control circuit for temperature compensation of the output signal of said magnetic sensor.

14. A belt tension adjusting device comprising an inner member supported so as to be pivotable about a fixing bolt passing through an eccentric hole formed in said inner member, a tension pulley rotatably mounted on said inner member, a tension adjusting spring and a hydraulic damper for pivoting said inner member and thus said tension pulley to adjust tension of a belt, and a magnetic sensor for detecting the position of said tension pulley,

wherein said tension adjusting spring is accommodated in said inner member, wherein a magnet is mounted on a pin supporting said tension adjusting spring, and wherein said magnetic sensor is fixed to said inner member so as to move relative to said magnet as said inner member pivots, to thereby detect the position of said inner member.

15. The belt tension adjusting device as claimed in claim 14 wherein said magnet is provided so as to move along a straight line that passes said magnetic sensor, a straight line parallel thereto, or a rotation locus relative to said magnetic sensor, and mounted such that a gap between said magnet and said magnetic sensor changes as the belt stretches.

16. The belt tension adjusting device as claimed in claim 14 wherein said magnetic sensor is a Hall sensor which outputs a linear output or an ON-OFF signal.

17. The belt tension adjusting device as claimed in claim 14 wherein an output signal of said magnetic sensor is sent to a control circuit and a temperature sensor is provided parallel to said magnetic sensor, an output of said temperature sensor being sent to said control circuit for temperature compensation of the output signal of said magnetic sensor.

18. A belt tension adjusting device comprising an inner member supported so as to be pivotable about a fixing bolt passing through an eccentric hole formed in said inner member, a tension pulley rotatably mounted on said inner member, a tension adjusting spring and a hydraulic damper for pivoting said inner member and thus said tension pulley to adjust tension of a belt, and a magnetic sensor for detecting the position of said tension pulley,

wherein said tension adjusting spring is accommodated in said inner member, wherein a magnet is mounted on a pin provided on said inner member so as to support a rod which protrudes from said hydraulic damper, wherein said magnetic sensor is fixed to said hydraulic damper to detect the position of said tension pulley.

19. The belt tension adjusting device as claimed in claim 18 wherein said magnet is provided so as to move along a straight line that passes said magnetic sensor, a straight line parallel thereto, or a rotation locus relative to said magnetic sensor, and mounted such that a gap between said magnet and said magnetic sensor changes as the belt stretches.

20. The belt tension adjusting device as claimed in claim 18 wherein said magnetic sensor is a Hall sensor which outputs a linear output or an ON-OFF signal.

24. The belt tension adjusting device as claimed in claim 18 wherein an output signal of said magnetic sensor is sent to a control circuit and a temperature sensor is provided parallel to said magnetic sensor, an output of said temperature sensor being sent to said control circuit for temperature compensation of the output signal of said magnetic sensor.

21. A belt tension adjusting device comprising an inner member supported so as to be pivotable about a fixing bolt passing through an eccentric hole formed in said inner member, a tension pulley rotatably mounted on said inner member, a tension adjusting spring and a hydraulic damper for pivoting said inner member and thus said tension pulley to adjust tension of a belt, and a magnetic sensor for detecting the position of said tension pulley,

wherein said tension adjusting spring is accommodated in said inner member, wherein two magnets having different polarities are mounted on said inner member, and wherein said magnetic sensor is fixed to said hydraulic damper to detect the position of said tension pulley.

22. The belt tension adjusting device as claimed in claim 21 wherein said magnetic sensor is a Hall sensor which outputs a linear output or an ON-OFF signal.

23. The belt tension adjusting device as claimed in claim 21 wherein an output signal of said magnetic sensor is sent to a control circuit and a temperature sensor is provided parallel to said magnetic sensor, an output of said temperature sensor being sent to said control circuit for temperature compensation of the output signal of said magnetic sensor.

25. The belt tension adjusting device as claimed in claim 21 wherein said magnet is provided so as to move along a straight line that passes said magnetic sensor, a straight line parallel thereto, or a rotation locus relative to said magnetic sensor, and mounted such that a gap between said magnet and said magnetic sensor changes as the belt stretches.

26. A belt tension adjusting device comprising an inner member supported so as to be pivotable about a fixing bolt passing through an eccentric hole formed in said inner member, a tension pulley rotatably mounted on said inner member, a tension adjusting spring and a hydraulic damper for pivoting said inner member and thus said tension pulley to adjust tension of a belt, and a magnetic sensor for detecting the position of said tension pulley,

wherein said tension adjusting spring is accommodated in said inner member, wherein a tapered magnet is mounted on said inner member, and wherein said magnetic sensor is fixed to said hydraulic damper to detect the position of the tension pulley.

27. The belt tension adjusting device as claimed in claim 26 wherein said magnet is provided so as to move along a straight line that passes said magnetic sensor, a straight line parallel thereto, or a rotation locus relative to said magnetic sensor, and mounted such that a gap between said magnet and said magnetic sensor changes as the belt stretches.

28. The belt tension adjusting device as claimed in claim 26 wherein said magnetic sensor is a Hall sensor which outputs a linear output or an ON-OFF signal.

29. The belt tension adjusting device as claimed in claim 26 wherein an output signal of said magnetic sensor is sent to a control circuit and a temperature sensor is provided parallel to said magnetic sensor, an output of said temperature sensor being sent to said control circuit for temperature compensation of the output signal of said magnetic sensor.

30. A belt tension adjusting device comprising an inner member supported so as to be pivotable about a fixing bolt passing through an eccentric hole formed in said inner member, a tension pulley rotatably mounted on said inner member, a tension adjusting spring and a hydraulic damper for pivoting said inner member and thus said tension pulley to adjust tension of a belt, and a magnetic sensor for detecting the position of said tension pulley,

wherein an output signal of said magnetic sensor is sent to a control circuit and a temperature sensor is provided parallel to said magnetic sensor, an output of said temperature sensor being sent to said control circuit for temperature compensation of the output signal of said magnetic sensor.

31. A belt tension adjusting device comprising an inner member supported so as to be pivotable about a fixing bolt passing through an eccentric hole formed in said inner member, a tension pulley rotatably mounted on said inner member, a tension adjusting spring and a hydraulic damper for pivoting said inner member and thus said tension pulley to adjust tension of a belt, and a magnetic sensor for detecting the position of said tension pulley,

wherein a magnet is provided so as to move along a straight line that passes said magnetic sensor, a straight line parallel thereto, or a rotation locus relative to said magnetic sensor, and mounted such that a gap between said magnet and said magnetic sensor changes as the belt stretches.

32. A belt tension adjusting device comprising an inner member supported so as to be pivotable about a fixing bolt passing through an eccentric hole formed in said inner member, a tension pulley rotatably mounted on said inner member, a tension adjusting spring and a hydraulic damper for pivoting said inner member and thus said tension pulley to adjust tension of a belt, and a magnetic sensor for detecting the position of said tension pulley,

wherein an output signal of said magnetic sensor is sent to a control circuit and a temperature sensor is provided parallel to said magnetic sensor, an output of said temperature sensor being sent to said control circuit for temperature compensation of the output signal of said magnetic sensor.