Temperature compensated fill valve/pressure switch
First Claim
1. An improved fluid pressure monitoring switch of the type including a housing adapted for mounting within a container, at least one moving contact and at least one fixed contact both disposed within said housing, said switch operative to monitor the fluid pressure within the container and to shift from a first contact state to a second contact state when the fluid pressure falls below a selected level, the improvement comprising;
- a capsule comprising a substantially rigid wall member and a compliant wall member, said wall members defining therebetween a sealed cavity pressurized to a predetermined value, means whereby said compliant wall member is operative to virtually effect a preselectable compensation characteristic by substantially varying the volume of said cavity as a function of cavity and container fluid pressures, said compliant wall member operatively engaging said moving contact for displacement with respect to said fixed contact as a function of fluid temperature within said capsule, and thereby varying said selected level as a function of said fluid temperature; and
capsule retention means operative to maintain said rigid wall member in a fixed relationship with said housing.
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Accused Products
Abstract
A device (10) for filling a pneumatic tire and sensing the air pressure therein has a check valve (20) disposed within a valve stem (126b) and a pressure sensing switch which is temperature compensated to adjust for air pressure changes within the tire due to changes in ambient temperature. Substantially perfect compensation can be achieved, within a limited range of operation, whereby the set point pressure versus temperature characteristic will track with the related tire pressure versus temperature characteristic. A sealed capsule (110) is assembled and pressurized prior to installation within the device. A manual set point calibration feature is provided. The switch can be employed independently of, as well as in conjunction with, the check valve.
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Citations
37 Claims
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1. An improved fluid pressure monitoring switch of the type including a housing adapted for mounting within a container, at least one moving contact and at least one fixed contact both disposed within said housing, said switch operative to monitor the fluid pressure within the container and to shift from a first contact state to a second contact state when the fluid pressure falls below a selected level, the improvement comprising;
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a capsule comprising a substantially rigid wall member and a compliant wall member, said wall members defining therebetween a sealed cavity pressurized to a predetermined value, means whereby said compliant wall member is operative to virtually effect a preselectable compensation characteristic by substantially varying the volume of said cavity as a function of cavity and container fluid pressures, said compliant wall member operatively engaging said moving contact for displacement with respect to said fixed contact as a function of fluid temperature within said capsule, and thereby varying said selected level as a function of said fluid temperature; and capsule retention means operative to maintain said rigid wall member in a fixed relationship with said housing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A device for pressurizing a container and monitoring fluid pressure therein, said device comprising:
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a body portion defining an inlet passage and adapted to be positioned in an aperture within a wall of said container; valve means disposed within said passage and operative to selectively pass fluid therethrough; switch means disposed within said body portion and comprising at least one moving contact and at least one fixed contact, said switch means operating to monitor the fluid pressure within the container and to shift from a first contact state to a second contact state when the fluid pressure falls below a selected level; a capsule comprising a first, substantially rigid wall member and a second, compliant wall member, said wall members defining a sealed cavity pressurized to a predetermined value, means whereby said second member is operative to virtually effect a preselectable compensation characteristic by substantially varying the volume of said cavity as a function of cavity and container fluid pressures, said second wall member operatively engaging said switch means to displace said moving contact with respect to said fixed contact as a function of fluid temperature within said capsule, and thereby varying said selected level as a function of said fluid temperature; and capsule retention means operative to maintain said first wall member in a fixed relationship with said body portion. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of manufacturing a device for pressurizing a container and monitoring fluid pressure therein, said method comprising the
forming a body for said device, said body defining an inlet passage and adapted to be positioned in an aperture within a wall of said container; -
installing switch means within said body, said switch means comprising at least one moving contact and at least one fixed contact, and operative to monitor the fluid pressure within the container and to shift from a first contact state to a second contact state when the fluid pressure falls below a selected level; forming a capsule discretely from said body, said capsule comprising a first, substantially rigid wall member and a second, compliant wall member, and defining a sealable cavity; pressurizing fluid within said cavity to a predetermined value; sealing said cavity; and installing the capsule within said body whereby said first wall member if fixed with respect thereto and said second wall member is operative to virtually effect a preselectable compensation characteristic by substantially varying the volume of said cavity as a function of cavity and container fluid pressures, and said second wall member operatively engages said switch means to displace said moving contact with respect to said fixed contact as a function of fluid temperature within said capsule, and thereby varying said selected level as a function of said fluid temperature. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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25. A fill valve/temperature compensated pressure switch adapted for use with a pneumatic tire and associated mating wheel, said valve-switch comprising:
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a body defining a switch receiving portion and a valve stem portion, said switch receiving portion adapted to be positioned adjacent the inside surface of a wall of said wheel with said valve stem portion for projecting outwardly through an aperture in said wall, said valve stem portion defining valve core receiving means within an inlet passage for interconnecting the interior of said tire with the atmosphere; a valve core disposed within said inlet passage and operative to selectively pass air therethrough; a switch disposed within said switch receiving portion and comprising at least one moving electrical contact and at least one fixed electrical contact, the switch operating to monitor the air pressure within the tire and to change conductive state when the air pressure falls below a set point level; a prepressurized temperature compensating sealed capsule comprising a rigid body portion and a compliant diaphragm disposed within the switch receiving portion and means whereby said diaphragm is operatively engaging the switch to displace the moving contact with respect to the fixed contact as a function of fluid temperature within the capsule and thereby vary the set point level as a function of the air temperature within the tire, said diaphragm operable, under the influence of cavity and tire fluid pressures, for inward and outward excursions with respect to said rigid body portion while in a first contact state, to substantially vary the volume of said cavity as a function of said cavity and tire fluid pressures to virtually effect a preselectable temperature compensation characteristic; and means operative to selectively position the rigid body portion of the capsule with respect to the switch to effect establishment of said set point level - View Dependent Claims (26, 27, 28)
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29. A method of manufacturing a device for monitoring fluid pressure within a container, said method comprising the steps of:
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forming a housing for said device, said housing adapted to be positioned within said container; installing switch means within said housing, said switch means comprising at least one moving contact and at least one fixed contact, and operative to monitor the fluid pressure within the container and to shift from a first contact state to a second contact state when the fluid pressure falls below a selected level; forming a capsule comprising a substantially rigid wall member and compliant wall member defining a sealable cavity therebetween; pressurizing fluid within said cavity to a predetermined value; sealing said cavity; and installing said capsule within said housing whereby said rigid wall member is fixed with respect thereto and said compliant wall member is operative to virtually effect a preselectable temperature compensation characteristic by substantially varying the volume of said cavity as a function of the cavity and container fluid pressure, and said compliant wall member operatively engaging said switch means to displace said moving contact with respect to said fixed contact as a function of fluid temperature within said capsule, and thereby varying said selected level as a function of said fluid temperature. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36)
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37. An improved fluid pressure monitoring switch of the type including a housing adapted for mounting within a container, at least one moving contact and at least one fixed contact both disposed within said housing, said switch operative to monitor the fluid pressure within the container and to shift from a first contact state to a second contact state when the fluid pressure falls below a selected level the improvement comprising:
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a capsule comprising a structurally rigid element and defining a sealed cavity defined at least in part by a compliant wall member, said cavity pressurized to a predetermined value, means whereby said compliant wall member is operatively engaging said moving contact for displacement with respect to said fixed contact as a function of fluid temperature within said capsule, and thereby varying said selected level as a function of said fluid temperature, whereby said compliant wall member is operable, under the influence of cavity and container fluid pressures for inward and outward excursions with respect to said rigid element while in said first contact state to substantially vary the volume of said cavity as a function of said cavity and container fluid pressures to virtually effect a preselectable temperature compensation characteristic; and capsule retention means operative to maintain said rigid element in a fixed relationship with said housing.
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Specification