Temperature compensated measuring apparatus

Claim 2

A measuring apparatus, comprising a. a housing (H): b. a pan carrier member (5) connected for rectilinear movement relative to said housing, said pan carrier member being displaceable upon the application of load thereto from an initial no-load position toward a loadeD position; c. a string member (8) connected under tension between said housing and said pan carrier member, said string member having a physical property that varies as a function both of the displacement of said pan carrier member from said initial position and of variations in temperature; d. means for exciting said string member to a condition of oscillation, whereby the frequency of oscillation of said string member is a function of the magnitude of the load applied to said pan carrier member; and e. temperature compensating means including at least one temperature-responsive permanent magnet system for applying to at least one of said pan carrier and string members a biasing force of a direction and magnitude to compensate for variations in said physical property as a function of temperature.

Claim 3

Apparatus as defined in claim 1, wherein said magnet system includes a first pair of cooperating permanent magnets (11, 11'') of opposite polarity connected with said housing and with said string member, respectively, said magnets being arranged to effect a reduction in the initial tension in said string member, said magnets having such a force of attraction relative to the temperature coefficient of said string member that temperature-responsive variations in the length of bending stiffness of said string member are compensated for by the temperature-responsive variation in the strength of said magnetic force of attraction, whereby the frequency of oscillation of said string member is independent of variations in temperature.

Claim 4

Apparatus as defined in claim 2, wherein said temperature compensation magnet means comprises a second pair of cooperating permanent magnets (14, 16) of opposite polarity connected with said pan carrier and with said housing, respectively, for applying to said pan carrier a biasing force in one direction, and a third pair of permanent magnets (14'', 16'') of like polarity connected with said pan carrier and with said housing, respectively, for applying to said pan carrier a biasing force in the same direction.

Claim 5

A measuring apparatus, comprising a. a housing; b. a pan carrier (5) connected for rectilinear movement relative to said housing, said pan carrier being displaceable upon the application of a load thereto from a no-load position toward a loaded position; c. a traction spring (18) connected between said housing and said pan carrier to resist movement of said pan carrier from said no-load position, said traction spring having a physical property that varies as a function both of the displacement of said pan carrier from said initial no-load position and of variations in temperature; and d. temperature compensating means including at least one temperature-responsive permanent magnet system for applying to said traction spring a biasing force of a direction and magnitude to compensate for variations in said physical property as a function of temperature, said magnet system including a first pair of cooperating permanent magnets (21, 22) of opposite polarity connected with said pan carrier and with said housing, respectively, for applying to said pan carrier a biasing force in one direction, and a second pair of cooperating permanent magnets (21'', 22'') connected with said pan carrier and with said housing, respectively, for applying to said pan carrier a biasing force in the opposite direction, the magnitude of said biasing forces being such relative to the spring constant of said traction spring as to correct for adverse influences on balance sensitivity that result from temperature-responsive variations in said spring constant.

Claim 6

A measuring apparatus, comprising a. a housing; b. a pan carrier (5) connected for rectilinear movement relative to said housing, said pan carrier being displaceable upon the application of a load thereto from a no-load position toward a loaded position; c. a traction spring (18) connected between said housing and said pan carrier to resist movement of said pan carrier from said no-load position, said traction spring having a physical property that varies as a function both of the displacement of said pan carrier from said initial no-load position and of variations in temperature; and d. temperature compensating means including at least one temperature-responsive permanent magnet system for applying to said traction spring a biasing force of a direction and magnitude to compensate for variations in said physical property as a function of temperature, said magnet system including a first pair of cooperating permanent magnets (21, 22) of opposite polarity connected with said pan carrier and with said housing, respectively, for applying to said pan carrier a biasing force in one direction, and a second pair of cooperating permanent magnets (21'', 22'') connected with said pan carrier and with said housing, respectively, for applying to said pan carrier a biasing force in the opposite direction, the magnitude of said biasing forces being such relative to the spring constant of said traction spring as to correct for adverse influences on balance sensitivity that result from temperature-responsive variations in said spring constant.

Claim 7

A measuring apparatus, comprising a. a housing; b. a pan carrier connected for rectilinear movement relative to said housing, said pan carrier being displaceable upon the application of a load thereto from a no-load position toward a loaded position; c. a traction spring connected between said housing and said pan carrier to resist movement of said pan carrier from said no-load position in the direction of said loaded position, said traction spring having a physical property that varies as a function both of the displacement of said pan carrier from said initial no-load position and of variations in temperature; and d. temperature compensating means including at least one temperature-responsive permanent magnet system for applying to said traction spring a biasing force of a direction and magnitude to compensate for variations in said physical property as a function of temperature, said magnet system including a pair of cooperating permanent magnets (24, 24'') connected with said housing and with said pan carrier, respectively, said magnets being arranged in horizontally spaced relation when said pan carrier is in the no-load position, said magnets having a mutual force of attraction that is so related to the spring constant of said traction spring as to correct for adverse influences on balance sensitivity that result from temperature-responsive variations in said spring constant.

Claim 8

A measuring apparatus, comprising a. a housing; b. a pan carrier connected for rectilinear movement relative to said housing, said pan carrier being displaceable upon the application of a load thereto from a no-load position toward a loaded position; c. a traction spring connected between said housing and said pan carrier to resist movement of said pan carrier from said no-load position in the direction of said loaded position, said traction spring having a physical property that varies as a function both of the displacement of said pan carrier from said initial no-load position and of variations in temperature; and d. temperature compensating means including at least one temperature-responsive permanent magnet system for applying to said traction spring a biasing force of a direction and magnitude to compensate for variations in said physical property as a function of temperature, said magnet system including a pair of cooperating permanent magnets (24, 24'') connected with said housing and with said pan carrier, respectively, said magnets being arranged in horizontally spaced relation when said pan carrier is in the no-load position, said magnets having a mutual force of attraction that is so related to the spring constant of said traction spring as to correct for adverse influences on balance sensitivity that result from temperature-responsive variations in said spring constant.