Force measuring apparatus of the vibratory string type

Force measuring apparatus of the type including at least one oscillatory string the frequency of oscillation of which affords an indication of the magnitude of a load to be measured, comprising

• a. a stationary frame member;
• b. a movable pan carrier member connected for vertical movement between normal no-load and full-load positions relative to said frame member;
• c. oscillatory string means connected under tension between said frame and pan carrier members, said string means including at least one string member connected at one end with one of said frame and pan carrier members, and a spring member connecting the other end of said string member with the other of said frame and pan carrier members;
• and
• d. compensating means for applying a corrective force on said string to compensate for the non-linearity of said string and spring members throughout the entire range of travel of said pan carrier member between said no-load and full load positions, said compensating means including non-linear coil spring means connected in tension between said stationary frame and movable pan carrier members for applying to said oscillatory string means a correction force that varies non-linearly with the displacement of said movable member from said no-load position toward said full-load position, thereby to modify the dependency of the frequency change of the string on the load force and to produce a linear variation in the oscillating frequency with respect to load.

Force measuring apparatus of the type including at least one oscillatory string the frequency of oscillation of which affords an indication of the magnitude of a load to be measured, comprising

• a. a stationary frame member;
• b. a movable pan carrier member connected for vertical movement between normal no-load and full-load positions relative to said frame member;
• c. oscillatory string means connected under tension between said frame and pan carrier members, said string means including at least one string member connected at one end with one of said frame and pan carrier members, and a spring member connecting the other end of said string member with the other of said frame and pan carrier members;
• and
• d. compensating means for applying a corrective force on said string to compensate for the non-linearity of said string and spring members throughout the entire range of travel of said pan carrier member between said no-load and full-load positions, said compensating means including spiral spring means (38) for applying to said oscillatory string means a correction force that varies quadratically with the displacement of said movable member from said no-load position toward said full-load position, thereby to modify the dependency of the frequency change of the string on the load force and to produce a linear variation in the oscillating frequency with respect to load.

Force measuring apparatus of the type including at least one oscillatory string the frequency of oscillation of which affords an indication of the magnitude of a load to be measured, comprising

• a. a stationary frame member;
• b. a movable pan carrier member connected by linkage means for vertical movement between normal no-load and full-load positions relative to said frame member;
• c. oscillatory string means connected under tension between said frame and pan carrier members, said string means including at least one string member connected at one end with one of said frame and pan carrier members, and a spring member connecting the other end of said string member with the other of said frame and pan carrier members;
• and
• d. compensating means for applying a corrective force on said string to compensate for the non-linearity of said string and spring members throughout the entire range of travel of said pan carrier member between said no-load and full-load positions, said string and spring means being so connected between said movable and stationary members as to bias said movable member toward an initial no-load position (.alpha.) in which the weight of the movable member on a non-linearly increasing effective lever arm of said linkage means varies relatively strongly non-linearly for applying to said oscillatory string means a correction force that varies with the displacement of said movable member from said no-load position toward said full-load position, thereby to modify the dependency of the frequency change of the string on the load force and to produce a linear variation in the oscillating frequency with respect to load.

Force measuring apparatus of the type including at least one oscillatory string the frequency of oscillation of which affords an indication of the magnitude of a load to be measured, comprising

• a. a stationary frame member;
• b. a movable pan carrier member connected for vertical movement between normal no-load and full-load positions relative to said frame member;
• c. oscillatory string means connected under tension between said frame and pan carrier members, said string means including at least one string member connected at one end with one of said frame and pan carrier members, and a spring member connecting the other end of said string member with the other of said frame and pan carrier members;
• and
• d. compensating means for applying a corrective force on said string to compensate for the non-linearity of said string and spring members throughout the entire range of travel of said pan carrier member between said no-load and full-load positions, said compensating means including a linear coil spring (41), and means (42, 43) connecting said linear coil spring in tension between said link means and said stationary member to produce a linearly decreasing moment on said link means, thereby to modify the dependency of the frequency change of the string on the load force and to produce a linear variation in the oscillating frequency with respect to load.