Force transducer

Details Force transducer Force transducer

1984-11-02

1986-09-16

Ruehl, Charles A.

Measuring and testing

Dynamometers

Responsive to force

338 47, 338100, G01L 118, H01L 1010

Patent

active

046114971

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

This invention relates to transducers for responding electrically to forces and torques applied to the transducers. Detection of changes in electrical values corresponding to applied forces and torques and electrical circuitry for processing the detected change of values are disclosed in U.S. Pat. Nos. 4,055,078 and 4,240,288 both issued D'Antonio et al. Those disclosures are incorporated by reference.
It is well known that conventional carbon composition resistors change resistance value in response to the application of pressure to them. By detecting the resistance change, the amount and direction of an applied force can be determined. Transducers incorporating resistors are known in the art. Those transducers are adaptable to many applications. It is desirable in some applications to apply a prestress or biasing force to the resistors to avoid a non-linear response characteristic when weak forces are applied and to enable detection of both compressive and tensile forces. See the patents to D'Antonio.
In many applications it is necessary that the transducer be small, lightweight, inexpensive and simple to manufacture and use, yet reliable and precise in operation.


SUMMARY OF THE INVENTION

The invention achieves a lightweight, small transducer that is simple in construction and reliable in performance. The transducer includes at least one force variable impedance element, which is preferably a conventional carbon composition resistor having a cylindrical body. Force transmitting members, preferably two symmetrical members, bear on the impedance element. The members are preferably opposed and spaced and include surfaces complementary in shape to that of the impedance element. The members can approach each other when compressive forces are applied and retract when those forces are relieved. An annular retainer retains the members in place to engage and bear on the impedance element. The members preferably have an arcuate surface, opposite the impedance element engaging surface, which bears on the inside surface of the retainer. Preferably, the members include surfaces adjacent the arcuate surface which are spaced from the retainer to avoid binding when the members move in response to applied forces, which may result from applied torques.
In one embodiment, the arcuate surfaces of the members are tapered and the inside surface of the retainer is tapered in a complementary fashion. When the members are pressed to seat more deeply in the retainer, the force produced is applied to the impedance element. By adjusting the relative seated position of the members with respect to the retainer, a biasing force may be applied to the impedance element to prestress it. By using a biasing prestress, both compressive and tensile forces can be detected by the transducer. The embodiment includes apertures in the force members by which the transducer may be mounted on rods. The movement of the rods applies the force to be detected.
In another embodiment particularly useful for sensing torques, a retainer holds opposing force members against an impedance element. Blocks engage the retainer at each of a pair of force members, and posts engage the respective opposing force members. When torque is applied in either of two opposite directions, opposing compressive forces are transmitted to the impedance element by the force members.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional front view of an embodiment of a transducer according to the invention.
FIG. 2 is a cross sectional view of the transducer embodiment of FIG. 1 taken along line II--II of FIG. 1.
FIG. 3 is a cross sectional front view of another embodiment of a transducer according to the invention.
FIG. 4 is a cross sectional side view of the transducer embodiment of FIG. 3 taken along the line IV--IV of FIG. 3.


DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In FIGS. 1 and 2 an embodiment of a transducer according to the invention is shown in sectional front and side views. Like elements are given the same reference num

REFERENCES:
patent: 2090188 (1937-08-01), Dahlstrom
patent: 2898761 (1959-08-01), Hast
patent: 4055078 (1977-10-01), D'Antonio et al.
patent: 4163204 (1979-07-01), Sado et al.

Affiliated with

Also associated with

Rating

Force transducer does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Force transducer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Force transducer will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1989810