Device for measuring strain in rotating bodies

Claim 1

A device for measuring strain in a rotating shaft which comprises a strain gauge bonded to said shaft and being operative to produce a direct current output signal, the voltage amplitude of which is proportional to strain in said shaft; a direct current power source connected to the input of said strain gauge; a voltage-to-frequency converter corotatably mounted on said shaft, said voltage-to-frequency converter including a direct current amplifier for receiving and amplifying the direct current output signal of said strain gauge, a relaxation oscillator circuit connected to the output of said amplifier for converting the amplified direct current signal into a pulsating signal, the frequency of which is linearly proportional to the amplified direct current signal, and a negative feedback circuit interconnecting said relaxation oscillator circuit and the input of said amplifier; a pulse transformer for transmitting said pulsating signal from said shaft to a stationary readout point, said pulse transformer having a primary winding mounted on said shaft and being connected to said voltage-to-frequency converter and a stationary secondary winding; and a frequency meter connected to said secondary winding of said pulse transformer for measuring the frequency of said pulsating signal.

Claim 2

A device for measuring strain in a rotating shaft which comprises a strain gauge bonded to said shaft and being operative to produce a direct current output signal, the voltage amplitude of which is proportional to strain in said shaft; a direct current power source connected to the input of said strain gauge; a voltage-to-frequency converter corotatably mounted on said shaft, said voltage-to-frequency converter including a direct current amplifier for receiving and amplifying the direct current output signal of said strain gauge, a relaxation oscillator circuit connected to the output of said amplifier for converting the amplified direct current signal into a pulsating signal, the frequency of which is linearly proportional to the amplified direct current signal, and a negative feedback circuit interconnecting said relaxation oscillator circuit and the input of said amplifier; a pulse transformer for transmitting said pulsating signal from said shaft to a stationary readout point, said pulse transformer having a primary winding mounted on said shaft and being connected to said voltage-to-frequency converter and a stationary secondary winding; and a frequency meter connected to said secondary winding of said pulse transformer for measuring the frequency of said pulsating signal.

Claim 7

A device for measuring force delivered to a drilling string by a rotary table assembly having a housing, a drive shaft journaled to said housing, means for drivingly coupling said drive shaft to said drilling string, said device comprising: a strain gauge bonded to said drive shaft and adapted to produce a direct current output signal having a voltage proportional to the strain in said shaft; a voltage-to-frequency converter mounted for corotation with said shaft and connected to said said strain gauge for converting said direct current output signal into a pulsating signal, the frequency of which is proportional to the voltage of said strain gauge output signal, said voltage-to-frequency converter including an amplifier, a relaxation oscillator circuit connected to the output of said amplifier, and a feedback circuit from said relaxation oscillator circuit to the input of said amplifier; a pulse transformer having a primary winding mounted for corotation with said shaft and being connected to said voltage-to-frequency converter, and a stationary secondary winding; means for delivering a direct current power source to said strain gauge and to said voltage-to-frequency converter; and a frequency meter located at a stationary readout point and connected in circuit with said secondary winding of said pulse transformer.

Claim 8

A device for measuring force delivered to a drilling string by a rotary table assembly having a housing, a drive shaft journaled to said housing, means for drivingly coupling said drive shaft to said drilling string, said device comprising: a strain gauge bonded to said drive shaft and adapted to produce a direct current output signal having a voltage proportional to the strain in said shaft; a voltage-to-frequency converter mounted for corotation with said shaft and connected to said said strain gauge for converting said direct current output signal into a pulsating signal, the frequency of which is proportional to the voltage of said strain gauge output signal, said voltage-to-frequency converter including an amplifier, a relaxation oscillator circuit connected to the output of said amplifier, and a feedback circuit from said relaxation oscillator circuit to the input of said amplifier; a pulse transformer having a primary winding mounted for corotation with said shaft and being connected to said voltage-to-frequency converter, and a stationary secondary winding; means for delivering a direct current power source to said strain gauge and to said voltage-to-frequency converter; and a frequency meter located at a stationary readout point and connected in circuit with said secondary winding of said pulse transformer.

Claim 11

A device for measuring the torque in a rotating shaft comprising a strain gauge bonded to said rotating shaft and being operative to deliver a direct current output signal, the voltage amplitude of which is indicative of the torsional strain in said rotating shaft; a case secured to one end of said rotating shaft; a body mounted in said case for corotation therewith; a voltage-to-frequency converter mounted on said body and being connected to the output of said strain gauge, said voltage-to-frequency converter including a relaxation oscillator circuit and heing operative to receive and convert the direct current output signal of said strain gauge into a pulsating signal having a frequency indicative of the voltage of said direct current output signal; a stationary shaft journally mounted in said body; a pulse transformer having a primary winding mounted on said body and a secondary winding mounted on said stationary shaft, said primary winding being connected to said voltage-to-frequency converter and being adapted to transmit said pulsating signal thereof to said secondary winding; and a stationary meter connected to said secondary winding for measuring the frequency of said pulsating signal.

Claim 12

A device for measuring the torque in a rotating shaft comprising a strain gauge bonded to said rotating shaft and being operative to deliver a direct current output signal, the voltage amplitude of which is indicative of the torsional strain in said rotating shaft; a case secured to one end of said rotating shaft; a body mounted in said case for corotation therewith; a voltage-to-frequency converter mounted on said body and being connected to the output of said strain gauge, said voltage-to-frequency converter including a relaxation oscillator circuit and heing operative to receive and convert the direct current output signal of said strain gauge into a pulsating signal having a frequency indicative of the voltage of said direct current output signal; a stationary shaft journally mounted in said body; a pulse transformer having a primary winding mounted on said body and a secondary winding mounted on said stationary shaft, said primary winding being connected to said voltage-to-frequency converter and being adapted to transmit said pulsating signal thereof to said secondary winding; and a stationary meter connected to said secondary winding for measuring the frequency of said pulsating signal.

Claim 13

A device for measuring the torque in a rotating shaft comprising a strain gauge bonded to said shaft and being operative to deliver a direct current output signal, the voltage amplitude of which is indicative of the torsional strain in said rotating shaft; a body secured to said rotating shaft for corotation therewith; a voltage-to-frequency converter mounted on said body and connected to the output of said strain gauge, said voltage-to-frequencY converter including a direct current amplifier, a relaxation oscillator circuit and being operative to receive, amplify, and convert the direct current output signal of said strain gauge into a pulsating signal having a frequency proportional to the voltage of said direct current output signal; a stationary member journalled mounted to said body; a pulse transformer having a primary winding mounted on saidbody and a secondary winding mounted on said stationary member, said primary winding being connected to said voltage-to-frequency converter and being adapted to transmit said pulsating signal thereof to said secondary winding; and a stationary meter connected to said secondary winding for measuring the frequency of said pulsating signal.

Claim 14

A device for measuring the torque in a rotating shaft comprising a strain gauge bonded to said shaft and being operative to deliver a direct current output signal, the voltage amplitude of which is indicative of the torsional strain in said rotating shaft; a body secured to said rotating shaft for corotation therewith; a voltage-to-frequency converter mounted on said body and connected to the output of said strain gauge, said voltage-to-frequencY converter including a direct current amplifier, a relaxation oscillator circuit and being operative to receive, amplify, and convert the direct current output signal of said strain gauge into a pulsating signal having a frequency proportional to the voltage of said direct current output signal; a stationary member journalled mounted to said body; a pulse transformer having a primary winding mounted on saidbody and a secondary winding mounted on said stationary member, said primary winding being connected to said voltage-to-frequency converter and being adapted to transmit said pulsating signal thereof to said secondary winding; and a stationary meter connected to said secondary winding for measuring the frequency of said pulsating signal.