IP Library › Granted Patent US 12661744
Granted Patent B2
US 12661744 · App. 18/983,510 · Granted Jun 23, 2026

Hydraulic piston with embedded linear variable differential transducer for precision position sensing

Inventors: Joshua Robert Seyler (Stuart, FL); Parag H. Mathuria (Palm Beach Gardens, FL); Lajos H. Horvath (Jupiter, FL); James Masloski (Lake Worth, FL)
Assignee: RTX Corporation
B23P19/067F01D5/025F01D5/026F05D2220/30F05D2230/60F05D2240/24F05D2240/60
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Quick Facts
Patent No.
US 12661744
App. No.
18/983,510
Granted
Jun 23, 2026
Kind
B2
Abstract

A tie bolt stretch system including a rotor assembly including a compressor section coupled with a turbine section by a curvic coupling; a tie bolt joining the compressor section to the turbine section; a stretch tool in operative communication with the tie bolt; the stretch tool comprising: a hydraulic piston in operative communication with the tie bolt, the hydraulic piston including a shaft with a predetermined dimension; a sensor in operative communication with the stretch tool, the sensor indicates a dimensional change of the predetermined dimension; and a controller in operative communication with the sensor and a servo valve fluidly coupled with a hydraulic pump; the hydraulic pump fluidly coupled with the hydraulic piston; wherein the controller is configured to operate the hydraulic piston responsive to a signal from the sensor to attain a predetermined preload stretch on the tie bolt, curvic coupling, compressor section and turbine section.

Claims (52)

1 . A tie bolt stretch system comprising:

a rotor assembly including a compressor section coupled with a turbine section by a curvic coupling;

a tie bolt in operative communication with the rotor assembly, the tie bolt joining the compressor section to the turbine section;

a stretch tool in operative communication with the tie bolt; the stretch tool comprising:

a hydraulic piston in operative communication with the tie bolt, the hydraulic piston including a shaft with a predetermined dimension;

a sensor in operative communication with the stretch tool, the sensor configured to indicate a dimensional change of the predetermined dimension; and

a controller in operative communication with the sensor and a servo valve; the servo valve is fluidly coupled with a hydraulic pump; the hydraulic pump fluidly coupled with the hydraulic piston; wherein the controller is configured to operate the hydraulic piston responsive to a signal from the sensor to attain a predetermined preload stretch on the tie bolt, curvic coupling, compressor section and turbine section.

2 . The tie bolt stretch system according to claim 1 , further comprising:

a powerhead compressor within the compressor section;

a power turbine within the turbine section; and

a predetermined contact stiffness between the powerhead compressor and the power turbine; wherein the predetermined preload stretch is determined based at least in part on the predetermined contact stiffness.

3 . The tie bolt stretch system according to claim 1 , wherein the predetermined preload stretch on the tie bolt along with internal rotor geometric interfaces is configured to influence a rotor generated vibration.

4 . The tie bolt stretch system according to claim 1 , wherein the sensor is configured to measure the change in location of the hydraulic piston.

5 . The tie bolt stretch system according to claim 1 , wherein the stretch tool is configured to apply a tensile force on the tie bolt and the rotor assembly to preload the tie bolt and the rotor assembly.

6 . The tie bolt stretch system according to claim 5 , wherein the tensile force applied to the tie bolt is linear along an axis formed between the compressor section joined to the turbine section.

7 . The tie bolt stretch system according to claim 1 , wherein the sensor comprises at least one of a strain gauge, a linear variable differential transducer, and a laser device configured to measure the change in location of the hydraulic piston.

8 . A tie bolt stretch system comprising:

a rotor assembly including a compressor section coupled with a turbine section by a curvic coupling; the compressor section including at least one of a powerhead compressor and a load compressor;

a tie bolt in operative communication with the rotor assembly, the tie bolt joining the compressor section to the turbine section;

a stretch tool in operative communication with the tie bolt; the stretch tool comprising:

a hydraulic piston in operative communication with the tie bolt, the hydraulic piston including a shaft with a predetermined dimension;

a sensor in operative communication with the stretch tool, the sensor configured to indicate a dimensional change of the predetermined dimension; and

a controller in operative communication with the sensor and a servo valve; the servo valve is fluidly coupled with a hydraulic pump; the hydraulic pump fluidly coupled with the hydraulic piston; wherein the controller is configured to operate the hydraulic piston responsive to a signal from the sensor to attain a predetermined preload stretch on the tie bolt, curvic coupling, compressor section and turbine section.

9 . The tie bolt stretch system according to claim 8 , further comprising:

a load curvic coupling within the compressor section between the powerhead compressor and the load compressor;

a power turbine within the turbine section; and

a predetermined contact stiffness between the powerhead compressor and the power turbine, wherein the predetermined preload stretch is determined based at least in part on the predetermined contact stiffness.

10 . The tie bolt stretch system according to claim 8 , wherein the predetermined preload stretch on the tie bolt along with internal rotor geometric interfaces is configured to influence a rotor generated vibration.

11 . The tie bolt stretch system according to claim 8 , wherein the sensor is configured to measure the change in location of the hydraulic piston.

12 . The tie bolt stretch system according to claim 8 , wherein the stretch tool is configured to apply a tensile force on the tie bolt and the rotor assembly to preload the tie bolt and the rotor assembly.

13 . The tie bolt stretch system according to claim 8 , wherein the sensor comprises at least one of a strain gauge, a linear variable differential transducer, and a laser device configured to measure the change in location of the hydraulic piston.

14 . A process for stretching a tie bolt with a tie bolt stretch system comprising:

forming a rotor assembly coupling a compressor section with a turbine section through a curvic coupling;

coupling a tie bolt in operative communication with the rotor assembly;

joining the compressor section to the turbine section with the tie bolt;

coupling a stretch tool in operative communication with the tie bolt; the stretch tool comprising:

a hydraulic piston in operative communication with the tie bolt, the hydraulic piston including a shaft with a predetermined dimension;

a sensor in operative communication with the stretch tool, the sensor configured to indicate a dimensional change of the predetermined dimension; and

a controller in operative communication with the sensor and a servo valve; the servo valve is fluidly coupled with a hydraulic pump; the hydraulic pump fluidly coupled with the hydraulic piston; wherein the controller is configured to operate the hydraulic piston responsive to a signal from the sensor to attain a predetermined preload stretch on the tie bolt, curvic coupling, compressor section and turbine section.

15 . The process of claim 14 , further comprising:

forming a powerhead compressor within the compressor section;

forming a power turbine within the turbine section; and

creating a predetermined contact stiffness between the powerhead compressor and the power turbine; wherein the predetermined preload stretch is determined based at least in part on the predetermined contact stiffness.

16 . The process of claim 14 , further comprising:

configuring the predetermined preload stretch on the tie bolt along with internal rotor geometric interfaces to influence a rotor generated vibration.

17 . The process of claim 14 , further comprising:

configuring the sensor to measure the change in location of the hydraulic piston.

18 . The process of claim 14 , further comprising:

configuring the stretch tool to apply a tensile force on the tie bolt and the rotor assembly to preload the tie bolt and the rotor assembly.

19 . The process of claim 14 , further comprising:

applying the tensile force to the tie bolt configured as purely linear along an axis formed between the compressor section joined to the turbine section.

20 . The process of claim 14 , wherein the sensor comprises at least one of a strain gauge, a linear variable differential transducer, and a laser device configured to measure the change in location of the hydraulic piston.