# US 7,461,707 B2 · Electric horizontal directional drilling machine system

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- Number: US 7,461,707 B2
- Document ID: US7461707B2
- Status: Granted
- Kind: B2
- Application number: 11/456,800
- Filed: 2006-07-11
- Published: 2007-01-11
- Granted: 2008-12-09
- Earliest claimed: 2005-07-11
- Assignees: The Charles Machine Works, Inc.
- Inventors: Michael F. Gard
- Web page: https://patentgrep.com/patent/US7461707B2

## CPC

- H02P 27/06: using DC to AC converters or inverters (H02P27/05 takes precedence)
- E21B 3/02: Surface drives for rotary drilling
- E21B 7/046: {horizontal drilling (drilling with mechanical conveying means E21B7/003)}
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

An electric horizontal directional drilling machine. An electric horizontal directional drilling machine is powered by an electric power assembly. The power assembly is made up of a fuel cell and inverter, or multiple fuel cells with synchronized inverters, are used to power an electric motor controller and electric motor. The electric motor operates hydraulic pumps used to advance a drill string and downhole tool through the earth and operate various machine functions. Mechanical functions of the drilling machine may also be satisfied through the use of electric rotary actuators (e.g., motors) and linear actuators (e.g., linear motors and solenoids).

## Claims

### Claim 1

An electrically powered horizontal directional drilling machine comprising:
an electric power assembly comprising:
plurality of direct current power sources;
plurality of inverters, each one of the plurality of inverters operatively connected to one of each of the plurality of power sources;
an electrical transformer having a plurality of input windings; and
a control unit operatively connected to each inverter;
wherein each of the at least one inverters is connected to an input winding of the transformer;
an electric motor operatively connected to the power assembly;
a drill string, having a first end and a second end;
a drive system powered by the electric motor and operatively connectable to the first end of the drill string; and
a downhole tool connectable to the second end of the drill string;
wherein the drive system is adapted to advance the drill string and the downhole tool though the earth.

### Claim 2 (depends on 1)

The machine of claim 1, wherein each of the direct current power sources comprises a fuel cell.

### Claim 3 (depends on 1)

The machine of claim 1 wherein the electric power assembly further comprises a plurality of synchronizers, one each coupled to each of the plurality of inverters.

### Claim 4 (depends on 1)

The machine of claim 1 wherein the plurality of inverters of the electric power assembly each comprise a single phase inverter.

### Claim 5 (depends on 1)

The machine of claim 1 further comprising an electric motor controller operatively connected to the electric power assembly and adapted to adjust motor output.

### Claim 6 (depends on 1)

The machine of claim 1 wherein the transformer coupled to each inverter is adapted to provide a common voltage.

### Claim 7 (depends on 1)

The machine of claim 1, wherein each of the at least one inverters is adapted to maintain frequency and amplitude in response to control signals from the control unit.

### Claim 8 (depends on 2)

The machine of claim 2, wherein the control unit is adapted to maintain a timing relationship between the plurality of inverters.

### Claim 9 (depends on 8)

The machine of claim 8, wherein the power assembly further comprises a clock assembly connected to the control unit and the plurality of inverters, the clock assembly adapted to provide clock signals to the plurality of inverters.

### Claim 10 (depends on 2)

The machine of claim 2, wherein the transformer has a single output winding.

### Claim 11 (depends on 2)

The machine of claim 2, wherein the transformer has a plurality of output windings.

### Claim 12 (depends on 11)

The machine of claim 11, wherein the control unit is adapted to maintain a timing relationship between the plurality of inverters.