# US 12,015,364 B2 · Impact tools and control modes

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- Number: US 12,015,364 B2
- Document ID: US12015364B2
- Status: Granted
- Kind: B2
- Application number: 17/571,246
- Filed: 2022-01-07
- Published: 2022-06-23
- Granted: 2024-06-18
- Earliest claimed: 2020-12-18
- Assignees: Black & Decker Inc.
- Applicants: Black & Decker Inc.
- Inventors: Brian E. Friedman; Peter Hague Wadeson; Eric Louis Kunz; Bhanuprakash Villuri; Tyler Petrus; Wing W. Lin
- Web page: https://patentgrep.com/patent/US12015364B2

## CPC

- H02P 29/027: {the fault being an over-current}
- B25B 21/02: with means for imparting impact to screwdriver blade or nut socket
- B25B 21/023: {for imparting an axial impact, e.g. for self-tapping screws}
- B25B 21/026: {Impact clutches}
- B25B 23/1475: {for impact wrenches or screwdrivers}
- B25B 23/18: Devices for illuminating the head of the screw or the nut
- B25D 17/06: Hammer pistons; Anvils {; Guide-sleeves for pistons}
- B25F 5/00: Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
- H02P 3/06: for stopping or slowing an individual dynamo-electric motor or dynamo-electric converter
- H02P 6/157: {wherein the commutation is function of electro-magnetic force [EMF]}
- H02P 6/21: Open loop start
- H02P 6/28: Arrangements for controlling current (H02P6/10 takes precedence)
- H02P 29/032: Preventing damage to the motor, e.g. setting individual current limits for different drive conditions
- B25D 2250/095: Electric motors
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- B25B: TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING, OR HOLDING
- B25D: PERCUSSIVE TOOLS {(percussive machines for forging B21J; hand-held drilling machines, in general B23B45/00, for wood B27C3/08; drilling machines, used for mining or quarrying, with reciprocating tool which is turned intermittently when out of contact with the working face E21B1/00)}
- B25F: COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR {(machines or arrangements of machines for performing specified combinations of different metal-working operations not covered by a single other subclass B23P23/00 and subgroups)}

## Abstract

A power tool includes a housing, a brushless motor received in the housing, a power switch coupled to the housing and actuatable by a user, a controller configured to control power delivery to the motor in response to actuation of the power switch, and an output spindle configured to rotate when the motor is energized. The controller is configured to maintain an amount of current delivered to the motor to be less than or equal to a current limit by turning off or reducing power to the motor for a time period if the current exceeds the current limit and then restarting power delivery to the motor. The time period is greater than the duration of one full current cycle.

## Claims

### Claim 1

A power tool comprising:
a housing;
a brushless motor received in the housing;
a power switch coupled to the housing and actuatable by a user;
a controller configured to control power delivery to the motor in response to actuation of the power switch;
an output spindle configured to rotate when the motor is energized; and
an impact mechanism configured to be driven by the motor and configured to rotationally drive the output spindle, the impact mechanism configured to selectively apply rotational impacts to the output spindle when a torque on the output spindle exceeds a torque threshold,
wherein the controller is configured to apply a current limit to current delivered to the motor over a plurality of current cycles by turning off or reducing power to the motor for a time period if the current exceeds the current limit during a current cycle and then restoring power delivery to the motor at the end of the time period,
wherein the current limit is selected and the controller is operable so that, when driving a fastener into a hard joint, the current limit is reached while applying rotational impacts, and the impact mechanism continues to apply rotational impacts to the fastener while the current limit is applied.

### Claim 2 (depends on 1)

The power tool of claim 1, wherein the time period is less than the duration of two full current cycles.

### Claim 3 (depends on 1)

The power tool of claim 1, wherein, the time period is a fixed amount of time.

### Claim 4 (depends on 1)

The power tool of claim 1, wherein the time period is a sum of a duration of time remaining in the current cycle plus one full additional current cycle.

### Claim 5 (depends on 1)

The power tool of claim 1, wherein the current limit is selected to allow the impact mechanism to impact while inhibiting damage to components of the power tool.

### Claim 6 (depends on 1)

The power tool of claim 1, wherein the controller is further configured to control power delivered to the motor during a first phase of operation with open loop control and a baseline conduction band and advance angle setting when a sensed tool operation parameter is one of above or below a threshold value, and to control power delivered to the motor during a second phase of operation with closed speed loop control and an increased conduction band and advance angle setting when the sensed tool operation parameter is the other of above or below the threshold value.

### Claim 7 (depends on 1)

The power tool of claim 1, wherein the controller is configured to control power delivered to the motor with a first target rotational speed for a predetermined time period after the controller detects the first impact or after a motor speed has dropped below a speed threshold value, and the controller is configured to control power delivered to the motor with a second target rotational speed after the predetermined time period, the second target rotational speed greater than the first target rotational speed and the first target rotational speed being less than a motor speed when the first impact is detected or when the motor speed drops below the speed threshold value.

### Claim 8 (depends on 7)

The power tool of claim 7, wherein the controller is configured to control power delivered to the motor with the first target rotational speed using a first closed loop control with a first conduction band value and a first angle advance value, and the controller is configured to control power delivered to the motor with the second target rotational speed using a second closed loop control with a second conduction band value and a second angle advance value, wherein at least one of the second conduction band value is greater than the first conduction band value or the second advance angle value is greater than the first advance angle value.

### Claim 9 (depends on 1)

The power tool of claim 1, wherein, when driving a fastener into the hard joint while applying rotational impacts, the current limit is reached during a plurality of the current cycles.

### Claim 10 (depends on 9)

The power tool of claim 9, wherein, when driving a fastener into the hard joint while applying rotational impacts, the current limit is reached during at least 35% of the current cycles.

### Claim 11 (depends on 1)

The power tool of claim 1, wherein, when driving a fastener into a soft joint while applying rotational impacts, the current limit generally is not reached.

### Claim 12 (depends on 11)

The power tool of claim 11, wherein, when driving a fastener into the soft joint while applying rotational impacts, the current limit is reached less than 5% of the current cycles.

### Claim 13

A method for controlling power delivery to a brushless motor in a power tool including an impact mechanism configured to be driven by the motor and configured to rotationally drive an output spindle, the impact mechanism configured to selectively apply rotational impacts to the output spindle when a torque on the output spindle exceeds a torque threshold, the method comprising:
receiving an input from a user-actuatable power switch; and
applying, via a controller, a current limit to current delivered to the motor over a plurality of current cycles by turning off or reducing power to the motor for a time period if the current exceeds the current limit during a current cycle and then restoring power delivery to the motor at the end of the time period,
wherein the current limit is selected and the controller is operable so that, when driving a fastener into a hard joint, the current limit is reached while applying rotational impacts, and the impact mechanism continues to apply rotational impacts to the fastener while the current limit is applied.

### Claim 14 (depends on 13)

The method of claim 13, wherein the time period is less than the duration of two full current cycles.

### Claim 15 (depends on 13)

The method of claim 13, wherein, the time period is a fixed amount of time.

### Claim 16 (depends on 13)

The method of claim 13, wherein the time period is a sum of a duration of time remaining in the current cycle plus one full additional current cycle.

### Claim 17 (depends on 13)

The method of claim 13, further comprising selecting the current limit to allow the impact mechanism to impact while inhibiting damage to components of the power tool.

### Claim 18 (depends on 13)

The method of claim 13, further comprising controlling power delivered to the motor during a first phase of operation with open loop control and a baseline conduction band and advance angle setting when a sensed tool operation parameter is one of above or below a threshold value, and controlling power delivered to the motor during a second phase of operation with closed speed loop control and an increased conduction band and advance angle setting when the sensed tool operation parameter is the other of above or below the threshold value.

### Claim 19 (depends on 13)

The method of claim 13, further comprising controlling power delivered to the motor with a first target rotational speed for a predetermined time period after the controller detects the first impact or after a motor speed has dropped below a speed threshold value, and controlling power delivered to the motor with a second target rotational speed after the predetermined time period, the second target rotational speed greater than the first target rotational speed and the first target rotational speed being less than a motor speed when the first impact is detected or when the motor speed drops below the speed threshold value.

### Claim 20 (depends on 19)

The method of claim 19, further comprising controlling power delivered to the motor with the first target rotational speed using a first closed loop control with a first conduction band value and a first angle advance value, and controlling power delivered to the motor with the second target rotational speed using a second closed loop control with a second conduction band value and a second angle advance value, wherein at least one of the second conduction band value is greater than the first conduction band value or the second advance angle value is greater than the first advance angle value.

### Claim 21 (depends on 13)

The method of claim 13, wherein, when driving a fastener into the hard joint while applying rotational impacts, the current limit is reached during a plurality of the current cycles.

### Claim 22 (depends on 21)

The method of claim 21, wherein, when driving a fastener into the hard joint while applying rotational impacts, the current limit is reached during at least 35% of the current cycles.

### Claim 23 (depends on 13)

The method of claim 13, wherein, when driving a fastener into a soft joint while applying rotational impacts, the current limit generally is not reached.

### Claim 24 (depends on 23)

The method of claim 23, wherein, when driving a fastener into the soft joint while applying rotational impacts, the current limit is reached less than 5% of the current cycles.