Driving tool

Patent metadata

Field	Value
Publication number	US-9943952-B2
Application number	US-201414565993-A
Country	US
Kind code	B2
Filing date	Dec 10, 2014
Priority date	Dec 11, 2013
Publication date	Apr 17, 2018
Grant date	Apr 17, 2018

Abstract

An electro-pneumatic tool drives a fastener into a workpiece by energizing an electric motor to drive a first piston and generate compressed air in a first cylinder. The compressed air is then supplied to a second cylinder and causes a second piston to move and drive the fastener into the workpiece. After the first piston has passed through its top dead center, braking is applied to the first piston according to one or more braking parameters. Then, if a control unit determines that the first piston has come to a stop at a position that is outside a predetermined range about the bottom dead center of the first piston, one or more of the braking parameters is changed in a subsequent fastener driving cycle to cause the first piston to stop closer to its bottom dead center after conclusion of the subsequent fastener driving cycle.

First claim

The invention claimed is:

1. A driving tool configured to drive a driven article out of an ejection port, comprising:
a first cylinder;
a first piston slidably housed within the first cylinder;
a drive mechanism configured to drive the first piston;
a second cylinder in fluid communication with the first cylinder;
a second piston slidably housed within the second cylinder;
a communication path providing fluid communication between the first cylinder and the second cylinder;
a valve member provided in the communication path;
a sensor configured to directly or indirectly detect the position of the first piston; and
a controller configured to control movement of the first piston and operation of the driving tool such that:
the first piston is driven from its bottom dead center to its top dead center while the valve member is closed and fluid communication between the first cylinder and the second cylinder is blocked, in order to generate compressed air inside the first cylinder;
the valve member is then opened to supply the compressed air inside the first cylinder to the second cylinder via the communication path and cause the second piston to move and strike the driven article so that it driven out of the ejection port;
the first piston is stopped at a stopped position by braking the first piston with the drive mechanism or a brake after the first piston has passed through its top dead center; and
if the controller determines that the stopped position of the first piston detected by the sensor after a first driving operation ends is at a position other than its bottom dead center, then the braking of the first piston is adjusted such that the stopped position of the first piston after a second driving operation ends, which follows the first driving operation, is closer to its bottom dead center than after the first driving operation ended.

2. The driving tool according to claim 1 , wherein the controller is configured such that:
the braking of the first piston in the first driving operation occurs when a first amount of time has elapsed since the start of movement of the first piston from its bottom dead center; and
if the controller determines that the stopped position of the first piston after the first driving operation ends is a position other than the bottom dead center, then the braking of the first piston in the second driving operation occurs when a second amount of time, which differs from the first amount of time, has elapsed since the start of movement of the first piston from its bottom dead center.

3. The driving tool according to claim 2 , wherein the controller is configured such that:
in the first driving operation, if the controller determines that the first piston has stopped after passing beyond its bottom dead center, then the controller sets the second amount of time to be shorter than the first amount of time; and
the braking of the first piston in the second driving operation occurs when the second amount of time has elapsed since the start of movement of the first piston from its bottom dead center.

4. The driving tool according to claim 2 , wherein the controller is configured such that:
in the first driving operation, if the controller determines that the first piston has stopped before its bottom dead center, then the controller sets the second time to be longer than the first time; and
the braking of the first piston in the second driving operation occurs when the second amount of time has elapsed since the start of movement of the first piston from its bottom dead center.

5. The driving tool according to claim 1 , wherein the controller is configured such that:
in the first driving operation, when a predetermined amount of time has elapsed since the start of movement of the first piston from its bottom dead center, the braking of the first piston produces a first braking force; and
if the controller determines that the stopped position of the first piston after the first driving operation ends is a position other than the bottom dead center, then in the second driving operation, when the predetermined amount of time has elapsed since the start of movement of the first piston from its bottom dead center, the braking of the first piston produces a second braking force that differs from the first braking force.

6. The driving tool according to claim 1 , wherein the controller is configured such that:
in the first driving operation, the braking of the first piston is continuous for a first amount of braking time when a predetermined amount of time has elapsed since the start of movement of the first piston from its bottom dead center; and
if the controller determines that the stopped position of the first piston after the first driving operation ends is a position other than the bottom dead center, then in the second driving operation, when the predetermined amount of time has elapsed since the start of movement of the first piston from the bottom dead center, the braking of the first piston is continuous for a second amount of braking time that differs from the first amount of braking time.

7. The driving tool according to claim 1 , wherein:
the drive mechanism comprises a crank mechanism configured to reciprocally drive the first piston;
the crank mechanism comprises a crankshaft and a linking member, which links the crankshaft to the first piston;
the sensor is configured to output a detection result based upon a detected position of the crankshaft; and
the controller is configured to:
calculate a crank angle of the crankshaft based on the detection result of the sensor;
cause the braking of the first piston in the first driving operation when the crank angle is a first angle; and
if the controller determines that the stopped position of the first piston after the first driving operation ends is a position other than its bottom dead center, then in the second driving operation, the controller is configured to cause the braking of the first piston when the crank angle is a second angle that differs from the first angle.

8. The driving tool according to claim 7 , wherein the controller is configured such that:
in the first driving operation, if the controller determines that the first piston has stopped after passing beyond its bottom dead center, then the controller sets the second angle to be smaller than the first angle; and
the braking of the first piston in the second driving operation occurs when the crank angle is the second angle.

9. The driving tool according to claim 7 , wherein the controller is configured such that:
in the first driving operation, if the controller determines that the first piston has stopped before its bottom dead center, then the controller sets the second angle to be larger than the first angle; and
the braking of the first piston in the second driving operation occurs when the crank angle is the second angle.

10. The driving tool according to claim 1 , wherein:
the drive mechanism comprises an electric motor configured to drive the first piston; and
the controller is configured to cause the braking of the first piston by controlling the current supplied to the electric motor.

11. The driving tool according to claim 1 , wherein:
the drive mechanism comprises a crank mechanism configured to drive the first piston;
the crank mechanism comprises a crankshaft and a linking member, which links the crankshaft to the first piston;
the sensor is configured to output a detection result based upon a detected position of an element selected from the group consisting of the crankshaft, the linking member, and a rotary shaft of an electric motor drivably coupled to the crankshaft; and
the controller

Assignees

• Makita Corp

Inventors

• Kato Itsuku

Classifications

• B25C1/047 Primary

  Mechanical details · CPC title

• F15B15/149

  Fluid interconnections, e.g. fluid connectors, passages · CPC title

• F15B2211/8855

  Compressible fluids, e.g. specific to pneumatics · CPC title

• B25C1/06

  operated by electric power · CPC title

• F15B9/09

  with electrical control means · CPC title