Rotary impact tool

Patent metadata

Field	Value
Publication number	US-9427852-B2
Application number	US-201113814250-A
Country	US
Kind code	B2
Filing date	Aug 8, 2011
Priority date	Aug 17, 2010
Publication date	Aug 30, 2016
Grant date	Aug 30, 2016

Abstract

A rotary impact tool comprises: a motor that is a rotation driving source; an impact generation device for generating a pulse impact by rotation of the motor and applying a rotational torque to an output shaft by the impact; a torque sensor for measuring the torque applied to the output shaft; and a control means for halting the motor when the torque measured by the torque sensor has reached a target torque having been set. The control means is configured to change an increased torque value for one impact according to the target torque having been set.

First claim

The invention claimed is:

1. A rotary impact tool comprising:
a motor comprising a rotation driving source;
an impact generator that generates a pulse impact by rotation of the motor and applies a rotational torque to an output shaft by the pulse impact;
a torque sensor for measuring the rotational torque applied to the output shaft; and
a controller for halting the motor when the rotational torque measured by the torque sensor has reached a predetermined target torque,
wherein the controller is configured to change an increased torque value for one impact with time from a start of generating the pulse impact, the increased torque value being a difference between torques to be output by two successive impacts,
wherein the predetermined target torque includes at least a first target torque and a second target torque that is different from the first target torque,
wherein the controller is configured to store, as the increased torque value:
at least two increased torque values for the first target torque, which respectively correspond to second and third torques to be output by second and third impacts; and
at least two second increased torque values for the second target torque, which respectively correspond to the second and third torques to be output by the second and third impacts,
wherein a second increased torque value corresponding to the second torque to be output by the second impact, of the two second increased torque values, is different from a first increased torque value corresponding to the second torque to be output by the second impact, of the two first increased torque values,
wherein the controller is configured to add, when the predetermined target torque is the first target torque, as the second torque, the first increased torque value corresponding to the second torque to be output by the second impact into a first torque to be output by a first impact, and, as the third torque, a first increased torque value corresponding to the third torque to be output by the third impact, of the two first increased torque values, into the second torque to be output by the second impact,
wherein the controller is configured to add, when the predetermined target torque is the second target torque, as the second torque the second increased torque value corresponding to the second torque to be output by the second impact into the first torque to be output by the first impact, and, as the third torque, a second increased torque value corresponding to the third torque to be output by the third impact, of the two second increased torque values, into the second torque to be output by the second impact, and
wherein the controller limits the increased torque value for one impact to a value so as to apply the impact at least a predetermined number of times until the predetermined target torque is reached.

2. The rotary impact tool according to claim 1 ,
wherein, when an error range of the predetermined target torque is up to ±x % of the predetermined target torque, x being greater than 0, the number of times the impact is to be applied until a lower limit in a range of the predetermined target torque is reached is greater than or equal to a value obtained by dividing 50 by x.

3. The rotary impact tool according to claim 1 ,
wherein the controller performs setting such that the lower the predetermined target torque is, the less the increased torque value is.

4. The rotary impact tool according to claim 1 ,
wherein the controller stores a reference torque, and reduces the increased torque value when the predetermined target torque is lower than the reference torque, and increases the increased torque value when the predetermined target torque is higher than the reference torque.

5. The rotary impact tool according to claim 1 ,
wherein the second target torque is lower than the first target torque, and
the second increased torque value is less than the first increased torque value.

6. The rotary impact tool according to claim 1 ,
wherein the controller limits an output from the motor according to the predetermined target torque.

7. The rotary impact tool according to claim 6 ,
wherein the controller limits a maximum rotation speed of the motor according to the predetermined target torque.

8. The rotary impact tool according to claim 6 ,
wherein the controller limits a maximum acceleration of the motor according to the predetermined target torque.

9. The rotary impact tool according to claim 1 ,
wherein the controller changes the increased torque value for one impact according to only a magnitude of the predetermined target torque.

10. The rotary impact tool according to claim 2 ,
wherein the controller performs setting such that the lower the predetermined target torque is, the less the increased torque value is.

11. The rotary impact tool according to claim 2 ,
wherein the controller stores a reference torque, and reduces the increased torque value when the predetermined target torque is lower than the reference torque, and increases the increased torque value when the predetermined target torque is higher than the reference torque.

12. The rotary impact tool according to claim 2 ,
wherein the second target torque is lower than the first target torque, and
the second increased torque value is less than the first increased torque value.

13. The rotary impact tool according to claim 2 ,
wherein the controller limits an output from the motor according to the predetermined target torque.

14. The rotary impact tool according to claim 1 ,
wherein the controller changes the increased torque value for one impact according to a value of a difference between the predetermined target torque, and the torque measured by the torque sensor, and according to a magnitude of the predetermined target torque.

15. The rotary impact tool according to claim 2 ,
wherein the controller changes the increased torque value for one impact according to a value of a difference between the predetermined target torque, and the torque measured by the torque sensor, and according to a magnitude of the predetermined target torque.

16. The rotary impact tool according to claim 1 , the first target torque and the second target torque being appropriate for workpieces of different sizes.

Assignees

• Mizuno Mitsumasa
• Ohashi Toshiharu
• Panasonic Ip Man Co Ltd

Inventors

• Mizuno Mitsumasa
• Ohashi Toshiharu

Classifications

• B25B23/1405 Primary

  for impact wrenches or screwdrivers · CPC title