WO1998038013A1

WO1998038013A1 - A tool incorporating a vibratable handle assembly

Info

Publication number: WO1998038013A1
Application number: PCT/IE1998/000018
Authority: WO
Inventors: Rudi Zellman; Hans Himbert; John Alfred; Erik Conn Jansson
Original assignee: Uirlis Torc Teoranta
Priority date: 1997-02-28
Filing date: 1998-03-02
Publication date: 1998-09-03
Also published as: AU6633298A

Abstract

A torque wrench incorporating a vibratable handle assembly comprises a steel tube (11) having at one end an adaptor (12) to, in use, engage a tool head (18) and at the other end a hand grip (60) enabling a user to engage and operate the tool. Sensing means within the tube (11) generate a signal indicative of the torque on the tool head, and a motor within the tube (11) is responsive to the sensing means to cause the hand grip (12) to vibrate when the signal reaches a pre-determined threshold value.

Description

A TOOL INCORPORATING A VIBRATABLE HANDLE ASSEMBLY

The present invention relates to a tool, in particular, an electronic to^"rque wrench, incorporating a vibratable handle assembly.

Conventional mechanical torque tools, especially click wrenches and screw drivers, provide a user with an audible and tactile feedback (click) , when the tool reaches a pre-set torque limit. These clicks are typically generated by spring/lever systems. These tools and mechanisms, however, are subject to wear and lack accuracy. Another disadvantage of these tools is that a user can easily over-torque a fastener/bolt without being aware of it. Such tools are being largely superseded by electronic torque tools which are far more accurate and allow a user to electronically store and adjust both the pre-set torque limit and to store and download measured data. These electronic tools traditionally only provide an audible and/or visible indicator that the pre-set torque limit has been reached or exceeded. Such tools, however, do not satisfactorily warn a user not to over-stress the bolt particularly if the tool is being used in a dimly lit or noisy environment .

It is an object of the present invention to provide a tool which provides a user with tactile feedback to provide the user with an improved warning not to over-stress the bolt.

Accordingly, the present invention provides a tool incorporating a vibratable handle assembly, the tool comprising a body having an adaptor to, in use, engage a tool head, a hand grip enabling a user to engage and operate the tool, and sensing means for generating a signal indicative of the state of the tool head, the body further including vibratable means responsive to the sensing means to cause the hand grip to vibrate when the signal reaches a pre-determined threshold value.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a side view of a torque wrench according to the invention including a vibratable handle assembly;

Fig. 2 is a plan view of the torque wrench of Fig. 1;

Fig. 3 is an exploded view of the hand grip end of the torque wrench of Fig. 1;

Fig. 4 is a detailed exploded view looking in the opposite direction to Fig. 3 of a vibrating motor assembly incorporated in the hand grip end of the torque wrench; and

Fig. 5 is a block diagram of the electronic circuit incorporated in the torque wrench.

Referring now to the drawings, a torque wrench 10 comprises a hollow generally cylindrical elongate steel tube 11. A generally cylindrical tool head adaptor 12 is dimensioned for a sliding fit into one end 13 of the tube 11, and a generally cylindrical plastics sleeve 60 is dimensioned for a sliding fit over the opposite end 63 of the tube 11 to provide a hand grip. The hand grip 60 is secured to the tube 11 by a grub screw 61, Fig. 3, which passes through respective holes 62A and 62B respectively in the hand grip 60 and tube 1.1.

The adaptor 12 is preferably fabricated from steel . The adaptor 12 is held in place within the end of the tube 11 by a pin (not shown) which passes through a hole in the tube into a corresponding hole in the adaptor. The adaptor 12 has a widened neck portion 14 to provide a step and an 0-ring 15 is located over the adaptor to sit against the step, Fig. 1. When the adaptor is inserted into the tube 11 the 0-ring bears against the end 13 of the tube 11 to prevent over- insertion of the adaptor into the tube 11 and provide a sealed fit between the adaptor 12 and the tube 11.

The external diameter of the adaptor 12 narrows to a reduced diameter hollow head 16 on which opposite flat surfaces 17 are formed. Each flat surface 17 incorporates a respective hole 19, Fig. 2. The internal surface of the head 16 is generally rectangular, allowing conventional tool heads, for example, a ratchet 18 to be mounted in the head 16.

Sockets of various sizes (not shown) may, in use, be mounted on the free end 20 of the ratchet 18. The wrench 10 may then be rotated back and forth about the tool head to secure a bolt (not shown) . As the bolt is secured, the applied torque on the tool head increases .

This torque is sensed by Thick Film Resistor strain gauge sensors (not shown) mounted on the adaptor 12 within the tube 11. The sensors are preferably connected in a Wheatstone Bridge network 100, Fig. 5, and an analog differential signal, generated from the bridge 100, is converted via an analog-to-digital converter (ADC) 102 to a digital signal which in turn is fed to a microcontroller 104.

The microcontroller 104 is mounted on a PCB (not shown) located inside a mid-section 21 of the tube 11 behind a panel 22 containing a keypad 130 (Fig. 5), an LCD display 106 and red and green LEDs 108. The panel 22 is mounted over an aperture 50 formed in the side of the mid-section 21 of the tube, Fig. 3. The panel 22 is secured to the tube 11 by a pair of grub screws 51, only one shown. The panel 22 is coupled to the PCB which contains the microcontroller 104 to enable a user to view and adjust, inter alia, a torque threshold value. The microcontroller 104 is programmed to receive and store input from the keypad 130 to adjust the pre-determined threshold value, which is stored in a nonvolatile memory (EEPROM 110) coupled to the microcontroller.

Referring particularly to Fig. 5, the digital parts of the circuit are powered by a 5V digital power supply 124, and the analog parts of the circuit are powered by an analog power supply 126, both derived from a 9V battery. The LCD display 106 and the LEDs 108 are driven by respective drive circuits 106A, 108A. The torque wrench also includes a buzzer 128 driven by a drive circuit 128A.

In use, a reset circuit 112 starts up a program in the microcontroller 104. The microcontroller, which controls activities on the circuit, goes through an initialisation routine and waits for a valid reading from the ADC 102.

The torque applied to the torque wrench is transformed to a change in resistance in the strain gauge bridge 100. This results in a change in voltage at the bridge outputs which is amplified by a pre-amplifier 114. This is then converted to a binary number for the microcontroller 104 by the ADC 102.

The user of the torque wrench may optionally store the displayed reading with time and date in the EEPROM 110 for later retrieval or serial download through an RS232 interface 118 to a computer or serial printer. A real time clock 116 with battery back up 122 keeps track of the time and date.

Low battery voltage is detected by a circuit 120 which feeds a voltage to the ADC 102. The microcontroller 104 then turns on a ' lo-bat' symbol on the LCD display 106. If the battery voltage falls below a predetermined level, the torque wrench no longer takes ADC readings and will not work.

If the torque tool has not been used for 60 seconds, the microcontroller 104 puts the circuit into a low power or sleep mode to conserve battery power - pressing the ON key 112 wakes it up again.

In use, the user selects an operating value of torque, X say, and a tolerance, A say, and enters these into the memory 110 by the keypad 130. This establishes upper and lower threshold values (X-A) and (X+A) respectively. In use, the microcontroller 104 monitors the signal produced by the sensors 100 and compares the signal with the threshold values. The microprocessor 104 is programmed to perform the following sequence of events during increasing torque:

(1) If the torque is below the lower threshold (X-A) , the green LED 108 flashes and the buzzer 128 gives an approaching alarm. The approaching alarm is a quickening beeping of the buzzer as the "GO" region, (X-A) to (X+A) , is approached.

(2) On entering the GO region, i.e. when the lower toque threshold (X-A) is reached, the approaching alarm becomes a continuous beep for 1/2 second and the green LED 108 is lit continuously.

(3) If the torque exceeds (X+A) the red LED is lit intermittently and the buzzer gives an interrupted alarm, i.e. it beeps on and off.

Steps 2 and 3 are not repeated if the torque falls out of the GO range and then re-enters it, unless the torque falls to less than 10% of X and then starts to increase again.

This, however, may not be sufficient warning for a user to indicate the torque threshold value has been met, particularly, in dimly lit or noisy environments. Therefore, the torque wrench is also provided with means to give a tactile warning to the user, in the present embodiment when the lower threshold value (X-A) is reached. This tactile warning takes the form of a 1/2 second vibration of the handle at step (2) above.

In the present embodiment of the invention, the microcontroller 104 is coupled to a motor 24 via a motor drive circuit 24A. The motor 24 is mounted within the end 63 of the tube 11 opposite the tool head, Fig. 3. An example of a suitable miniature D.C. motor is manufactured by Dome Co.

Ltd., Japan under model no. P06K. The motor 24 has a generally cylindrical housing and is powered via two wires 25 which extend from one end of the motor towards the mid- section 23 of the tube where they connect to the PCB.

A motor jig 2"7 comprises a semi-cylindrical body 28 conforming to the internal diameter of the tube 11, Fig. 3. A faceplate 31 is formed on the face of the jig 27 directed away from the mid-section 32. The faceplate 31 extends beyond the edges of the body 28 of the jig to prevent over- insertion of the jig 27 into the tube 11. A pair of radial flanges 29 project from the body 28 of the jig towards the mid-section 23. A seating 28A projects from the side of the flanges 29 opposite the body 28. The motor 24 is mounted parallel to the longitudinal axis of the tube 11 within a semi-cylindrical recess 26 formed in the seating 28, Fig. 4. The total transverse width of the motor/jig assembly is such that it just fits within the tube 11.

A shaft 40 projects from the end of the motor 24 opposite the wires 25, Fig. 4. An eccentric member in the form of a semi- cylindrical body 30 is mounted on the shaft 40. The body 30 projects beyond the end 63 of the tube 11 into the hand grip 60. When the sensor signal exceeds the lower threshold value (X-A) the microcontroller 104 actuates the drive circuit 24A so that the motor 24 is switched on for a pre-determined time, in this embodiment 1/2 second, and the shaft 40, together with the body 30, begins to rotate. During such rotation the semi-cylindrical cam 30 generates a dynamic imbalance, which in turn generates a tactile vibration in the wrench handle. This is turn causes the handle or hand grip to vibrate and to indicate to the user that the pre-determined lower torque limit has been reached and therefore causing the operator to cease tightening (torquing) and as a result avoiding the bolt or fastener being stressed.

The jig 27 also acts as a battery terminal for a battery housed within the hand grip 60. The battery (not shown) of the type with both terminals at the same end, is inserted into the hand grip by removing a stopper 64 which is inserted into the end of the hand grip 60 remote from the tube 11. A pair of reduced thickness seats 52 are defined in the faceplate 31 and accommodate respective electrical spring contacts 53 which bear against the battery terminals when inserted in the hand grip. Each contact 53 is connected via a respective wire 54, which passes on either side of the seating 28, to the PCB to power the microcontroller, its associated circuitry and the strain gauge circuitry.

The invention is not limited to the embodiments described herein which may be modified or varied without departing from the scope of the invention.

Claims

1. A tool incorporating a vibratable handle assembly, the tool comprising a body having an adaptor to, in use, engage a tool head, a hand grip enabling a user to engage and operate the tool, and sensing means for generating a signal indicative of the state of the tool head, the body further including vibratable means responsive to the sensing means to cause the hand grip to vibrate when the signal reaches a pre- determined threshold value.

2. A tool as claimed in claim 1, wherein the vibratable means comprises an electric motor mounted within the tool, the motor having a shaft carrying an eccentric member which causes the hand grip to vibrate when the motor rotates.

3. A tool as claimed in claim 1 or 2 , wherein the eccentric member is located within the hand grip.

4. A tool as claimed in claim 3, wherein the body is of elongate form with the adaptor mounted at one end of the body and a hollow sleeve constituting the hand grip slidably mounted over the other end of the body, and wherein the motor is mounted in the said other end of the body with the eccentric member projecting beyond the said other end into the hand grip.

5. A tool as claimed in any preceding claim, wherein the sensing means generates a signal indicative of the torque on the tool head.

6. A tool as claimed in any preceding claim, wherein the sensing means is coupled to the vibratable means via a microcontroller, the microcontroller being coupled to a memory in which the pre-determined threshold value is stored.

7. A tool as claimed in claim 6, wherein the tool incorporates a keypad which is coupled to the microcontroller, the microcontroller being programmed to receive and store input from the keypad to adjust the pre- determined threshold value.