EP0133557B1 - Ratchet wrench for driving screws - Google Patents

Description

The invention relates to a ratchet hand wrench for tightening screws, with a key head, from the underside of which an output shaft protrudes, a first sensor for the tightening torque, a second sensor for the angle of rotation, an optical detector connected to the key head and one with optically recognizable markings Impulse wheel, an evaluation electronics coupled to the first and the second transducer, which triggers an optical and / or acoustic signal when the tightening values defined for the screw to be tightened are reached, and an angle transmitter arm that can be rotated relative to the key head and is provided with a support foot that is used to fix the Angle of rotation reference size can be fixed via the support foot.

Such a ratchet hand wrench is known from DE-A 2932044. This hand key has a key head with an output shaft which protrudes from the underside of the key head. A first sensor for the angle of rotation is located on the hand wrench. The transducers are connected to evaluation electronics, which trigger an optical signal when the measured values for the angle of rotation and the torque match the preset target values. The angle of rotation sensor is located above the key head and consists of a rotary potentiometer, the resistance part of which is non-rotatably connected to the key head. The tap arm of the rotary potentiometer is connected to an angle encoder arm which is designed as a relatively rigid cable. The free end of the cable is attached to a fixed reference part, so that it does not change its position when the key is turned and thus the tap arm of the potentiometer is also held in a fixed position. The angle of rotation is determined on the basis of the change in resistance due to the relative movement between the tapping arm and the resistance body. The extent to which the resistance part of the potentiometer can move relative to the fixed tapping arm when the key is turned is determined and predetermined by the length of the resistance part. Therefore, the hand wrench cannot be turned over any area. Since the angle encoder arm acts on the tap arm above the key head, a tilting movement of the key head causes a change in the position of the angle encoder arm and key head. This also changes the position of the tap arm relative to the resistance part of the potentiometer, so that a misalignment is measured.

In the case of the known hand-held key, instead of the rotary potentiometer, it is also possible to use a measurement sensor which has an optical detector connected to the key head and a pulse wheel provided with optically recognizable markings. For correct measurement of the angle of rotation, the position of the impulse wheel must not change when the key is turned. For this purpose, the impulse wheel is designed as a disk with high inertia, which is mounted on the key head with low friction. With this measuring device, however, the angle of rotation cannot be measured exactly, since the disk does not exactly maintain its position when the hand key is actuated.

The invention has for its object to provide a ratchet hand wrench in which the angle of rotation is measured exactly and which is easy to use by hand.

To achieve this object, it is provided according to the invention that the angle transmitter arm is arranged below the key head, that the detector is arranged on the underside of the key head and the pulse wheel is rotatably coupled to the angle transmitter arm, that the evaluation electronics consist of a freely programmable microprocessor, in which a keyboard is used Numerical values and / or instructions can be entered and are assigned to the memory for the input and the respective screw connection values as well as a display for the inputs and / or missing entries, the display showing the user the respective screw connection state while tightening the screw, and that in the extension of the output shaft above the key head, a support head for gripping by hand is rotatably mounted.

In the hand wrench according to the invention, the angle transmitter arm is arranged below the key head and is coupled to the impulse wheel in a rotationally fixed manner. Below the key head is the detector, which turns when the hand key is rotated relative to the pulse wheel, which is fixed in place due to the angle encoder arm fixed to a reference part. In this way, the angle of rotation can be detected exactly.

When tightening a screw with the hand wrench according to the invention, the angle transmitter arm is due to its arrangement below the key head, approximately at the level of the head of the screw to be tightened. The lateral tilting of the key head around the screw head (pendulum movements) that may occur during screwing cannot therefore affect the position of the angle encoder arm, so that angle measurement errors are largely excluded.

With the hand wrench according to the invention, a holding force can be applied to the key head when a screw is tightened via the ball-bearing support head. This prevents the key head from tilting when tightening, so that the tightening force is almost completely converted into a tightening torque. Because of the ball bearings, there are no additional moments when the support head is supported by hand and therefore no measurement errors due to the additional moments.

The handheld key according to the invention is characterized by simple operation, even without operating instructions, since the built-in microprocessor on the display indicates the missing entries in response to a keyword. In addition, an objective quality assessment of the screw connection, which is displayed to the user and can be documented, is guaranteed by entering setpoints and tolerance limits in the microprocessor via the keyboard and by storing these values.

Further advantageous refinements of the invention result from claims 2 to 10.

An exemplary embodiment of the invention is explained in more detail below with reference to the figures.

• Fig. einen Teilschnitt durch den Kopf einer beispielsweisen Ausführungsform des Ratschenhandschlüssels,
• Fig. 2 die mittels einer Hülse nach unten verlegte Basis mit einem ihr zugeordneten in Achsrichtung verstellbaren Abstützbezugspunkt für den Winkelgeberarm,
• Fig. ein Blockschaltbild der Auswerteeinheit einschliesslich der Messwertaufnehmer für das Anziehdrehmoment und den Drehwinkel,
• Fig. 4 einen Ratschenhandschlüssel in perspektivischer Darstellung.

Show it:

• 1 shows a partial section through the head of an exemplary embodiment of the ratchet hand wrench,
• 2 shows the base, which is laid down by means of a sleeve, with a support reference point for the angle transmitter arm which is adjustable in the axial direction,
• 1 shows a block diagram of the evaluation unit including the measuring sensors for the tightening torque and the angle of rotation,
• Fig. 4 shows a ratchet hand wrench in perspective.

As shown in the figure, a reflex probe 4 is attached to the underside of the head 1 of the ratchet hand wrench 3 provided with an actuating arm 2, which is embodied in the exemplary embodiment by a small semiconductor light-emitting diode 4 '(as a transmitter) and a photo transistor 4 "as a receiver having a reflective light barrier (See Fig. 3) A pulse wheel 6 is attached to the base 5 of the key 3, which is rotatable relative to the output. The radiation plane of the reflex probe is axially parallel to the longitudinal axis of the flats 7 having the key output surface 8. Accordingly, the pulse wheel 6 assigned to the reflex probe 4 is cylindrical in shape and provided with an axially parallel line division 9. Such an arrangement of the reflex probe and the impulse wheel permits a relatively large axial play and relatively large assembly tolerances. The base 5 lying in the same direction as the output shaft 8, with which a holding fork 10 can be mechanically screwed, for example by screwing is connected, the hand wrench can also be rotated through 360 °, so that tightening processes can also be carried out in these areas.

A support head 11 is rotatably mounted on the end of the output shaft 8 projecting upward above the ratchet head 1 by means of a ball bearing 12. The support head is expediently latched by known means for the slight tightening of the screw with the output shaft. To screw in the screw until it is in contact with the workpiece, you can turn the support knob or, if necessary, separate it. The latter if the screw is to be prevented from going through during "ratcheting". The support button 11 can be removed in cramped conditions or placed on an extension. The lateral force applied via the support button in response to the tensile force on the handle largely ensures that the force is applied centrally, so that measurement errors due to additional moments are eliminated.

The rotation angle measuring device works as follows:

The ratchet 13 is fixed when the screw, not shown here, is tightened. Therefore, the reflex probe 4 rotates with the actuating arm 2 of the key and the output shaft 8 by the same angle as the screw.

Base 5 and impulse wheel 6 stand still. This creates a relative movement between the reflex probe 4 and the pulse wheel 6, with the result of a pulse generation for the rotation angle measurement. The pulses obtained are fed to a microprocessor via a suitable pulse shaper.

To improve the resolution between the reflex probe 4 and the pulse wheel 6 a fixed to the output shaft 8 counter visor 14 is inserted with the same pitch as the pulse wheel.

This counter visor also prevents a possible flexibility of the ratchet in the measurement result. In addition, with such a counter screen, the generation of angular pulses during the catch-up process can be suppressed and the angle of rotation of the output shaft based on the base can be measured directly.

The device for torque measurement, which preferably consists of a strain gauge bridge (DMS bridge) 15 and an A / D converter 16, is arranged in the hand wrench (see FIG. 3).

As illustrated in FIG. 2, the base 5 can be laid down using an extension sleeve 18. This means that the support reference point 19 (magnet) can also be attached to the screw near extensions. As a result, angular fields attributable to pendulum movements of the operator can be kept very small. The extension sleeve 18 is firmly connected to the base 5. An extension shaft 8 'extends coaxially through them, which is attached to the square 20 and has a square 20' at the other end. The extension sleeve 18 is provided with a second base 5 ′ which is engaged by the second holding fork 10 ′, which is connected to the support reference point 19 via a shaft.

3 shows that the light beam emitted by the semiconductor diode 4 ', for example in the form of a GaAs diode, reaches the impulse wheel 6 via the counter diaphragm 14 and from there, according to the line division, to a photo, for example transistor-designed receiver 4 "is thrown back. After suitable conversion of the light pulses arriving in the receiver in a pulse shaper 21, these arrive in the microprocessor 22. Accordingly, the torque values determined with the aid of the strain gauge measuring bridge 15 are converted to the A / D converter 16 Microprocessor fed.

The microprocessor is equipped with a keyboard 23, by means of which the desired data (setpoints, limit values, tightening method, etc.) can be entered; (Default values).

It is possible to enter the data or settings for a large number of different screwing cases and to store them in numbered memories 24, so that the data can be called up easily when needed or reused.

The end values reached during a large number of screwing operations can be saved with data and time.

For this purpose, a corresponding quartz clock 25 is assigned to the microprocessor.

The stored values can be called up at any time, for example when all screw connections on a vehicle have been completed. A data memory 26 is also connected to the microprocessor. The data including a previously entered code for the operator and the customer order can be called up if necessary, for example during the times when the hand key is not required and is in a storage position (breaks in operation).

The data entry can directly result in a control strip print or be saved in general data processing systems in order to be documented on the accompanying documents of the product. Such a printer is designated 27 in FIG. 3.

An alpha-numerical display 29 is assigned to the microprocessor 22 built into the hand key, on which the microprocessor uses a keyword to indicate the next entries that are still missing. This ensures safe operation even without instructions for use.

• Phase 1: Die Schraube liegt an, die Wnikelzählung beginnt.
• Phase 2: Die Schraube ist etwa zu 50% angezogen.
• Phase 3: Die Schraube ist etwa zu 90% angezogen.
• Phase4: Die Schraubverbindung ist fest, die Anziehwerte der Schraube liegen im Toleranzbereich.
• Phase 5: Die Schraube ist zu stark angezogen.

The user of the key is guided in different phases while tightening the screw in question. These can be broken down as follows, for example:

• Phase 1: The screw is in contact, the particle counting begins.
• Phase 2: The screw is about 50% tightened.
• Phase 3: The screw is about 90% tightened.
• Phase4: The screw connection is firm, the tightening values of the screw are within the tolerance range.
• Phase 5: The screw is tightened too much.

The display can be made by a bar, the length of which corresponds to the current tightening phase. Another possibility is to assign certain colored light signals to the individual tightening phases. For example, phase 1 can be made visible by a lamp 30 emitting permanent yellow light and the second phase by the same lamp in flashing mode. To identify the third phase, a further lamp 31 is provided, which flashes green alternately with lamp 30, so that yellow flashes alternately with green.

The fourth phase is assigned the lamp 31 with continuous green light. In the case of incorrect screwing, to which phase 5 corresponds, a lamp 32 with a permanent red light is recommended.

Alternatively or at the same time, there is the possibility of using colored light signals on the handle of the key to activate the colored light signals so that they can be easily recognized from all sides and positions.

Additionally or alternatively, the microprocessor 22 can also work on an acoustic signal generator 33, which makes the individual phases recognizable by signals through different frequencies and repetition times.

The limits between tightening phases 1, 2 and 3 are not entered, but calculated automatically. This means simplifying operation.

The support surface of the hand key is designed so that the key, while it is stored, enables various additional functions to be carried out. The batteries installed in the key can be charged via a line leading to the charger. However, it is also possible to charge the batteries inductively. Furthermore, the data stored in the microprocessor can be queried or printed out and new data can be entered into the microprocessor or into the memory or memories.

There is the possibility of integrating the printer 27 as a unit with the battery charger 34 into the tool storage.

In order to expand the working range of a hand key according to the invention, the actuating arm 2 or the handle tube can be made telescopically extendable. For yield point controlled tightening processes, the default values are theoretically derived mathematically from the entered nominal or limit values for torque and angle, so that no additional operation is required.

Appropriate programming can also be used for quality assessment procedures that could not previously be used in practice due to complicated evaluation mechanisms.

As indicated in FIG. 4, the hand key contains a socket 35 in the handle part 2 ', into which a plug 37 connected to a lead 36 can be inserted for charging the batteries in the key.

Claims (10)

1. Ratchet wrench for tightening screws comprising

- a wrench head (1) from whose underside extends a driven shaft (8),

- a first pickup for measuring data concerning the tightening torque,

- a second pickup for measuring data concerning the angle of rotation and including an optical detector (4) connected to the wrench head (1) and a pulse wheel (6) provided with optically visible marks,

- evaluating electronics coupled to the second pickup for measuring data and initiating an optical and/or acoustic signal upon reaching tightening values defined for the screw to be tightened and

- an angle indicator arm rotatable relative to the wrench head (1) and provided with a support base (19) said arm being fixable via the support base (19) for fixing the reference value of the angle of rotation,

characterized in that

- the angle indicator arm is provided beneath the wrench head (1),

- the detector is arranged at the underside of the wrench head (1) and the pulse wheel (6) is coupled nonrotatingly to the angle indicator arm,

- the evaluating electronics consist of a freely programmable microprocessor (22) into which, via a keyboard (23), numerical values and/or orders may be inputted and to which memories (24, 26) for the input values and the respective screw tightening values and a display (29) for the input data and/or still missing input data are coordinated, the display (29) showing to the user during the screw tightening operation the respective screwing codition and

- in the extension of the driven shaft above the wrench head (1), a support head (11) is pivotally provided for manual actuation.

2. Wrench head as defined in claim1, characterized in that, via a forked holder (10), the angle indictor arm is hingedly connected to a base (5) rotatable relative to the wrench head (1) and to the driven shaft (8), a pulse wheel (6) being fixed to said base.

3. Wrench as defined in claim 2, characterized in that the base (5) is extended by an adaptor sleeve (18) in which is accomodated a coaxial adaptor driven shaft (8') mounted on the driven shaft (8).

4. Wrench as defined in one or more of claims 1 to 3, characterized in that between detector (4) and pulse wheel (6), there is provided in cylindrical shield (14) provided coaxially with respect to the pulse wheel (6) and being connected nonrotatingly to the driven shaft (8).

5. Wrench as defined in one or more of claims 1 to 4, characterized in that the detector (4) is a reflex light barrier consisting of a light emitting diode (4') and of a phototransistor (4"), the radiation plane extending in parallel to the wrench axis, and that the pulse wheel (6) is a cylinder provided with graduation marks (9).

6. Wrench as defined in one or more of claims 1 to 5, characterized in that the support head (11) is mounted to be removable and to be lockable on the driven shaft (8).

7. Wrench head as defined in one or some of claims 1 to 6, characterized in that the microprocessor (22) is provided in or at a handle (2) projecting from the wrench head (2).

8. Wrench head as defined in one or more of claims 1 to 7, characterized in that the microprocessor (22) is connected to a number of indicator lamps (30, 31, 32) of different colors which show the respective screwing condition and/or to an acousting signal generator (33) showing the respective screwing condition.

9. Wrench as defined in one or more of claims 1 to 8, characterized in that in or at a handle (2) projecting from the wrench head (1), a battery is accomodated to supply energy for the evaluating electronics and the pickup for measuring data.

10. Wrench as defined in one or more of claims 1 to 9, characterized in that the first pickup for measuring data comprises a wire resistance strain gauge-bridge (15) and an A/D converter (16).

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