GB2409770A

GB2409770A - Electrical machine tool

Info

Publication number: GB2409770A
Application number: GB0427612A
Authority: GB
Inventors: Albrecht Hofmann; Harald Krondorfer; Markus Heckmann; Thomas Schomisch
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2003-12-20
Filing date: 2004-12-16
Publication date: 2005-07-06
Anticipated expiration: 2024-12-16
Also published as: CN1628936A; DE10360251A1; GB0427612D0; GB2409770B; CN100439046C

Abstract

The invention is based on an electrical machine tool with a power supply unit (32, 132), which can be removed on the device side, to supply a drive motor with power, and with a switch (14, 114), which can be operated at least indirectly, to switch the drive motor on and off. It is proposed that an unlatching unit (22, 122) is provided, to guide the switch (14, 114) into a switched-off position when the power supply unit (32, 132) is connected, in the case that when the power supply unit (32, 132) was disconnected, the switching means (26, 126) to operate the switch (14, 114) was locked in an On position.

Description

Electrical machine tool

Prior art

The invention is based on an electrical machine tool according to the precharacterizing clause of Claim 1.

In general, battery-driven electrical machine tools have a plug-in end for a battery block. This contains, on the one hand, electrical contacts, and on the other hand, a locking system with mechanical locking. An electrical switch, which is operated via a switching means, is used to switch the electrical machine tool on and off. So that it is unnecessary to operate the switching means permanently during working use, it can be locked in the On position, in which the switch is switched on. After the lock is released, the switch generally snaps back automatically into the Off position, in which the switch is switched off.

When the battery block is replaced, it can happen that the switching means inadvertently remains locked in the On position, and when the charged battery block is connected, the electrical machine tool starts, which is not wanted.

Advantages of the invention The invention is based on an electrical machine tool with a power supply unit, which can be removed on the device side, to supply a drive motor with power, and with a switch, which can be operated at least indirectly, to switch the drive motor on and off.

It is proposed that an unlatching unit should be provided, to guide the switch into a switched-off position when the power supply unit is connected. The unlatching unit thus forcedly switches the switch off when the power supply unit is connected. The unlatching unit is designed, for instance by its dimensioning, and/or equipped, for instance by one or more additional components, to cause forced switching off of the switch. In this way, undesired starting of the electrical machine tool can be effectively prevented if a switching means to operate the switch has remained in the On position. The power supply unit is preferably a secondary or primary battery block. The operational safety of an electrical machine tool with lockable switching means is increased.

A defined arrangement to connect the power supply unit can be achieved if a switching means which can be operated externally is provided, particularly designed or equipped, to operate the switch when the power supply unit is disconnected and to lock in an On position. When the power supply unit is disconnected from the electrical machine tool, the switching means to operate the switch can be locked in an On position, irrespective of any setting by the operator. Preferably, the switch is connected, at least indirectly, to the switching means, which can preferably be operated externally. When the power supply unit is connected, the unlatching unit can then be operated forcedly via the switching means and/or an indirect connection.

If a spring element is provided, to bring the unlatching unit into an initial position to connect the power supply unit by a spring force of the spring element, irrespective of a position of the switching means, a defined state can be created before the power supply unit is connected. The spring element can be in the form of a compression spring, which pushes the unlatching unit into the initial position.

The unlatching unit can then, for instance, hook itself fast onto a switching means, and lock it in the initial position. Alternatively, the spring element can be a tension spring or torsion spring, which pulls the unlatching unit out, for instance from engagement with a switching means. To reconnect the power supply unit, the appropriate components are brought suitably into position.

If the unlatching unit, when the power supply unit is connected, is in at least indirect contact with the power supply unit, and if the power supply unit is intended to carry the unlatching unit along with it in its insertion movement, the forced switching off of the switch can be initiated in a simple, reliable manner.

High security against undesired starting of the electrical machine tool when the power supply unit is connected is ensured if the unlatching unit is provided, particularly formed or designed, for forced making of a contact between the unlatching unit and the power supply unit, before corresponding electrical contact means between switch and power supply unit come into contact. The geometry of the unlatching unit and the arrangement of the electrical contacts can be adapted in various types of electrical machine tool, in a useful, sensible manner.

Secure switching off of the switch when the power supply unit is connected is ensured if the unlatching unit has a first element, and the switching means has a corresponding second element, for bringing into and out of engagement together. Preferably, when the power supply unit is removed, the first element is in contact with the second element of the switching means, in such a way that the switching means is locked in an On position. Irrespective of how the operator has set the switching means, it is in a defined switching position, and when the power supply unit is connected, the unlatching unit always switches the switching means reliably into the Off position.

According to a first preferred embodiment, the switching means is a pushbutton, which engages with the operating device to operate a switching key of the switch.

Preferably, the unlatching unit is a tappet, to push the pushbutton when the power supply unit is connected, and to carry the operating device with it to switch off the switch. By connecting the tappet to the operating device of the switch, switching off the switch when the power supply unit is connected can be easily and securely achieved.

According to a second, preferred embodiment, the switching means includes a pawl, with which a switching key of the switch is in contact. Preferably, the unlatching unit includes an angular lever, which is carried so that it can be pivoted, for latching the switching means and to pivot when the power supply unit is connected. By unlatching the lever from the pawl, when the power supply unit is connected the switching key can be forcedly switched off, without the necessity of providing a further operating device.

Drawings Further advantages are given in the following drawing description. In the drawings, embodiments of the invention are shown. The drawings, description and claims include numerous features in combination. The person skilled in the art will also usefully consider the features individually, and combine them into sensible further combinations.

Fig. 1 shows a section of an arrangement according to the invention according to a first embodiment, with a switching key which operates a switching key of a switch indirectly, and Fig. 2 shows a section of an arrangement according to the invention according to a second embodiment, with a pawl which operates a switching key of a switch directly.

Description of the embodiments

Fig. 1 shows schematically a section of an electrical machine tool according to a first embodiment of the invention. A power supply unit 32, which is arranged in a housing 10, can be removed on the device side and is in the form of a battery block, is used to supply electric power to an electrical drive motor (not shown). The power supply unit 32, which is in the form of a battery block, has an angled neck 34, which points towards a switch 14, with electrical contact means 40, e.g. sockets. The switch 14 is connected to corresponding electrical contact means 38, e.g. plugs, which can be inserted into the sockets.

When the power supply unit 32 is plugged in, the drive motor is switched on and off via the switch 14, by an operating device 20 in the form of an adjusting bolt pressing on a switching key 8 of the switch 14. The operating device 20 in the form of an adjusting bolt can be moved via a switching means 26, which is in the form of a pushbutton and can be operated externally. A compression spring 16 automatically switches the switch 14 off after releasing the switching means 26 in the form of a pushbutton. The switching means 26 in the form of a pushbutton can be locked in an On position, in which the switch 14 remains switched on, by a locking lug 28 which is formed on the switching means 26 being suspended in a corresponding recess 12 of the housing 10.

When the power supply unit 32 is connected, an unlatching unit 22 in the form of a tappet is used to switch off the switch 14 forcedly, before the electrical contact means 40 of the power supply unit 32 come into electrical contact with the electrical contact means 38 which are assigned to the switch 14.

When the power supply unit 32 is removed, the unlatching unit 22 in the form of a tappet, irrespective of the position of the switching means 26 in the form of a pushbutton, is brought into a defined initial position by a spring element 24 in the form of a compression spring, which is arranged between the housing 10 and unlatching unit 22. When the power supply unit 32 is connected, e.g. after the preferred battery block is charged, this initial position ensures that the switch 14 is switched off.

When the power supply unit 32 is plugged in, the switch 14 can be switched on and off by the switching means 26 in the form of a pushbutton being shifted into the appropriate position in a longitudinal guide of a guide element 50 which is let into the housing 10. This is indicated in the figure by an arrow. The switching means 26 in the form of a pushbutton engages with a dog 46 in a recess 48 of the operating device 20 in the form of an adjusting bolt. If the switching means 26 in the form of a pushbutton is pushed to the right in the figure, the operating device 20 in the form of an adjusting bolt is released from the switching key 18 of the switch 14, which is thus switched off. The unlatching unit 22 in the form of a tappet is functionless when the power supply unit 32 is plugged in.

When the power supply unit 32 is removed, the spring element 24 in the form of a compression spring presses the unlatching unit 22 in the form of a tappet into its initial position, in the direction of the usual fitting location of the power supply unit 32. The unlatching unit 22 in the form of a tappet slides with an oblique outer contour of a lug 30 over a corresponding oblique outer contour 52 on the locking lug 28 of the switching means 26 in the form of a pushbutton, in which case the unlatching unit 22 in the form of a tappet can deviate transversely to the longitudinal axis of the unlatching unit 22 in the form of a tappet.

When the power supply unit 32 is connected into the housing 10, the unlatching unit 22 in the form of a tappet comes into contact with a spherical contact zone 42 with a corresponding recess 44 in an outer contour of the power supply unit 32, and as the power supply unit 32 is inserted further, is pushed by it against the spring force of the spring element 24 in the form of a compression spring. The unlatching unit 22 in the form of a tappet pushes the locking lug 28 a little forwards, and brings it out of engagement with the recess 12. The operating device 20 in the form of an adjusting bolt is pushed by the spring force of the compression spring 16 of the switch 14 into the Off position, and the switch 14 is switched off. The length of the unlatching unit 22 in the form of a tappet is chosen so that an electrical contact between the electrical contact means 38, 40 can only be made after the switch 14 is switched off.

Fig. 2 shows schematically a section of an electrical machine tool according to a second embodiment of the invention. A power supply unit 132, which is arranged in a housing 110, can be removed on the device side and is in the form of a battery block, is used to supply electric power to an electrical drive motor (not shown). The power supply unit 132 in the form of a battery block has an angled neck 134, which points towards a switch 114, with electrical contact means 140, e.g. sockets. The switch 114 is connected to corresponding electrical contact means 138, e.g. plugs, which can be inserted into the sockets. On a side facing the electrical contact means 140, the neck 134 has a contour, which seen from the contact means 140, begins with a lug 136 and changes into an indentation 144.

In this indentation 144, a leg, near the fulcrum, of an unlatching unit 122 in the form of an angular lever can pivot backwards and forwards.

When the power supply unit 132 is plugged in, the drive motor is switched on and off via the switch 114, by a switching means 126 in the form of a pawl, which can be operated externally and functions simultaneously as an operating device for the switch 114, pressing on a switching key 118 of the switch 114. The switching means 126 in the form of a pawl can be rotated to a limited extent around a fulcrum A, which is arranged on a side of the switching means 126 facing away from the switch 114.

After the switching means 126 in the form of a pawl is released, a compression spring 116 automatically switches off the switch 114. The switching means 126 in the form of a pawl can be locked in an On position, in which the switch 114 remains switched on, by a hook-shaped formation 120 which is formed on an outlying leg 128 of the switching means 126 being suspended in a corresponding pin 130 of the unlatching unit 122 in the form of a lever.

The formation 120 ends with a lug 142, which prevents sliding down from the pin 130. An outer contour from the lug 142 to the outlying leg 128 of the switching means 126 in the form of a pawl has an indentation 144, which is formed so that the pin 130 can slide over this outer contour, as long as the switching means 126 engages with the unlatching unit 122.

The unlatching unit 122 in the form of a lever can be pivoted around a fulcrum B which is arranged above the pin 130, which is connected to a spring element 124 in the form of a tension spring, which is connected to the housing 10 on the side facing away from the pin 130.

When the power supply unit 132 is connected, the lug 136 grazes the unlatching unit 122 and causes locking of the switching means 126 in the form of a pawl, so that forced switching off of the switch 114 follows.

To switch on, the switching means 126 in the form of a pawl is pressed, so that the switching key 118 of the switch 114 is operated and the switch 114 is switched on. To lock the On position, the unlatching unit 122 in the form of a lever is pivoted to the left in the figure. The pin 130 engages with the corresponding formation 120, and locks the switching means 126 in the form of a pawl.

To release the locking manually, the switching means 126 in the form of a pawl is pressed briefly inwards. The unlatching unit 122 in the form of a lever is released, and the spring element 124 in the form of a tension spring pulls the unlatching unit 122 in the form of a lever out of engagement. The unlatching unit 122 in the form of a lever is pivoted manually in the direction of the spring element 124. The lug 142 is overcome by the pin 130, and the unlatching unit 122 in the form of a lever comes out of engagement.

When the power supply unit 132 is removed, the lug 136 carries the unlatching unit 122 in the form of a lever with it, so that the pin 130 moves along the indentation 144 to the left in the figure, against the spring force of the spring element 124 in the form of a tension spring. After the power supply unit 132 is removed, the switching means 126 in the form of a pawl remains locked in the On position.

When the power supply unit 13 2 is connected, the locking is automatically released by the lug 136 carrying the unlatching unit 122 in the form of a lever with it and bringing the pin 130 out of engagement with the leg 128.

Because of the spring force of the compression spring 116 of the switch 114, the switching means 126 in the form of a pawl moves down away from the switching key 118, so that the switch 114 is switched off. The electrical contact means 138, 140, which correspond to each other, can only then make an electrical connection between the switch 114 and the power supply unit 132, and the manual machine tool is ready for operation.

Reference symbols housing 12 recess 14 switch 16 compression spring 18 switching key operating device 22 unlatching unit 24 spring element 26 switching means 28 locking lug lug 32 power supply unit 34 neck 38 contact means contact means 42 contact zone 44 recess 46 dog 48 recess guide element 52 oblique outer contour housing 114 switch 116 compression spring 118 switching key formation 122 unlatching unit 124 spring element 126 switching means 128 leg pin 132 power supply unit 134 neck 136 lug 138 contact means 140 contact means 142 lug 144 indentation 146 recess A fulcrum B fulcrum

Claims

Claims 1. Electrical machine tool with a power supply unit (32, 132),

which can be removed on the device side, to supply a drive motor with power, and with a switch (14, 114), which can be operated at least indirectly, to switch the drive motor on and off, characterized in that an unlatching unit (22, 122) is provided, to guide the switch (14, 114) into a switched-off position when the power supply unit (32, 132) is connected, in the case that when the power supply unit (32, 132) was disconnected, the switching means (26, 126) to operate the switch (14, 114) was locked in an On position.
2. Electrical machine tool according to Claim 1, characterized in that a spring element (24, 124) is provided, to bring the unlatching unit (22, 122) into an initial position to connect the power supply unit (32, 132) by a spring force of the spring element (24, 124), irrespective of a position of the switching means (26, 126) .
3. Electrical machine tool according to Claim 1 or 2, characterized in that when the power supply unit (32, 132) is connected, the unlatching unit (22, 122) is in at least indirect contact with the power supply unit (32, 132), and the power supply unit (32, 132) is intended to carry the unlatching unit (22, 122) along with it in its insertion movement.
4. Electrical machine tool according to one of the preceding claims, characterized in that the unlatching unit (22, 122) is provided for forced making of a contact between the unlatching unit (22, 122) and the power supply unit (32, 132), before corresponding electrical contact means (38, 40, 138, 140) between switch (14, 114) and power supply unit (32, 132) come into contact.
5. Electrical machine tool according to one of the preceding claims, characterized in that the unlatching unit (22, 122) has a first element (30, 130), and the switching means (26, 126) has a corresponding second element (28, 128), for bringing into and out of engagement together.
6. Electrical machine tool according to one of the preceding claims, characterized in that the switching means (26) is a pushbutton, which engages with the operating device (20) to operate a switching key (18) of the switch ( 14) .
7. Electrical machine tool according to Claim 6, characterized in that the unlatching unit (22) includes a tappet, to push the pushbutton when the power supply unit (32) is connected, and to carry the operating device (20) with it to switch off the switch (14).
8. Electrical machine tool according to one of Claims 1 to 5, characterized in that the switching means (126) includes a pawl, with which a switching key (118) of the switch ( 114) is in contact.
9. Electrical machine tool according to Claim 8, characterized in that the unlatching unit (122) includes an angular lever, which is carried so that it can be pivoted, for latching the switching means (126) and to pivot when the power supply unit (132) is connected.

lO.An electrical machine tool substantially as herein described with reference to the accompanying drawings.