Patent Application
20050161241
The invention relates to a handle for an electric tool.
Electric tools are provided with handles for operating them. Drills or pneumatic drills, for example, are provided with a handle that permits the electric tool to be held in the working position. This handle is frequently associated with an on-off switch and/or other controls. In the broadest sense, therefore, the handle is used to operate the electric tool. It permits the electric tool to be held in the working position, a force to be exerted, in particular along the central axis of the device and therefore parallel to the axis of a tool being used, for example a drill bit, and a torque to be exerted, which is used as a reaction torque opposing the torque resulting from the rotation of the tool when a load is placed on it.
In addition, auxiliary handles are known, which permit a two-handed operation of an electric tool. The main handle, which is usually situated at the end of the electric tool oriented away from the insert tool, is held with the one hand. This hand also operates the electric switch device, which is usually accommodated in this handle. In order to provide support, particularly in high-torque machines and in applications in which a powerful torque is exerted on the operator, for example when drilling with large diameters, when using annular drill bits, or when using the electric tool as a drive unit for a mixer, an auxiliary handle is provided, which permits the operator to also exert an assisting reaction torque with his other hand. Usually, this auxiliary handle is attached to the front end of the electric tool, i.e. the end associated with the tool-receiving socket. The handle is usually mounted either by means of an internal thread provided inside the machine, for example in the collar of the machine, or (more universally) through the use of a clamping strap or clamping device that is associated with the auxiliary handle and is slid over the collar of the machine and locked by means of a screw clamping mechanism.
A feature common to these handles known from the prior art is that they cannot be used for functions other than those mentioned above, namely holding the electric tool in a particular working position and exerting forces and/or a torque.
Specifically in high-torque electric tools or in electric tools that exert very powerful forces on the work piece, for example pneumatic drills, it is known that safe handling requires two-handed operation. The electric tools known from the prior art with the handles known from the prior art always supply the same output to the tool-receiving socket regardless of whether one or two handles are mounted and regardless of whether the operator is working with one or two hands. It is therefore possible, with the sudden occurrence of a spike in torque, for the electric tool to be thrown from the operator's hands. This is particularly the case if the insert tool, for example a large diameter drill bit or annular drill bit, jams in the work piece and the torque causes the machine to start rotating around the drill bit axis. If the user is not prepared for these abruptly occurring spikes in torque and is only holding the machine e.g. with the main handle at the rear end of the electric tool, then the rotation can easily throw the machine from the hand holding the electric tool, which can cause injuries to the operator. In particular, it is also possible here for the machine to slip out from the work piece and damage the work piece during the time that the insert tool and the driven tool-receiving socket are coasting to a final stop from the running state. It is also possible for it to damage nearby objects and injure the user himself.
Current designs for safely operating an electric tool known from the prior art by exerting the required reaction forces and the required reaction torque are only effective if the operator uses them conscientiously. Experience has shown that particularly with operators who regularly and routinely use electric tools, there is a significant degree of habitual negligence with regard to careful, safe practices with electric tools. For example, even high-powered and high-torque electric tools are often casually held with one hand or auxiliary handles are not even installed because an auxiliary handle has a natural tendency to lend the machine a slightly less agile feel.
The handle according to the invention includes at least one detecting unit. In comparison to the embodiment forms known from the prior art, it has the advantage that various physical values can be detected and used for operation control.
In the embodiment of the detecting unit in the form of an equipment detecting unit, it is possible to determine, for example, whether a handle, in particular an auxiliary handle, is attached to the electric tool. It is possible to detect other equipment features, as long as the detecting unit is suitably designed to do so. For example, a chuck setting can be detected, thus allowing inferences to be drawn regarding the presence of the tool and the torque to be expected from it.
When embodied in the form of an operation-detecting unit, the device senses whether and how the operator is grasping the electric tool.
The values detected generate electrical signals inside the detecting unit integrated into the handle. In this connection, either a binary state change of the signal occurs, depending on whether or not the detecting unit has detected the corresponding value, or a signal change (or a change in an applied voltage) occurs, which is essentially analogous or essentially proportional to the detected value. It is likewise possible for the detecting unit to generate a signal in a form appropriate to the intended use, which signal corresponds to an applied or detected value and is transmitted, for example via contacts or a bus system, to the electric tool and to a control and/or regulating unit integrated into the tool to which the handle is connected. The physical values detected can be signaled to the electric tool and evaluated there by means of the control and/or regulating unit or a switching device integrated into the electric tool. The control and/or regulating unit then automatically triggers a corresponding operating behavior of the electric tool. The same is true for the switching device; the control and/or regulating unit can change the operating behavior on an essentially continuous basis, while the switching device produces a binary state or changes it, e.g. switches the tool on or off.
The ability of the handle to function as a holding device for the electric tool is therefore independent of whether or not such a control and/or regulating unit is provided in the electric tool. The handle therefore offers an appropriately equipped electric tool additional functions that facilitate operation of the electric tool and/or make it safer. Independent of this, it can also be used simply as a holding device or as a combined holding and switching device in electric tools that are not so equipped, as is already known from the prior art. The term switching device here is essentially understood to mean the electrical on/off switch.
As described above, the handle can include a unit for detecting the machine equipment that is present or a unit for detecting one or more types of operation of the machine.
It is thus possible, as part of the operation detection, to determine whether the operator is holding the handle. To this end, the detecting unit can be embodied in the form of a contact sensor extending over a certain span of the handle surface, or in the form of a force sensor. It is then possible to detect whether the operator is holding the electric tool with only one hand or whether he is operating it with two hands. The term two-handed operation applies only when the operator is holding both the main handle and the installed auxiliary handle at the same time. The force sensor can also be embodied so that it detects any forces occurring in the region in which it is installed or permits conclusions to be drawn regarding the direction and magnitude of an applied force (vector), for example the holding force. In this case, the detection can occur the moment the electric tool is switched on in order to determine whether it is permissible to supply the maximum possible output when the operator is holding the electric tool with both hands or whether only a reduced output capacity is permitted due to a one-handed operation. The detection can also occur during operation of the electric tool, for example in order to be able to react to a release of the auxiliary handle by reducing the output. It is particularly advantageous to provide a combination of operation detection at the moment the electric tool is switched on and operation detection during operation.
By embodying the detecting unit as a torque sensor, it is also possible to detect a torque acting on the machine by detecting the reaction torque that the operator must exert and to evaluate this using a control and/or regulating unit of the drive that is integrated into the electric tool. Such a torque sensor can be positioned in an advantageous, structurally simple manner, for example on the screw clamping mechanism that encompasses the collar of the electric tool close to the power end, namely the drill chuck or the tool-receiving socket, for example. It can, for example, be embodied as an expansion band or can be comprised of several parts, for example with a corresponding mechanical locking mechanism on the electric tool and on the handle.
In the same way, the forces to be exerted by the operator, in particular holding forces, can be detected and supplied for evaluation to a control and/or regulating unit inside the electric tool. As a function of this detection, the control and/or regulating unit controls or regulates the torque and speed of the electric motor. To this end, a force sensor is provided, which detects the force transmitted between the operator and the handle.
The precise location of the corresponding detecting unit inside the handle is unimportant to the function of the invention, as long as the detection of the physical value to be recorded occurs with a sufficient degree of reliability.
The embodiment of a detecting unit in the form of an acceleration sensor even permits the evaluation of an acceleration of the electric tool out of its working position due to a sudden jamming of the machine and, after this is supplied to a control and/or regulating unit in the machine, permits an automatic shutoff of the drive unit of the electric tool or a triggering of an automatic braking mechanism of the tool-receiving socket, thus almost completely excluding a danger to the operator. The acceleration sensor is advantageously disposed inside a handle. Namely, if the handle experiences an acceleration (for example at one of its ends), then it thus possible to correctly conclude that an atypical and undesirable operating state is in the process of occurring, for example a jamming of the insert tool in the work piece. In other words, the acceleration of the electric tool detected in the handle occurs specifically due to the sudden occurrence of a force vector in a direction that is atypical during regular operation. Here, too, the precise location of the detecting unit in the handle is unimportant to the function of the invention, as long as the detection occurs with a sufficient degree of reliability.
The value detected by the detecting unit in and/or on the handle is transmitted to the electric tool via a contacting device. It is advantageous if such a transmitting device is embodied in the form of a contact device and a counterpart contacting device, in which the position and size of the contact areas correspond to each other.
In a particularly advantageous embodiment, the transmitting device operates in a contactless manner, namely through the use of an infrared interface between the handle and the electric hand tool or through the use of a suitable radio signal transmission device. In another advantageous embodiment, the transmission device is embodied to function inductively or capacitively.
The operation control of the electric tool therefore occurs in steps so that a detection is carried out as to whether the electric tool is being held by at least one handle, i.e. is being grasped firmly by it, and based on the results of this detection, the unit executes a corresponding regulation of the available output power and therefore the available torque at the power end.
In a modification of the invention, a detection is also carried out as to whether an auxiliary handle is attached to the electric tool.
In a modification of the invention, when the detection determines that the electric tool is equipped with a main handle and an auxiliary handle and both handles are being held, i.e. are being grasped firmly, then a higher torque is supplied at the power end than when either an auxiliary handle is not present or one of the handles is not being grasped firmly. This assures that the maximum power output of the electric tool is supplied only if the operator complies with safe operating practices and is holding the electric tool with both hands.
In a preferred modification of the invention, during the course of operation control, detecting units in the handle or in several handles continuously monitor the operating states of the electric tool for the occurrence of an abnormal operating force and/or an abnormal operating torque between the electric tool and the work piece and therefore between the electric tool and the operator and/or an abnormal operating acceleration. In this connection, a value is seen to be abnormal when it exceeds a particular preset value. Upon detection of at least one abnormal operating value, a control and/or regulating unit associated with the electric tool can reduce the power output more or less rapidly and more or less sharply, to zero if need be, possibly by switching off the drive motor, and/or an automatic braking mechanism can be triggered, which achieves a particularly rapid stopping of the insert tool and/or of the power end.
The invention will be explained below in conjunction with several exemplary embodiments and the drawings.
In this exemplary embodiment, the detecting unit 6 is embodied as a capacitive detecting unit 9. The required electrical connections 8 to the electric tool, not shown, are routed through the grip 3 of the handle 1 and are connected to the electric tool by a suitable contacting device that is not shown in detail here. If an operator grasps the handle 1, this produces a change in the electrical capacitance in the detecting unit 6. This change can be repeated at the electrical connections 8.
As an additional detecting unit 6, an acceleration sensor 10 is provided, which is located inside the grip 3, at an end of the handle 1 oriented away from the machine. The precise location of the acceleration sensor 10 in the handle 1 is unimportant, as long as it reliably detects the occurrence of an acceleration. Preferably, the acceleration detector is placed at a location in the handle 1 that is powerfully affected by the occurrence of an acceleration, thus permitting the detector to easily and reliably detect such an acceleration. The acceleration sensor 10 also contacts the electric tool, not shown, via suitable electrical lines and contacts 11.
The fact that the electrical connections 8 and 11 are connected signals the electric tool, not shown, that the auxiliary handle 2 is attached, thus permitting the electrical values from the detecting units 6, namely the capacitance sensor 9 and the acceleration sensor 10, to be evaluated.
It is naturally possible to provide an auxiliary handle 2 with only one detecting unit or with more detecting units than are shown here; separate connections are provided for each detecting unit and for each detected value. The latter feature is not required if the selection of the data format (for example digital or multiplex) allows the transmission to occur over one channel or over fewer channels than there are values to be transmitted. Where and how the connections are produced is unimportant, as long as the above-described function is achieved. In particular, it is also possible for there to be a contactless transmission, for example by means of infrared, a suitable radio band, capacitive means, inductive means, or in the broadest sense, optical means.
In a particularly preferable embodiment form, the contact is produced by means of a standardized connection module that automatically produces the contact, as long as the auxiliary handle 2 and a handle 1 are attached to the electric tool, not shown. In this instance, the electric connection is inevitably produced as part of the mechanical coupling.
The transmission of the detected to torque (signaling) to the electric tool 12 occurs, for example, via a contacting device 21 that can be connected directly or by means of a cable connection 22 or, in a particularly preferable embodiment form, directly via contacting devices 23 contained in the collar 14 of the electric tool 12, disposed directly opposite the torque detecting unit 20.
A corresponding multi-poled embodiment of contacting devices 23 between the collar 12 and the fastening device 16 of the auxiliary handle 2 also makes it possible for additional physical values detected by other detecting units 6 inside the auxiliary handle 2 to also be transmitted to the electric tool 12 by means of electrical signaling. It is naturally also possible to transmit other values because the contacting devices 23 are embodied as multi-poled, not in accordance with the number of values or channels to be transmitted, but through selection of a suitable data format (possibly digital or multiplex).
It is naturally also possible to design the torque detector and the contacting device differently, as long as the above-described functions are reliably fulfilled. Where and how the contacts of the contacting devices 23 are produced is unimportant, as long as the functions described above are fulfilled. In particular, it is also possible for there to be a contactless transmission, for example by means of infrared, a suitable radio band, capacitive means, inductive means, or in the broadest sense, optical means.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102004003202.5 | Jan 2004 | DE | national |
