EP2050112B1 - Control device, in particular in the form of an electric switch for electric hand tools - Google Patents

Abstract

A control device, in particular an electrical switch for use for an electrical tool such as a rechargeable-battery and/or plug-powered electrical tool having an electric motor. The switch has a housing for holding at least one heat-generating component such as a power transistor, a MOSFET, a triac or the like, which is arranged in particular in an electrical circuit arrangement which, for example, is used for open-loop and/or closed-loop control of the electric motor by appropriate open-loop and/or closed-loop control of the electrical load current flowing through the component to the electric motor. A means for thermal conduction is connected on the one hand to the housing of the electrical switch, and/or to the heat-generating component, in particular to the power semiconductor which is located in the housing, and on the other hand to a cooled area which is associated with the switch.

Description

The invention relates to a power tool according to the preamble of patent claim 1.

Such electrical switches find use for an electric hand tool with an electric motor, such as for a cordless and / or mains power tool. These power tools may be drills, grinders, saws, planers, angle grinders, or the like.

From the DE 195 08 925 A1 an electrical switch for a power tool is known, which has a housing for receiving an electrical circuit arrangement for controlling and / or regulating the electric motor. Such a circuit arrangement may be an electronic component for the control and / or regulation of the rotational speed of the electric motor, for example by pulse width modulation. The circuit located in the housing now again contains at least one component, such as a power semiconductor, a power transistor, a MOS-FET, a triac o. The like., Which serves for the corresponding control and / or regulation of the flowing through the component to the electric motor electrical load current.

Due to its function as a power component, the component generates a power loss in the form of heat, which is dissipated from the housing. Likewise, other parts of the circuit can generate heat loss. To guide this heat is a heat sink located on the outside of the housing. It has now been found that in some cases the heat dissipation that can be achieved is not sufficient. This can especially in a high-power switch for DC motors in power tools to be the case, for example, in power tools that work with lithium-ion batteries. It is obvious that in such cases, the reliability of the switch and thus also of the power tool suffers.

From the DE 30 45 610 A1 a power tool with an electric motor is known, wherein a control circuit is provided with a housing located in the Elcktrozeugs power semiconductor for controlling the electric motor. The power semiconductor communicates with a heat sink to dissipate heat. A usable for a power tool electrical switch with a housing in which a power semiconductor is located in the US 6 049 460 A shown. In and / or on the housing of the electrical switch, a heat sink for dissipating heat from the power semiconductor is arranged. Next is in the WO 2005/045863 A1 to see an electrical switch with a heat sink, wherein the electrical switch has a fan for cooling the heat sink. Finally, the shows US 2006/091858 A1 a power tool with a battery, wherein in the housing of the battery, a control circuit is located with a power semiconductor. The power semiconductor is connected to a heat sink in thermally conductive connection. In this document is flat rate mentions that for the removal of heat from the heat sink in the battery, a heat pipe or a fan can be provided.

The invention has for its object to improve the removal of heat from the housing of the electrical switch. In particular, to be sought in this context for solutions, as the heat generated at the power semiconductor of the switch heat efficiently and quickly dissipated and can be transported in a region of the power tool, where the heat is dissipated by the existing engine cooling air flow.

This object is achieved in a generic power tool by the characterizing features of claim 1.

In the power tool according to the invention, a means for heat conduction is on the one hand with the housing of the electrical switch and / or with the heat-generating component, in particular with the power semiconductor in the housing, and on the other hand with a cooled area in combination. The cooled area is located outside and / or separately from the housing and in particular associated with the electrical switch. The means for heat conduction consists of a heat pipe in the manner of a heat pipe, whereby the heat can be dissipated particularly efficiently. The heat pipe has an evaporation region at one end and a condensation region at the other end. Appropriately, for this purpose, the heat pipe is closed at one end with an evaporator plate and at the other end with a condensation plate. In the heat pipe, a fluid is further included, so that the fluid under phase change, under evaporation and condensation, heat between the evaporation region and the condensation region transported. Advantageously, with the aid of the invention, the reliability of the switch and thus the reliability of the power tool is increased. Further embodiments of the invention are the subject of the dependent claims.

Further applications in the power tool for such a circuit, in particular in the form of an electronic module, the control and / or regulation of the freewheel, for example by diodes, the torque, for example by current control for the electric motor, or other characteristics, such as automatic shutdown, automatic control , electronic braking, electronic soft start of the electric motor o. The like., To be. Even in such applications, an increase in the reliability is achieved with the help of the heat dissipation of the invention of the circuit arrangement.

The heat pipe can be connected mechanically and / or thermally to the power semiconductor. In a simple construction, the one end of the heat pipe is attached in the manner of a housing attachment to the housing in the region of the power semiconductor, for example, the simple installation by means of a screw half. It makes sense for the sake of compactness of the arrangement that the housing attachment comprises the standing in thermal contact with the power semiconductor evaporator plate.

The heat pipe can be designed in the manner of a flexible and / or preformed hose. Whose course can then be adjusted according to the space between the housing and the cooled area corresponding to the housing guide in the electrical tool, so the circumstances of the power tool housing accordingly. As a result, the heat pipe needs no additional space in the power tool.

The cooled area can be arranged at an appropriate point in and / or on the power tool. It is particularly favorable if this is located in the region of the engine cooling air flow. For a compact design, it is advisable that the condensation plate is arranged in the cooled area, in which case the motor cooling air flow flows around the condensation plate.

In summary, can be found for a particularly preferred embodiment that a heat pipe is mechanically and / or thermally connected to the power semiconductor, so that the heat pipe transports the heat in the range of engine cooling air flow. With the help of heatpipes heat can be transported very efficiently and quickly from one warm place to another cooler place, which is why these heatpipes are sometimes called thermal superconductors. The heat transfer can amount to about 100 to 10,000 times in terms of the amount of heat and the speed compared to a geometrically identical component made of solid copper as a heat sink.

The advantages achieved by the invention are, in particular, that can open up new, higher power ranges due to the improved heat dissipation. Furthermore, it is a passive cooling system, so that no energy for the operation of the means for cooling is needed, which is an advantage especially when used in battery-powered tools. Finally, the use of smaller sized electronic components and lower specified power semiconductors is possible, resulting in cost savings. In addition, can be dispensed with the need for today's switches and expensive heat sink. With the aid of the invention, a direct current (DC) high-power circuit breaker for use in hand-held power tools of the upper power segment is advantageously created, which is particularly suitable for power tools that work with lithium-ion batteries.

Fig.

ein geöffnet dargestelltes Gehäuse für ein Elektrowerkzeug.

An embodiment of the invention with various developments and refinements is shown in the drawing and will be described in more detail below.
It shows the

FIG.

an open illustrated housing for a power tool.

In the figure, a housing half shell 2 for a power tool 1 is shown in such a way that the present in the power tool housing of the power tool 1 electric motor 3 with fan wheel 10 which generates the cooling air flow for the electric motor 3, and the electrical switch 4 can be seen. The power tool 1 may be a battery and / or a mains power tool, for example, a drill, a grinder, a saw, a planer, an angle grinder o. The like. Act.

The switch 4 has a housing 5, which serves for receiving a movable switch contact and a fixed contact comprehensive, not shown contact system. The housing 4 is received in the Gehäusehalbschale 2 such that an arranged on the housing 5, manually movable by the user actuating member 6 protrudes from the handle on the housing half shell 2. The actuator 6 acts on the switching contact for switching the contact system, so that the power tool 1 by means of the actuator 6 and / or can be switched off. On the housing 5 are still electrical connections 7 for connecting the switch 4 with a power source, such as a battery, and not visible, further electrical connections for connecting the switch 4 to the electric motor. 3

Finally, in the housing 5 of the switch 4, an electrical circuit arrangement for controlling and / or regulating the electric motor 3. The circuit serves as control electronics for speed change of the electric motor 3. For this purpose, the circuit arrangement at least one associated, heat-generating power device, such as a power semiconductor, a power transistor , a MOS-FET, a triac o. The like., On, whereby a corresponding control and / or regulation of the flowing through the power component to the electric motor 3 electrical load current takes place.

In order to dissipate the heat loss generated, for example, from the power component and / or the circuit arrangement of the housing 5 of the switch 4, is a means 8 for heat conduction on the one hand with the housing 5 of the electric switch 4 and on the other hand with a switch 4 associated cooled area 9 in connection. The cooled area 9 is arranged in and / or on the power tool 1 at a suitable location. It is particularly efficient when the cooled region 9 is located in the engine cooling air flow for the electric motor 3 of the power tool 1, by the end of the means 8 for heat conduction in the vicinity of the only schematically indicated fan wheel 10 on the electric motor 3 ends away from the switch 4. Of course, the switch 4 facing the end of the means 8 for heat conduction also directly with the heat-generating Component, in particular with the power semiconductor located in the housing 5 are in communication.

As shown in FIG. Further, the means 8 for heat conduction consists of a heat pipe 11 in the manner of a heat pipe. The heat pipe 11 has at one end an evaporation region 12, which may consist of a heat pipe 11 final evaporator plate, and at the other end a condensation region 13, which may consist of a heat pipe 11 final, fan-like designed condensation plate on. In the heat pipe 11, a fluid is contained, so that the fluid in known operation with phase change, ie by evaporation of the evaporator plate 12 and by condensation on the condensation plate 13, heat between the evaporator plate 12 and the condensation plate 13 transported.

The heat pipe 11 is connected mechanically and / or thermally to the power semiconductor located in the housing 5. For this purpose, one end of the heat pipe 11 is attached in the manner of a housing attachment 14 on the housing 5 in the region of the power semiconductor. For attachment, a screw 15 can be used. The housing cover 14 comprises the standing in thermal contact with the power semiconductor evaporator plate 12th

The heat pipe 11 is configured in the manner of a flexible and / or preformed hose. The course of the heat pipe 11 can thus be adjusted according to the available space between the housing 5 and the cooled area 9, that is according to the housing guide in the housing half-shell 2 of the power tool 1. In the present case, as can be seen from the figure, the heat pipe 11 is approximately S-shaped.

The invention is not limited to the described and illustrated embodiment. Rather, it also encompasses all expert developments within the scope of the invention defined by the claims. Thus, the invention can be used not only in power tool switches as a high-performance switch in AC and / or DC power tools, but can also be found on other switches, such as those for household electrical appliances, electrical gardening equipment, machine tools o. Likewise, the invention can also with control devices or without housing, for example, for the power electronics of the power tool, for motor vehicles o. The like., Use.

Reference numeral list:

1:

power tool

2:

Housing shell

3:

electric motor

4:

(electrical) switch

5:

Housing (from switch)

6:

actuator

7:

(electrical) connection (of the switch)

8th:

Means for heat conduction

9:

refrigerated area

10:

Fan wheel (to electric motor)

11:

heat pipe

12:

Evaporation region / evaporator plate

13:

Condensation region / condensation plate

14:

housing attachment

15:

screw

Claims (4)

1. Electric tool, such as a battery-operated and/or mains-powered electric tool, for example drills, grinding machines, saws, planes, angle-grinders or the like, comprising an electric motor (3) and an electric switch (4) with a housing (5) for mounting a movable switching contact as well as a fixed contact and for mounting at least one heat-generating component, such as a power transistor, a MOSFET, a triac or the like, which is arranged in particular in an electric circuit arrangement, which is used for controlling and/or regulating the electric motor (3) for example by the corresponding control and/or regulation of the electrical load current flowing through the component to the electric motor (3), wherein a means (8) is provided for heat conduction, which is connected on the one hand to the housing (5) of the electric switch (4) and/or to the heat-generating component, in particular to the power semiconductor located in the housing (5), and on the other hand to a cooled area (9) located In and/or on the electric tool (1) which is assigned in particular to the switch (4), characterised in that the means (8) for heat conduction consists of a thermal pipe (11) in the form of a heating pipe, in that the heating pipe (11) comprises at a first end a vaporisation region (12) and at the other end a condensation region (13), and in particular is closed off at the first end by a vaporisation plate and at the other end by a condensation plate, and in that also the heating pipe (11) contains a fluid, such that with a change in phase the fluid transports heat between the vaporisation region (12) and the condensation region (13).
2. Electric tool according to claim 1, characterised in that the heating pipe (11) is joined mechanically and/or thermally to the power semiconductor, in that preferably one end of the heating pipe (11) is secured in the manner of a housing fitting (14) onto the housing (5) in the region of the power semiconductor, in particular by means of a screw (15), and in that also preferably the housing fitting (14) comprises the vaporisation plate (12) which is in thermal contact with the power semiconductor.
3. Electric tool according to claim 1 or 2, characterised in that the heating pipe (11) is designed in the form of a flexible and/or preshaped hose, the path of which is preferably adjusted to the structural space between the housing (5) and the cooled area (9), in particular to the housing guide in the electric tool (1).
4. Electric tool according to any one of claims 1 to 3, characterised in that the cooled area (9) is located in and/or on the electric tool (1) in the region of the motor cooling airflow for the electric motor (3).

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