Power tool with overheating protection

Abstract

Electric tools, in particular leaf blowers, containing a drive unit, a control unit (100) for controlling the drive unit, a temperature monitoring unit configured to transmit a temperature value to the control unit (100), wherein the temperature value is characteristic of a temperature of the drive unit, wherein the control unit (100) is configured to gradually control the operation of the drive unit depending on the temperature value.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a power tool, in particular a leaf blower. TECHNICAL BACKGROUND

[0002] Power tools, especially leaf blowers, are often designed for short bursts of use. Accordingly, power tools may contain components, such as a drive unit, that can overheat, particularly during prolonged continuous use.

[0003] Furthermore, state-of-the-art power tools regularly feature overheating protection, which protects the components from overheating.

[0004] For example, a drive unit can be controlled in such a way that operation is prevented / interrupted if a predetermined temperature limit is exceeded.

[0005] However, this can lead to a reduced maximum continuous operating time of the power tool.

[0006] This disclosure therefore addresses the problem of providing improved overheating protection for power tools. BRIEF DESCRIPTION OF THE INVENTION

[0007] This problem is solved by a power tool according to claim 1. Further embodiments, configurations and advantages will become apparent from the dependent claims and the following description.

[0008] According to one aspect of the present disclosure, a power tool, in particular a leaf blower, is provided. The power tool comprises a drive unit and a control unit for controlling the drive unit. Furthermore, the power tool comprises a temperature monitoring unit configured to transmit a temperature value to the control unit, the temperature value being characteristic of a temperature of the drive unit. The control unit is configured to control the operation of the drive unit gradually depending on the temperature value.

[0009] The details of one or more aspects of the disclosure are set forth in the accompanying figures and the following description. Other features, objects, and advantages of the principles described in this disclosure will become apparent from the description and drawings, as well as from the claims. BRIEF DESCRIPTION OF THE FIGURES

[0010] The invention will now be explained in more detail with reference to embodiments, without these being intended to restrict the scope of protection defined by the claims.

[0011] The accompanying drawings illustrate embodiments and, together with the description, serve to explain the principles of the invention. The elements of the drawings are relative to one another and not necessarily to scale. Identical reference numerals denote similar parts. Fig. Figure 1 schematically shows an overheating protection scheme of a control unit according to embodiments of the present disclosure. Fig. Figure 2 schematically shows a rotational speed profile as a function of temperature according to embodiments of the present disclosure. DETAILED DESCRIPTION

[0012] The principles described in this disclosure relate to improved overheating protection for a power tool, in particular a leaf blower. For this purpose, a control unit is provided which performs a gradual control of a drive unit of the power tool depending on the temperature of the drive unit.

[0013] In some embodiments, the power tool can include at least two selectable operating modes. The control unit can control the drive unit based on the selected operating mode, in addition to the drive unit's temperature.

[0014] This revelation describes a power tool. In this context, "power tool" can refer to, for example, battery-operated, especially cordless, tools. For instance, "power tool" can refer to a leaf blower, especially a battery-operated one, a chainsaw, hedge trimmers, a lawn trimmer, a brush cutter, or similar equipment.

[0015] The power tool has a drive unit. This drive unit can be, for example, an electric motor. The electric motor can be configured to drive a pump. The pump can be used to generate an airflow that can be used to move leaves or similar debris. In some embodiments, the electric motor can drive the tool directly or indirectly, for example, via a gearbox.

[0016] Furthermore, the power tool has a control unit for controlling the drive unit. The control unit may, for example, include a processor. The control unit can be single-part or multi-part, meaning it can consist of several components.

[0017] The power tool includes a temperature monitoring unit. This unit is configured to transmit a temperature reading to the control unit. This reading indicates the temperature of the drive unit. For example, it could indicate the operating temperature of the drive unit.

[0018] The control unit is configured to control the operation of the drive unit, for example according to an overheating protection scheme, gradually depending on the temperature value. For the purposes of this disclosure, "gradual" is to be understood as, for example, "step-by-step." Instead of just two operating states, namely on and off, "step-by-step" can therefore mean that different operating modes are available in the context of overheating protection. This can mean that, regardless of the various settings for the power and / or speed of the power tool during normal operation, in addition to the possibility of switching off the drive unit when a certain temperature is exceeded, the power and / or speed of the power tool can be gradually reduced.

[0019] In some embodiments, the control unit can be configured to stop the operation of the drive unit as soon as the temperature exceeds a maximum limit. For example, it may then be necessary to restart the power tool, such as by pressing a power button, to restart the drive unit. In some embodiments, this maximum limit may be around 90°C. In such embodiments, the control unit can be configured to stop the operation of the drive unit as soon as the temperature indicates that this maximum limit has been exceeded.

[0020] According to some embodiments, the control unit can be configured to start the operation of the drive unit if a signal to switch on the drive unit is present and the temperature is below the maximum limit. In some embodiments, the power tool has a main on / off switch. In such embodiments, the drive unit can start operating when the main on / off switch is turned on and the signal to switch on the drive unit is present. The signal to switch on the drive unit can be generated, for example, by pressing the power button and transmitted to the control unit.

[0021] In some embodiments, the control unit can be configured to operate the drive unit in a first operating mode as long as the temperature does not exceed a first temperature limit. If the temperature exceeds the first temperature limit, the control unit can be configured to operate the drive unit in a second operating mode as long as the temperature does not exceed the maximum limit. The drive unit can have a rotational speed greater than zero in both the first and second operating modes. In this way, at least one additional stage besides switching off the drive unit is available. Naturally, embodiments can have two or more additional stages besides switching off the drive unit, and in particular, three or more additional stages besides switching off the drive unit.

[0022] According to some embodiments, the control unit can be configured to operate the drive unit in the first operating mode as soon as the temperature falls below the first temperature limit. For example, the power tool may have coolants that are only activated once the first temperature limit is exceeded. However, it is also conceivable that the temperature of the drive unit could decrease after exceeding the first temperature limit due to changes in external influences. In such cases, the control unit can be configured to operate the drive unit in the first operating mode again.

[0023] In some embodiments, the control unit can be configured to control the rotational speed of the drive unit. This speed can be controlled directly or indirectly. Indirect control can be achieved, for example, by controlling the supplied current. In some embodiments, the control unit can be configured to control the power supplied to the drive unit. For the sake of clarity, the following description will focus solely on speed control.

[0024] In some embodiments, the first operating mode can have a first rotational speed and the second operating mode can have a second rotational speed. The first rotational speed can be greater than the second rotational speed.

[0025] In some embodiments, the second operating mode can have, for example, a continuously decreasing rotational speed.

[0026] According to some embodiments, the control unit can be configured to reduce the first speed to a substantially constant level down to the second speed as soon as the temperature exceeds the first temperature limit. In other embodiments, the control unit can be configured to increase the second speed to a substantially constant level down to the first speed as soon as the temperature falls below the first temperature limit.

[0027] In some embodiments, the control unit can be configured to operate the drive unit in a variety of operating modes. Each operating mode can have a corresponding predetermined speed and a predetermined temperature limit up to which the respective operating mode can be used. Once a respective temperature limit is exceeded or fallen below, the speed can be adjusted essentially constantly at a predetermined rate until the next predetermined speed is reached. The predetermined rate can be the same for all operating mode changes.

[0028] According to some embodiments, the power tool can have at least two selectable operating modes. The control unit can be configured to additionally control the operation of the drive unit depending on a selected operating mode.

[0029] In some embodiments, the temperature monitoring unit can be configured to transmit the temperature value to the control unit essentially continuously during operation of the drive unit. In other embodiments, the temperature value can be transmitted to the control unit every 5 seconds, and in particular every 2 seconds.

[0030] The following section refers in detail to embodiments of the disclosure, some examples of which are illustrated in the figures. Each example serves to illustrate the disclosure, not to limit it. For example, features that are shown or described as part of embodiments can be used with other embodiments to produce further embodiments.

[0031] Fig. Figure 1 schematically shows an overheating protection scheme of a control unit 100 of an electric tool according to some embodiments of the present disclosure.

[0032] The power tool can, for example, be configured as a leaf blower. The power tool comprises a drive unit, a control unit 100 for controlling the drive unit, and a temperature monitoring unit configured to transmit a temperature value to the control unit 100, where the temperature value is characteristic of the drive unit's temperature. The control unit 100 is configured to gradually control the operation of the drive unit, according to the illustrated overheating protection scheme, depending on the temperature value.

[0033] The power tool according to the illustrated embodiment further comprises a main on / off switch and a power button.

[0034] When the power button is pressed, a signal to switch on the drive unit is transmitted to the control unit 100 101. It is also checked whether the main on / off switch is switched on 102. The temperature monitoring unit transmits a current temperature value to the control unit 100.

[0035] If the temperature exceeds a maximum limit of 110, the drive unit will not operate. The maximum limit of 110 corresponds, for example, to approximately 90°C.

[0036] If the temperature reading indicates that the drive unit's temperature is below the maximum limit of 110, the control unit queries an operating stage (103). For example, a normal operating stage or a high-speed operating stage may be selected.

[0037] If the high-speed operating stage is selected and the temperature falls below a first temperature limit 111, the control unit 100 operates the drive unit 130 in a first operating mode 201. This first operating mode 201 is associated, for example, with a first rotational speed 211 of, for example, 13,900 to 14,900 revolutions per minute, in particular of approximately 14,400 revolutions per minute. The first temperature limit 111 can be approximately 75°C.

[0038] If, for example, the temperature exceeds the first temperature limit 111 of approximately 75°C after a certain operating period, the control unit 100 switches the drive unit to a second operating mode 202. This second operating mode 202 is assigned, for example, a second temperature limit 112 of approximately 78°C. When the drive unit is operated in the second operating mode 202, the current speed of the drive unit is reduced, for example, to the second speed 212, to approximately 13,100 to 14,100 revolutions per minute, and in particular to approximately 13,600 revolutions per minute. For example, the control unit 100 can be configured to reduce the first speed 211 to the second speed 212 at a rate of 100 to 1,000 revolutions per minute per second.

[0039] If, as a result of the reduction in rotational speed or due to external and / or other circumstances, the temperature drops below the first temperature limit 111 of approximately 75°C, the control unit 100 can return the drive motor to the first operating mode 201. This can be done at the same rate used to reduce the rotational speed.

[0040] If the temperature continues to rise and exceeds the second temperature limit 112 of approximately 78°C, the control unit 100 switches the drive unit to the third operating mode 203. The third operating mode 203 is assigned, for example, a third temperature limit 113 of approximately 81°C. When the drive unit is operating in the third operating mode 203, the rotational speed is reduced, for example, to the third speed 213 of approximately 12,300 to 13,300 revolutions per minute, and in particular to approximately 12,800 revolutions per minute. This reduction can occur at the same rate used to decrease the rotational speed from the first operating mode 201 to the second operating mode 202.

[0041] If, as a result of the reduction in rotational speed or due to external or other circumstances, the temperature drops below the second temperature limit 112 of approximately 78°C, the control unit 100 can switch the drive motor back to the second operating mode 202. This can be done at the same rate used to reduce the rotational speed.

[0042] If the temperature continues to rise and exceeds the third temperature limit 113 of approximately 81°C, the control unit switches the drive unit to the fourth operating mode 204. The fourth operating mode 204 is assigned, for example, the maximum limit 110. When the drive unit is operating in the fourth operating mode 204, the rotational speed is reduced, for example, to the fourth speed range of 11,500 to 12,500 revolutions per minute, specifically to 12,000 revolutions per minute. This reduction can occur at the same rate used to reduce the rotational speed from the first operating mode 201 to the second operating mode 202, or from the second operating mode 202 to the third operating mode 203.

[0043] If, as a result of the reduction in rotational speed or due to external or other circumstances, the temperature drops below the third temperature limit 113 of approximately 81°C, the control unit 100 can switch the drive motor back to the third operating mode 203. This can be done at the same rate used to reduce the rotational speed.

[0044] If the temperature continues to rise and exceeds the maximum limit of 110, the control unit 100 will stop the operation of the drive unit 120. To restart the drive unit, the power button must be pressed again in certain embodiments.

[0045] If the normal operating mode is selected and the temperature falls below the maximum limit of 110, the power tool operates in a fifth operating mode 205. This fifth operating mode 205 can, for example, be assigned a fifth speed of 9450 to 10450 revolutions per minute, in particular 9950 revolutions per minute.

[0046] Fig. Figure 2 schematically shows a rotational speed profile as a function of temperature according to embodiments of the present disclosure.

[0047] The representation from Fig. 2 refers to a similar overheating protection scheme of a control unit 100 of a power tool from Fig. 1.

[0048] In the first operating mode 201, the drive unit operates at a first speed 211. If the first temperature limit 111 is exceeded, the speed is reduced to the second speed 212 at a predetermined rate. The control unit 100 then operates the drive unit in the second operating mode 202.

[0049] As in connection with Fig. As described in section 1, the rotational speed can be increased back to the first rotational speed 211 when the temperature value drops below the first temperature limit 111.

[0050] If the temperature rises above the second temperature limit 112, the rotational speed is reduced to the third speed 213 at the predetermined rate. The control unit 100 then operates the drive unit in the third operating mode 203.

[0051] As in connection with Fig. As described in section 1, the rotational speed can be increased again to the second rotational speed 212 when the temperature value drops below the second temperature limit 112.

[0052] If the temperature rises above the third temperature limit 113, the rotational speed is reduced to the fourth speed 214 at a predetermined rate. The control unit 100 then operates the drive unit in the fourth operating mode 204.

[0053] As in connection with Fig. As described in 1, the rotational speed can be increased again to the third rotational speed 213 when the temperature value drops below the second temperature limit 112.

[0054] If the temperature value rises above the maximum limit of 110, the control unit 100 controls the drive unit in such a way that the drive unit stops.

[0055] The preceding description presents a power tool, in particular a leaf blower, with reference to specific examples. It should be noted that various aspects and embodiments disclosed herein can be combined in ways other than those shown in the figures. In particular, more or fewer operating modes may be deemed appropriate. Furthermore, it is conceivable to use different temperature limits and / or rotational speeds. These can be determined depending on the components. It is assumed that various modifications to the aforementioned embodiments can be made without deviating from the scope of the disclosure and the following claims. REFERENCE MARK LIST 100 control units 101 Switching on the drive unit 102 Main on / off switch switched on 103 Operating stage 110 maximum limit 111 first temperature limit 112 second temperature limit 113 third temperature limit 120 Stop drive unit 130 drive unit operation 201 first operating mode 202 second operating mode 203 third operating mode 204 fourth operating mode 205 fifth operating mode 211 first rotation 212 second speed 213 third speed 214 fourth speed

Claims

[1] Electric tool, in particular leaf blower, comprising a drive unit, a control unit (100) for controlling the drive unit, a temperature monitoring unit configured to transmit a temperature value to the control unit (100), wherein the temperature value is characteristic of a temperature of the drive unit, wherein the control unit (100) is configured to gradually control the operation of the drive unit depending on the temperature value. [2] Power tool (100) according to claim 1, wherein the control unit (100) is configured to stop the operation of the drive unit (120) as soon as the temperature value exceeds a maximum limit (110). [3] Power tool (100) according to claim 2, wherein the control unit (100) is configured to start the operation of the drive unit (130) when a signal to switch on the drive unit is present and the temperature value is below the maximum limit (110). [4] Power tool (100) according to one of claims 2-3, wherein the control unit (100) is configured to operate the drive unit in a first operating mode (201) as long as the temperature value does not exceed a first temperature limit (111), and to operate the drive unit in a second operating mode (202) as long as the temperature value does not exceed the maximum limit (110), wherein the drive unit has a rotational speed greater than 0 in both the first operating mode (201) and the second operating mode (202). [5] Power tool (100) according to claim 4, wherein the control unit (100) is configured to operate the drive unit in the first operating mode (201) as soon as the temperature value falls below the first temperature limit (111). [6] Power tool (100) according to one of claims 4-5, wherein the control unit (100) is configured to to control the speed of the drive unit, and / or wherein the first operating mode (201) has a first speed and wherein the second operating mode (202) has a second speed, the first speed being greater than the second speed. [7] Power tool (100) according to claim 6, wherein the control unit (100) is configured to reduce the first speed substantially constant to the second speed or to increase the second speed substantially constant to the first speed as soon as the temperature value exceeds / falls below the first temperature limit (111). [8] Power tool (100) according to one of claims 6-7, wherein the control unit (100) is configured to operate the drive unit in a plurality of operating modes (201, 202, 203, 204, 205) with a corresponding predetermined speed and an associated predetermined temperature limit (110, 111, 112, 113) and wherein the control unit (100) is configured to adjust the speed substantially constantly at a predetermined rate until the next predetermined speed is reached, as soon as a temperature limit (110, 111, 112, 113) is exceeded / fall below. [9] Power tool (100) according to one of claims 1-8, wherein the power tool has at least two selectable operating stages (103) and wherein the control unit (100) is configured to additionally control the operation of the drive unit depending on a selected operating stage (103). [10] Power tool (100) according to one of claims 1-9, wherein the temperature monitoring unit is configured to transmit the temperature value to the control unit (100) substantially continuously during operation of the drive unit.

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