Patent Description:
In recent years, with the miniaturization of the structure of electric tools, there are more and more users favoring electric drills, and application scenarios of the electric drills are becoming more and more extensive. In some occasions, the users have higher and higher requirements for the electric drills. For example, while the users require the structure of the electric drills to be miniaturized, it also puts forward higher requirements for a rotational speed to meet performance requirements of the electric tools. As a speed of a motor of the electric drills increases, heat generated by a gearbox for housing drive components increases. In current prior arts, since the motor will generate a large amount of heat during a low-speed or a high-speed operation, it is also extremely important to effectively and comprehensively dissipate heat for the motor. An example of such an electric tool is <CIT>, disclosing the preamble of claim <NUM>.

Therefore, prior arts provide many solutions with particular regards to a heat dissipation problem of the motor of the electric drills, but ignore the heat dissipation problem of the gearbox when the electric tools are running at a high speed. If the heat dissipation problem of the gearbox cannot be effectively solved while increasing the speed of the motor of the electric tools, it will eventually lead to a failure of the gearbox, which will also make the electric drills unable to function normally.

In order to solve deficiencies of prior arts, the present disclosure provides an electric drill having a miniaturized structure while achieving high efficiency and comprehensive heat dissipation.

The present disclosure adopts technical solutions described below to realize the above objective.

An electric drill, including: a housing provided with an air inlet and an air outlet; a motor received in the housing, wherein the motor at least includes a motor shaft; a fan supported by the motor shaft; a transmission assembly configured to connect the motor shaft to an output shaft; and a gearbox configured to accommodate the transmission assembly; wherein, the gearbox is formed with a passage provided in the gearbox rear cover according to claim <NUM>; and at least a part of a flow path of an airflow that enters the housing from the air inlet and flows out of the housing from the air outlet is provided on the passage.

In an example, a diverter rib configured to guide the airflow is provided within the passage.

In an example, an outer surface of the gearbox extending in a circumferential direction is provided with a first vent, the first vent is arranged at an end of the passage, a rear surface of the gearbox opposite to the fan is provided with a second vent, and the second vent is provided at the other end of the passage.

In an example, the housing is provided with a first air inlet configured to cool the motor.

In an example, the housing is provided with a second air inlet opposite to the first vent. In an example, a first fan blade is provided on a side of the fan opposite to the motor, and a second fan blade is provided on a side of the fan opposite to the gearbox.

In an example, the housing is provided with a first air outlet, and the first air outlet is arranged along the radial direction of the first fan blade.

In an example, the housing is provided with a second air outlet, and the second air outlet is arranged along the radial direction of the second fan blade.

The gearbox includes a box body and a gearbox rear cover, and the gearbox rear cover is provided opposite to the fan along the extending direction of the motor shaft.

The passage is provided in the gearbox rear cover. In an example, an outer surface of the gearbox rear cover extending in a circumferential direction is provided with a first vent, the first vent is arranged at an end of the passage, a rear surface of the gearbox rear cover opposite to the fan is provided with a second vent, and the second vent is provided at the other end of the passage.

In an example, the gearbox rear cover is made of metal material.

The gearbox is received in the housing, and the passage is for an airflow to flow.

The present disclosure provides an electric drill and an electric tool. A passage is provided in a gearbox rear cover for an airflow to flow, and at least a part of a flow path of the airflow that enters a housing from an air inlet and flows out of the housing from an air outlet is provided on the passage. Meanwhile, the present disclosure provides the passage for the airflow to flow for heat dissipation of a motor, ensuring that the electric drill can realize comprehensive and effective heat dissipation during a high-speed operation, especially for the gearbox and the motor.

The present disclosure is described below in detail in conjunction with drawings and examples.

<FIG> shows an electric tool as a specific example of the present disclosure. The electric tool is an electric drill <NUM>, which can at least provide a torque to assist a screw to drive into a workpiece, and can provide an impact force for a hammering operation to meet the different needs of users. Obviously, the following examples are some of the examples of the present disclosure, but not all of the examples of the present disclosure.

Referring to <FIG> and <FIG>, the electric drill <NUM> includes a housing <NUM>, a motor <NUM>, a fan <NUM>, a gearbox <NUM>, an output shaft <NUM> and a drill bit (not shown in the drawings). The housing <NUM> is formed with a handle <NUM> for the users to hold. One end of the handle <NUM> is connected with a power interface for connecting to a DC or an AC power supply. In some examples, a battery pack <NUM> is connected to the power interface, and the battery pack <NUM> is detachably connected to the electric drill <NUM>. Of course, it is to be understood that the power interface can also be connected to an alternating current, such as a commercial power. The handle <NUM> is also provided with a main control switch <NUM> for controlling the start and stop of the electric drill <NUM>. Of course, in some examples, the main control switch <NUM> can also realize a speed regulation function. The users control a rotation speed of the electric drill <NUM> by controlling a stroke of the main control switch <NUM> pressed. The greater the stroke is, the higher the rotation speed of the electric drill <NUM> is; on the contrary, the lower the rotation speed of the electric drill <NUM> is. The housing <NUM> forms an accommodating space (not shown in the figure) along the direction of a first straight line <NUM>, and the motor <NUM>, the fan <NUM> and the gearbox <NUM> are sequentially arranged in the above accommodating space. The motor <NUM> is supported by the housing <NUM> and drives the output shaft <NUM> to drive the drill bit to rotate. The motor <NUM> includes a motor shaft <NUM>, and the fan <NUM> is supported by the motor shaft <NUM> to dissipate heat for the electric drill <NUM>. The electric drill <NUM> includes a transmission assembly <NUM>, the gearbox <NUM> forms an accommodating space 41a, and the transmission assembly <NUM> is arranged in the accommodating space 41a. The transmission assembly <NUM> is connected to the motor shaft <NUM> and the output shaft <NUM>. The motor <NUM> drives the output shaft <NUM> to rotate by means of the transmission assembly <NUM>, thereby driving the drill bit to rotate to complete the processing of the workpiece.

The users will encounter various working conditions when using the electric drill <NUM>. When the users need the electric drill <NUM> to operate at a high speed, an increase of the rotational speed of the motor <NUM> will inevitably increase the heat generated by the gearbox <NUM> gradually. The electric drill <NUM> in this example is a hand-held electric drill. In order to improve the feeling of hands of the users, the material of the gearbox <NUM> is plastic or other light materials, thereby reducing the weight of the electric drill <NUM>. The high-speed operation of the motor <NUM> will inevitably cause the gearbox <NUM> to generate high heat. If the gearbox <NUM> is in a high-heat environment for a long time, a life of the gearbox <NUM> will inevitably be affected. Next, a structure of an electric drill <NUM> will be introduced in detail, so that during the operation of the electric drill <NUM>, especially during a high-speed operation of the electric drill <NUM>, the heat of both the motor <NUM> and the gearbox <NUM> can be comprehensively and effectively dissipated, so that the electric drill <NUM> is structurally miniaturized and lightweight, while having good dissipation effect.

Referring to <FIG> and <FIG>, the housing <NUM> is provided with a first air inlet <NUM> and a first air outlet <NUM>. The first air inlet <NUM> is optionally provided on a rear side of the housing <NUM>. The first air inlet <NUM> is also optionally provided on one of the left or right sides of the housing <NUM>. It is to be understood that the first air inlet <NUM> should be provided on the housing <NUM> near the motor <NUM>. In this disclosure, the number and specific positions of the first air inlet <NUM> are not limited, and the designer can design the first air inlet <NUM> based on actual usage. The first air outlet <NUM> is distributed on the housing <NUM> along the radial direction of the fan <NUM>. Referring to <FIG>, in an example, the fan <NUM> is a double-blade fan. The fan <NUM> includes a first fan blade <NUM> close to the motor <NUM> and a second fan blade <NUM> close to the gearbox <NUM>. In an example, the first air outlet <NUM> is arranged on the housing <NUM> along the radial direction of the first fan blade <NUM>. When the electric drill <NUM> is started, the fan <NUM> operates, the airflow enters the housing <NUM> from the first air inlet <NUM>, flows through the motor <NUM> and then flows out of the housing <NUM> from the first air outlet <NUM>, thereby taking away most of the heat of the motor <NUM>. Most of the airflow in the above heat dissipation process is generated by the first fan blade <NUM>.

Referring to <FIG> and <FIG>, in this example, the gearbox <NUM> includes a box body <NUM> and a gearbox rear cover <NUM>. The box body <NUM> is formed with an accommodating space 41a for accommodating the transmission assembly <NUM>. Specifically, the box body <NUM> is made of a plastic material, which can reduce a weight of a complete machine of the electric drill <NUM>. The gearbox rear cover <NUM> is arranged to be adjacent to the fan <NUM> along the direction of the first straight line <NUM>. Specifically, the gearbox rear cover <NUM> is formed with a front surface 42a away from the fan <NUM>, a rear surface 42b close to the fan <NUM>, and an outer surface 42c. In an example, the gearbox rear cover <NUM> is made of metal or other materials with good thermal conductivity. In this example, the rear surface 42b of the gearbox rear cover <NUM> is provided opposite to the second fan blade <NUM> of the fan <NUM>. The gearbox <NUM> includes a connecting portion <NUM> for a fixed connection between the box body <NUM> and the gearbox rear cover <NUM> during assembly. The box body <NUM> is provided with a slot <NUM>, and the gearbox rear cover <NUM> is provided with a buckle <NUM> matching the slot <NUM>. The fixed connection between the box body <NUM> and the gearbox rear cover <NUM> during assembly is realized by means of the slot <NUM> and the buckle <NUM>.

Referring to <FIG>, in this example, the gearbox <NUM> is provided with a passage <NUM> for the airflow to flow. It should be noted here that since the gearbox rear cover <NUM> is provided with a passage <NUM> for the airflow to flow, the gearbox rear cover <NUM> must have a certain thickness, but the thickness of the gearbox rear cover <NUM> in this disclosure is not limited, and people who are skilled in the art can independently design the thickness of the gearbox rear cover <NUM> according to an actual situation. It should be noted that the gearbox rear cover <NUM> can be hollowed with a thickness, or the gearbox rear cover <NUM> can be solid with a thickness. Specifically, the gearbox rear cover <NUM> is provided with a first vent <NUM> and a second vent <NUM>. The first vent <NUM> and the second vent <NUM> constitute two ends of the passage <NUM>. The first vent <NUM> is arranged along the circumferential direction of the gearbox rear cover <NUM>, and the second vent <NUM> is provided on a surface of the gearbox <NUM> opposite to the fan <NUM>. The housing <NUM> is also provided with a second air inlet <NUM> and a second air outlet <NUM>. Specifically, the second air inlet <NUM> is arranged opposite to the first vent <NUM>, and the second air outlet <NUM> is arranged along the radial direction of the second fan blade <NUM> of the fan <NUM>. When the electric drill <NUM> is started, the fan <NUM> operates, the airflow enters the housing <NUM> from the second air inlet <NUM>, enters the gearbox rear cover <NUM> from the first vent <NUM>, flows through the passage <NUM>, then flows out of the gearbox rear cover <NUM> from the second vent <NUM>, and then flows out of the housing <NUM> from the second air outlet <NUM> after passing by the second fan blade <NUM>. Most of the airflow in the above heat dissipation process of the gearbox <NUM> is generated by the second fan blade <NUM>.

Referring to <FIG>, both the first air outlet <NUM> and the second air outlet <NUM> are provided on the housing <NUM> along the radial direction of the fan <NUM>. Specifically, the first air outlet <NUM> is arranged on the housing <NUM> along the radial direction of the first fan blade <NUM>. The second air outlet <NUM> is arranged on the housing <NUM> along the radial direction of the second fan blade <NUM> of the fan <NUM>. In this example, the first air outlet <NUM> and the second air outlet <NUM> are relatively close but isolated from each other, so that most of the airflow entering from the first air inlet <NUM> flows out of the first air outlet <NUM>, and most of the airflow entering from the air outlet <NUM> flows out of the second air outlet <NUM>. According to this design, a flow rate of the airflow can be maximized, and a heat dissipation effect of the electric drill <NUM> can be improved.

Referring to <FIG>, the passage <NUM> includes a first portion 423a and a second portion 423b. The first portion 423a is provided between a front surface 42a and a rear surface 42b of the gearbox rear cover <NUM>. The second portion 423b is disposed between an outer surface 42c and an inner surface 42d of the gearbox rear cover <NUM>. The first vent <NUM> is provided on the first portion 423a and is distributed on the outer surface 42c of the gearbox rear cover <NUM> in the circumferential direction of the gearbox rear cover <NUM>. Specifically, with the connecting portion <NUM> as a central axis, the first vent <NUM> is symmetrically distributed on both sides of the connecting portion <NUM>. The second vent <NUM> is disposed on the second portion 423b of the passage <NUM>, and is symmetrically distributed on the rear surface 42b of the gearbox rear cover <NUM> with the connecting portion <NUM> as the central axis. In this example, the first vent <NUM> is set as an entrance of the airflow, and the second vent <NUM> is set as an exit of the airflow. When the airflow flows through the passage <NUM> after entering the passage <NUM> from the first vent <NUM>, the airflow first enters the first portion 423a of the passage <NUM>, then passes through the second portion 423b of the passage <NUM>, and finally flows out of the passage <NUM> from the second vent <NUM>.

In some examples, the gearbox rear cover <NUM> also includes a diverter rib <NUM> for an airflow guidance. Referring to <FIG> and <FIG>, in order to better guide the airflow, a plurality of diverter ribs <NUM> are set in the passage <NUM>. Specifically, the diverter rib <NUM> is provided in the first portion 423a of the passage <NUM>. Specifically, the diverter rib <NUM> is provided between the front surface 42a and the rear surface 42b of the gearbox rear cover <NUM>, and divides the first portion 423a of the passage <NUM> into several fan-shaped portions. When the airflow flows to the first vent <NUM>, the airflow is divided into multiple airflows by a plurality of diverter ribs <NUM>. As shown by arrow a in <FIG>, when the airflow flows in the direction of arrow a, the included angle α between a flow direction in the first portion 423a and a flow direction in the second portion 423b is <NUM>°. In order to improve a flow velocity of the airflow and thus enhance a heat dissipation efficiency of the gearbox <NUM>, a total area of the first vent <NUM> in this example is set to be greater than or equal to a total area of the second vent <NUM>. The total area of the first vent <NUM> and the total area of the second vent <NUM> are not limited, and the designer can design the first vent <NUM> and the second vent <NUM> according to a specific operating environment.

Claim 1:
An electric drill (<NUM>), comprising:
a housing (<NUM>) provided with an air inlet and an air outlet;
a motor (<NUM>) received in the housing (<NUM>), wherein the motor (<NUM>) at least comprises a motor shaft (<NUM>);
a fan (<NUM>) supported by the motor shaft (<NUM>);
a transmission assembly (<NUM>) configured to connect the motor shaft (<NUM>) to an output shaft (<NUM>); and
a gearbox (<NUM>) configured to accommodate the transmission assembly (<NUM>), wherein the gearbox (<NUM>) includes a box body (<NUM>) and a gearbox rear cover (<NUM>), and the gearbox rear cover (<NUM>) is provided opposite to the fan (<NUM>) along the extending direction of the motor shaft (<NUM>); characterized in that
the gearbox (<NUM>) is formed with a passage (<NUM>) provided in the gearbox rear cover (<NUM>) and provided for an airflow to flow, and at least a part of a flow path of the airflow that enters the housing (<NUM>) from the air inlet and flows out of the housing (<NUM>) from the air outlet is provided on the passage (<NUM>).