Patent Description:
When being charged, high-power chargers applied in the field of power tools generate a considerable amount of heat inside. If the generated heat cannot be dissipated in time, some important electronic elements in the high-power chargers will fail, thereby damaging the chargers and even battery packs.

Document <CIT> discloses a wireless charging device (<NUM>) comprising a shell (<NUM>), a coil module (<NUM>), a main board module (<NUM>) and a heat dissipation assembly (<NUM>). Document <CIT> discloses an electric vehicle charger that may include power electronics, one or more controllers, and one or more cable/connector plugs. Document <CIT> discloses a converter comprising: a housing; a heat-generating component disposed inside the housing; and a heat-dissipating module disposed on the heat-generating component.

To overcome the deficiencies of the related art, the present invention provides a charger which has high heat dissipation efficiency, a compact structure, and the function of high-power output as defined in the independent claim attached. Preferred embodiments of the invention are defined in dependent claims attached.

The present invention provides the charger, where the heat dissipation channel for the airflow to flow through is formed in the housing and includes at least the first channel and the second channel, the first channel has the first port facing the air inlet of the housing and the second port facing away from the air inlet, and the airflow flowing out of the fan enters the first channel from the first port, flows out from the second port, and enters the second channel. The second channel has a smaller cross-sectional area than the first port of the first channel so that the airflow flowing through the first port can accelerate through the second channel, thereby improving the heat dissipation efficiency of the whole charger.

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

As shown in <FIG>, a charger <NUM> as an example of the present invention can charge a battery pack. The battery pack may provide electrical energy for some handheld power tools such as electric drills and angle grinders. Of course, the battery pack may also provide electrical energy for large power tools, for example, garden tools such as smart mowers. The charger <NUM> in this example has relatively high output power and is particularly suitable for charging battery packs of some large power tools. In fact, the teachings of the present invention are applicable to any type of charger which charges battery packs.

As shown in <FIG>, the charger <NUM> can charge a power tool with a plurality of battery parks, such as a riding mower <NUM>. In some example, the charger <NUM> can charge a wheeled vehicle, such as a UTV (Utility Vehicle) or an ATV (All Terrain Vehicle).

As shown in <FIG>, the charger <NUM> includes a housing <NUM> assembled from an upper housing <NUM>, a lower housing <NUM>, a left housing <NUM>, and a right housing <NUM>, where an air inlet <NUM> for an airflow to flow through is disposed on the left housing <NUM> and an air outlet <NUM> for the airflow to flow through is disposed on the right housing <NUM>. The airflow can flow into the housing <NUM> from the air inlet <NUM> on the housing <NUM> and flow out of the housing from the air outlet <NUM> on the housing <NUM>. In some other examples, the housing may be assembled from an upper housing and a lower housing along an up and down direction, which may be understood as that parts of the left housing and the right housing which are originally disposed alone are integrally formed with the upper housing or the lower housing separately. Of course, the housing may be assembled from a left housing and a right housing along a left and right direction, which may be understood as that parts of the upper housing and the lower housing which are originally disposed alone are integrally formed with the left housing or the right housing separately. In addition, it is to be noted that specific components of the housing <NUM> in the present invention cannot limit the present invention.

The housing <NUM> is formed with an accommodation space 10a in which a fan <NUM> for generating a cooling airflow and a circuit board assembly <NUM> for implementing a charging function of the charger <NUM> are disposed. The fan <NUM> is disposed near the air inlet <NUM> and used for drawing air outside the housing <NUM> into the housing <NUM> via the air inlet <NUM> to generate the cooling airflow. The circuit board assembly <NUM> includes a circuit board <NUM>, heating elements <NUM> disposed on the circuit board <NUM>, and a heat dissipation member <NUM> connected to the heating elements <NUM> in a thermally conductive manner.

A printed circuit is disposed on the circuit board <NUM> and used for connecting, for example, resistors, capacitors, and corresponding semiconductor elements to implement the function of the charger <NUM>. When energized, the heating elements <NUM> generate heat. Specifically, the heat generated by the heating elements <NUM> is greater than or equal to <NUM> kWh. The heating elements <NUM> are electrically connected to the circuit board <NUM>. Multiple heating elements <NUM> of different types and different specifications may be disposed in the charger <NUM>. In some examples, the heating elements <NUM> may be power semiconductor devices or transformers such as field-effect transistors and may be provided with weld legs to be welded onto the circuit board <NUM>.

The heat dissipation member <NUM> is connected to the heating elements <NUM> in the thermally conductive manner to transfer out the heat generated by the heating elements <NUM> when energized. In some examples, the heat dissipation member <NUM> may be implemented in the form of a heat sink which may be a whole plate or multiple separate plates. Of course, thermal conduction among the separate plates is cut off, and an optimal heat dissipation effect cannot be achieved. At least a part of the heat dissipation member <NUM> is in contact with surfaces of the multiple heating elements <NUM>, and the heat generated by the multiple heating elements <NUM> is conducted to the heat dissipation member <NUM> according to the principle of thermal conduction and then dissipated under the action of the cooling airflow. In general, to enhance the heat dissipation effect of the heat dissipation member <NUM>, a surface of the heat dissipation member <NUM> in contact with the multiple heating elements <NUM> is designed to have a plate structure so that a maximum contact area between the heat dissipation member <NUM> and the multiple heating elements <NUM> is obtained. In addition, one end of the heat dissipation member <NUM> is configured to be in the shape of a comb so that a maximum heat dissipation area is obtained. The heat dissipation member <NUM> may be disposed in the housing <NUM> of the charger <NUM>. Of course, the heat dissipation member <NUM> may be exposed from the housing <NUM> and implement a heat dissipation function as a part of the housing <NUM>. It is to be noted that the function of the heat dissipation member <NUM> in this example is to transfer, with the good thermal conductivity of the heat dissipation member <NUM>, the heat generated by the multiple heating elements <NUM> to air, the preceding material and shape of the heat dissipation member <NUM> cannot limit the present invention, and those skilled in the art should specifically configure the material and shape of the heat dissipation member <NUM> according to actual conditions.

In some examples, the charger <NUM> further includes a deflector <NUM> detachably disposed in the housing <NUM> and used for guiding a flow direction of the cooling airflow flowing into the housing <NUM> so that the heat dissipation efficiency of the charger <NUM> is improved. Specifically, the deflector <NUM> is disposed in the accommodation space 10a formed by the housing <NUM> and detachably connected to the upper housing <NUM>. After the deflector <NUM> is fixedly mounted to the upper housing <NUM>, the deflector <NUM>, the lower housing <NUM>, and part of the upper housing <NUM> constitute a heat dissipation channel <NUM> for the cooling airflow to flow through. It is to be noted that the deflector <NUM> in this example can be detachably connected to the upper housing <NUM> through assembly, and such design has the advantage of facilitating later maintenance such as reducing maintenance costs. On the other hand, the heat dissipation channel can be flexibly adjusted according to heat dissipation requirements so that different heat dissipation requirements are met. Of course, the deflector <NUM> may be configured to be integrally formed with the housing <NUM>, which is not limited herein. The deflector <NUM> is configured to be made of the same material as the housing <NUM>, such as plastics. Of course, the deflector <NUM> may be configured to be made of another material with good thermal conductivity, and the material of the deflector <NUM> is not limited in the present invention.

Referring to <FIG>, the heat dissipation channel <NUM> has at least a first cross-sectional area S1 and a second cross-sectional area S2, where the first cross-sectional area S1 is larger than the second cross-sectional area S2 so that the cooling airflow which flows out of part of the heat dissipation channel having the first cross-sectional area S1 can accelerate to flow out of part of the heat dissipation channel having the second cross-sectional area, so as to dissipate the heat rapidly. It is to be understood that the preceding cross-sectional areas are substantially perpendicular to the flow direction of the cooling airflow. Specifically, the heat dissipation channel <NUM> includes a first channel <NUM>, a second channel <NUM>, and a third channel <NUM> which sequentially communicate with one another. When the charger <NUM> starts working, the fan <NUM> is started and the air outside the housing <NUM> enters the housing <NUM> from the air inlet <NUM>, flows through the fan <NUM>, sequentially passes through the first channel <NUM>, the second channel <NUM>, and the third channel <NUM>, and then flows out from the air outlet <NUM>, thereby constituting the cooling airflow which dissipates the heat in the space inside the housing <NUM>. Directions of arrows in <FIG> show the flow direction of the cooling airflow. Specifically, the first channel <NUM> has a first port <NUM> facing the air inlet <NUM> and a second port <NUM> facing away from the air inlet <NUM>, where the first port <NUM> has a larger cross-sectional area S1 than the second port <NUM>. In other words, the first channel <NUM> is configured to be in the shape of a bell mouth, and the first port <NUM> has a larger caliber than the second port <NUM>. The fan <NUM> has a fan air inlet <NUM> facing the air inlet <NUM> and a fan air outlet <NUM> facing away from the air inlet <NUM>. The fan air outlet <NUM> is disposed opposite to the first port <NUM> of the first channel <NUM>, and a cross-sectional area of the fan air outlet <NUM> is substantially the same as a cross-sectional area S1 of the first port <NUM>. Specifically, to improve the heat dissipation efficiency of the charger <NUM>, the cross-sectional area S1 of the first port <NUM> of the first channel <NUM> is set to be larger than a cross-sectional area of the second port <NUM> so that the cooling airflow can gradually accelerate in the first channel <NUM> and rapidly flow through the second channel <NUM>, where a cross-sectional area S2 of the second channel <NUM> remains substantially unchanged and is substantially the same as the cross-sectional area of the second port <NUM> of the first channel <NUM>. In some examples, to improve the heat dissipation effect of the charger <NUM>, the heat dissipation channel <NUM> is configured to be a relatively closed space, which refers to that there are no other air inlets or air outlets through which the airflow can flow except the first port <NUM> and a fourth port <NUM>. The heat dissipation channel <NUM> is configured to be relatively closed, which has the advantage that after the cooling airflow flowing out from the fan air outlet <NUM> enters the first channel <NUM>, the first channel <NUM> in the shape of the bell mouth can cause pressure of the airflow in the first channel <NUM> to gradually increase and the airflow to accelerate through the second channel <NUM> and rapidly carry the heat generated by the circuit board assembly <NUM> out of the housing <NUM>. The fan <NUM> and the first channel <NUM> in this example are sequentially disposed from left to right. It is to be noted that the fan <NUM> may be partially disposed in the first channel <NUM> and it is the most important to ensure that almost all of the cooling airflow flowing out from the fan air outlet <NUM> can flow into the heat dissipation channel <NUM>. Therefore, the fan <NUM> may be disposed on a left side of the first channel <NUM> or partially overlap the first channel <NUM>.

In some examples, the fan <NUM> may be disposed near the air outlet <NUM>. When the charger <NUM> starts working, the fan <NUM> is started and under the action of the fan <NUM>, the air outside the housing <NUM> enters the housing <NUM> from the air inlet <NUM>, sequentially passes through the first channel <NUM>, the second channel <NUM>, and the third channel <NUM>, flows through the fan <NUM>, and finally flows out from the air outlet <NUM>. After entering the housing <NUM> from the air inlet <NUM>, the cooling airflow directly enters the heat dissipation channel <NUM>. Since the cross-sectional area of the first port <NUM> of the first channel <NUM> is larger than the cross-sectional area of the second port <NUM>, the cooling airflow gradually accelerates in the first channel <NUM> to rapidly flow through the second channel <NUM> and carry away the heat on the circuit board assembly <NUM>.

The circuit board assembly <NUM> is at least partially disposed in the second channel <NUM>. Specifically, the heating elements <NUM> and the heat dissipation member <NUM> connected to the heating elements <NUM> in the thermally conductive manner are at least partially disposed in the second channel <NUM>. In this manner, the cooling airflow enters the housing <NUM> from the air inlet <NUM>, passes through the fan <NUM>, flows through the first channel <NUM>, enters the second channel <NUM>, takes away the heat on the circuit board assembly <NUM> at least partially disposed in the second channel <NUM>, flows through the third channel <NUM>, and finally flows out of the housing <NUM> from the air outlet <NUM>. Specifically, the third channel <NUM> has a third port <NUM> away from the air outlet <NUM> and the fourth port <NUM> close to the air outlet <NUM>, where a cross-sectional area of the third port <NUM> is substantially the same as the cross-sectional area of the second channel <NUM>, a cross-sectional area of the fourth port <NUM> is larger than the cross-sectional area of the third port <NUM>, and further, the cross-sectional area of the fourth port <NUM> is smaller than or equal to the cross-sectional area of the first port <NUM>. In this example, a ratio of the cross-sectional area of the fan air outlet <NUM> to the cross-sectional area of the second channel <NUM> is greater than or equal to <NUM> and less than or equal to <NUM>. Specifically, the ratio of the cross-sectional area of the fan air outlet <NUM> to the cross-sectional area of the second channel <NUM> is <NUM>. The cross-sectional area of the fan air outlet <NUM> is defined as an area of a circle having a blade of the fan <NUM> as a radius.

The charger <NUM> in this example is particularly suitable for charging battery packs of the large power tools or battery packs with large capacities. Output power of the charger in this example ranges from <NUM> W to <NUM> W. It is to be understood that the charger <NUM> has relatively high output power, the circuit board assembly <NUM> inevitably generates a relatively large amount of heat when energized, and therefore, the fan <NUM> for generating the cooling airflow must have a relatively high rotational speed to generate a large amount of air, causing noise with a relatively great influence. Specifically, when the output power of the charger <NUM> in this example can be as high as <NUM> W, in order that the heat can be better dissipated so as to ensure that the charger can charge the battery pack normally and safely, preferably, the blade of the fan <NUM> has a diameter of <NUM>, and the rotational speed of the fan <NUM> is higher than or equal to <NUM> rpm and lower than or equal to <NUM> rpm. When the fan <NUM> rotates at a high speed, after the air enters the housing <NUM> from the air inlet <NUM>, relatively loud noise is generated on the blade and a nearby inner wall of the housing due to the high-speed flow of the air, affecting user experience.

In some examples, referring to <FIG> and <FIG>, the fan <NUM> includes an outer fan frame <NUM> arranged along a radial direction of the fan <NUM> and used for fixedly mounting the fan <NUM> to the housing <NUM>. A shock-absorbing material <NUM> such as rubber or foam is wrapped on an outer side of the outer fan frame <NUM>. When the fan <NUM> rapidly rotates, in particular, when the airflow impinges on the fan <NUM> rapidly, the shock-absorbing material can reduce the vibration of the fan <NUM> to a certain extent, thereby reducing the noise.

In some examples, referring to <FIG> and <FIG>, the charger <NUM> further includes multiple second air inlets <NUM> disposed on the left housing <NUM> and a second air outlet <NUM> disposed on the right housing <NUM>. Specifically, the multiple second air inlets <NUM> are disposed above and below the air inlet <NUM> separately, and the second air outlet <NUM> is disposed above the air outlet <NUM>. Referring to <FIG>, after entering the housing <NUM> from the air inlet <NUM> and the second air inlets <NUM> separately, the airflow gathers together, passes through the fan air inlet <NUM> of the fan <NUM>, and then enters the heat dissipation channel <NUM>. The air inlet structure designed above can avoid the following case to a large extent: after flowing into the housing <NUM> and before flowing into the fan air inlet <NUM>, the cooling airflow flows without being guided and thus relatively loud noise is generated due to friction between the cooling airflow and the inner wall of the housing <NUM>.

In this example, a distance between the fan air inlet <NUM> and an inner wall 15a of the housing in the left and right direction is L1, where the inner wall 15a of the housing is disposed opposite to the air inlet <NUM>. L1 can also be considered as a distance between the fan air inlet <NUM> and the air inlet <NUM>. A blade <NUM> of the fan <NUM> has a diameter D1, and when a ratio of the diameter D1 of the blade to the distance L1 is greater than or equal to <NUM>, the charger <NUM> generates lowest noise in operation. It is to be noted that it is relatively proper that the preceding ratio relationship is applicable to the case where only one fan is provided. In some other examples, multiple fans <NUM> are provided. In this case, those skilled in the art need to set a proper distance L1 according to actual conditions. The preceding distance L1 may be obtained through simulation or a relatively proper distance L1 may be obtained through data of multiple tests so that the charger <NUM> has less noise interference in operation. Further, in this example, a distance L1 between the fan air inlet <NUM> and the air inlet <NUM> in the left and right direction is set to be greater than or equal to <NUM>, the diameter D1 of the blade <NUM> is set to be <NUM>, and a distance L2 between the fan air outlet <NUM> and the circuit board <NUM> in the left and right direction is set to be greater than or equal to <NUM>. The charger <NUM> designed in this manner, in particular, the charger with the function of high-power output, can ensure a compact structure and low noise and has a relatively good heat dissipation effect and relatively good user experience so that on the basis of the own noise of the fan, the charger <NUM> can control, in the working process, the overall noise to be in a range of <NUM> dB or lower.

In some examples, referring to <FIG>, the charger <NUM> may be used for charging various power tools such as the riding mower <NUM>. The riding mower <NUM> has a battery pack <NUM> and a tool interface <NUM> for charging. The charger <NUM> further includes a charging device <NUM>, a storage assembly <NUM> for storing the charging device <NUM>, and a power cable <NUM>. Specifically, the power cable <NUM> is used for receiving external power supplies such as mains electricity so as to charge the power tools. Preferably, the charging device <NUM> is in the form of a charging gun and electrically connected to the circuit board assembly in the charger <NUM> through a charging cable <NUM>. The storage assembly <NUM> serves as a component where the gun is hung, so as to avoid damage caused by the random placement of the charging device <NUM>. The charging device <NUM> is electrically connected to the tool interface <NUM> of the power tool so that converted electrical energy accessed by the power cable <NUM> is transmitted to the power tool and used for charging the power tool. The charger <NUM> may also be fixedly mounted to a wall by the storage assembly <NUM>. The housing <NUM> of the charger <NUM> and a wall <NUM> form a winding portion <NUM> for storing the power cable <NUM> or the charging cable <NUM>. Specifically, the winding portion <NUM> has an accommodation space 71a capable of accommodating cables. In some special charging conditions, the power cable <NUM> or the charging cable <NUM> is relatively long. When the charger <NUM> is mounted onto and hung from the wall, an excessively long cable falls on the ground, easily trips a user up, and also affects aesthetics. The user may wind the excessively long cable on the charger <NUM> along the winding portion <NUM> and arrange the excessively long cable in the accommodation space 71a.

In some examples, referring to <FIG>, the charging device <NUM> further includes a charging terminal <NUM>, a grip <NUM>, and a sealing ring <NUM> disposed on the charging terminal <NUM>. When the user needs to charge the power tool, the user may hold the grip <NUM> of the charging device <NUM> and plug into the power tool. Specifically, in order that the user feels better when holding the charging device <NUM>, it is set that an included angle α between an extension direction of the grip <NUM> and an extension direction of the charging terminal <NUM> ranges from <NUM>° to <NUM>°. Further, it is set that the included angle α between the extension direction of the grip <NUM> and the extension direction of the charging terminal <NUM> is <NUM>°. When the charging terminal <NUM> of the charger <NUM> is inserted into the tool interface <NUM> of the power tool, the sealing ring <NUM> disposed between the grip <NUM> and the charging terminal <NUM> can better seal the charging terminal <NUM> in the tool interface <NUM> of the power tool, so as to prevent moisture from entering the charging terminal <NUM> under working conditions such as rain and thus avoid a safety hazard.

Claim 1:
A charger, comprising:
a housing (<NUM>) formed with an air inlet (<NUM>) and an air outlet (<NUM>);
a fan (<NUM>) disposed in the housing and used for generating a heat dissipation airflow entering from the air inlet and flowing out from the air outlet; and
a circuit board assembly (<NUM>) comprising at least heating elements which generate heat when energized;
wherein a heat dissipation channel (<NUM>) for the heat dissipation airflow to flow through is provided in the housing and comprises at least a first channel (<NUM>), a second channel (<NUM>) and a third channel (<NUM>), sequentially communicating with each other, the heat dissipation airflow sequentially flowing through the first channel, the second channel, and the third channel,
at least part of the heating elements are disposed in the second channel, and a cross-sectional area of a first port (<NUM>) of the first channel facing the air inlet is larger than a cross-sectional area of the second channel so that the heat dissipation airflow flowing through the first channel is capable of accelerating through the second channel;
characterized in that
the first to third channels are aligned along a rotation axis of the fan.