Patent Description:
A riding lawn mower needs to be equipped with a charging device for charging it. Since a battery pack needed by the riding lawn mower has a relatively large capacity, to increase charging efficiency, a charging device applicable to the riding lawn mower needs to have a relatively strong power output capability. After the power output capability of the charging device is improved, the charging device has an increased volume and a reduced heat dissipation effect.

<CIT>, <CIT> and <CIT> are prior art documents.

To solve the deficiency of the related art, the present application provides a charging apparatus with a small overall volume and high output power.

To achieve the preceding object, the present application adopts the technical solutions as set out in the appended claims.

With the preceding technical solutions, the PFC circuit and the LLC resonant circuit with high voltage conversion efficiency are disposed in the circuitry of the charging apparatus so that the charging apparatus has a high-power output capability and a relatively small volume.

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

<FIG> shows a charging apparatus <NUM> as an example of the present application, and a battery pack can be charged by the charging apparatus <NUM>. The preceding battery pack may power some handheld power tools. These handheld power tools may be electric drills, angle grinders, or the like. The preceding battery pack may also power large power tools, for example, garden tools such as intelligent mowers or snow throwers. The charging apparatus <NUM> in this example has relatively high output power and is particularly applicable for providing charging functions for battery packs of some large power tools with relatively high output power. The preceding large power tools with the relatively high output power may be riding lawn mowers, the snow throwers, and intelligent walking power tools. In fact, the teachings of the present application are applicable to any type of charging apparatus by which the battery pack is charged. In this example, the battery pack may be mounted to a power tool, a charging input interface is formed on the housing of the power tool and connected to a charging circuit disposed in the power tool, and the charging circuit can transmit electrical energy accessed by the charging input interface to the battery pack mounted to the power tool in this case.

As shown in <FIG>, the charging apparatus <NUM> includes a housing <NUM> assembled from an upper housing <NUM>, a lower housing <NUM>, a left housing <NUM>, and a right housing <NUM>. The left housing <NUM> is provided with an air inlet <NUM> for an airflow to flow through. The right housing <NUM> is provided with an air outlet <NUM> for the airflow to flow through. 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 application cannot limit the present application.

The housing <NUM> is formed with an accommodating space <NUM>, where a fan <NUM> for generating a cooling airflow and a circuit board assembly <NUM> for implementing the charging function of the charging apparatus <NUM> are disposed in the accommodating space <NUM>. 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 printed circuit board <NUM> and multiple electronic elements disposed on a second surface <NUM> of the printed circuit board <NUM>. The preceding electronic elements include at least heat-generating elements <NUM> and heat dissipation members <NUM> forming heat-conducting connections to the heat-generating elements <NUM>.

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

The heat dissipation members <NUM> are connected to the heat-generating elements <NUM> in the thermally conductive manner to transfer out the heat generated by the heat-generating elements <NUM> when energized. In some examples, a heat dissipation member <NUM> may be implemented in the form of a heat sink which may be a whole plate or multiple separate plates. Referring to <FIG>, at least part of the heat dissipation member <NUM> is in contact with surfaces of the multiple heat-generating elements <NUM>, and the heat generated by the multiple heat-generating 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 effects of the heat dissipation members <NUM>, surfaces of the heat dissipation members <NUM> in contact with the multiple heat-generating elements <NUM> are designed to have plate-shaped structures so that surface contact between the heat dissipation members <NUM> and the multiple heat-generating elements has the maximum contact area. In addition, one end of the heat dissipation member <NUM> is configured to be in the shape of a comb so that the heat dissipation member <NUM> has the maximum heat dissipation area. The heat dissipation members <NUM> may be disposed in the housing <NUM> of the charging apparatus <NUM>. Alternatively, of course, the heat dissipation members <NUM> may be exposed out 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 a good heat-conducting property of the heat dissipation member <NUM>, the heat generated by the multiple heat-generating elements <NUM> to air, the preceding material and shape of the heat dissipation member <NUM> cannot limit the present application, and those skilled in the art should specifically configure the material and shape of the heat dissipation member <NUM> according to actual conditions.

The charging apparatus <NUM> further includes a baffle <NUM> detachably disposed in the housing <NUM> and used for guiding the flow direction of the cooling airflow flowing into the housing <NUM> so that the heat dissipation efficiency of the charging apparatus <NUM> is improved. Specifically, the baffle <NUM> is disposed in the accommodating space <NUM> formed by the housing <NUM> and detachably connected to the upper housing <NUM>. Referring to <FIG>, after the baffle <NUM> is fixedly mounted to the upper housing <NUM>, the baffle <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. The baffle <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 satisfied. Of course, the baffle <NUM> may be configured to be integrally formed with the housing <NUM>, which is not limited herein. The baffle <NUM> may be configured to be made of the same material as the housing <NUM>, such as plastics. The baffle <NUM> may be configured to be made of another material with a good heat-conducting property, and the material of the baffle <NUM> is not limited in the present application.

In an embodiment of the invention, referring to <FIG>, the charging apparatus <NUM> further includes first elements <NUM> disposed between the printed circuit board <NUM> and the lower housing <NUM>. At least part of a first element <NUM> abuts against a first surface <NUM> of the printed circuit board <NUM>. When the charging apparatus <NUM> vibrates under the action of an external force, the first elements <NUM> can be elastically deformed, thereby reducing the probability that the printed circuit board <NUM> is broken due to the external force. In this example, the lower housing <NUM> is formed with or connected to accommodating portions <NUM> for accommodating at least parts of the first elements <NUM>. An accommodating portion <NUM> is a recess, the first element <NUM> is partially disposed in the preceding recess, and the recess and the lower housing <NUM> are integrally formed. The top end of the first element <NUM> is slightly higher than the top end of the accommodating portion <NUM> so that the printed circuit board <NUM> is not in direct contact with the accommodating portion <NUM>. In the invention, the first element <NUM> is a sealant with a heat-conducting function and is used for transferring the heat on the circuit board assembly to the housing, and the thermal conductivity of the first element <NUM> is greater than or equal to <NUM> W/(m·K).

In this embodiment, the ratio of projection areas of the first elements <NUM> on the first surface <NUM> of the printed circuit board <NUM> to the area of the first surface <NUM> is higher than or equal to <NUM> and lower than or equal to <NUM>. In some examples, the ratio of projection areas of the first elements <NUM> on the first surface <NUM> of the printed circuit board <NUM> to the area of the first surface <NUM> is higher than or equal to <NUM> and lower than or equal to <NUM>. In some examples, the ratio of projection areas of the first elements <NUM> on the first surface <NUM> of the printed circuit board <NUM> to the area of the first surface <NUM> is higher than or equal to <NUM> and lower than or equal to <NUM>. In some examples, the ratio of projection areas of the first elements <NUM> on the first surface <NUM> of the printed circuit board <NUM> to the area of the first surface <NUM> is <NUM>.

Since the charging apparatus in the present application has a relatively strong power output capability, the overall weight of the charging apparatus is relatively heavy and the heat dissipation efficiency of the charging apparatus is reduced if conventional adhesive injection is used. Therefore, the first elements in the preceding example are used so that the heat dissipation efficiency of the charging apparatus can be improved and the overall weight of the charging apparatus can be reduced.

In some examples, the charging apparatus <NUM> may be used for charging a variety of power tools such as the riding lawn mowers or riding snow throwers. Referring to <FIG>, <FIG>, and <FIG>, the charging apparatus <NUM> further includes an input power cord <NUM> for receiving an external alternating current power supply such as mains and an output power cord <NUM> for outputting electrical energy to charge the power tools. The output power cord <NUM> is at least partially disposed in the accommodating space <NUM> formed by the housing <NUM>. Specifically, the output power cord <NUM> has a first end <NUM> and a second end <NUM>. The housing <NUM> is formed with a first through hole (not shown in the figure), where the first end <NUM> of the output power cord <NUM> passes through the preceding first through hole to be electrically connected to the printed circuit board <NUM>. The second end <NUM> of the output power cord <NUM> is connected to a charging interface <NUM> for an electrical connection to the charging input interface of the power tool. In some examples, the charging interface <NUM> is electrically connected to the power tool in the form of a charging gun. In this example, the output power of the charging apparatus <NUM> is greater than or equal to <NUM> W and less than or equal to <NUM> W. In some examples, the output power of the charging apparatus <NUM> is greater than or equal to <NUM> W and less than or equal to <NUM> W. In some examples, the output power of the charging apparatus <NUM> is greater than or equal to <NUM> W and less than or equal to <NUM> W. In some examples, the maximum output power of the charging apparatus <NUM> is greater than or equal to <NUM> W and less than or equal to <NUM> W. The wire diameter of the output power cord <NUM> is greater than or equal to <NUM> AWG and less than or equal to <NUM> AWG. The length of the portion of the output power cord <NUM> disposed outside the housing <NUM> is greater than or equal to <NUM> and less than or equal to <NUM>.

To facilitate the operation of the charging interface <NUM> by a user to charge the power tool, a designer increases the length of the output power cord <NUM> during design, thereby satisfying charging requirements of different distances. When the user charges the power tool using the charging interface <NUM> or forgets to store the output power cord <NUM> after the charging ends, the output power cord is damaged because the user stamps on it. In summary, since the charging interface <NUM> is frequently operated by the user, the cable of the power cord is easily damaged and the contact of the power cord with the printed circuit board <NUM> is poor. When the user needs to replace the damaged power cord, a lot of time is consumed and even the printed circuit board is damaged.

The output power cord <NUM> in this example is detachable and easy to mount. Referring to <FIG>, the first end <NUM> of the output power cord <NUM> is connected to the printed circuit board <NUM> by detachable first fasteners <NUM> so that a charging interface <NUM> is electrically connected to the printed circuit board <NUM>. A positive wire and a negative wire extend out of the output power cord <NUM>, and one end of a wire is connected to a gasket having a conductive function. Mounting portions <NUM> for electrical and fixed connections to the first fasteners <NUM> are connected to the printed circuit board <NUM>. In this example, a first fastener <NUM> is a screw. Of course, the first fastener <NUM> may be a connector. A first portion of the connector is electrically connected to the first end <NUM> of the output power cord <NUM>, and a second portion of the connector is electrically connected to the printed circuit board <NUM>. The first portion of the connector and the second portion of the connector are connected to each other through plugging. The connector in this example has a waterproof function. It is to be understood that the preceding only illustrates an example in which the output power cord <NUM> is detachably and electrically connected to the printed power board <NUM>, which should not be construed as the only manner.

The screw is used for fastening or the connector is used for the connection so that the output power cord <NUM> and the printed circuit board <NUM> are electrically connected to each other, and the later maintenance can be facilitated, thereby reducing the maintenance costs.

In this example, the charging apparatus <NUM> further includes a second fastener <NUM> for fixing the output power cord <NUM> to the lower housing <NUM>, thereby avoiding a poor contact between the output power cord <NUM> and the printed circuit board <NUM> caused when the user drags the output power cord <NUM>. In this example, the second fastener <NUM> is fastened to the lower housing <NUM> by screws.

In some examples, the charging apparatus <NUM> further includes multiple magnetic rings sleeved on the input power cord <NUM> and the output power cord <NUM> and used for improving the interference-proof capability to high-frequency signals. Referring to <FIG>, a first magnetic ring <NUM> is sleeved on the output power cord <NUM>, and a second magnetic ring <NUM> and a third magnetic ring <NUM> are sleeved on the input power cord <NUM>. In this example, the distance from the first magnetic ring <NUM> to the first end <NUM> of the output power cord <NUM> on an extension path of the output power cord <NUM> is less than or equal to <NUM>.

When the charging apparatus <NUM> charges the battery pack in the power tool, a charge current outputted by the charging apparatus <NUM> is greater than or equal to <NUM> A and less than or equal to <NUM> A. It is to be understood that when the charging apparatus <NUM> is in a working state, the circuit board assembly <NUM> generates much heat. If the heat in the charging apparatus <NUM> cannot be dissipated in time, the working efficiency of the charging apparatus <NUM> may be reduced or even a safety hazard may be caused. In this example, the heat generated by the heat-generating elements <NUM> during the working of the charging apparatus <NUM> is greater than <NUM> kWh. In some examples, a fan is obliquely disposed so that more air is blown to the circuit board assembly <NUM> so that the heat dissipation effect of the charging apparatus <NUM> is improved and the height of the charging apparatus in the up and down direction can be reduced, thereby making the charging apparatus more compact.

Referring to <FIG> and <FIG>, a charging apparatus 100a includes a fan 20a for generating a cooling airflow to dissipate heat in the interior space of the charging apparatus 100a. The fan 20a is disposed at an end which is in a housing 10a and faces away from air outlets 16a. The fan 20a has a fan air inlet 21a facing air inlets 15a and a fan air outlet 22a facing away from the air inlets 15a. When the charging apparatus 100a begins working, the fan 20a starts, air outside the housing 10a generates the cooling airflow under the action of the fan 20a, and the direction of the cooling airflow is shown by arrows in <FIG>. After entering the housing 10a from the air inlets 15a, the cooling airflow flows through the fan air inlet 21a, the fan 20a, and the fan air outlet 22a, then passes through a circuit board assembly 30a, and finally flows out from the air outlets 16a so that heat in the housing 10a is carried away and the heat of the charging apparatus 100a is dissipated. In some examples, the flow direction of the cooling airflow flowing out from the fan air outlet 22a is configured to be oblique with respect to a printed circuit board 31a.

In some examples, the fan 20a includes an outer fan frame arranged along the radial direction of the fan 20a and used for fixedly mounting the fan 20a to the housing 10a. A vibration damping material such as rubber or foam is wrapped on the outer side of the outer fan frame. When the fan 20a rapidly rotates, in particular, when the airflow impinges on the fan 20a rapidly, the vibration damping material can reduce the vibration of the fan 20a to a certain extent, thereby reducing noise. Blades of the fan 20a rotate about a rotation axis 201a. The rotation axis 201a is configured to be oblique with respect to the printed circuit board 31a. In some examples, the included angle α between the rotation axis 201a and the printed circuit board 31a is greater than <NUM>° and less than or equal to <NUM>°. The included angle α between the rotation axis 201a and the printed circuit board 31a is greater than or equal to <NUM>° and less than or equal to <NUM>°. In some examples, the included angle α between the rotation axis 201a and the printed circuit board 31a is <NUM>°.

In some examples, the fan can be disposed at the air outlet side of the charging apparatus. Referring to <FIG>, a charging apparatus 100b includes a fan 20b disposed at an end which is in a housing 10b and faces away from an air inlet 15b. The fan 20b has a fan air inlet 21b facing the air inlet 15b and a fan air outlet 22b facing away from the air inlet 15b. When the charging apparatus 100b begins working, the fan 20b starts, air outside the housing 10b generates the cooling airflow under the action of the fan 20b, and the direction of the cooling airflow is shown by arrows in <FIG>. After entering the housing 10b from the air inlet 15b, the cooling airflow flows through a printed circuit board 31b, the fan air inlet 21b, the fan 20b, and the fan air outlet 22b and finally flows out from an air outlet 16b so that heat in the housing 10b is carried away and heat of the charging apparatus 100b is dissipated. In this example, blades of the fan 20b rotate about a rotation axis 201b. The rotation axis 201b is configured to be oblique with respect to the printed circuit board 31b.

In some examples, the included angle β between the rotation axis 201b and the printed circuit board 31b is greater than <NUM>° and less than or equal to <NUM>°. The included angle β between the rotation axis 201b and the printed circuit board 31b is greater than or equal to <NUM>° and less than or equal to <NUM>°. In some examples, the included angle between the rotation axis 201b and the printed circuit board 31b is <NUM>°.

Two examples are described above in which the fans are arranged obliquely with respect to the printed circuit boards. When the charging apparatuses work and the fans run, the cooling airflows generated by the fans are arranged obliquely with respect to the printed circuit boards. Thus, on the one hand, the amount of air flowing through the printed circuit boards can be increased, thereby improving heat dissipation effects. On the other hand, the fans are disposed obliquely so that the heights of the fans in the up and down direction are reduced, thereby reducing the heights of the charging apparatuses. Thus, the charging apparatuses have more compact structures and smaller volumes.

In some examples, the fan may be arranged in another manner. Referring to <FIG> and <FIG>, a fan 20c is disposed at the upper end of a charging apparatus 100c, thereby shortening the length of the charging apparatus 100c in the left and right direction. Specifically, the charging apparatus 100c includes a housing 10c assembled from an upper housing 11c, a lower housing 12c, a left housing 13c, and a right housing 14c. The housing 10c is formed with an accommodating space 101c, and the fan 20c for generating the cooling airflow and a circuit board assembly 30c for implementing the charging function of the charging apparatus 100c are arranged in the accommodating space 101c. The fan 20c is used for generating the cooling airflow so as to carry away heat generated in the charging apparatus 100c. The circuit board assembly 30c includes the printed circuit board 31c and multiple electronic elements disposed on the printed circuit board 31c. The printed circuit board <NUM> is disposed in the lower housing <NUM>.

In this example, the charging apparatus 100c further includes a deflector 18c fixedly mounted to the housing 10c. The deflector 18c is generally sheet-shaped and substantially parallel to the printed circuit board 31c. A mounting portion (not shown in the figure) for mounting the fan 20c is formed in the middle region of the deflector 18c. In this example, the fan 20c may be an axial fan or a centrifugal fan, which is not limited in the present application. Of course, in some examples, the fan 20c may be fixedly mounted to the housing 10c such as the upper housing 11c. In some examples, the fan 20c may be mounted to the deflector 18c and the upper housing 11c at the same time.

Specifically, the fan 20c rotates about a rotation axis 201c substantially perpendicular to the printed circuit board 31c. Within a first plane <NUM> perpendicular to the rotation axis 201c, a projection of the fan 201c on the first plane <NUM> is within a projection of the printed circuit board 31c on the first plane <NUM>, which may be understood as that the fan 20c is disposed entirely above the printed circuit board 31c.

The housing 10c is formed with at least first air vents 15c and second air vents 16c. The first air vents 15c and the second air vents 16c are disposed on two sides of the deflector <NUM> in the up and down direction. When the fan 20c rotates about the rotation axis 201c, the cooling airflow flowing through the first air vents 15c and the second air vents 16c can be generated. The housing 10c and the deflector 18c are formed with at least a first channel <NUM> and a second channel <NUM> for the preceding cooling airflow to flow through. The cooling airflow flows through at least the circuit board assembly 30c, thereby carrying away heat generated by heat-generating elements on the printed circuit board 31c.

In some examples, a first air vent 15c serves as an air inlet, and a second air vent 16c serves as an air outlet. Specifically, the first air vent 15c includes a first air inlet 151c and a second air inlet 152c. The second air vent 16c includes a first air outlet 161c and a second air outlet 162c. The first air inlet 151c and the second air inlet 152c are disposed on two sides of the fan 20c in the left and right direction. The first air outlet 161c and the second air outlet 162c are disposed on the two sides of the fan 20c in the left and right direction. In some examples, the first air inlet 151c and the second air inlet 152c are disposed on the upper housing 11c, and a first cooling airflow entering the housing 10c from the first air inlet 151c and flowing out of the housing 10c from the first air outlet 161c flows through the first channel <NUM>, the fan 20c, and the circuit board assembly 30c sequentially. A second cooling airflow entering the housing 10c from the second air inlet 152c and flowing out of the housing 10c from the second air outlet 162c flows through the second channel <NUM>, the fan 20c, and the circuit board assembly 30c sequentially. The flow direction of the first cooling airflow is shown by arrows a in <FIG>, and the flow direction of the second cooling airflow is shown by arrows b in <FIG>.

In some examples, the first air vent 15c serves as the air outlet, and the second air vent 16c serves as the air inlet. Specifically, as shown in <FIG>, the first air vent 15c includes a first air outlet 151c and a second air outlet 152c. The second air inlet 16c includes a first air inlet 161c and a second air inlet 162c. The first air outlet 151c and the second air outlet 152c are disposed on the two sides of the fan 20c in the left and right direction. The first air inlet 161c and the second air inlet 162c are disposed on the two sides of the fan 20c in the left and right direction. In some examples, the first air inlet 161c and the second air inlet 162c are disposed on the left housing 13c and the right housing 14c, respectively. The first air outlet 151c and the second air outlet 152c are disposed on the upper housing 11c. Specifically, a third cooling airflow entering the housing 10c from the first air inlet 161c and flowing out of the housing 10c from the first air outlet 151c flows through the circuit board assembly 30c, the fan 20c, and the first channel <NUM> sequentially. A fourth cooling airflow entering the housing 10c from the second air inlet 162c and flowing out of the housing 10c from the second air outlet 152c flows through the circuit board assembly 30c, the fan 20c, and the second channel <NUM> sequentially. The flow direction of the third cooling airflow is shown by arrows c in <FIG>, and the flow direction of the fourth cooling airflow is shown by arrows d in <FIG>.

With the preceding technical solution, the fan 20c is disposed on the upper portion of the charging apparatus 100c so that the length of the charging apparatus 100c in the left and right direction can be shortened. Thus, the whole charging apparatus has a shorter length and a more compact structure.

In some examples, the charging apparatus <NUM> further includes circuitry configured to control the state of the charging apparatus <NUM>. The charging apparatus <NUM> receives the external alternating current, performs voltage conversion through a voltage conversion circuit in the charging apparatus <NUM>, and finally outputs a charge voltage or a charge current satisfying requirements to charge the power tool.

Referring to <FIG>, the circuitry includes an alternating current input terminal <NUM>, a PFC circuit <NUM>, an LLC resonant circuit <NUM>, and a direct current output terminal <NUM>. The alternating current input terminal <NUM> is configured to receive the mains or other forms of alternating currents Uin. The PFC circuit <NUM> is configured to convert an accessed alternating current Uin into a first direct current Up. The LLC resonant circuit <NUM> is configured to convert the first direct current Up into a second direct current Uout. The direct current output terminal <NUM> is configured to output the second direct current Uout to charge the power tool or the battery pack mounted to the power tool. In some examples, the circuitry further includes a first controller <NUM> and a second controller <NUM>. The first controller <NUM> is electrically connected to the PFC circuit <NUM> to control the state of the PFC circuit <NUM>. The second controller <NUM> is electrically connected to the LLC resonant circuit <NUM> to control the state of the LLC resonant circuit <NUM>. In some examples, referring to <FIG>, the circuitry in <FIG> differs from the preceding circuitry in <FIG> in that only one controller <NUM> is provided, electrically connected to the PFC circuit <NUM> and the LLC resonant circuit <NUM> at the same time, and configured to control the state of the PFC circuit <NUM> and the state of the LLC resonant circuit <NUM>.

In this example, the output power of the charging apparatus <NUM> is greater than or equal to <NUM> W and less than or equal to <NUM> W. In some examples, the output power of the charging apparatus <NUM> is greater than or equal to <NUM> W and less than or equal to <NUM> W. In some examples, the effective voltage value of the alternating current Uin accessed by the alternating current input terminal <NUM> is greater than or equal to <NUM> V and less than or equal to <NUM> V. The voltage value of the first direct current Up outputted by the PFC circuit <NUM> is greater than or equal to <NUM> V and less than or equal to <NUM> V. The voltage value of the second direct current Uout outputted by the direct current output terminal <NUM> is greater than or equal to <NUM> V and less than or equal to <NUM> V. It is to be understood that the charging apparatus <NUM> in this example can convert the alternating current having the effective voltage value between <NUM> V and <NUM> V into the direct current having the voltage value between <NUM> V and <NUM> V. Specifically, the working state of the PFC circuit and the working state of the LLC resonant circuit <NUM> are controlled by the first controller <NUM> and the second controller <NUM>. Thus, the voltage value of the second direct current Uout outputted by the direct current output terminal <NUM> is controlled so that charge voltage requirements of different power tools are satisfied.

In the related art, a common PFC circuit <NUM> includes an interleaved PFC circuit and a bridgeless PFC circuit. In this example, a common LLC resonant circuit <NUM> includes a full-bridge LLC resonant circuit and a half-bridge LLC resonant circuit. The interleaved PFC circuit can obtain a relatively high power factor and reduce harmonic pollution to a power grid, thereby being widely used.

The circuit schematic and working principle of the circuitry in the present application are described below with reference to <FIG> and <FIG>. In this example, the interleaved PFC circuit is used as the PFC circuit <NUM>, and the full-bridge LLC resonant circuit is used as the LLC resonant circuit <NUM>.

Referring to <FIG>, the PFC circuit <NUM> includes a rectifier bridge <NUM>, a step-up circuit <NUM>, and an output filter capacitor C1. The rectifier bridge <NUM> is composed of four diodes D1, D2, D3, and D4 and configured to convert an inputted alternating current voltage into a direct current voltage. The input terminal of the rectifier bridge <NUM> receives the alternating current Uin. The step-up circuit <NUM> is connected to the output terminal of the rectifier bridge <NUM> and configured to step up the direct current voltage converted by the rectifier bridge <NUM>. The output filter capacitor C1 is connected to the output terminal of the step-up circuit <NUM> and a load, and the direct current voltage stepped up by the step-up circuit <NUM> is applied to the output filter capacitor C1 and a stable voltage is provided for the load. Specifically, the step-up circuit is a boost circuit. The step-up circuit <NUM> includes two groups of step-up branches which are interleaved with each other. Each group of step-up branches include one inductor and two switch transistors, where the two switch transistors are connected in series with the inductor. A first group of step-up branches include at least an inductor L1 and a switch transistor Q1 and a switch transistor Q3 which are connected in series with the inductor L1. The second group of step-up branches include at least an inductor L2 and a switch transistor Q2 and a switch transistor Q4 which are connected in series with the inductor L2. The preceding components are connected in parallel with each other structurally such that the main circuit of the interleaved PFC circuit <NUM> is formed, which implements the conversion of the low voltage into the high voltage and the conversion of the alternating current into the direct current. The output filter capacitor C1 is connected to the output terminals of the two groups of step-up branches. The stability of the output voltage can be ensured by the output filter capacitor C1. The first controller <NUM> outputs drive signals to a driver circuit <NUM> to control the conducting states of the two switch transistors Q1 and Q3 and the conducting states of the two switch transistors Q2 and Q4. The switch transistors Q1 and Q3 and the switch transistors Q2 and Q4 are alternately turned on.

In this example, gallium nitride transistors are selected as the four switch transistors Q1, Q3, Q2, and Q4. Gallium nitride transistors have better breakdown capabilities, higher electron densities, higher electron mobility, and higher working temperatures than traditional silicon-based semiconductors. Since a gallium nitride transistor can withstand a higher switching frequency, the power loss of the interleaved PFC circuit <NUM> can be reduced, which is conducive to reducing the volume and weight of the charging apparatus. In this example, the frequencies of the drive signals which are outputted by the driver circuit <NUM> to control the two switch transistors Q1 and Q3 and the two switch transistors Q2 and Q4 to be on and off range from <NUM> to <NUM>. The driver circuit <NUM> outputs drive signals of corresponding frequencies based on control signals outputted by the first controller <NUM> so that the on and off states of the two switch transistors Q1 and Q3 and the on and off states of the two switch transistors Q2 and Q4 are controlled. Thus, the voltage value of the first direct current Up outputted by the interleaved PFC circuit <NUM> varies between <NUM> V and <NUM> V.

Referring to <FIG>, the LLC resonant circuit <NUM> includes an input terminal <NUM>, an inverter circuit <NUM>, a resonant circuit <NUM>, an isolation transformer <NUM>, a rectifier and filter circuit <NUM>, an output terminal <NUM>, a driver circuit <NUM> electrically connected to at least the inverter circuit <NUM>, and a second controller <NUM> electrically connected to the driver circuit <NUM>. The input terminal <NUM> of the LLC resonant circuit <NUM> is electrically connected to the PFC circuit <NUM> and is configured to receive the first direct current Up outputted by the PFC circuit <NUM>. The output terminal <NUM> of the LLC resonant circuit <NUM> is configured to output the second direct current Uout to supply the charge voltage to the power tool.

Specifically, the inverter circuit <NUM> includes four switch transistors Q5, Q6, Q7, and Q8. The switch transistor Q5 and the switch transistor Q7 are connected in series with each other and connected to the output terminal <NUM>, and the switch transistor Q6 and the switch transistor Q8 are connected in series with each other and connected to the output terminal <NUM>. In this example, the four switch transistors Q5, Q6, Q7, and Q8 are transistors. In this example, gallium nitride transistors are selected as the four switch transistors Q5, Q6, Q7, and Q8.

The resonant circuit <NUM> includes a resonant inductor Lr, a resonant capacitor Cr, and an excitation inductor Lm. The resonant inductor Lr, the resonant capacitor Cr, and the excitation inductor Lm are sequentially connected in series between a node A formed through the series connection of the switch transistor Q5 and the switch transistor Q7 and a node B formed through the series connection of the switch transistor Q6 and the switch transistor Q8. The excitation inductor Lm is also electrically connected to two sides of the output terminal of the transformer <NUM>. In this example, the ratio of excitation inductance Lm to resonant inductance Lr is higher than or equal to <NUM> and lower than or equal to <NUM>. In some examples, the ratio of the excitation inductance Lm to the resonant inductance Lr is higher than or equal to <NUM> and lower than or equal to <NUM>. In this example, the quality factor Q of the resonant circuit <NUM> is greater than or equal to <NUM> and less than or equal to <NUM>. In some examples, the quality factor Q of the resonant circuit <NUM> is greater than or equal to <NUM> and less than or equal to <NUM>. In some examples, the quality factor Q of the resonant circuit <NUM> is greater than or equal to <NUM> and less than or equal to <NUM>.

The isolation transformer <NUM> is electrically connected to the resonant circuit <NUM> and is configured to transform a voltage outputted by the resonant circuit <NUM>. In some examples, the transformation ratio N of the isolation transformer is higher than or equal to <NUM> and lower than or equal to <NUM>. In some examples, the transformation ratio N of the isolation transformer is higher than or equal to <NUM> and lower than or equal to <NUM>. In this example, the isolation transformer <NUM> is a planar transformer. Compared with a common transformer, the planar transformer is a transformer with a small volume and a very high working frequency. The planar transformer has a smaller volume and higher electrical energy conversion efficiency so that the volume of the heat dissipation member can be reduced, thereby further reducing the overall volume and weight of the charging apparatus.

The rectifier and filter circuit <NUM> is electrically connected to the transformer <NUM> and is configured to rectify and filter a voltage outputted by the transformer <NUM>. In this example, the rectifier and filter circuit <NUM> includes at least a diode D5, a diode D6, and an output filter capacitor C<NUM>.

In this example, the interleaved PFC circuit and the full-bridge LLC rectifier circuit are combined such that high-efficiency conversion of the alternating current into the direct current is implemented and it is ensured that the circuitry of the charging apparatus has a smaller volume. The output power of the charging apparatus in this example is greater than or equal to <NUM> W and less than or equal to <NUM> W. In this example, the ratio of the output power of the charging apparatus to the volume of the charging apparatus is higher than or equal to <NUM> W/cm<NUM> (<NUM> W/in<NUM>) and lower than or equal to <NUM> W/cm<NUM> (<NUM> W/in<NUM>). In some examples, the ratio of the output power of the charging apparatus to the volume of the charging apparatus is higher than or equal to <NUM> W/cm<NUM> (<NUM> W/in<NUM>) and lower than or equal to <NUM> W/cm<NUM> (<NUM> W/in<NUM>).

Of course, in some examples, other forms of circuits may be used as the PFC circuit to implement the function of voltage conversion. For example, the bridgeless PFC circuit is used. Referring to <FIG>, a bridgeless PFC circuit 72a is configured to access the alternating current Uin and convert the accessed alternating current Uin into the first direct current Up. The bridgeless PFC circuit 72a differs from the preceding interleaved PFC circuit shown in <FIG> in that the bridgeless PFC circuit 72a is provided with no bridge circuit and the first controller <NUM> outputs control signals to the driver circuit <NUM> to control a switch transistor Q21 and a switch transistor Q22 to be on and off. The switch transistor Q21 and the switch transistor Q22 are gallium nitride transistors. The preceding bridgeless PFC circuit is used so that a circuit structure is simpler. Thus, the complexity of the circuitry is reduced and the volume of a charging system can be reduced. <FIG> only exemplarily introduces one type of bridgeless PFC circuit. In fact, those skilled in the art may use other forms of bridgeless PFC circuits to implement the function of voltage conversion.

In some examples, other forms of circuits may be used as the LLC resonant circuit <NUM> to implement the function of voltage conversion. For example, a half-bridge LLC resonant circuit is used. Referring to <FIG>, a half-bridge LLC resonant circuit 73a is configured to access the first direct current Up and convert the first direct current Up into the second direct current Uout so that the second direct current Uout is outputted to charge the power tool. The half-bridge LLC resonant circuit 73a differs from the preceding full-bridge LLC resonant circuit shown in <FIG> in that the half-bridge LLC resonant circuit 73a makes the circuit structure simpler. Thus, the complexity of the circuitry is reduced and the volume of the charging system can be reduced. <FIG> only exemplarily introduces another type of LLC resonant circuit. In fact, those skilled in the art may use other forms of LLC resonant circuits to implement the function of voltage conversion.

Claim 1:
A charging apparatus (<NUM>) for charging a power tool or a battery pack adapted to the power tool, comprising:
a housing (<NUM>) formed with an accommodating space (<NUM>); and
a circuit board assembly (<NUM>) disposed in the accommodating space and comprising a printed circuit board (<NUM>) provided with a plurality of electronic elements;
wherein output power of the charging apparatus is greater than or equal to <NUM> W and less than or equal to <NUM> W, and a ratio of the output power of the charging apparatus to a volume of the charging apparatus is higher than or equal to <NUM> W/cm<NUM> and lower than or equal to <NUM> W/cm<NUM>.
characterized in that
the charging apparatus (<NUM>) further includes first elements (<NUM>) disposed between the printed circuit board (<NUM>) and the lower housing (<NUM>), wherein the first element (<NUM>) is a sealant with a heat-conducting function and is used for transferring the heat on the circuit board assembly to the housing, and the thermal conductivity of the first element (<NUM>) is greater than or equal to <NUM> W/(m·K).