Patent Application
20180212546
This application claims the benefit under 35 U.S.C. § 119(a) of Chinese Patent Application No. CN 201710053549.0, filed on Jan. 24, 2017, the disclosure of which is incorporated herein by reference in its entirety.
The present disclosure relates to an electric tool, and particularly relates to an electric tool which can be connected to different power supplies.
Existing electric tools include two categories. One category is powered by an alternating current power supply, and the other category is powered by a direct current power supply. The tools powered by the alternating current power supply generally can be used only in places close to a socket of the power supply, and it is inconvenient to use these electric tools within a working range away from the socket of the power supply. The direct current power supply needs to be configured for supplying power, so that alternating current electric tools can be operated in places away from the socket of the power supply.
For the electric tools powered by the direct current power supply, since electric energy reserve of the direct current power supply is limited, when the electric energy of the direct current power supply is used up, it will be very convenient for users if the alternating current power supply can be connected or a direct current power supply having enough electric energy can be selected to enable the electric tools to continue to complete operation.
Therefore, an electric tool which can be connected to different voltage inputs needs to be designed.
To solve defects found in the existing art, a purpose of the present disclosure is to provide an electric tool which can be connected to different voltage inputs.
To realize the above purpose, the present disclosure adopts the following technical solution.
An electric tool includes a motor including a plurality of windings, a power circuit configured to selectively access a first power supply and a second power supply for supplying power for the motor and including an output anode and an output cathode for outputting electric energy, a connecting circuit including a switching device configured to enable the connecting circuit to have a first connection state in which a first number of windings are connected between the output anode and the output cathode and a second connection state in which a second number of windings are connected between the output anode and the output cathode, and a signal source configured to send a first control signal, when the power circuit accesses the first power supply, to the switching device so that the connecting circuit is in the first connection state, and to send a second control signal, when the power circuit accesses the second power supply, to the switching device so that the connecting circuit is in the second connection state, wherein the connecting circuit is electrically connected with the motor and the power circuit, and the signal source is electrically connected with the connecting circuit.
Further, the connecting circuit may have a first connection state in which a first number of windings are connected in series between the output anode and the output cathode and a second connection state in which a second number of windings are connected in series between the output anode and the output cathode.
Further, a voltage of the first power supply accessed by the power circuit may be greater than or equal to a voltage of the second power supply accessed by the power circuit.
Further, the first power supply accessed by the power circuit may be an alternating current power supply with the second power supply accessed by the power circuit being a direct current power supply.
Further, the signal source may be a controller and/or a relay.
Another electric tool includes a motor including a first winding, a second winding and a third winding, a power circuit configured to selectively connect a first power supply and a second power supply for supplying power for the motor and including an output anode and an output cathode, a connecting circuit including a first connecting circuit including a first switch and a second switch, wherein one of two connecting ends of the first winding is connected between the first switch and the second switch, a second connecting circuit including a third switch and a fourth switch, wherein the other one of two connecting ends of the first winding is connected between the third switch and the fourth switch, a third connecting circuit including a fifth switch and a sixth switch, wherein one of two connecting ends of the second winding is connected between the fifth switch and the sixth switch, and a fourth connecting circuit including a seventh switch and an eighth switch, wherein one of two connecting ends of the third winding is connected between the seventh switch and the eighth switch, and a signal source configured to send a first control signal, when the power circuit accesses the first power supply, to the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, the seventh switch and the eighth switch so that the first winding is connected between the output anode and the output cathode, and send a second control signal, when the power circuit accesses the second power supply, to the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, the seventh switch and the eighth switch so that the first winding and the second winding are connected between the output anode and the output cathode, wherein the connecting circuit is electrically connected with the power circuit and the motor and the signal source is electrically connected with the connecting circuit.
Further, a voltage of the first power supply accessed by the power circuit may be greater than a voltage of the second power supply accessed by the power circuit.
Further, the first power supply accessed by the power circuit may be an alternating current power supply with the second power supply accessed by the power circuit being a direct current power supply.
Further, the signal source may include a controller or a relay.
Another electric tool includes a motor including a plurality of windings, a power circuit configured to selectively access a first power supply and a second power supply for supplying power for the motor, a connecting circuit including a switching device configured to enable the connecting circuit to have a first state in which only one of two connecting ends of the winding is connected to other windings and a second state in which two connecting ends of the winding are respectively connected to different windings, and a signal source configured to send a first control signal, when the power circuit accesses the first power supply, to the switching device so that the connecting circuit is in the first connection state, and to send a second control signal, when the power circuit accesses the second power supply, to the switching device so that the connecting circuit is in the second connection state.
The present disclosure has a beneficial effect that an electric tool which can be connected to different voltage inputs is provided. The electric tool has basically the same output properties when connected to power supplies with different voltages.
The present disclosure is described in detail below in combination with drawings and specific examples.
By referring to an electric tool 100 shown in
The miter saw includes a base 101, a working table 102, a saw blade 103, a power circuit 110, a connecting circuit 120 and a motor 130. The base 101 is configured to support the working table 102. The miter saw can be stably placed on the ground or an operating plane. The working table 102 is rotatably connected to the base 101, and is configured to support a processing piece. The saw blade 103 is pivotably connected with the working table 102 through a bracket, and is configured to cut the processing piece. The motor 130 is provided to drive the saw blade 103 to cut the processing piece placed on the working table 102.
An integral structure of the miter saw is roughly the same as a general miter saw structure, and is not repeated in detail herein for the sake of brevity.
As an example, the first power supply 111 is a battery pack having a first voltage value and the second power supply 112 is a battery pack having a second voltage value, wherein the first voltage value is greater than or equal to the second voltage value. Specifically, the first power supply 111 and the second power supply 112 are detachable battery packs.
As another example, the first power supply 111 is an alternating current power supply having the first voltage value, and the second power supply 112 is a direct current power supply having the second voltage value. Specifically, a value range of the first voltage value is 210V to 230V, and a value range of the second voltage value is 110V to 130V. The first power supply 111 and the second power supply 112 access alternating current commercial power through respective corresponding alternating current plugs.
As another example, the first power supply 111 accessed by the power circuit 110 is an alternating current power supply, and the second power supply 112 accessed by the power circuit 110 is a direct current power supply. Specifically, the power circuit 110 includes a first power supply 111 access port, a second power supply 112 access port, and a voltage conversion circuit. The first power supply 111 access port accesses the first power supply 111, and the second power supply 112 access port accesses the second power supply 112. The electric energy of the first power supply 111 accessed by the first power supply 111 access port is converted, through the voltage conversion circuit, into direct current voltage having a preset voltage value for output. More specifically, the voltage conversion circuit may be a rectification circuit including four semiconductor elements, and can convert alternating current into direct current for output. It should be noted that the access of the first power supply 111 and/or the second power supply 112 by the power circuit 110 includes direct accessing or indirect accessing.
As shown in
Specifically, the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the fifth switch K5, the sixth switch K6 and the eighth switch K8 are semiconductor switches, such as IGBT, MOSFET or semiconductor switches composed of triodes and diodes. In the below description, the above switches are in the form of a MOSFET and each of the switches has a respective source electrode, gate electrode and drain electrode.
As shown in
The motor 130 includes a first-phase winding 131, a second-phase winding 132 and a third-phase winding 133, wherein the first-phase winding has a first connecting end 131a and a second connecting end 131o, the second-phase winding has a third connecting end 132b and a fourth connecting end 132o, and the third-phase winding has a fifth connecting end 133c and a sixth connecting end 133o. As a connection mode, as shown in
The controller 140 is configured to send a first control signal, when the power circuit 110 accesses the first power supply 111, to the switches in the connecting circuit 120 so that the connecting circuit 120 has a first connection state in which a first number of windings are connected between the output anode 110a and the output cathode 110b, and send a second control signal, when the power circuit 110 accesses the second power supply 112, to the switches in the connecting circuit 120 so that the connecting circuit 120 has a second connection state in which a second number of windings are connected between the output anode 110a and the output cathode 110b. It should be noted, the first number of the windings may be a number different from that of the second number of the windings.
Specifically, when the power circuit 110 accesses the first power supply 111, e.g., 220V alternating current commercial power, the controller 140 sends the first control signal to the switches in the connecting circuit 120 so that the connecting circuit 120 has a first connection state in which two phase windings, e.g. the first-phase or first winding and the second-phase or second winding, are connected in series between the output anode 110a and the output cathode 110b. When the power circuit 110 accesses the second power supply 112, e.g., direct current, the controller 140 sends the second control signal to the switches in the connecting circuit 120 so that the connecting circuit 120 has a second connection state in which one phase winding, e.g. the first-phase or first winding is connected between the output anode 110a and the output cathode 110b.
In combination with
When the power circuit 110 accesses the alternating current commercial power, the controller 140 sends a control signal which enables the third switch K3 and the sixth switch K6 to be switched on, so that the third switch K3 and the sixth switch K6 in the connecting circuit 120 are switched on. Current output by the power circuit 110 successively flows through the input anode 120a, the third switch K3, the first-phase winding, the second-phase winding, the sixth switch K6 and the input cathode 120b so as to form a closed current loop so that the first winding 131 and the second winding 132 generate magnetomotive force in space, and magnetic fields of a stator and a rotor of the motor 130 interact so that the motor 130 rotates to convert electric energy into mechanical energy for output so as to drive the saw blade to operate. To facilitate description, a conduction state of the connecting circuit 120 when the third switch K3 and the sixth switch K6 are switched on is defined as K3K6, a driving state of the motor 130 when the first connecting end 131a is connected to the input anode 120a and the third connecting end 132b is connected to the input cathode 120b is defined as AB. Namely, the controller 140 sends a control signal which enables the third switch K3 and the sixth switch K6 to be switched on, the conduction state of the connecting circuit 120 is K3K6, and the driving state of the motor 130 is correspondingly AB.
The controller 140 sends a control signal which enables the fifth switch K5 and the fourth switch K4 to be switched on, so that the fifth switch K5 and the fourth switch K4 in the connecting circuit 120 are switched on, i.e., the conduction state of the connecting circuit 120 is K5K4. Current output by the power circuit 110 successively flows through the input anode 120a, the fifth switch K5, the second-phase winding 132, the fourth switch K4, the first-phase winding 131 and the input cathode 120b so as to form a closed current loop, i.e., the driving state of the motor 130 is correspondingly BA.
The power circuit 110 accesses the alternating current commercial power, and the controller 140 successively outputs different control signals to the switches in the connecting circuit 120 so as to change the driving state of the motor 130, so that the phase windings of the motor 130 are operated according to a certain order and then the motor 130 rotates to convert electric energy into mechanical energy for output so as to drive the saw blade to operate. Table 1 is a corresponding relationship table of the conduction states of the connecting circuit 120 and the driving states of the motor 130 within the duration of one period, i.e., the duration in which the rotor of the motor 130 rotates by one circle when the power circuit 110 accesses the alternating current commercial power. The controller 140 successively outputs corresponding control signals according to a sequence from top to bottom shown in Table 1.
It can be known from the above table that, when the power circuit 110 accesses the alternating current commercial power, the second connecting end 131o, the fourth connecting end 132o and the sixth connecting end 133o are connected to the neutral point O1 and the three phase windings form a star-shaped or Y-shaped connection.
When the power circuit 110 accesses the direct current, such as two 56V battery packs connected in parallel, the controller 140 outputs a control signal, which enables the third switch K3 and the second switch K2 to be switched on, to the connecting circuit 120 so that the third switch K3 and the second switch K2 are switched on. Current output by the power circuit 110 successively flows through the input anode 120a, the third switch K3, the first-phase winding, the second switch K2 and the input cathode 120b so as to form a closed current loop so that the first-phase winding generates magnetomotive force. Similarly, to facilitate description, the conduction state of the above connecting circuit 120 is defined as K3K2; and a state when the first connecting end 131a is connected to the input anode 120a and the second connecting end 131o (i.e., the neutral point O1) is connected to the input cathode 120b is defined as the driving state AO of the motor 130.
The controller 140 outputs a control signal, which enables the first switch K1 and the fourth switch K4 to be switched on, to the connecting circuit 120 so that the first switch K1 and the fourth switch K4 are switched on. Current output by the power circuit 110 successively flows through the input anode 120a, the first switch K1, the first-phase winding 131, the fourth switch K4 and the input cathode 120b. At this moment, the second connecting end 131o (i.e., the neutral point O1) is connected to the input anode 120a and the first connecting end 131a is connected to the input cathode 120b. The conduction state of the connecting circuit 120 is K1K4, and the driving state of the motor 130 is correspondingly OA.
Table 2 is a corresponding relationship table of the conduction states of the connecting circuit 120 and the driving states of the motor 130 within the duration of one period, i.e., the duration in which the rotor of the motor 130 rotates by one circle when the power circuit 110 accesses the direct current. The controller 140 successively outputs corresponding control signals to the connecting circuit 120 according to a sequence from top to bottom shown in Table 2, so as to drive the motor 130 to rotate. It can be known from the above table that, when the power circuit 110 accesses the direct current, e.g. from the battery pack, the three phase windings form a triangle-shaped or Δ-shaped connection.
In the miter saw of the subject example, when the power circuit 110 accesses different power supplies, the controller 140 as a signal source responds to different accessed power supplies to output corresponding control signals to an electronic switch, thereby realizing switching of the driving states of the motor 130 between the different power supplies, ensuring that output properties of the motor 130 during accessing different power supplies are basically consistent, and enhancing use experience of the user. Meanwhile, the electronic switch realizes state switching when the motor 130 accesses different power supplies, thereby realizing low production cost and small space occupation of the electric tool, so that the integral structure of the electric tool is more compact. The output properties herein include a rotating speed, an output voltage, an output power and other property parameters of the motor 130.
It should be noted that if the first power supply 111 and the second power supply 112 accessed by the power circuit 110 are identical, and the power circuit 110 access the same voltage, output of different rotating speeds of the motor 130 can be apparently realized by adopting the connecting circuit 120 and the controller 140 in the present embodiment, thereby satisfying a demand on a working condition that the same motor 130 outputs different rotating speeds at the same voltage. It is easy for those skilled in the art to contemplate that the solution is also within a protection scope of the present disclosure.
Referring to a schematic diagram illustrating an internal structure of a miter saw of another example shown in
The motor 230 includes a first-phase winding 231, a second-phase winding 232 and a third-phase winding 233. The first connecting end 231a of the first-phase winding 231 is connected with the first terminal 221a, the third connecting end 232b of the second-phase winding 232 is connected with the second terminal 222b, and the fifth connecting end 233c of the third-phase winding 233 is connected with the third connecting end 232b.
Specifically, the relay 240 includes a first relay 241, a second relay 242 and a third relay 243. Each relay 240 has one static contact and two movable contacts. One of the static contact and the two movable contacts is defined to be connected in a first contact state of the relay 240, and another one of the static contact and the two movable contacts is defined to be connected in a second contact state of the relay 240. The static contact of the first relay 241 is connected to the second connecting end 231o, the static contact of the second relay 242 is connected to the fourth connecting end 232o, and the static contact of the third relay 243 is connected to the sixth connecting end 233o.
A condition that the first power supply 211 accessed by the power circuit 210 is alternating current commercial power and the accessed second power supply 212 is direct current is illustrated below.
When the power circuit 210 accesses the alternating current commercial power, the first relay 241, the second relay 242 and the third relay 243 are in the first contact state. Namely, the first static contact 241a is connected to the second movable contact 241c, the second static contact 242a is connected to the fourth movable contact 242c, and the third static contact 243a is connected to the sixth movable contact 243c. Meanwhile, the controller outputs a control signal that enables the first switch Q1 and the fourth switch Q4 to be switched on so that the first connecting end 231a is connected to the output anode of the power circuit 210 and the third connecting end 232b is connected to the output cathode of the power circuit 210. In other words, the conduction state of the connecting circuit 220 is Q1Q4; and the driving state of the motor 230 is correspondingly AB. Similarly, the controller successively outputs corresponding control signals to the connecting circuit 220 according to a sequence from top to bottom shown in Table 3, so as to drive the motor 230 to rotate.
It can be known from Table 3 that when the power circuit 210 accesses the alternating current commercial power, the second connecting end 231o, the fourth connecting end 232o and the sixth connecting end 233o are connected to the neutral point O2 and the three phase windings form star-shaped connection. Namely, only the second connecting end 231o in two connecting ends of the first-phase winding 231 is connected to the second-phase winding 232 and the third-phase winding 233.
When the power circuit 210 accesses the direct current, the first relay 241, the second relay 242 and the third relay 243 are in the first contact state. Namely, the first static contact 241a is connected to the first movable contact 241b, the second static contact 242a is connected to the third movable contact 242b, and the third static contact 243a is connected to the fifth movable contact 243b. Meanwhile, the controller outputs a control signal that enables the first switch Q1 and the fourth switch Q4 to be switched on so that the first connecting end 231a is connected to the output anode of the power circuit 210 and the third connecting end 232b is connected to the output cathode of the power circuit 210. In other words, the conduction state of the connecting circuit 220 is Q1Q4, and the driving state of the motor 230 is correspondingly AB.
It should be noted that when the power circuit 210 accesses the direct current, the controller also successively outputs corresponding control signals to the connecting circuit 220 according to a sequence from top to bottom shown in Table 3, so as to drive the motor 230 to rotate. A difference from accessing the alternating current is that the three phase windings of the motor 230 form an angular connection. Namely, two connecting ends of the first-phase winding 231 are respectively connected to one end of the second-phase winding 232 and the third-phase winding.
The miter saw in above examples can also realize the change of the driving states of the motor 230 when the power circuit 210 accesses different power supplies, so that the motor 230 has approximately the same output properties when switching between accessing two different power supplies.
The above shows and describes a basic principle, main features and advantages of the present disclosure. Those skilled in the art should understand that above embodiments do not limit the present disclosure in any form. Technical solutions obtained by adopting equivalent replacements or equivalent transformations fall within the protection scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201710053549.0 | Jan 2017 | CN | national |
