阅读说明：本技术 一种直流电机、直流电机的控制方法及烹饪器具 (Direct current motor, control method of direct current motor and cooking appliance ) 是由 任富佳 冯国华 阮华平 潘艳丽 刘连超 宋龙龙 于 2021-09-16 设计创作，主要内容包括：本发明提供了一种直流电机、直流电机的控制方法及烹饪器具,涉及烹饪器具的技术领域,该直流电机用于安装在烹饪器具的内胆,包括驱动板：驱动板包括控制电源正极的VDC端子、控制地线的GND端子、控制反馈信号的FG端子和控制转速和旋转方向的PWM端子。通过本发明,缓解了带有加热风机的烹饪器具所使用的直流电机控制端子接口较多,控制复杂,成本较高,可靠性差的技术问题,达成了对烹饪器具上直流电机的驱动程序的优化,达到了简化直流电机成本,提高可靠性的技术效果。(The invention provides a direct current motor, a control method of the direct current motor and a cooking appliance, and relates to the technical field of cooking appliances, wherein the direct current motor is arranged in an inner container of the cooking appliance and comprises a driving plate: the driving board includes a VDC terminal for controlling a positive electrode of the power supply, a GND terminal for controlling a ground, an FG terminal for controlling a feedback signal, and a PWM terminal for controlling a rotation speed and a rotation direction. According to the invention, the technical problems of more direct current motor control terminal interfaces, complex control, higher cost and poor reliability of the cooking appliance with the heating fan are solved, the optimization of the driving program of the direct current motor on the cooking appliance is achieved, and the technical effects of simplifying the cost of the direct current motor and improving the reliability are achieved.)

1. A direct current motor, characterized in that, for mounting in the inner container (100) of a cooking appliance, it comprises a drive plate (700):

the driving board (700) includes a VDC terminal for controlling a positive electrode of a power supply, a GND terminal for controlling a ground line, an FG terminal for controlling a feedback signal, and a PWM terminal for controlling a rotation speed and a rotation direction.

2. The direct current motor according to claim 1, characterized in that the direct current motor comprises a motor body, a bracket (300) and a sealing assembly;

the motor body has a motor shaft (200);

the support (300) is provided with a shaft hole, the support (300) is sleeved on the motor shaft (200) through the shaft hole, and the motor shaft (200) is used for penetrating through the support (300) and penetrating through the inner container (100);

the sealing component is sleeved on the motor shaft (200), and a sealing space is formed among the inner container (100), the support (300), the motor shaft (200) and the sealing component.

3. The direct current motor according to claim 2, wherein the sealing assembly comprises a first sealing member (400), the first sealing member (400) is sleeved on the motor shaft (200) and is installed between the bracket (300) and the inner container (100), and the first sealing member (400) is used for being pressed and abutted with the inner container (100).

4. The direct current motor according to claim 3, wherein a protrusion (310) surrounding the motor shaft (200) is disposed on a side of the bracket (300) facing the inner container (100), a first groove (410) surrounding the motor shaft (200) is disposed on a side of the first sealing member (400) facing the bracket (300), and the protrusion (310) is inserted into the first groove (410).

5. The direct current motor according to claim 3, characterized in that the first sealing member (400) is of a sealing ring structure, and the end surface of the first sealing member (400) facing the inner container (100) is provided with a second groove (420) surrounding the motor shaft (200).

6. The direct current motor according to claim 2, wherein the sealing assembly comprises a second sealing member (500), the second sealing member (500) is sleeved on the motor shaft (200) and located in the shaft hole, and the second sealing member (500) is in interference fit with the hole wall of the shaft hole and the motor shaft (200), respectively.

7. The direct current motor according to claim 6, characterized in that the outer wall of the motor shaft (200) is provided with a third annular groove (210), and the second sealing member (500) is mounted in the third annular groove (210).

8. The direct current motor according to claim 6, wherein the hole wall of the shaft hole of the bracket (300) is annularly stepped, including multiple layers of annular steps, and the radius of the annular steps is gradually increased along the direction close to the inner container (100).

9. The direct current motor according to claim 6, wherein the hole wall of the shaft hole is provided with a first layer of annular steps, a second layer of annular steps and a third layer of annular steps in a direction close to the output end of the motor shaft (200), and the second sealing member (500) is provided on the second layer of annular steps.

10. The direct current motor according to claim 9, further comprising a baffle (510), the baffle (510) being mounted to the third layer of annular steps.

11. The direct current motor according to claim 2, wherein the sealing assembly comprises a third sealing member, the third sealing member is sleeved on the motor shaft (200) on the side of the bracket (300) away from the inner container (100), and the third sealing member is in sealing connection with the bracket (300) and simultaneously realizes dynamic sealing fit with the motor shaft (200).

12. A direct current motor according to claim 11, characterized in that the third seal is a sealed bearing (600).

13. The direct current motor according to claim 2, wherein the driving plate (700) is disposed on a side of the motor body away from the inner container (100).

14. The direct current motor according to claim 2, wherein the driving plate (700) is provided outside the cooking appliance, the driving plate (700) being electrically connected with the motor body.

15. A method for controlling a dc motor, characterized in that the method is applied to a dc motor according to any one of claims 1-14; the direct current motor comprises a controller and a PWM terminal for controlling the rotating speed and the rotating direction; the method comprises the following steps:

the controller detects whether the potential of the PWM terminal changes within a set time;

if not, the controller sends a rotation direction switching signal to the direct current motor so that the direct current motor switches the rotation direction.

16. The method of controlling a direct current motor according to claim 15, wherein the PWM terminal is configured to output a PWM signal during operation of the direct current motor, the method comprising:

the controller detects whether the PWM terminal outputs the PWM signal;

if yes, the controller sets the rotating speed of the direct current motor according to the PWM signal.

17. The method according to claim 16, wherein the PWM signal is a square wave, and the step of setting the rotation speed of the dc motor according to the PWM signal by the controller comprises:

and the controller acquires the duty ratio of the square wave and controls the rotating speed of the direct current motor according to the duty ratio.

18. The method of controlling a direct current motor according to claim 17, wherein the set time is at least one order of magnitude higher than a pulse width of the PWM signal.

19. The method of controlling a direct current motor according to claim 15, wherein the direct current motor further includes an FG terminal that controls a feedback signal, the method comprising:

the controller acquires the rotating speed and the rotating direction of the direct current motor fed back by the FG terminal;

and the controller sets the rotating speed and the rotating direction of the direct current motor according to the obtained rotating speed and the rotating direction of the direct current motor.

20. A cooking appliance, comprising an inner container (100), fan blades and the dc motor of any one of claims 1 to 14, wherein the dc motor is installed outside the inner container (100), the fan blades are installed inside the inner container (100), and a motor shaft (200) of the dc motor penetrates through the inner container (100) to be in transmission connection with the fan blades.

Technical Field

The invention relates to the technical field of cooking appliances, in particular to a direct current motor, a control method of the direct current motor and a cooking appliance.

Background

In recent years, kitchen appliances such as a steaming and baking all-in-one machine, an oven, a steam box, and the like, which are sealed and used for heating food, have gradually come into the field of view of the public. They use the heating fan to strengthen the heat convection to in the kitchen electric cavity in order to heat food mostly, and specifically, motor body fixes in the inner bag back wall outside, and the axle stretches into the cavity through the inner bag trompil and drives the flabellum rotatory.

The fan product that present use heating fan's kitchen utensils and appliances used is alternating current motor mostly, can only one-way single-speed rotatory, can't change rotation rate and direction of rotation, therefore is difficult to guarantee the temperature homogeneity in the cavity, leads to the fact the difficulty for the development debugging of product, and the culinary art effect in the user use is difficult to guarantee. If a direct current motor is adopted, the functions of rotating speed adjustment, reversing and the like can be realized, and better temperature uniformity and cooking performance are brought.

However, the current dc motor has many driving terminals of the control board, and usually has five pin terminals including a VDC terminal for controlling the positive electrode of the power supply, a GND terminal for controlling the ground, an FG terminal for controlling the feedback signal, a CW/CCW terminal for controlling the rotation direction, and a PWM terminal for controlling the rotation speed.

In a conventional dc motor, power is usually supplied via VDC and GND, and then, the rotation speed is adjusted by the duty ratio of a PWM signal, and the rotation speed and the rotation direction data are fed back via FG, and the rotation direction of the motor is controlled by the high/low level of CW/CCW. This makes the control panel control of direct current motor complicated, and the cost is higher, and the fault rate is high, and the reliability is poor.

Disclosure of Invention

The invention aims to provide a direct current motor, a control method of the direct current motor and a cooking utensil, and aims to solve the technical problems that in the prior art, the cooking utensil with a heating fan has more direct current motor control terminal interfaces, is complex to control, has higher cost and is poor in reliability.

The invention provides a direct current motor, which is used for being installed in an inner container of a cooking appliance, and comprises a driving plate: the driving board includes a VDC terminal for controlling a positive electrode of the power supply, a GND terminal for controlling a ground, an FG terminal for controlling a feedback signal, and a PWM terminal for controlling a rotation speed and a rotation direction.

Further, the direct current motor comprises a motor body, a bracket and a sealing assembly; the motor body is provided with a motor shaft; the support is provided with a shaft hole, the support is sleeved on the motor shaft through the shaft hole, and the motor shaft penetrates through the support and is arranged in the inner container in a penetrating manner; the sealing assembly is sleeved on the motor shaft, and a sealing space is formed among the inner container, the bracket, the motor shaft and the sealing assembly.

Further, seal assembly includes first sealing member, and first sealing member cover is established at the motor shaft, and installs between support and inner bag, and first sealing member is used for compressing tightly the butt with the inner bag.

Furthermore, one side of the support facing the inner container is provided with a protrusion surrounding the motor shaft, one side of the first sealing element facing the support is provided with a first groove surrounding the motor shaft, and the protrusion is connected with the first groove in an inserting mode.

Furthermore, the first sealing element is of a sealing ring structure, and a second groove surrounding the motor shaft is formed in the end face, facing the inner container, of the first sealing element.

Further, the sealing assembly comprises a second sealing element, the second sealing element is sleeved on the motor shaft and is located in the shaft hole, and the second sealing element is in interference fit with the hole wall of the shaft hole and the motor shaft respectively.

Furthermore, an annular third groove is formed in the outer wall of the motor shaft, and a second sealing element is mounted in the third groove.

Furthermore, the hole wall of the shaft hole of the support is in an annular step shape and comprises a plurality of layers of annular steps, and the radius of each annular step is gradually increased along the direction close to the inner container.

Further, along the direction of being close to the output of motor shaft, the pore wall in shaft hole is equipped with first layer annular ladder, second floor annular ladder and third layer annular ladder, and the second sealing member is established at second floor annular ladder.

Further, the direct current motor further comprises a baffle plate, and the baffle plate is installed on the third layer of annular ladder.

Further, the sealing assembly comprises a third sealing element, the motor shaft on one side, away from the inner container, of the support is sleeved with the third sealing element, and when the third sealing element is connected with the support in a sealing mode, the third sealing element is matched with the motor shaft in a dynamic sealing mode.

Further, the third seal is a seal bearing.

Further, the drive plate sets up the one side of keeping away from the inner bag at motor body.

Further, the driving plate is arranged outside the cooking appliance and electrically connected with the motor body.

A second aspect of the present invention provides a method for controlling a dc motor, which is applied to the dc motor; the direct current motor comprises a controller and a PWM terminal for controlling the rotating speed and the rotating direction; the method comprises the following steps: the controller detects whether the potential of the PWM terminal changes within a set time; if not, the controller sends a rotation direction switching signal to the direct current motor so as to enable the direct current motor to switch the rotation direction.

Further, the PWM terminal is used for outputting a PWM signal during operation of the dc motor, and the method includes: the controller detects whether the PWM terminal outputs a PWM signal or not; if yes, the controller sets the rotating speed of the direct current motor according to the PWM signal.

Further, the PWM signal is a square wave, and the step of setting the rotation speed of the dc motor by the controller according to the PWM signal includes: the controller obtains the duty ratio of the square wave and controls the rotating speed of the direct current motor according to the duty ratio.

Further, the set time is at least one order of magnitude higher than the pulse width of the PWM signal.

Further, the direct current motor also comprises an FG terminal for controlling a feedback signal, and the method comprises the following steps: the controller acquires the rotating speed and the rotating direction of the direct current motor fed back by the FG terminal; and the controller sets the rotating speed and the rotating direction of the direct current motor according to the obtained rotating speed and the rotating direction of the direct current motor.

The invention provides a cooking appliance, which comprises an inner container, fan blades and the direct current motor, wherein the direct current motor is arranged outside the inner container, the fan blades are arranged in the inner container, and a motor shaft of the direct current motor penetrates through the inner container to be in transmission connection with the fan blades.

The direct current motor, the control method of the direct current motor and the cooking utensil provided by the invention have the beneficial effects that:

the invention provides a direct current motor, a control method of the direct current motor and a cooking appliance, wherein the direct current motor is used for being installed in an inner container of the cooking appliance and comprises a driving plate: the driving board includes a VDC terminal for controlling a positive electrode of the power supply, a GND terminal for controlling a ground, an FG terminal for controlling a feedback signal, and a PWM terminal for controlling a rotation speed and a rotation direction.

According to the invention, the rotation speed of the motor is controlled by adjusting the duty ratio of the PWM signal, and the rotation direction of the motor is controlled by comparing the unchanged duration time of the PWM signal with the set time, so that the function of controlling the rotation direction of the motor of a CW/CCW terminal in the prior art is combined on the PWM terminal, and the PWM terminal can control the rotation direction and the rotation speed of the direct current motor, thereby reducing one terminal, corresponding control circuits and elements, simplifying the structure of the direct current motor, and reducing the production cost and the use risk of the direct current motor. The invention solves the technical problems of more direct current motor control terminal interfaces, complex control, higher cost and poor reliability of the cooking appliance with the heating fan.

The invention also provides a control method of the direct current motor and a cooking utensil, which have all the technical characteristics of the direct current motor, so the technical effects are also achieved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a terminal schematic diagram of a driving board of a dc motor according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a direct current motor (a driving board is disposed on a side of a motor body away from an inner container) according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a dc motor (a driving board is disposed outside a cooking appliance) according to an embodiment of the present invention;

fig. 4 is a sectional view of a dc motor according to an embodiment of the present invention;

fig. 5 is a cross-sectional view of a dc motor (a motor shaft is provided with a third groove) according to an embodiment of the present invention;

fig. 6 is a cross-sectional view of a dc motor (a sealing bearing is disposed on a motor shaft) according to an embodiment of the present invention;

fig. 7 is a square wave diagram of a PWM signal of a dc motor according to an embodiment of the present invention;

fig. 8 is a logic diagram of a control method of a dc motor according to an embodiment of the present invention.

Icon: 100-inner container; 200-motor shaft; 210-a third groove; 300-a scaffold; 310-a bump; 400-a first seal; 410-a first groove; 420-a second groove; 500-a second seal; 510-a baffle; 600-sealing the bearing; 700-driving the board.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that the terms "upper", "lower", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on orientations or positional relationships shown in the drawings or orientations or positional relationships conventionally laid out when products of the present invention are used, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," "fourth," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.

Furthermore, the terms "horizontal", "vertical" and the like do not imply that the components are required to be absolutely horizontal or pendant, but rather may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Some embodiments of the invention are described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.

The kitchen electricity that heats food such as roast all-in-one, steam ager, oven has gradually walked into popular field of vision in recent years, and they are mostly through heating the fan and strengthen the heat convection of the inside cavity of kitchen electricity in order to heat food, and particularly, motor body fixes in the inner bag rear wall outside, and the axle stretches into the cavity through the inner bag trompil and drives the flabellum rotatory.

The fan product that present use heating fan's kitchen utensils and appliances used is alternating current motor mostly, and alternating current motor can only one-way single-speed rotatory, can't change rotation rate and direction of rotation, therefore is difficult to guarantee the temperature homogeneity in the cavity, and is unfavorable to the development and debugging of product, and the culinary art effect in the user use also is difficult to guarantee. If a direct current motor is adopted, the functions of rotating speed adjustment, reversing and the like can be realized, and better temperature uniformity and cooking performance are brought.

However, the existing direct current motor has a simple structure and low installation tightness with the inner container, and cannot meet two working conditions of the steaming and baking integrated machine with the steam function and the baking function. In the use of kitchen utensils and appliances, volatile gases such as steam that the steaming in-process produced and grease that the baking in-process produced all probably permeate inner structure such as rotor, bearing behind the support along inner bag outer wall and motor shaft, lead to the bearing to rust, the rotor card dies, consequence such as motor inefficacy has improved the cost of maintenance of kitchen utensils and appliances, has influenced user's normal use.

Based on the technical scheme, the invention provides the direct current motor, the control method of the direct current motor and the cooking utensil, and aims to solve the technical problems that in some technologies, the cooking utensil with the heating fan has more direct current motor control terminal interfaces, is complex to control, has higher cost and is poor in reliability.

The present invention provides a dc motor for being mounted on an inner container 100 of a cooking appliance, comprising a driving plate 700: as shown in fig. 1, the driving board 700 includes a VDC terminal to control a positive electrode of a power supply, a GND terminal to control a ground, an FG terminal to control a feedback signal, and a PWM terminal to control a rotation speed and a rotation direction.

According to the invention, the rotation speed of the motor is controlled by adjusting the duty ratio of the PWM signal, and the rotation direction of the motor is controlled by comparing the unchanged duration time of the PWM signal with the set time, so that the function of controlling the rotation direction of the motor of a CW/CCW terminal in the prior art is combined on the PWM terminal, and the PWM terminal can control the rotation direction and the rotation speed of the direct current motor, thereby reducing one terminal, corresponding control circuits and elements, simplifying the structure of the direct current motor, and reducing the production cost and the use risk of the direct current motor. The invention solves the technical problems of more direct current motor control terminal interfaces, complex control, higher cost and poor reliability of the cooking appliance with the heating fan.

In this embodiment, as shown in fig. 4, the dc motor includes a motor body, a bracket 300, and a sealing assembly; the motor body has a motor shaft 200; the support 300 is provided with a shaft hole, the support 300 is sleeved on the motor shaft 200 through the shaft hole, and the motor shaft 200 is used for penetrating through the support 300 and being arranged in the inner container 100; the sealing component is sleeved on the motor shaft 200, and a sealing space is formed among the inner container 100, the bracket 300, the motor shaft 200 and the sealing component.

In consideration of beauty, the direct current motor is arranged in a space between the inner container 100 and the outer wall of the cooking appliance, the motor shaft 200 extends into the cavity of the cooking appliance through the opening on the inner container 100, and the motor body is connected with the inner container 100 through the motor shaft 200. When the cooking utensil is used, the motor body drives the motor shaft 200 to rotate, so as to drive the fan blades in the cooking utensil to rotate and strengthen the heat convection in the wall body of the cooking utensil.

The sealing space is provided between the inner container 100 and the motor body, in this embodiment, the sealing space is an annular space surrounding the motor shaft 200, and the left and right wall surfaces of the sealing space along the direction of the motor shaft 200 are the inner container 100 and the bracket 300, respectively. When the cooking appliance is used, volatile gases such as water vapor and grease may flow out of the cavity of the cooking appliance along the gap between the inner container 100 and the motor shaft 200, and permeate into the internal structures such as the rotor and the bearing behind the bracket 300 or other devices in the space between the inner container 100 and the outer wall, thereby causing damage and corrosion. Through the arrangement of the sealed space, the volatile gas is sealed in the sealed space, so that the two situations can be avoided.

In this embodiment, the sealing assembly includes a first sealing member 400, the first sealing member 400 is sleeved on the motor shaft 200 and is installed between the bracket 300 and the inner container 100, and the first sealing member 400 is used for pressing and abutting against the inner container 100. Specifically, the first sealing member 400 is not in contact with the motor shaft 200, and the sealing space is an annular space between the first sealing member 400, the motor shaft 200, the inner container 100, and the bracket 300. The left and right end surfaces of the annular space along the direction of the motor shaft 200 are the inner container 100 and the bracket 300, respectively, and the end surfaces along the tangential direction of the motor shaft 200 are the outer surface of the motor shaft 200 and the inner surface of the first sealing member 400, respectively. The first sealing member 400 is abutted against the inner container 100 and the bracket 300 along the square of the motor shaft 200, respectively. The primary function of the first sealing member 400 is to prevent volatile gas, which seeps along the motor shaft 200, from entering the space between the inner container 100 and the outer wall of the cooking appliance, contaminating and corroding other devices between the inner container 100 and the outer wall.

Optionally, as shown in fig. 4, a protrusion 310 surrounding the motor shaft 200 is disposed on a side of the bracket 300 facing the inner container 100, a first groove 410 surrounding the motor shaft 200 is disposed on a side of the first sealing member 400 facing the bracket 300, and the protrusion 310 is inserted into the first groove 410. Specifically, the length of the protrusion 310 is greater than the depth of the first groove 410, the cross section of the protrusion 310 is the same as that of the first groove 410, after the protrusion 310 is matched with the first groove 410, the tip of the protrusion 310 abuts against the bottom of the first groove 410, and the groove wall of the first groove 410 limits the protrusion 310, so that the first groove 410 and the protrusion 310 are relatively fixed. The cooperation of the protrusion 310 and the first groove 410 stabilizes the relative position of the first sealing member 400 and the bracket 300, so that the first sealing member 400 is not dislocated or deformed during the rotation of the dc motor, and the stability of the sealed space is ensured.

Preferably, the first sealing member 400 is a sealing ring structure, and the end surface of the first sealing member 400 facing the inner container 100 is provided with a second groove 420 surrounding the motor shaft 200. The inner ring and the outer ring of the second groove 420 enable the contact surface of the first sealing element 400 and the inner container 100 to have two layers of sealing, the sealing effect of the first sealing element 400 is further improved, and the arrangement of the second groove 420 enables the first sealing element 400 and the inner container 100 to be in double-layer line contact instead of surface contact. The line contact prevents the water accumulation and leakage caused by the deformation of the contact surface of the first sealing member 400 and the inner container 100, compared to the surface contact.

In this embodiment, as shown in fig. 4, the sealing assembly includes a second sealing member 500, the second sealing member 500 is sleeved on the motor shaft 200 and is located in the shaft hole, and the second sealing member 500 is in interference fit with the hole wall of the shaft hole and the motor shaft 200 respectively. The second sealing member 500 blocks the path of the volatile gas entering the motor body, and its main function is to prevent the volatile gas leaking along the motor shaft 200 from entering the motor body, and contaminating and corroding the rotor, bearings and other structures of the motor body.

Further, as shown in fig. 5, the outer wall of the motor shaft 200 is formed with a third groove 210 having a ring shape, and the second sealing member 500 is mounted in the third groove 210. The provision of the third groove 210 prevents misalignment and inclination of the second seal 500 in the direction of the motor shaft 200, thereby preventing seal failure that may be caused by misalignment and inclination of the second seal 500. Specifically, the width of the third groove 210 is the same as the width of the second seal 500.

In this embodiment, the hole wall of the shaft hole of the bracket 300 is in an annular step shape, which includes multiple layers of annular steps, and the radius of the annular steps is gradually increased along the direction close to the inner container 100.

Specifically, along the direction of being close to the output of motor shaft 200, the pore wall in shaft hole is equipped with first layer annular ladder, second floor annular ladder and third layer annular ladder, and second sealing member 500 establishes at second floor annular ladder. The first annular step abuts against the outer surface of the motor shaft 200, and the second sealing element 500 is prevented from being dislocated towards the motor body.

Further, as shown in fig. 4 and 5, the dc motor further includes a baffle 510, and the baffle 510 is mounted on the third layer of annular step. The baffle 510 abuts against the lower surface of the third annular step and the outer surface of the motor shaft 200, respectively, and prevents the second sealing member 500 from being misaligned in the direction of the output end of the motor shaft 200. The baffle 510 and the first layer of annular steps respectively limit the second sealing element 500 left and right along the direction of the motor shaft 200, and the position of the second sealing element 500 is stabilized.

In this embodiment, as shown in fig. 6, the sealing assembly includes a third sealing member, the third sealing member is sleeved on the motor shaft 200 at a side of the bracket 300 away from the inner container 100, and the third sealing member is in sealing connection with the bracket 300, and meanwhile, the third sealing member is in dynamic sealing fit with the motor shaft 200. The third sealing element and the second sealing element 500 are sleeved on the motor shaft 200 and are abutted to the outer surface of the motor shaft 200, and the second sealing element 500 and the third sealing element are used for preventing volatile gas from permeating into the motor body to pollute the rotor, the bearing and other structures in the motor body. Therefore, the second sealing member 500 and the third sealing member may be disposed at the same time, or only one of them may be disposed, depending on the structure and sealing requirements of the dc motor.

Specifically, the third seal is a seal bearing 600. It should be noted that the third sealing element is not necessarily the sealing bearing 600 in this embodiment, as long as it can be in dynamic sealing engagement with the motor shaft 200 and can perform a sealing function along the direction of the motor shaft 200.

Preferably, as shown in fig. 2, the driving plate 700 is disposed on a side of the motor body away from the inner container 100. Under the condition, the driving board 700 is not in contact with a heat source of the cooking appliance, namely the inner container 100, so that the working environment temperature of electronic components on the driving board 700 is reduced, the problem that the driving board 700 is not high-temperature-resistant is solved, and the reliability of the driving board 700 is improved.

Alternatively, as shown in fig. 3, the driving plate 700 is provided outside the cooking appliance, and the driving plate 700 is electrically connected with the motor body. The connection mode of the driving plate 700 and the cooking utensil enables the driving plate 700 to work at normal temperature, and further guarantees the temperature requirement of the working environment of the driving plate 700.

The structure of the dc motor has been explained above, and how the PWM terminal of the dc motor can control both the rotation speed and the rotation direction of the motor is explained next.

The embodiment of the invention provides a control method of a direct current motor, which is applied to the direct current motor; the direct current motor comprises a controller and a PWM terminal for controlling the rotating speed and the rotating direction; the method comprises the following steps: the controller detects whether the potential of the PWM terminal changes within a set time; if not, the controller sends a rotation direction switching signal to the direct current motor so as to enable the direct current motor to switch the rotation direction; if yes, the controller does not send a signal, and the direct current motor keeps the existing rotating direction unchanged.

Specifically, the PWM terminal is used for outputting a PWM signal during the operation of the dc motor, and the control method includes: the controller detects whether the PWM terminal outputs a PWM signal or not; if yes, the controller sets the rotating speed of the direct current motor according to the PWM signal.

As shown in fig. 7, the PWM signal is a square wave, and the step of setting the rotation speed of the dc motor by the controller according to the PWM signal includes: the controller obtains the duty ratio of the square wave and controls the rotating speed of the direct current motor according to the duty ratio.

It should be noted that the set time needs to be at least one order of magnitude higher than the pulse width of the PWM signal. During the normal rotation speed adjustment process of the PWM signal, the PWM signal will also switch between the high level and the low level, i.e. the PWM will be continuously maintained at the high level for a period of time, then maintained at the low level for a period of time, and then switched back to the high level for a period of time, and so on. In order to distinguish the wave band for regulating the rotation direction of the direct current motor from the wave band for normally regulating the rotation speed of the PWM signal, the setting time needs to be at least one order of magnitude higher than the pulse width of the PWM signal, and in this case, the duration for maintaining the same level in the wave band for regulating the rotation direction of the direct current motor is at least one order of magnitude longer than the duration for maintaining the same level in the wave band for normally regulating the rotation speed of the PWM signal, so that the mutual influence of the PWM signal for regulating the rotation direction of the direct current motor and the PWM signal for normally regulating the rotation speed of the direct current motor is avoided.

In this embodiment, the dc motor further includes an FG terminal that controls a feedback signal, and the method includes: the controller acquires the rotating speed and the rotating direction of the direct current motor fed back by the FG terminal; and the controller sets the rotating speed and the rotating direction of the direct current motor according to the obtained rotating speed and the rotating direction of the direct current motor.

The following describes a specific working principle of the control method of the dc motor provided by the present invention:

the direct current motor provided by the embodiment of the invention has four terminals in total. A VDC terminal for controlling the positive electrode of the power supply, a GND terminal for controlling the ground, an FG terminal for controlling the feedback signal, and a PWM terminal for controlling the rotation speed and the rotation direction, respectively.

After the motor is started, the VDC terminal and the GND terminal provide power, the rotating speed is adjusted through the duty ratio of the PWM signal, the rotating direction is adjusted through detecting the unchanged duration time of the PWM signal, and finally the rotating speed and the rotating direction data are fed back through the FG terminal.

Specifically, as shown in fig. 7, the PWM signal is a square wave with different duty ratios, and when the duty ratio is 0%, the square wave is a continuous low level; the square wave is continuously high when the duty cycle is 100%. And starting the motor when the direct current motor detects that the PWM signal has a signal, and rotating according to the default rotating direction. The direct current motor can adjust the rotating speed of the motor according to the duty ratio by detecting the duty ratio of the PWM signal, the rotating speed of the motor is accelerated when the duty ratio is increased, and the rotating speed of the motor is decelerated when the duty ratio is reduced.

Meanwhile, the motor will detect the time when the PWM maintains the same level, and compare the time with the set time: when the time is less than the set time, the existing rotating direction is maintained unchanged, and when the time is more than the set time, the rotating direction of the motor is changed. For example, the longer straight line in the middle of fig. 7 is the duration of the PWM signal maintaining the low level, and if the duration is less than the set time, the current rotation direction is not convenient to be positioned, and if the duration is greater than the set time, the rotation direction of the motor is changed.

It should be noted that, because the motor is switched back and forth between the high level and the low level in the process of changing the rotating speed, in order to avoid that the detection structure makes a misjudgment when the motor normally adjusts the speed and changes the rotating direction of the motor, the setting time should be at least one order of magnitude higher than the pulse width of the PWM signal.

In the present embodiment, the frequency of the PWM signal is 10 khz, the pulse width period of the PWM signal is 0.1ms, and the set time for detecting the change of the rotation direction of the motor is 100 ms. That is, the set time is 3 orders of magnitude higher than the pulse width.

The frequency of the PWM signal is different according to the type and usage environment of the dc motor, and the setting time set according to the frequency of the PWM signal is also changed accordingly. The setting time is at least one order of magnitude higher than the pulse width of the PWM signal, however, if the setting time is too much higher than the pulse width of the PWM signal, the normal rotation speed adjustment of the motor is influenced, and the specific setting time is set according to the frequency of the PWM signal and the service condition of the motor, so that the occurrence of misjudgment is avoided as much as possible.

Through the process, when a user uses the direct current motor, the rotation speed of the motor is controlled by adjusting the duty ratio, the rotation direction of the motor is controlled by comparing the duration time of the PWM signal which does not change with the set time, and the function of controlling the rotation direction of the motor of the CW/CCW terminal in the prior art is combined on the PWM terminal, so that one terminal, corresponding control circuits and elements are reduced, the structure of the direct current motor is simplified, and the production cost and the use risk of the direct current motor are reduced.

A logic diagram of the control method of the dc motor according to the present invention is shown in fig. 8.

The embodiment of the invention also provides a cooking appliance, which comprises an inner container 100, fan blades and the direct current motor, wherein the direct current motor is arranged outside the inner container 100, the fan blades are arranged in the inner container 100, and a motor shaft 200 of the direct current motor penetrates through the inner container 100 and is in transmission connection with the fan blades.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.