Door opening and closing device for household appliance and household appliance

By designing a door opening and closing device that can drive two sets of transmission components at the same time, the torque demand and structural complexity problems during automatic switching of refrigerator doors are solved, and a flexible switching mode switching and protection mechanism is realized, reducing costs and resistance.

CN222909785UActive Publication Date: 2025-05-27BSH ELECTRICAL APPLIANCES (JIANGSU) CO LTD +1
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Patent Information

Application Number
CN202421295682.9
Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
Filing Date
2024-06-06
Publication Date
2025-05-27
Estimated Expiration
2034-06-06

AI Technical Summary

Technical Problem

现有冰箱门的自动开关门装置存在开门瞬间需要较大扭矩、结构复杂、成本高以及在自动开关和手动开关之间切换时阻力明显的问题。

Method used

A door opening and closing device is designed to drive two sets of transmission components simultaneously through a driving part to realize two different door opening processes, and switch to manual switching mode during the automatic opening and closing of the door body, and even activate the protection mechanism when an obstacle is encountered.

Benefits of technology

It realizes flexible switching between automatic switches and manual switches of the door body, reduces the resistance when opening and closing the door, avoids damage to components on the transmission path when encountering obstacles, simplifies the driving structure and reduces costs.

✦ Generated by Eureka AI based on patent content.

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Abstract

The utility model provides a door opening and closing device and a household appliance. The first transmission assembly of the door opening and closing device comprises a first transmission part and a push rod in transmission connection with the first transmission part, and the push rod is arranged on the side away from a door shaft; the second transmission assembly comprises a second transmission part and a crank, a crank shaft of the crank is connected with the second transmission part and arranged on the side close to the door shaft, and the tail end of a crank arm is slidably connected to the door body; and the driving part is used for simultaneously driving the first transmission assembly and the second transmission assembly. The push rod can overcome large resistance when the door body is opened; the crank can continuously open the door body by a large angle after the door body is opened. And the two groups of structures are matched with each other, so that the door body is continuously opened to a larger angle. In addition, the first transmission assembly and the second transmission assembly are driven by the driving parts at the same time, so that the number of the driving parts is reduced, and the size of the whole door opening and closing device is reduced.
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Description

Technical Field

[0001] The utility model relates to the technical field of household appliances, in particular to a door opening and closing device and household appliances. Background Art

[0002] The automation of household appliances can improve the user experience. For example, the automatic opening and closing function of the refrigerator door solves the pain point that it is inconvenient for users to open and close the door manually. However, there are still many problems with the solutions for automatic opening and closing of refrigerator doors in the prior art. For example, a large torque is required at the moment of opening the refrigerator door, and then a smaller torque is required when the door is continuously opened at a larger angle. The corresponding systems are respectively set to realize the corresponding functions, which may result in the door opening and closing device being relatively large in size, complex in structure, and high in cost. Furthermore, when switching between automatic door opening and closing and manual door opening and closing, users will feel obvious resistance, and even when encountering obstacles during the automatic door opening and closing process, the door opening and closing device may be damaged due to the reaction force.

[0003] Therefore, an improved solution is needed to realize automatic opening and closing of the door of the household appliance. Utility Model Content

[0004] The embodiment of the utility model provides a door opening and closing device, which can realize the automatic opening and closing of a door body, and can not only open the door body, but also further open the door body to a relatively large angle.

[0005] The embodiment of the utility model provides a door opening and closing device, which can realize two different door opening processes by simultaneously driving two sets of transmission components through one driving part.

[0006] The embodiment of the utility model provides a door opening and closing device, which can be switched to a manual opening and closing mode during the process of automatic opening and closing of the door body. Even if the door body encounters obstacles or other resistance during this process, the protection mechanism can be activated to avoid damage to the components on the transmission path.

[0007] The embodiment of the utility model also provides a household appliance with the function of automatically opening and closing the door.

[0008] The utility model provides a door opening and closing device for household appliances, wherein the household appliances include a main body and a door body connected to the main body through a door shaft, and the door opening and closing device includes: a first transmission assembly includes a first transmission part and a push rod transmission-connected thereto, the push rod is arranged on a side away from the door shaft; a second transmission assembly includes a second transmission part and a crank, wherein a crank shaft of the crank is connected to the second transmission part and is arranged on a side close to the door shaft, and the end of the crank arm is slidably connected to the door body; and a driving part, which is used to simultaneously drive the first transmission assembly and the second transmission assembly.

[0009] Compared with the prior art, in the present utility model, the push rod can apply a relatively large force to the door body, which can overcome the relatively large resistance when the door body is opened; the crank can continue to open the door body by a relatively large angle after the door body is opened. The two sets of structures cooperate with each other to continuously open the door body to a relatively large angle.

[0010] Furthermore, the push rod is arranged at a position far from the door shaft, which can reduce the requirement for the force needed to push open the door body. The crankshaft is arranged at a position close to the door shaft, which can increase the length range of the crank arm, so that the length of the crank arm can meet the requirement of driving the door body to continuously open by a relatively large angle, and can also meet the requirement of driving the door body to switch from the open state at a relatively large angle to the closed state.

[0011] In addition, the first transmission component and the second transmission component are simultaneously driven by the driving part, thereby reducing the number of driving parts, and further reducing the volume of the entire door opening and closing device.

[0012] In a possible embodiment, the door opening and closing device further includes a third transmission component connected to the driving part, and the third transmission component is respectively in transmission connection with the first transmission component and the second transmission component. By connecting the first transmission component and the second transmission component through the third transmission component, two door opening methods can be simultaneously realized through a set of driving parts. The first transmission component is driven to open the door body, and then the second transmission component is driven to continuously open the door body by a relatively large angle. In addition, this solution simplifies the driving structure and also reduces the cost.

[0013] In a possible embodiment, the third transmission component includes a worm and a worm wheel, and the output end of the driving part is connected to the worm, and the driving part and the third transmission component are in transmission connection through the worm wheel and the worm. The structure of the worm and worm wheel has a self-locking performance, which can prevent free rotation caused by the action of external forces.

[0014] In a possible embodiment, the first transmission component and the second transmission component further include at least one reset mechanism connected to the first transmission part and / or the second transmission part, and the reset mechanism is configured to block or restore the power transmission of the first transmission part or the second transmission part according to the state of the external force. Through the setting of the reset mechanism, a protection mechanism can be formed for the mechanisms or components on the transmission path. Specifically, when the door body is automatically opening and closing, if the user manually intervenes to open or close the door, the reset mechanism is subjected to a certain external force, thereby blocking the power transmission of the transmission part. When the external force disappears, the reset mechanism can enable the transmission part to transmit power again.

[0015] In a possible embodiment, the reset mechanism includes an elastic part and a groove part, wherein the elastic part supports the first transmission part and / or the second transmission part, the groove part is connected to the first transmission part and / or the second transmission part, and the first transmission part and / or the second transmission part can move along the groove part.

[0016] In a possible embodiment, the slot portion includes a first end portion and a second end portion, wherein when the first transmission portion and / or the second transmission portion move to the second end portion, the first transmission portion and / or the second transmission portion are disengaged from the transmission path.

[0017] In this embodiment, the first or second transmission portion is respectively connected to the elastic portion and the slot portion. The first or second transmission portion is relatively fixed to the elastic portion and is relatively movable with respect to the slot portion. When the elastic portion is subjected to an external force, it drives the first or second transmission portion to move relative to the slot portion, thereby blocking the transmission path of the first or second transmission portion and preventing the normal transmission of power. In addition, when the external force on the elastic portion is withdrawn (manually switched to automatic or the obstacle is removed), the elastic portion returns to its initial state under the action of its own elastic force, thereby restoring the transmission path of the first or second transmission portion and enabling the normal transmission of power.

[0018] In a possible embodiment, the first transmission portion includes a first gear and a second gear meshing with the first gear, wherein the first gear is connected to the push rod to drive the push rod to move, and the second gear is connected to the reset mechanism. When the push rod is subjected to an external force, such as a force manually applied by a user or other obstacles, the first gear transmits the external force to the second gear, so that the reset mechanism is subjected to the external force, causing the second gear connected thereto to disengage from its initial position and cutting off the transmission path, thereby protecting the components on the transmission path from damage. In addition, when the external force disappears, the reset mechanism can make the second gear return to its initial position again to normally transmit power.

[0019] In a possible embodiment, the second transmission portion includes a third gear and a fourth gear meshing with the third gear, wherein the third gear is coaxially connected to the crank, and the fourth gear is connected to the reset mechanism. When the crank is subjected to an external force, such as a force manually applied by a user or other obstacles, the third gear transmits the external force to the fourth gear, so that the reset mechanism is subjected to the external force, causing the fourth gear connected thereto to disengage from its initial position and cutting off the transmission path, thereby protecting the components on the transmission path from damage. In addition, when the external force disappears, the reset mechanism can make the fourth gear return to its initial position again to normally transmit power.

[0020] An appliance includes a main body and a door body connected thereto, and further includes the aforementioned door opening and closing device, wherein the door opening and closing device is disposed on the main body.

[0021] In a possible embodiment, the appliance further includes a sliding groove disposed on the door body, wherein the end of the crank is disposed in the sliding groove and is movable along the sliding groove.

[0022] In a possible embodiment, the length of the sliding groove satisfies at least: the movement stroke of the end of the crank in the sliding groove can cause the door body to open a preset angle. Brief Description of the Drawings

[0023] Figure 1 is a schematic structural view of the door opening and closing device in the closed state in an embodiment of the present utility model;

[0024] Figure 2 is a partially enlarged schematic view of part X of the door opening and closing device in an embodiment of the present utility model;

[0025] Figure 3 is a schematic structural view of the door opening and closing device in the open state in an embodiment of the present utility model;

[0026] Figure 4 is a partially enlarged schematic view of part Y of the door opening and closing device in an embodiment of the present utility model;

[0027] Figure 5 is a schematic structural view of the door opening and closing device when encountering an obstacle in an embodiment of the present utility model;

[0028] Figure 6 is Figure 5 an enlarged schematic view of part A in;

[0029] Figure 7 is Figure 5 an enlarged schematic view of part B in;

[0030] Figure 8 is a schematic view of the reset mechanism in an embodiment of the present utility model. Detailed Description of the Embodiment

[0031] An embodiment of the present utility model provides an improved door opening and closing device for household electrical appliances, which can realize automatic opening and closing of the door. The door opening and closing device includes a driving part, a transmission assembly, and a reset mechanism connected to the transmission assembly. Among them, the driving part drives the transmission assembly to transmit power, and the reset mechanism can block or restore the power transmission of the transmission assembly. Furthermore, while realizing automatic opening or closing of the door body, a protection mechanism of the door opening and closing device can be constructed through the reset mechanism.

[0032] Through the above solution, when the door body switches to manual opening and closing during the automatic opening and closing process, or encounters an obstacle blocking the automatic opening and closing stroke, the reset mechanism can block the transmission assembly from transmitting power, thereby preventing damage to the door opening and closing device caused by manual operation or obstacles, especially damage to the transmission assembly and the driving part. When the manual opening and closing action is cancelled or the obstacle is removed, the reset mechanism can restore the transmission assembly to transmit power and realize automatic opening and closing of the door.

[0033] Referring to Figures 1 to 4 , schematic structural views of the door opening and closing device in the closed and open states and corresponding partially enlarged schematic views of parts X and Y are respectively shown.

[0034] The door opening and closing device 20 can be arranged on a household electrical appliance. Specifically, the household electrical appliance generally includes a main body 10 and a door body 11 connected by a door hinge 12, and the door opening and closing device 20 can be arranged on the main body 10. As Figure 1 and 3 , the household electrical appliance can be a refrigerator, which includes a box body and a door body, and the door opening and closing device can be arranged on the top of the box body. The household electrical appliance can also be a clothing care device, a dishwasher, etc.

[0035] The door opening and closing device 20 includes a driving part 21, a transmission assembly connected to the driving part 21, and a reset mechanism 50 connected to the transmission assembly. The reset mechanism 50 can block or restore the power transmission of the transmission assembly under the action of an external force.

[0036] Specifically, the driving part 21 is, for example, a motor for outputting a driving force. The selection of the motor can be determined according to the torque required for opening and closing the door body, especially at the moment when the door body changes from the closed state to the open state, a large torque is required. In addition, considering the overall volume of the household electrical appliance, a small-sized motor can be selected.

[0037] The transmission assembly is connected to the driving part 21. Among them, the transmission assembly can include a transmission part and an execution part. The transmission part is connected to the execution part. The transmission part transmits power, and the execution part directly acts on the door body 11. Through the power output by the driving part and the transmission part, the execution part can apply a force to the door body to open or close the door body 11. The transmission part can be a transmission gear set, and the execution part can be a door pusher such as a push rod or a crank.

[0038] Furthermore, the transmission assembly can instantaneously open the door body 11 through the transmission part and the execution part, and can also continue to open the door body at a larger angle after the door body 11 is opened. Taking a refrigerator as an example, the opening process of the door body can be decomposed into two steps. The first step is to overcome a large suction force to switch the door body from the closed state to the open state, and the second step is to continue to open the door body to a larger angle after the door body is opened at a small angle. In this process, the transmission assembly needs to output a large torque on the one hand to enable the door body to complete the first action, and needs to continuously output a small torque to the door body on the other hand to enable the door body to complete the second action.

[0039] In one embodiment, the automatic opening and closing of the door body 11 can be realized through two sets of transmission assemblies. Specifically, the transmission assembly can include a first transmission assembly 30 and a second transmission assembly 40. The first transmission assembly 30 can be arranged to apply a large force to the door body 11 at the moment of opening the door to overcome the large resistance at the moment of opening the door; the second transmission assembly 40 can be arranged to continue to open the door body at a relatively large angle after the door body 11 is opened. For example, for a refrigerator door body, the opening angle of the door body can reach 120 degrees, or even larger.

[0040] Further, the first transmission assembly 30 may include a first transmission part 31 and a push rod 32. The first transmission part 31 is connected to the push rod 32 and transmits power to the push rod 32. The first transmission part 31 may be configured as a gear set, and the push rod 32 is provided with a plurality of tooth parts, and the first transmission part 31 meshes with the tooth parts of the push rod 32. Preferably, in order to enable the first transmission assembly 30 to overcome the relatively large resistance at the moment of opening the door, the push rod 32 may be arranged at a position far from the door hinge, so as to reduce the acting force output by the push rod, and thus reduce the requirements for the motor.

[0041] For example, referring to Figure 2 and Figure 4 , the first transmission part 31 includes a first gear 310 and a second gear 311 that meshes with the external teeth of the first gear 310. The first gear 310 is meshed and connected to the push rod 32 through tooth parts to drive the push rod 32 to move, thereby pushing the door body 11 to open. Here, the push rod 32 may be arranged in a manner substantially perpendicular to the door body, applying a force perpendicular to the door body to the door body.

[0042] The second gear 311 is used to receive the power output by the driving part 21 and transmit the power to the first gear 310, thereby driving the push rod 32; the second gear 311 may also be connected to the reset mechanism 50. When the push rod 32 is subjected to an external force, the external force will be transmitted to the first gear 310, the second gear 311, and the driving part 21. In order to avoid damage to the components in the entire transmission path, when the reset mechanism 50 is subjected to an external force, the second gear 311 may be disconnected from the first gear 310 or an adjacent gear, thereby blocking the transmission of power in the transmission path. Referring to Figure 5 and Figure 6 , the states of the reset mechanism 50 and the second gear 311 at A are shown when the door body 11 encounters an obstacle OB during closing.

[0043] Further, the second transmission assembly 40 may include a second transmission part 41 and a crank 42. The second transmission part 41 is connected to the crank 42 and drives the crank 42 to rotate. The second transmission part 41 may also be configured as a gear set. For example, referring to Figure 2 and Figure 4 , the second transmission part 41 includes a third gear 410, the crank 42 includes a crankshaft 420 and a crank arm 421 connected to the crankshaft 420. The third gear 410 is coaxially arranged with the crankshaft 420, and the end of the crank arm 421 is connected to the door body 11 and may be arranged to move relative to the door body 11. The third gear 410 drives the crank 42 to rotate, and then drives the door body 11 to move through the crank arm 421.

[0044] Further, a sliding groove 14 may be provided on the door body 11, and the end of the crank arm 421 is disposed in the sliding groove 14. When the crank 42 moves under a driving force, the end of the crank arm 421 can move along the sliding groove 14. During this process, since the end of the crank arm 421 acts on the sliding groove 14 at the same time, the crank 42 can drive the door body 11 to move to open at a larger angle.

[0045] Further, as Figure 2 and Figure 4 , relative to the position of the push rod, the crankshaft 420 is disposed on the side close to the door shaft 12. When the door body 11 is in the closed state, the end of the crank arm 421 is disposed on the side away from the door shaft 12. In this way, the crank 42 can continuously drive the door body 11 to open at a larger angle.

[0046] Further, the length of the sliding groove 14 should at least satisfy that the movement stroke of the end of the crank arm 421 in the sliding groove 14 can enable the door body 11 to open a preset angle. For example, if the refrigerator door body can be opened to an angle of 120 degrees, then the end of the crank arm 421 slides in the sliding groove 14 and drives the door body to open. The sliding stroke of the crank arm 421 allowed by the sliding groove 14 can enable the door body to open to 120 degrees.

[0047] The second transmission part 41 further includes a fourth gear 411 meshing with the third gear 410, and the fourth gear 411 is connected to the reset mechanism 50. When manually opening or closing the door body or when the door body encounters an obstacle during the opening and closing process, an external force will be transmitted to the third gear 410, the fourth gear 411 and the driving part 21. To avoid damage to the components on the entire transmission path, when the reset mechanism 50 is acted on by an external force, it can disconnect the fourth gear 411 from the adjacent gears, thereby blocking the transmission of power on the transmission path. Refer to Figure 5 and Figure 7 , which shows the state where the reset mechanism 50 at B and the fourth gear 411 are disengaged from the adjacent gears when the door body 11 encounters an obstacle OB during closing.

[0048] For example, when manually intervening and accelerating the door opening during the automatic door opening process, or when the door body encounters an opening resistance, the reset mechanism is acted on by an external force to disconnect the fourth gear 411 from other adjacent gears, thereby avoiding damage to the relevant components on the transmission path by the external force. In addition, when the external force is withdrawn, the reset mechanism 50 can restore the connection between the fourth gear 411 and the adjacent gears, and then resume the transmission of power.

[0049] The above first, second, third, and fourth gears are only illustrative and do not constitute a limitation to this solution. That is to say, the number of gears included in the first transmission part or the second transmission part can be selected or adjusted according to the actual application scenario.

[0050] In one embodiment, the first transmission assembly 30 and the second transmission assembly 40 can be simultaneously driven by the driving part 21, thereby reducing the number of driving parts and further reducing the volume of the entire door opening and closing device. For example, by providing a third transmission assembly 60, the third transmission assembly 60 is respectively in transmission connection with the first transmission assembly 30 and the second transmission assembly 40.

[0051] Preferably, the third transmission assembly 60 and the driving part 21 can be in transmission connection through a worm and worm gear structure. The worm and worm gear structure has good self-locking performance and can prevent free rotation caused by the action of external forces.

[0052] Specifically, referring to FIGS. 2 and Figure 4 , the third transmission assembly 60 includes a worm 61 and a worm gear 62, and the output end of the driving part 21 is connected to the worm 61. The third transmission assembly 60 further includes a fifth gear set 63, the fifth gear set 63 is connected to the worm gear 62, and at the same time the fifth gear set 63 is respectively connected to the first transmission part 31 and the second transmission part 41. When the driving part 21 is powered on, the first transmission part 31 and the second transmission part 41 can be simultaneously driven through the third transmission assembly 60, and further the push rod 32 and the crank 42 can be simultaneously driven to work by one driving part 21.

[0053] In the foregoing embodiment, the reset mechanism 50 can block or restore the transmission of power by the transmission assembly according to the state of the external force. The reset mechanism 50 can be set as a slipping mechanism. The reset mechanism 50 can include an elastic part 51 and a groove part 52. The elastic part 51 can support the transmission part, and the groove part 52 can be connected to the shaft of the transmission part. When the elastic part 51 is subjected to an external acting force and undergoes elastic deformation, the elastic deformation force acts on the transmission part, causing the transmission part to move along the groove part 52. The transmission part can be composed of multiple gears. Which gear or which group of gears the elastic part is connected to depends on the gear layout and the force condition of the entire transmission path.

[0054] For example, referring to Figure 7 and Figure 8 , the specific structures of the reset mechanism 50 and the fourth gear 411 are shown. The elastic part 51 includes a spring and a bracket connected to one end of the spring. The bracket is connected and supports the fourth gear 411 through the gear shaft 4110; the groove part 52 includes a first end 521 and a second end 522. The gear shaft 4110 is arranged in the groove part 52 and can move along the groove part 52 between the first end 521 and the second end 522.

[0055] Specifically, referring to Figure 2 and Figure 4 , during the automatic opening and closing process of the door body, the gear shaft 4110 is located at the first end 521. At this position, the fourth gear 411 meshes with the adjacent gear and can normally transmit power. Referring to Figures 5 to 7, when the user manually intervenes during the automatic opening and closing process of the door body, or when the door body encounters an obstacle OB during the opening and closing process, at this time, the reset mechanism 50 is subjected to an external force, and correspondingly, the elastic part 51 is subjected to a force, and the gear shaft 4110 can move to the second end portion 522 in the groove portion 52, so that the fourth gear 411 cannot mesh with the adjacent gear, and thus the power cannot be transmitted normally. In addition, when the external force is withdrawn, due to the elastic force of the elastic part 51, the gear shaft 4110 returns to the first end portion 521 again, so that the fourth gear 411 meshes with the adjacent gear again and the transmission path is restored.

[0056] An embodiment of the present invention also discloses a household electrical appliance, and the household electrical appliance can be a refrigerator, a clothing care device, a dishwasher and other devices that need to open and close the door body. The household electrical appliance includes the aforementioned door opening and closing device, so as to realize the automatic opening and closing function of the door body. Regarding the door opening and closing device, it will not be described in detail here.

[0057] Although the specific embodiments have been described above, these embodiments are not intended to limit the scope of the disclosure of the present invention, even when only a single embodiment is described with respect to a specific feature. The feature examples provided in the disclosure of the present invention are intended to be illustrative rather than restrictive, unless otherwise stated. In specific implementations, according to actual needs and when technically feasible, the technical features of one or more dependent claims can be combined with the technical features of the independent claim, and can be combined in any appropriate way rather than only through the specific combinations listed in the claims from the technical features of the corresponding independent claim.

[0058] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A door opening and closing device for household appliances, wherein the household appliances include a main body and a door body connected to the main body through a door shaft, characterized in that: The door opening and closing device comprises: The first transmission assembly includes a first transmission part and a push rod transmission-connected thereto, wherein the push rod is arranged at a side away from the door shaft; The second transmission assembly includes a second transmission part and a crank, wherein a crank shaft of the crank is connected to the second transmission part and is arranged on a side close to the door axis, and the end of the crank arm is slidably connected to the door body; and a driving part, which is used to simultaneously drive the first transmission assembly and the second transmission assembly.

2. The door opening and closing device according to claim 1, characterized in that: It also includes a third transmission assembly connected to the driving part, and the third transmission assembly is transmission-connected to the first transmission assembly and the second transmission assembly respectively.

3. The door opening and closing device according to claim 2, characterized in that: The third transmission assembly includes a worm and a worm wheel, the output end of the driving unit is connected to the worm, and the driving unit and the third transmission assembly are connected through the worm wheel and the worm.

4. The door opening and closing device according to claim 1, characterized in that: The first transmission assembly and the second transmission assembly further include at least one reset mechanism connected to the first transmission part and / or the second transmission part, and the reset mechanism is configured to block or restore power transmission by the first transmission part or the second transmission part according to the state of the external force.

5. The door opening and closing device according to claim 4, characterized in that: The reset mechanism includes an elastic portion and a groove portion, wherein the elastic portion supports the first transmission portion and / or the second transmission portion, the groove portion is connected to the first transmission portion and / or the second transmission portion, and the first transmission portion and / or the second transmission portion can move along the groove portion.

6. The door opening and closing device according to claim 5, characterized in that: The groove portion comprises a first end portion and a second end portion, wherein when the first transmission portion and / or the second transmission portion moves to the second end portion, the first transmission portion and / or the second transmission portion disengages from a transmission path.

7. The door opening and closing device according to claim 4, characterized in that: The first transmission part includes a first gear and a second gear meshing with the first gear, wherein the first gear is connected to the push rod to drive the push rod to move, and the second gear is connected to the reset mechanism.

8. The door opening and closing device according to claim 4, characterized in that: The second transmission part includes a third gear and a fourth gear meshing with the third gear, wherein the third gear is coaxially connected to the crank, and the fourth gear is connected to the reset mechanism.

9. A household appliance, comprising a main body and a door connected thereto, characterized in that: It also includes a door opening and closing device as described in any one of claims 1 to 8, wherein the door opening and closing device is arranged on the main body.

10. The household appliance according to claim 9, characterized in that: It also includes a slide groove, which is arranged on the door body, wherein the end of the crank is arranged on the slide groove and can move along the slide groove.

11. The household appliance according to claim 10, characterized in that: The length of the slide groove at least satisfies that the movement stroke of the end of the crank in the slide groove can open the door body to a preset angle.