Adjustable torque limiting push rod actuator

Abstract

The present invention belongs to the technical field of actuators, and specifically relates to an adjustable torque-limiting push rod actuator. The actuator includes a housing and a push rod slidably connected to the housing, a fixed rotational power source and a rotatable planetary reduction gearbox are arranged in the housing; the planetary reduction gearbox includes a cylindrical inner ring rotatably assembled in the housing, and a transmission inner core group composed of at least one planetary frame unit engaged in the inner ring; the upstream end of the transmission inner core group is transmission-connected to the output end of the rotational power source, and the other downstream end of the transmission inner core group is transmission-connected to the push rod to drive the push rod to slide; a rotation constraint device is also arranged in the housing to limit the rotation of the inner ring within a certain torque range. The actuator has the advantages of small space occupation, reliable transmission, low transmission loss, and easy adjustment of the limit torque.

Description

Technical Field

[0001] The invention belongs to the technical field of actuators, and in particular relates to an adjustable torque limiting push rod actuator. Background Art

[0002] With the continuous development and progress of society, intelligent home appliances are becoming increasingly popular in the market. These appliances often incorporate numerous actuators to facilitate component movement. For example, a smart refrigerator may have a push rod actuator that pushes the door against atmospheric pressure and friction during the initial opening phase, as well as a rotary actuator that drives the door's full opening and closing. Another example is a smart oven, which may have a push rod actuator that pushes the door open.

[0003] In order to match a high-speed, low-torque motor with the actual action requirements of low speed and high torque, it is necessary to set a multi-stage reduction gear set with a complex structure and a large space in the actuator. In order to limit the working torque of the actuator to avoid accidental injury to the user and damage to the internal structure of the actuator, it is necessary to set a torque protection device in the actuator. At present, there are mainly three ways to set the torque protection device: the first is to connect it downstream of the reduction gear set, the second is to connect it upstream of the reduction gear set, and the third is to connect it in series in the reduction gear set. For example, our company disclosed an actuator in invention patent CN106761149A, which adopts the first connection method in which the torque protection device is set downstream of the reduction gear set. Its specific structure is described in paragraphs

[0027] to

[0028] of the specification. The clutch gear mechanism includes a left ratchet mechanism and a right ratchet mechanism, and the left ratchet mechanism and the right ratchet mechanism are capable of relative rotation. The left ratchet mechanism includes a left ratchet, a first gear meshing with the reduction gear mechanism, and a screw fixedly connected to the left ratchet and the first gear. The right ratchet mechanism includes a right ratchet, a second gear meshing with the rack, and a sleeve fixedly connected to the right ratchet and the second gear. A compression spring is disposed within the hollow barrel of the sleeve. The screw passes through the sleeve and the compression spring. The left ratchet and the right ratchet are engaged and connected. One end of the compression spring is connected to a spring mounting portion provided on the screw, and the other end is provided with a spring seat. A nut is disposed at the end of the screw and presses the spring seat against the compression spring. When the door is closed and encounters an obstacle or the operator applies excessive thrust, the pawl slides over the back of the ratchet teeth, allowing the left ratchet mechanism and the right ratchet mechanism to rotate relative to each other, preventing the transmission of abnormally large torque to the reduction gear mechanism and the motor worm, which could damage the gears and the motor. The reduction gear mechanism includes coaxially arranged third and fourth gears, a fifth gear meshing with the fourth gear, a sixth gear meshing with the fifth gear, and a reduction worm coaxially arranged with the sixth gear. The reduction worm meshes with the first gear of the clutch gear mechanism, and the third gear meshes with the motor worm of the motor. The third and first gears are worm gears or helical gears. The motor drives the reduction gear mechanism in both forward and reverse rotations, providing low-speed, high-torque to the clutch gear mechanism. The clutch gear mechanism then drives the rack to achieve the door opening and closing functions.

[0004] Although the torque protection device can currently be set downstream, upstream, and connected in series within the reduction gear set, regardless of the setting method, the reduction gear set and the torque protection device each independently perform the functions of reducing torque and increasing torque, and torque limitation, and cannot reduce the power transmission links between the motor and moving parts such as refrigerator doors and oven doors, nor can it reduce the space occupied by the reduction gear set and the torque protection device. Among them, the transmission link from the motor to the moving parts is an important factor affecting the reliability of the actuator. The more transmission links there are during the power transmission process, the less conducive it is to improving the reliability of the transmission. The larger the space occupied by the reduction gear set and the torque protection device, the greater the loss in the storage space of household appliances such as refrigerators and ovens. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention provides a push rod actuator with adjustable torque limitation.

[0006] The adjustable torque limiting push rod actuator provided by the present invention includes a housing and a push rod slidably connected to the housing, a fixed rotational power source and a rotatable planetary reduction gearbox are arranged in the housing; the planetary reduction gearbox includes a cylindrical inner ring rotatably assembled in the housing, and a transmission inner core group composed of at least one planetary frame unit engaged in the inner ring; the upstream end of the transmission inner core group is transmission-connected to the output end of the rotational power source, and the other downstream end of the transmission inner core group is transmission-connected to the push rod to drive the push rod to slide; a rotation constraint device is also provided in the housing to limit the rotation of the inner ring within a certain torque range. When the torque borne by the inner ring does not exceed the constraint limit of the rotation constraint device, the inner ring cannot rotate. When the torque borne by the inner ring exceeds the constraint limit of the rotation constraint device, the inner ring can rotate.

[0007] Furthermore, the rotation restraining device includes a bearing seat arranged in the shell for bearing the inner gear ring and a clamp for clamping the inner gear ring on the bearing seat.

[0008] Furthermore, a bearing seat is provided at each end of the corresponding inner gear ring, and a clamp is provided on each bearing seat. Both ends of each clamp have fastening screws that connect the clamp to the bearing seat; a compression spring is also provided on the fastening screw, and the compression spring applies an elastic force to the clamp to force the clamp to clamp toward the bearing seat.

[0009] Furthermore, rigid wavy inner stripes are provided on the inner surfaces of the bearing seat and the clamp; and flexible wavy outer stripes are provided on the outer peripheries of both ends of the inner gear ring.

[0010] Furthermore, an operating window that passes through the inside and outside is provided on the surface of the shell, and the fastening screw is directly opposite the operating window to facilitate adjustment of tightness.

[0011] Furthermore, the push rod has an engaging surface, and the downstream end of the transmission inner core group is connected to a first driving gear, which engages with the engaging surface to drive the push rod to slide.

[0012] Furthermore, the output end of the rotating power source has a second drive gear; the planetary carrier unit includes a planetary carrier and a group of planetary gears distributed circumferentially on the planetary carrier for receiving upstream power, and each planetary gear is engaged with the inner ring gear; each planetary carrier also has a central drive part on the rotation axis for outputting power to the downstream.

[0013] Furthermore, a first notch and a second notch are provided on the push rod, and a first micro switch and a second micro switch are provided in the shell; the first micro switch is located on the movement path of the first notch, and the second micro switch is located on the movement path of the second notch; when the first notch triggers the first micro switch, the push rod is in the initial position, and when the second notch triggers the second micro switch, the push rod is in the extreme extension position.

[0014] Beneficial Effects: Compared with the prior art, the adjustable torque-limiting push rod actuator provided by the present invention abandons the conventional connection method of placing the torque protection device downstream or upstream of the reduction gear set or simply connecting it in series within the reduction gear set. Instead, the torque protection is integrated into the reduction gear set, which reduces space occupation. More importantly, during normal transmission, the upstream power is directly transmitted to the downstream through the transmission core group in the planetary reduction gear box, without the need to pass through the torque protection device. This can improve the reliability of the transmission and reduce power loss during the transmission process. In addition, the adjustable torque-limiting push rod actuator provided by the present invention can conveniently adjust the limit torque at different stages. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the external structure of the actuator.

[0016] Figure 2 Schematic diagram of the internal structure of the actuator.

[0017] Figure 3 Schematic diagram of the actuator explosion.

[0018] Figure 4 and 5 All of them are schematic diagrams of the coordination between the rotary power source and the planetary reduction gearbox of Example 1.

[0019] Figure 6 and 7 Both are structural schematic diagrams of the planetary carrier unit.

[0020] Figure 8 Schematic diagram of the coordination between the rotary power source and the planetary reduction gearbox of Example 2.

[0021] In the figure, the housing 1, the push rod 2, the rotational power source 3, the planetary reduction gear box 4, the inner ring 41, the planetary carrier unit 42, the bearing seat 91, the clamp 92, the fastening screw 93, the compression spring 94, the operation window 11, the meshing surface 21, the first drive gear 5, the second drive gear 6, the planetary carrier 421, the planetary gear 422, the central drive part 423, the first recess 22, the second recess 23, the first micro switch 81, and the second micro switch 82. DETAILED DESCRIPTION

[0022] The present invention is further illustrated by the following examples, which are intended to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the present invention.

[0023] Unless otherwise defined, technical or scientific terms used in this disclosure should be understood to have the ordinary meanings understood by persons of ordinary skill in the art. The terms "first," "second," and similar expressions used in this disclosure do not denote any order, quantity, or importance, but are simply used to distinguish different components. Terms such as "include" or "comprising" mean that the elements or objects preceding the term include the elements or objects listed after the term, and their equivalents, without excluding other elements or objects. Terms such as "connected" or "connected" are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0024] Example 1

[0025] like Figures 1 to 3 As shown, an adjustable torque-limiting push rod actuator comprises a housing 1 that can be closed at the top and bottom. The housing 1 defines a receiving space and a slideway within which a push rod 2 is inserted and slides back and forth. Within the housing 1 are a fixed motor serving as a rotational power source 3 and a rotatable planetary reduction gearbox 4. In the following references to the transmission relationship, the direction closer to the rotational power source 3 is the upstream end of the power source, and the direction closer to the push rod 2 is the downstream end of the power source.

[0026] Planetary reduction gearbox 4 includes a cylindrical inner ring gear 41 rotatably mounted within housing 1, and a transmission core assembly comprised of at least one planetary carrier unit 42 meshing within inner ring gear 41. The upstream end of the transmission core assembly is transmission-connected to the output end of rotary power source 3, while the downstream end of the transmission core assembly is transmission-connected to push rod 2 to drive the push rod's movement. Also disposed within housing 1 is a rotation restraint device that limits the rotation of inner ring gear 41 within a certain torque range. When the torque applied to inner ring gear 41 does not exceed the restraint limit of the rotation restraint device, inner ring gear 41 cannot rotate. When the torque applied to inner ring gear 41 exceeds the restraint limit of the rotation restraint device, inner ring gear 41 is allowed to rotate.

[0027] When the adjustable torque-limited push rod actuator is in operation, the power of the rotational power source 3 is transmitted downstream through the planetary reduction gearbox 4, thereby driving the push rod 2 forward and backward. Due to the limited rotational restraint of the internal gear ring 41 by the rotation restraint device, if the push rod 2 encounters excessive resistance when being pushed out or retracted, the internal gear ring 41 will rotate to prevent the force from increasing indefinitely. This can prevent the push rod 2 from squeezing the user when being pushed out or retracted, and also prevent the internal structure of the actuator from being damaged by excessive force. In addition, if a large external force acts on the push rod 2, causing it to be forcibly pushed back or pulled out, the internal gear ring 41 can also overcome the restraint of the rotation restraint device and rotate, thus protecting the actuator structure.

[0028] Specific as Figure 2 、 3 As shown, the rotation restraint device includes a bearing seat 91 disposed within the housing 1 to support the inner gear ring 41, and a clamping hoop 92 that clamps the inner gear ring 41 to the bearing seat 91. The clamping action of the bearing seat 91 and the clamping hoop 92 applies a limited restraining force to the inner gear ring 41. If the force exceeds the restraining force generated by the clamping action, the inner gear ring 41 will rotate to prevent the force from increasing further. A bearing seat 91 is provided at each end of the inner gear ring 41. Each bearing seat 91 is equipped with a clamping hoop 92. Each clamping hoop 92 has a fastening screw 93 at each end that connects the clamping hoop 92 to the bearing seat 91. A compression spring 94 is also sleeved on the clamping screw 93, which applies an elastic force to the clamping hoop 92, urging it to clamp against the bearing seat 91. By adjusting the tightness of the clamping screw 93, the compression of the compression spring 94 can be varied, thereby conveniently adjusting the maximum restraining force of the rotation restraint device on the inner gear ring 41 to meet the different performance requirements of different application scenarios.

[0029] like Figure 2 、 3As shown, the inner surfaces of both the support base 91 and the clamp 92 are provided with rigid, wavy inner stripes. The support base 91 and the clamp 92 can be made of metal, hard plastic, or other materials, making the inner stripes relatively rigid. Flexible, wavy outer stripes are provided on the outer periphery of both ends of the inner gear ring 41. Corrugated rings made of materials such as rubber or silicone can be provided or directly molded on the outer periphery of the inner gear ring 41. The rigid-flexible combination of the inner and outer stripes allows for more accurate and extensive adjustment of the restraining force.

[0030] like Figure 1 As shown, an operating window 11 that passes through the inside and outside is provided on the surface of the shell 1, and the fastening screw 93 is facing the operating window to facilitate adjustment of tightness, convenient for unified adjustment of the restraint force before leaving the factory and calibration during use.

[0031] like Figure 2 、 3 As shown, the push rod 2 has an engagement surface 21 , and the downstream end of the transmission inner core group is connected to the first driving gear 5 , which engages with the engagement surface 21 to drive the push rod 2 to slide.

[0032] like Figure 4 、 5 As shown in Figures 6 and 7, the output end of the rotary power source 3 has a second drive gear 6; the planetary carrier unit 42 includes a planetary carrier 421 and a group of planetary gears 422 circumferentially distributed on the planetary carrier 421 for receiving upstream power, each planetary gear 422 meshing with the inner ring gear 41; each planetary carrier also has a central drive portion 423 on its rotation axis for outputting power downstream. The transmission core group of this embodiment has multiple planetary carrier units 42. The central drive portions 423 in the three planetary carrier units 42 near the upstream are all gears that mesh with the center of a group of planetary gears 422 in the next planetary carrier unit 42; the central drive portion 423 in the planetary carrier unit 42 near the downstream is a transmission shaft that is connected to the first drive gear 5 and drives the push rod 2 to slide.

[0033] like Figure 2 、 3 As shown, to facilitate accurate determination of the position of the push rod 2, a first notch 22 and a second notch 23 are provided on the push rod 2, and a first microswitch 81 and a second microswitch 82 are also provided within the housing 1. The first microswitch 81 is located in the motion path of the first notch 22, and the second microswitch 82 is located in the motion path of the second notch 23. When the first notch 22 triggers the first microswitch 81, the push rod 2 is in the initial position, and when the second notch 23 triggers the second microswitch 82, the push rod 2 is in the maximum extended position. In this way, the position of the push rod 2 can be accurately determined based on the triggering signals of the first microswitch 81 and the second microswitch 82, providing a basis for automatic control.

[0034] Example 2

[0035] This embodiment also provides an adjustable torque limiting push rod actuator, which differs from the first embodiment in the number of planetary carrier units 42 in the transmission core group. Other identical structures will not be described again.

[0036] Specific as Figure 7 、 8 As shown, this embodiment has only one planetary carrier unit 42 within the transmission core assembly. The output end of the rotational power source 3 is provided with a second drive gear 6. The planetary carrier unit 42 comprises a planetary carrier 421 and a set of planetary gears 422 circumferentially distributed on the planetary carrier 421 for receiving upstream power. Each planetary gear 422 meshes with the inner ring gear 41. A central drive unit 423 is also provided on the planetary carrier's rotation axis for outputting power downstream. This central drive unit 423 is a transmission shaft directly connected to the first drive gear 5, driving the push rod 2 to slide.

[0037] The above embodiments are exemplary and intended to illustrate the technical concepts and features of the present invention so that those skilled in the art can understand the present invention and implement it accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. An adjustable torque limiting push rod actuator, comprising a housing (1) and a push rod (2) slidably connected to the housing (1), characterized in that: A fixed rotational power source (3) and a rotatable planetary reduction gearbox (4) are provided in the housing (1); the planetary reduction gearbox (4) comprises a cylindrical inner gear ring (41) rotatably mounted in the housing (1), and a transmission inner core group composed of at least one planetary frame unit (42) meshed in the inner gear ring (41); the upstream end of the transmission inner core group is transmission-connected to the output end of the rotational power source (3), and the other downstream end of the transmission inner core group is transmission-connected to the push rod (2) to drive the push rod to slide; a rotation constraint device is also provided in the housing (1) for limiting the rotation of the inner gear ring (41) within a certain torque range, when the torque borne by the inner gear ring (41) does not exceed the constraint limit of the rotation constraint device, the inner gear ring (41) cannot rotate, and when the torque borne by the inner gear ring (41) exceeds the constraint limit of the rotation constraint device, the inner gear ring (41) can rotate; The rotation restraining device comprises a bearing seat (91) arranged in the housing (1) for bearing the inner gear ring (41) and a clamp (92) for clamping the inner gear ring (41) on the bearing seat (91); A bearing seat (91) is provided at each end of the inner gear ring (41), and a clamp (92) is provided on each bearing seat (91). Both ends of each clamp (92) have fastening screws (93) for connecting the clamp (92) to the bearing seat (91); a compression spring (94) is also sleeved on the fastening screw (93), and the compression spring (94) applies an elastic force to the clamp (92) to force the clamp (92) to clamp toward the bearing seat (91); Rigid wavy inner stripes are provided on the inner surfaces of the bearing seat (91) and the clamp (92); flexible wavy outer stripes are provided on the outer periphery of both ends of the inner gear ring (41); An operating window (11) that passes through the inside and outside is provided on the surface of the housing (1), and the fastening screw (93) faces the operating window to facilitate tightness adjustment.

2. The adjustable torque limiting push rod actuator according to claim 1, characterized in that: The push rod (2) has an engagement surface (21), and the downstream end of the transmission inner core group is connected to a first driving gear (5), and the first driving gear (5) engages with the engagement surface (21) to drive the push rod (2) to slide.

3. The adjustable torque limiting push rod actuator according to claim 2, characterized in that: The output end of the rotational power source (3) has a second driving gear (6); the planetary carrier unit (42) includes a planetary carrier (421) and a group of planetary gears (422) circumferentially distributed on the planetary carrier (421) for receiving upstream power, and each planetary gear (422) is meshed with the inner gear ring (41); and each planetary carrier also has a central driving part (423) on the rotation axis for outputting power to the downstream.

4. The adjustable torque limiting push rod actuator according to claim 1, characterized in that: The push rod (2) is further provided with a first notch (22) and a second notch (23), and the housing (1) is further provided with a first micro switch (81) and a second micro switch (82); the first micro switch (81) is located on the movement path of the first notch (22), and the second micro switch (82) is located on the movement path of the second notch (23); when the first notch (22) triggers the first micro switch (81), the push rod (2) is in the initial position, and when the second notch (23) triggers the second micro switch (82), the push rod (2) is in the extreme extension position.

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