Auxiliary locking device and linear actuator including same

Abstract

The utility model provides an auxiliary locking device which is installed on a transmission shaft, the transmission shaft comprises a bevel gear, and the auxiliary locking device comprises a fixed first shaft sleeve, a second shaft sleeve and a third shaft sleeve, the fixed second shaft sleeve is provided with a second groove, the second groove is provided with a second bottom face, when the transmission shaft rotates in the forward direction, the first end face of the transmission shaft makes contact with the first bottom face, and the second end face of the transmission shaft is spaced from the second bottom face; when the transmission shaft is braked or rotates reversely, the second end face of the transmission shaft makes contact with the second bottom face, the first end face of the transmission shaft is spaced from the first bottom face, the roughness of the second bottom face is larger than that of the first bottom face, and / or the roughness of the second end face of the transmission shaft is larger than that of the first end face. The utility model further relates to a linear actuator which comprises the auxiliary locking device. The transmission shaft can be locked in an auxiliary mode, and the requirement for machining and mounting precision of the bevel gear is lowered.

Description

Technical Field

[0001] The utility model relates to an auxiliary locking device and a linear actuator comprising the auxiliary locking device. Background Art

[0002] A linear actuator or transmission is an electrically driven device that converts the rotational motion of a motor into a linear reciprocating motion of an actuating component. Linear actuators are a versatile device that are widely used in industries such as household appliances, kitchen appliances, medical devices, agriculture, and automobiles.

[0003] For example, referring to CN110030350A, in a linear actuator, a motor drives a spindle with an external thread through a transmission system, and a tubular actuating element is provided at the outer end of the spindle, and the actuating element is formed as a whole with the spindle nut or fixed on the spindle nut, the spindle nut is engaged with the spindle thread, and the actuating element is arranged coaxially with the spindle. Therefore, when the motor drives the spindle to rotate, the spindle nut drives the actuating element to move linearly along the spindle. The actuating element usually carries a target object to be raised or lowered, such as one of the crossbeams of a bed frame, so when the actuating element moves linearly along the spindle, the target object will rise or fall with the actuating element.

[0004] When the motor rotates forward, the actuating element moves to a certain position along the spindle, and the motor is stopped. At this time, the load on the actuating element will force the spindle nut to have a tendency to move downward along the spindle, thereby causing the spindle to rotate in the opposite direction or have a tendency to rotate in the opposite direction. Therefore, in order to lock the actuating element at any position of the spindle, a locking device is required, which can lock the spindle nut in place relative to the spindle, so that the actuating element and the target object stay at the position desired by the user.

[0005] In addition, the transmission system of the linear actuator usually has helical gears. Due to the presence of the helical gears, the transmission shaft in the transmission system will be subjected to axial force during operation. In order to eliminate the axial force on the transmission shaft, high processing and installation accuracy are usually required for the helical gears, which increases the cost of the linear actuator.

[0006] In order to assist in locking the transmission shaft when necessary and to reduce the requirements on the machining and installation accuracy of the helical gear, the auxiliary locking device of the present application is provided. Utility Model Content

[0007] The utility model aims to solve the above technical problems and provides an auxiliary locking device installed on a transmission shaft, wherein the transmission shaft comprises a bevel gear, and the auxiliary locking device comprises: a fixed first sleeve having a first groove, wherein the first groove has a first bottom surface; and a fixed second sleeve having a second groove, wherein the second groove has a second bottom surface, wherein when the transmission shaft rotates forward, the first end surface of the first end of the transmission shaft contacts the first bottom surface of the first groove of the first sleeve, and the second end surface of the second end of the transmission shaft is spaced apart from the second bottom surface of the second groove of the second sleeve; when the transmission shaft is braked or rotated in the reverse direction, the second end surface of the second end of the transmission shaft contacts the second bottom surface of the second groove of the second sleeve, and the first end surface of the first end of the transmission shaft is spaced apart from the first bottom surface of the first groove of the first sleeve, wherein the roughness of the second bottom surface of the second groove of the second sleeve is greater than the first bottom surface of the first groove of the first sleeve, and / or the roughness of the second end surface of the transmission shaft is greater than the first end surface.

[0008] Preferably, the roughness of the first bottom surface of the first sleeve and / or the roughness of the first end surface of the transmission shaft are designed so that when the transmission shaft rotates in the forward direction, the friction between the first end surface of the transmission shaft and the first bottom surface of the first sleeve does not substantially affect the rotation of the transmission shaft.

[0009] Preferably, the roughness of the second bottom surface of the second sleeve and / or the roughness of the second end surface of the transmission shaft are designed so that when the transmission shaft is braked, the friction between the second end surface of the transmission shaft and the second bottom surface of the second sleeve can substantially hinder the rotation of the transmission shaft.

[0010] Preferably, the first sleeve and / or the second sleeve comprises at least one recessed portion for accommodating grease.

[0011] Preferably, the recessed portions are arranged in pairs.

[0012] Preferably, the recessed portion is provided on at least one of the top surfaces of the first and second sleeves, the side surfaces of the first and second grooves, and the first and second bottom surfaces.

[0013] Preferably, the outer contour of the first sleeve and / or the second sleeve is determined by the installation position and the installation space, so as to facilitate the fixing of the first and second sleeves.

[0014] The present application also relates to a linear actuator, comprising: a housing; a rear mounting member and a front mounting member; a motor, comprising a motor shaft, the motor shaft being capable of rotating in a forward and reverse direction; a transmission shaft, comprising a first gear and a second gear, the first gear being meshed with the motor shaft, at least one of the first gear and the second gear being a helical gear, the transmission shaft being capable of moving a certain distance in an axial direction, and the transmission shaft being accommodated in a chamber formed by the housing; a main shaft with an external thread, comprising a third gear being meshed with the second gear of the transmission shaft so as to receive rotational power from the motor; a main shaft nut with an internal thread, which is threadedly engaged with the main shaft, so that when the main shaft rotates, The spindle nut rises or falls along the axial direction of the spindle according to the rotation direction of the spindle; an inner tube, which is coaxially arranged with the spindle, a first end of the inner tube is fixed to the spindle nut, so that it can perform linear movement through the spindle nut, and the front mounting piece is connected to the second end of the inner tube, so that it can move linearly with the inner tube as a whole; an outer tube, which is coaxially arranged on the periphery of the inner tube, is used to guide the linear movement of the spindle nut and the inner tube, and is fixed to the shell; a locking device, which is used to lock the spindle to prevent it from rotating when necessary, wherein the linear actuator also includes an auxiliary locking device according to the aforementioned, and the auxiliary locking device is fixed in the chamber.

[0015] Preferably, the chamber is covered by a housing top cover.

[0016] Preferably, the locking device is formed by mutually meshing helical teeth of the first gear and the second gear.

[0017] The auxiliary locking device according to the utility model can advantageously assist in locking the transmission shaft when the motor is braked, and the linear actuator using the auxiliary locking device according to the utility model has lower manufacturing and installation tolerance requirements for the first gear and the second gear, thereby reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings show a preferred embodiment of the present utility model, wherein:

[0019] Figure 1 shows a perspective view of a linear actuator;

[0020] Figure 2 shows a side view of a linear actuator;

[0021] Figure 3 shows a cross-sectional view of a linear actuator;

[0022] Figure 4 is a perspective view of the linear actuator with the housing top cover removed, showing the motor shaft, the transmission shaft and the gears at the rear end of the main shaft;

[0023] Figure 5A side view of the drive shaft is shown;

[0024] Figure 6 A perspective view of a transmission shaft is shown;

[0025] Figure 7a , 7b A cross-sectional view of a transmission shaft is shown, wherein Figure 7a It shows the state when the transmission shaft is in positive rotation. Figure 7b Shows the state of the transmission shaft when it is braked;

[0026] Figure 8a , 8b showing a perspective view and a front view respectively showing a first sleeve;

[0027] Figure 9a , 9b A perspective view and a front view are shown respectively showing the second sleeve.

[0028] Description of Reference Numerals

[0029] 1 - Linear actuator 2 - Spindle 3 - Inner tube

[0030] 4—spindle nut 5—outer tube 6—housing

[0031] 7—motor 8—first gear 9—transmission shaft

[0032] 10—second gear 11—first sleeve 11'—first groove

[0033] 12—Second sleeve 12'—Second groove

[0034] 13 - third gear 14 - rear mounting piece 15 - front mounting piece

[0035] 16 - first end surface 17 - second end surface 18 - first bottom surface

[0036] 19—Second bottom surface 20—Motor shaft 21—Casing top cover

[0037] 22—chamber 23—recess 24, 24'—gap DETAILED DESCRIPTION

[0038] refer to Figure 1-3 , showing a perspective view, a side view and a cross-sectional view of the linear actuator 1, Figure 4 Linear actuator shown with housing cover removed

[0039] The linear actuator 1 includes: a housing 6; a rear mounting member 14 and a front mounting member 15; a motor 7 including a motor shaft 20, which can rotate in the forward and reverse directions; a transmission shaft 9 including a first gear 8 and a second gear 10, wherein the first gear 8 is meshed with the motor shaft 20, and at least one of the first gear 8 and the second gear 10 is a helical gear, and the transmission shaft 9 is accommodated in a chamber 22 formed by the housing 6; a main shaft 2 with an external thread, which includes a third gear 13 meshed with the second gear 10 of the transmission shaft 9 so as to receive rotational power from the motor 7; a main shaft nut 4 with an internal thread, which is meshed with the second gear 10 of the transmission shaft 9 The spindle 2 is threadedly engaged, so the spindle nut 4 rises or falls along the axial direction of the spindle 2 according to the rotation direction of the spindle 2; the inner tube 3 is coaxially arranged with the spindle 2, the first end of the inner tube 3 is fixed to the spindle nut 4, so that it can move linearly through the spindle nut 4, and the front mounting member 15 is connected to the second end of the inner tube 3, so that it can move linearly with the inner tube 3 as a whole; the outer tube 5 is coaxially arranged on the periphery of the inner tube 3, used to guide the linear movement of the spindle nut 4 and the inner tube 3, and is fixed to the housing 6; the locking device is used to lock the spindle 2 to prevent it from rotating when necessary. The chamber is covered by the housing top cover 21.

[0040] The first gear 8 and / or the second gear 10 of the transmission shaft 9 may be formed as one piece with the transmission shaft 9, or may be a separate gear fixedly mounted on the transmission shaft 9 in a manner well known to those skilled in the art, so as to rotate integrally with the transmission shaft 9 and cannot move axially relative to the transmission shaft 9. In the example shown in FIG. 7 , the first gear 8 is a separate gear, and the second gear 10 is formed as one piece with the transmission shaft 9. Similarly, the third gear 13 of the main shaft 2 may also be formed as one piece with the main shaft 2, or may be a separate gear fixedly mounted on the transmission shaft 9 in a manner well known to those skilled in the art, so as to rotate integrally with the transmission shaft 9 and cannot move axially relative to the transmission shaft 9. Figure 3 As shown, the third gear 13 is a separate gear which is mounted on one end of the main shaft 2 by a method well known in the art.

[0041] exist Figure 5 , 6 In the embodiment shown in , 7, the first gear 8 and the second gear 10 are both helical gears, which respectively form a worm gear transmission with the motor shaft 20 and the third gear 13 of the main shaft 2, thereby transmitting the rotational motion from the motor shaft 20 of the motor 7 to the main shaft 2 through the transmission shaft 9.

[0042] On the one hand, due to the existence of the helical gears, the transmission shaft 9 will be subjected to axial force during operation. Although in theory the axial force on the transmission shaft 9 can be offset by designing the helix angle of the helical teeth of the first gear 8 and the second gear 10, the axial force on the transmission shaft 9 cannot be completely eliminated due to manufacturing and installation errors.

[0043] On the other hand, as described in the background technology section, the motor 7 is started to rotate forward for a certain period of time. When the inner tube 3 extends a certain length from the outer tube 5 along the main shaft 2, the motor 7 is stopped. At this time, the load (not shown) carried on the inner tube 3 will force the spindle nut 4 to have a tendency to move downward along the main shaft 2, so that the main shaft 2 has a tendency to rotate in the opposite direction. The locking device can lock the main shaft 2 to prevent it from rotating, thereby locking the position of the spindle nut 4 on the main shaft 2, so that the inner tube 3 and the target object stay at the position desired by the user. When the motor 7 rotates in the opposite direction, the locking device does not work, or the driving force provided by the motor 7 can overcome the locking effect of the locking device, so that the drive shaft 9 rotates in the opposite direction. Preferably, the locking device is not an additional device, but is formed by setting the helical angle of the helical teeth of the first gear 8 and / or the second gear 10 so that the friction provided by the helical teeth meshing forms a self-locking, thereby forming a locking device. In this case, when the motor 7 rotates in the opposite direction, the driving force provided by the motor can overcome the friction between the meshing helical teeth and the friction provided by the auxiliary locking device, so that the drive shaft rotates.

[0044] According to the present invention, an auxiliary locking device is provided, which utilizes the axial force borne by the transmission shaft 9 to assist the locking device in locking the main shaft 2 to prevent rotation when necessary. Figure 5 , 6 , 7a, 7b, 8a, 8b, 9a, 9b, the auxiliary locking device comprises: a first sleeve 11, which has a first groove 11', the first end of the transmission shaft 9 is accommodated in the first groove 11', the first groove 11' has a first bottom surface 18; and a second sleeve 12, which has a second groove 12', the second end of the transmission shaft 9 is accommodated in the first groove 12', the first groove 12' has a second bottom surface 19, wherein the second end of the transmission shaft 9 is opposite to the first end. The first sleeve 11 and the second sleeve 12 are fixed in the chamber 22 formed by the housing 6, and are used to support the transmission shaft 9 for rotation. The distance between the first bottom surface 18 and the second bottom surface 19 is slightly greater than the axial length of the transmission shaft 9, so when one end surface of the transmission shaft contacts the first bottom surface 18 of the first sleeve 11, the other end surface of the transmission shaft does not contact the second bottom surface 19 of the second sleeve 12, and vice versa.

[0045] In the auxiliary locking device according to the utility model, one of the first bottom surface 18 of the first groove 11' of the first sleeve 11 and the second bottom surface 19 of the second groove 12' of the second sleeve 12 has a higher roughness than the other. Preferably, one of the first bottom surface 18 of the first groove 11' of the first sleeve 11 and the second bottom surface 19 of the second groove 12' of the second sleeve 12 is smooth and does not hinder the rotation of the transmission shaft when in contact with one end surface of the transmission shaft, and the other of the first bottom surface 18 and the second bottom surface 19 is rough and hinders the rotation of the transmission shaft when in contact with the other end surface of the transmission shaft.

[0046] The rough end surface and the smooth end surface are arranged according to the rotation direction of the transmission shaft 9. In the embodiment shown in the figure, when the transmission shaft 9 rotates in the forward direction ( Figure 7a ), the transmission shaft 9 is subjected to a force in the direction of the first sleeve 11, so that the first end face 16 of the first end of the transmission shaft 9 contacts the first bottom face 18 of the first sleeve 11, and the second end face 17 of the transmission shaft 9 is spaced apart from the second bottom face 19 of the second sleeve 12 by a certain gap 24; when the transmission shaft 9 is braked or rotated in the reverse direction ( Figure 7b ), the transmission shaft 9 is subjected to a force in the direction of the second sleeve 12, so that the second end surface 17 of the second end of the transmission shaft contacts the second bottom surface 19 of the second sleeve 12, and the first end surface 16 of the transmission shaft 9 is separated from the first bottom surface 18 of the first sleeve by a certain gap 24'. Therefore, in the embodiment shown in the figure, the roughness of the first bottom surface 18 is lower than the roughness of the second bottom surface 19.

[0047] Preferably, the first bottom surface 18 is smooth, so that when the transmission shaft 9 rotates in the forward direction, the friction between the first end surface 16 of the transmission shaft 9 and the first bottom surface 18 of the first sleeve 11 does not affect the rotation of the transmission shaft 9. The second bottom surface 19 is rough, so that when the transmission shaft 9 is braked, the friction between the second end surface 17 of the transmission shaft 9 and the second bottom surface 19 of the second sleeve 12 can hinder the rotation of the transmission shaft 9. It should be noted that when the transmission shaft 9 rotates in the reverse direction under the action of the motor 7, the driving force of the motor 7 can overcome the friction between the second end surface 17 of the transmission shaft 9 and the second bottom surface 19 of the second sleeve 12, so that the transmission shaft 9 can rotate in the reverse direction.

[0048] Therefore, for example, when the linear actuator 1 according to the utility model is used for a nursing bed, the rear mounting member 14 of the linear actuator is connected to the beam of the fixed part of the bed frame, and the front mounting member 15 is connected to the beam of the movable part of the bed frame. When the motor 7 is started, the motor 7 rotates forward, and the inner tube 3 drives the beam of the movable part of the bed frame to rise together, thereby raising the movable part of the bed frame. Since the motor 7 rotates forward, the rightward axial force applied to the transmission shaft 9 causes the first end face 16 of the transmission shaft to contact the first bottom face 18 of the first sleeve 11. Since the first bottom face 18 has a low roughness, or even is smooth, the contact between the transmission shaft 9 and the first bottom face does not hinder the rotation of the transmission shaft. When it is raised to the position required by the user, the motor 7 is stopped, and the drive shaft 9 no longer bears the axial force toward the first sleeve 11. The first end face 16 of the drive shaft 9 is spaced apart from the first bottom face 18 of the first sleeve 11. The inner tube 3 tends to descend due to the load of the movable part of the bearing bed frame. Therefore, the drive shaft 9 is subjected to an axial force toward the second sleeve 12, and the second end face 17 of the drive shaft 9 is in contact with the second bottom face 19 of the second sleeve 12. The roughness of the second bottom face 19 helps to prevent the drive shaft 9 from rotating. As known to those skilled in the art, the greater the load borne by the inner tube 3, the greater the friction between the second end face 17 of the drive shaft 9 and the second bottom face 19 of the second sleeve 12.

[0049] It is conceivable that, alternatively or additionally, the roughness of the first end surface 16 of the transmission shaft 9 is less than the roughness of the second end surface 17. Preferably, the first end surface 16 of the transmission shaft 9 is smooth and the second end surface 17 is rough. Figure 7a ), the first end face 16 of the transmission shaft 9 contacts the first bottom face 18 of the first sleeve 11, and the friction between them generates less resistance to the rotation of the transmission shaft 9, and the second end face 17 is spaced a certain distance 24 from the second bottom face 19 of the second sleeve 12; when the transmission shaft 9 rotates in the reverse direction ( Figure 7b ), the second end face 17 of the transmission shaft 9 contacts the second bottom face 19 of the second sleeve 12, and the friction between them produces a large resistance to the rotation of the transmission shaft 9, thereby assisting in locking the transmission shaft 9, and the first end face 16 is spaced a certain distance 24' from the first bottom face 18 of the first sleeve 11.

[0050] Therefore, the auxiliary locking device according to the utility model can advantageously assist in locking the transmission shaft 9 when the motor 7 stops, and the linear actuator 1 using the auxiliary locking device according to the utility model has lower manufacturing and installation tolerance requirements for the first gear and the second gear, thereby reducing costs.

[0051] refer to Figure 8a , 8b, 9a and 9b, which respectively show the front view and the stereoscopic view of the first sleeve 11 and the second sleeve 12. The outer contours of the first sleeve 11 and the second sleeve 12 are determined by their installation positions and installation spaces in the chamber 22 of the housing 6, which is conducive to their installation and fixation in the chamber 22.

[0052] refer to Figure 8a , 8b , 9a and 9b, wherein the first sleeve 11 and the second sleeve 12 are shown to include a plurality of recesses 23. Since both ends of the transmission shaft are accommodated in the sleeve and rotate in the sleeve, lubricating grease can be stored in the recesses 23, and the lubricating grease is conducive to absorbing the heat generated by friction, reducing and delaying the reduction or instability of the friction coefficient caused by the increase in the temperature of the parts, and affecting the braking performance. Preferably, a plurality of recesses 23 are arranged in pairs on the first and second sleeves. In addition, the recesses 23 can be arranged on at least one of the top surfaces of the first sleeve 11 and the second sleeve 12, the side surfaces of the first groove 11' and the second groove 12', and the first bottom surface 18 and the second bottom surface 19. In the embodiment shown in the figure, the first sleeve 11 includes two pairs of recesses 23, which are respectively arranged in the top surface of the first sleeve 11 and the first bottom surface 18; the second sleeve 12 includes three pairs of recesses 23, which are respectively arranged in the top surface of the second sleeve 12, the side surfaces of the second groove 12', and the second bottom surface 19.

[0053] From the description provided of the preferred embodiments, it will be apparent that modifications may be made by a person skilled in the art without thereby departing from the scope of the invention as defined by the following claims.

Claims

1. An auxiliary locking device, mounted on a transmission shaft, the transmission shaft comprising a helical gear, the auxiliary locking device comprising: A fixed first sleeve having a first groove, wherein the first groove has a first bottom surface; and a fixed second sleeve having a second groove, wherein the second groove has a second bottom surface, When the transmission shaft rotates forward, the first end surface of the first end of the transmission shaft contacts the first bottom surface of the first groove of the first sleeve, and the second end surface of the second end of the transmission shaft is spaced apart from the second bottom surface of the second groove of the second sleeve; when the transmission shaft is braked or rotates in the reverse direction, the second end surface of the second end of the transmission shaft contacts the second bottom surface of the second groove of the second sleeve, and the first end surface of the first end of the transmission shaft is spaced apart from the first bottom surface of the first groove of the first sleeve. The roughness of the second bottom surface of the second groove of the second sleeve is greater than that of the first bottom surface of the first groove of the first sleeve, and / or the roughness of the second end surface of the transmission shaft is greater than that of the first end surface.

2. The auxiliary locking device according to claim 1, characterized in that: The roughness of the first bottom surface of the first groove of the first sleeve and / or the roughness of the first end surface of the transmission shaft are designed so that when the transmission shaft rotates in the forward direction, the friction between the first end surface of the transmission shaft and the first bottom surface of the first groove of the first sleeve does not substantially affect the rotation of the transmission shaft.

3. The auxiliary locking device according to claim 1 or 2, characterized in that: The roughness of the second bottom surface of the second groove of the second sleeve and / or the roughness of the second end surface of the transmission shaft are designed so that when the transmission shaft is braked, the friction between the second end surface of the transmission shaft and the second bottom surface of the second groove of the second sleeve can substantially hinder the rotation of the transmission shaft.

4. The auxiliary locking device according to claim 1, characterized in that: The first sleeve and / or the second sleeve comprises at least one recess.

5. The auxiliary locking device according to claim 4, characterized in that: The recessed portions are arranged in pairs.

6. The auxiliary locking device according to claim 4 or 5, characterized in that: The recessed portion is disposed on at least one of the top surfaces of the first and second sleeves, the side surfaces of the first and second grooves, and the first and second bottom surfaces.

7. The auxiliary locking device according to claim 1, characterized in that: The outer contour of the first bushing and / or the second bushing is determined by the installation position and the installation space.

8. A linear actuator comprising: case; a rear mount and a front mount; a motor including a motor shaft, the motor shaft being capable of rotating in a forward direction and a reverse direction; A transmission shaft, comprising a first gear and a second gear, wherein the first gear is meshed with the motor shaft, at least one of the first gear and the second gear is a helical gear, the transmission shaft can move a certain distance in the axial direction, and the transmission shaft is accommodated in a chamber formed by the housing; a main shaft with an external thread including a third gear meshing with the second gear of the transmission shaft so as to receive rotational power from the motor; A spindle nut with an internal thread, which is threadedly engaged with the spindle, so that when the spindle rotates, the spindle nut rises or falls along the axial direction of the spindle according to the rotation direction of the spindle; an inner tube coaxially arranged with the spindle, a first end of the inner tube being fixed to the spindle nut so as to be linearly movable by the spindle nut, and the front mounting member being connected to a second end of the inner tube so as to be linearly movable integrally with the inner tube; An outer tube, which is coaxially arranged on the periphery of the inner tube, is used to guide the linear movement of the spindle nut and the inner tube, and is fixed to the housing; A locking device, which is used to lock the spindle to prevent it from rotating when necessary, Characterized in that the linear actuator further comprises an auxiliary locking device according to any one of claims 1 to 7, and the auxiliary locking device is fixed in the chamber.

9. The linear actuator according to claim 8, characterized in that The chamber is covered by a housing cover.

10. The linear actuator according to claim 8 or 9, characterized in that: The locking means are formed by mutually meshing helical teeth of the first and second gears.

Images