Braking device of linear actuator and linear actuator

Abstract

The present invention provides a brake device for a linear actuator, comprising a first torsion spring seat (3), a torsion spring (4), a second torsion spring seat (5) and a friction member, wherein the second torsion spring seat (5) is used for being relatively fixed with a rotating screw (1) of the linear actuator, and in a free state, the torsion spring (4) and the first torsion spring seat (3) and the second torsion spring seat (5) are all in interference fit, when the rotating screw (1) rotates in a positive direction, the first torsion spring seat (3) does not rotate, when the rotating screw (1) rotates in a reverse direction, the torsion spring (4) is tightly held, the second torsion spring seat (5), the torsion spring (4) and the first torsion spring seat (3) rotate synchronously, and the first torsion spring seat (3) and the friction member are in contact to generate friction force. In addition, the present invention also discloses a linear actuator using the above brake device, and the present invention has the advantage that the sound, current and noise of the linear actuator in the two states of extension and retraction are consistent, making it more convenient to use.

Description

[Technical field]

[0001] The invention relates to a brake device of a linear actuator and a linear actuator, belonging to the field of linear actuation equipment. [Background technology]

[0002] Linear actuators are currently widely used in various fields, including electric lifting tables, electric beds, electric sofas, etc. The structure of this linear actuator usually includes a driving motor, a rotating screw, and a transmission nut. The driving motor drives the rotating screw to rotate, and when the rotating screw rotates, it drives the transmission nut to move axially. The transmission nut can be connected to the driving object to achieve the driving purpose.

[0003] At present, linear actuators are used more and more widely. Among them, common linear actuators include electric push rods. Common electric push rods use torsion springs for self-locking. For example, Chinese invention patent CN204947822U discloses a self-locking electric push rod, which includes a transmission worm gear and a lead screw. The lead screw is provided with a torsion spring. With this structure, self-locking can be achieved by clamping the torsion spring. However, the torsion spring is in contact with the transmission worm gear. When the electric push rod is extended and retracted, the torsion spring collides with the transmission worm gear to generate noise, and the sound and current of the electric push rod in the extended and retracted states are inconsistent, which affects the use and makes it inconvenient to use. [Summary of the invention]

[0004] The technical problem to be solved by the present invention is to provide a brake device for a linear actuator, which is easy to use.

[0005] In order to solve the above technical problems, the preferred structure of the brake device of the linear actuator of the present invention includes a first torsion spring seat, a torsion spring, a second torsion spring seat and a friction member. The second torsion spring seat is used to be relatively fixed to the rotating screw of the linear actuator. In the free state, the torsion spring and the first torsion spring seat and the second torsion spring seat are all interference fits. When the rotating screw rotates in the forward direction, the first torsion spring seat does not rotate. When the rotating screw rotates in the reverse direction, the torsion spring is tightened, the second torsion spring seat, the torsion spring and the first torsion spring seat rotate synchronously, and the first torsion spring seat is in contact with the friction member to generate friction.

[0006] After adopting the above structure, firstly, the brake device of the linear actuator of the present invention comprises a first torsion spring seat, a torsion spring, a second torsion spring seat and a friction member, wherein the second torsion spring seat is used to be relatively fixed with the rotating screw of the linear actuator, that is, the second torsion spring seat can rotate together with the rotating screw, and in the free state, the torsion spring and the first torsion spring seat and the second torsion spring seat are all interference fit, so that the first torsion spring seat and the second torsion spring seat can be relatively fixed by the torsion spring, and the free state refers to the state when the rotating screw does not rotate, when the rotating screw rotates in the positive direction, the torsion spring is loosened, and the first torsion spring seat does not rotate, when the rotating screw rotates in the reverse direction, the torsion spring is tightened, and the second torsion spring seat, the torsion spring and the first torsion spring seat rotate synchronously, wherein the positive rotation refers to that when the rotating screw rotates in this direction, the linear actuator is in an extended state, and the reverse rotation refers to that when the rotating screw rotates in this direction, the linear actuator is in a retracted state, and the first torsion spring seat is in contact with the friction member to generate friction force, that is, self-locking is achieved by the friction force between the first torsion spring seat and the friction member.

[0007] Secondly, when in use, the rotating screw is subjected to two forces, one is the axial force in its axial direction, and the other is the torque that makes the rotating screw rotate in the opposite direction. Under the action of the axial force, the rotating screw moves in the opposite direction relative to its extension direction or has a tendency to move in the opposite direction, so that the first torsion spring seat and the friction member are pressed against each other to generate friction. Under the action of the friction force between the first torsion spring seat and the friction member, the torque that makes the rotating screw rotate in the opposite direction is offset, preventing the rotating screw from rotating in the opposite direction, thereby realizing self-locking. When the driving motor drives the rotating screw to retract and extend normally, since there is no load force in its axial direction, the first torsion spring seat and the friction member are not pressed tightly, so that the friction between them is small or non-existent, and the torque of the driving motor is sufficient to overcome the friction at this time to allow the rotating screw to retract and extend normally.

[0008] A commonly used linear actuator is provided with a gear that drives the rotating screw, and the gear is in contact with a torsion spring. Based on the above structure, the torsion spring and the gear that drives the rotating screw will not contact each other. The linear actuator achieves normal contraction by overcoming the smaller friction between the first torsion spring seat and the friction member. Therefore, there is no noise between the torsion spring and the gear when the linear actuator is extended and retracted. The sound and current of the linear actuator are consistent in the two states of extension and retraction, which does not affect the use and makes it more convenient to use.

[0009] Preferably, when the rotating screw is unloaded in the axial direction, the first torsion spring seat and the friction member are in contact with each other.

[0010] Preferably, when the rotating screw is unloaded in the axial direction, a floating gap exists between the first torsion spring seat and the friction member along the axial direction of the transmission screw.

[0011] Preferably, the second torsion spring seat comprises a flat hole, and the rotating screw rod is inserted into the flat hole.

[0012] Preferably, a plane bearing is provided between the first torsion spring seat and the second torsion spring seat.

[0013] Preferably, there is a gap between the first torsion spring seat and the second torsion spring seat in the axial direction of the rotating screw.

[0014] The present invention also discloses a linear actuator, including a first sleeve, a second sleeve, a rotating screw, a transmission nut, a transmission gear and a driving motor. The driving motor drives the rotating screw to rotate by driving the transmission gear. When the rotating screw rotates, it drives the transmission nut to move axially. The transmission nut moves to drive the first sleeve and the second sleeve to retract relative to each other. A brake device of any one of the above schemes is installed on the rotating screw.

[0015] Preferably, a spline connection is adopted between the gear and the rotating screw, so that the gear is circumferentially fixed relative to the rotating screw.

[0016] Preferably, the spline and the rotating screw are positioned by pins.

[0017] Preferably, the linear actuator further comprises a housing, and the friction member and the housing are an integral structure or the friction member and the housing are fixedly connected.

[0018] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings.

Brief Description of the Drawings

[0019] The present invention is further described in detail below with reference to the accompanying drawings, in which:

[0020] Figure 1 is a schematic diagram of a brake device according to the present embodiment;

[0021] Figure 2 is a schematic diagram of a second torsion spring seat in a brake device according to the first embodiment of the present invention;

[0022] Figure 3 is a schematic diagram of a first torsion spring seat in a brake device according to the first embodiment of the present invention;

[0023] Figure 4 is a schematic diagram of a gear in the linear actuator of the third embodiment;

[0024] Figure 5 is a schematic diagram of a spline in the linear actuator of the third embodiment;

[0025] Figure 6 is a side view of a spline in the linear actuator of the third embodiment;

[0026] Figure 7 is a schematic diagram of a rotating screw in the linear actuator of the third embodiment;

[0027] Figure 8 is a cross-sectional schematic diagram of the third linear actuator of this embodiment;

[0028] Fig. 9 for Figure 8 A partial enlarged view of . [Specific implementation method]

[0029] The technical solutions of the embodiments of the present invention are explained and described below in conjunction with the drawings of the embodiments of the present invention, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work are all within the protection scope of the present invention.

[0030] In the following description, terms such as "inside", "outside", "up", "down", "left", "right", etc. that indicate orientation or position relationship are based on the orientation or position relationship shown in the drawings and are only for the convenience of describing the embodiments and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0031] Embodiment 1:

[0032] like Figure 1 As shown, the preferred structure of the brake device of the linear actuator of this embodiment includes a first torsion spring seat 3, a torsion spring 4, a second torsion spring seat 5 and a friction member. The second torsion spring seat 5 is used to be relatively fixed to the rotating screw 1 of the linear actuator. In the free state, the torsion spring 4 and the first torsion spring seat 3 and the second torsion spring seat 5 are all interference fit. When the rotating screw 1 rotates in the forward direction, the first torsion spring seat 3 does not rotate. When the rotating screw 1 rotates in the reverse direction, the torsion spring 4 is tightened, and the second torsion spring seat 5, the torsion spring 4 and the first torsion spring seat 3 rotate synchronously. The first torsion spring seat 3 is in contact with the friction member to generate friction.

[0033] After adopting the above structure, firstly, the brake device of the linear actuator of the present invention comprises a first torsion spring seat 3, a torsion spring 4, a second torsion spring seat 5 and a friction member, wherein the second torsion spring seat 5 is used to be relatively fixed with the rotating screw 1 of the linear actuator, that is, the second torsion spring seat 5 can rotate together with the rotating screw 1, and the torsion spring 4 and the first torsion spring seat 3 and the second torsion spring seat 5 are all interference fits, so that when the torsion spring 4 is tightened, the first torsion spring seat 3 and the second torsion spring seat 5 can be relatively fixed by the torsion spring 4, and the free state refers to when the rotating screw does not rotate. When the screw rod 1 rotates in the forward direction, the first torsion spring seat 3 does not rotate; when the screw rod 1 rotates in the reverse direction, the torsion spring 4 is tightened, and the second torsion spring seat 5, the torsion spring 4 and the first torsion spring seat 3 rotate synchronously, wherein the forward rotation means that when the screw rod rotates in this direction, the linear actuator is in an extended state; the reverse rotation means that when the screw rod rotates in this direction, the linear actuator is in a retracted state, and the first torsion spring seat 3 contacts with the friction member to generate friction force, that is, self-locking is achieved by the friction force between the first torsion spring seat 3 and the friction member.

[0034] Secondly, when in use, the rotating screw 1 is subjected to two forces, one is the axial force in its axial direction, and the other is the torque that makes the rotating screw 1 rotate in the opposite direction. Under the action of the axial force, the rotating screw 1 moves in the opposite direction relative to its extension direction or has a tendency to move in the opposite direction, so that the first torsion spring seat 3 and the friction member are pressed against each other to generate friction. Under the action of the friction force between the first torsion spring seat 3 and the friction member, the torque that makes the rotating screw 1 rotate in the opposite direction is offset, preventing the rotating screw 1 from rotating in the opposite direction, thereby achieving self-locking. When the driving motor drives the rotating screw 1 to retract normally, since there is no load force in its axial direction, the first torsion spring seat 3 and the friction member are not pressed tightly, so that the friction between them is small or non-existent, and the torque of the driving motor is sufficient to overcome the friction at this time to allow the rotating screw 1 to retract normally.

[0035] A commonly used linear actuator is provided with a gear that drives the rotating screw 1 to rotate, and the gear is in contact with the torsion spring 4. Based on the above structure, the torsion spring 4 and the gear that drives the rotating screw 1 to rotate will not contact each other. The linear actuator achieves normal contraction by overcoming the smaller friction between the first torsion spring seat 3 and the friction member, so that there is no noise between the torsion spring and the gear when the linear actuator is extended and retracted. The sound and current of the linear actuator in the extended and retracted states are consistent, which does not affect the use, making it more convenient to use.

[0036] By adopting the above scheme, there is no need to use interference fit between the torsion spring 4 and the transmission gear 2 to achieve self-locking, so as to prevent the inconsistency of the processing precision from causing the unstable interference between the torsion spring and the transmission worm gear, thereby causing the unstable self-locking force of the mechanism. In addition, no friction occurs between the torsion spring 4 and the transmission gear 2, so when the transmission gear 2 is made of plastic material, it will not be deformed by friction and heat, and when the transmission gear 2 is made of metal material, it will not generate noise due to friction to affect the use.

[0037] In order to optimize the self-locking ability of the brake device, in this embodiment, when the rotating screw rod 1 is unloaded in the axial direction, the first torsion spring seat 3 and the friction member are in contact with each other, that is, in the initial state, the first torsion spring seat 3 and the friction member are in contact, so that the first torsion spring seat 3 can be pressed against the friction member only by the deadweight of the mechanism to achieve self-locking. When the rotating screw rod 1 contracts normally, the friction force between the first torsion spring seat 3 and the friction member needs to be overcome. Therefore, when the load applies an axial force to the rotating screw rod 1, the friction force between the first torsion spring seat 3 and the friction member can be enhanced, thereby improving the self-locking ability of the brake device. The greater the axial force applied by the load to the rotating screw rod 1, the stronger the self-locking ability of the brake device.

[0038] In order to optimize the structure, Figure 2 , Figure 3 and Figure 7 As shown, in this embodiment, the second torsion spring seat 5 preferably includes a flat hole 8, and the rotating screw rod 1 is inserted in the flat hole 8, that is, the second torsion spring seat 5 is circumferentially fixed with the screw rod 1 through the flat hole 8, and the rotating screw rod 1 is at the position of the second torsion spring seat 5 and cooperates with the flat hole 8, so that the rotating screw rod 1 can rotate in the flat hole 8 and drive the second torsion spring seat 5 to rotate, and the hole in the first torsion spring seat 3 is a circular hole, and the rotating screw rod 1 is inserted therein, and the inner diameter of the circular hole is larger than the outer diameter of the rotating screw rod 1 here, so that the rotating screw rod 1 can rotate in the circular hole without driving the first torsion spring seat 3 to rotate.

[0039] In order to make the brake device work better, in this embodiment, a plane bearing 9 is preferably provided between the first torsion spring seat 3 and the second torsion spring seat 5, so that the second torsion spring seat 5 can rotate relative to the first torsion spring seat 3 through the plane bearing 9. Through the plane bearing 9, when the second torsion spring seat 5 rotates, it will not drive the first torsion spring seat 3 to rotate together, thereby preventing the first torsion spring seat 3 and the second torsion spring seat 5 from axially moving when the rotating screw rod 1 is extended and retracted, causing them to contact each other and affecting the extension and retraction, thereby making the brake device work better.

[0040] In order to better achieve self-locking, the first torsion spring seat 3 and the second torsion spring seat 5 described in this embodiment preferably have a gap in the axial direction of the rotating screw rod 1, thereby preventing the second torsion spring seat 5 from contacting the first torsion spring seat 3 during rotation. The friction between the first torsion spring seat 3 and the second torsion spring seat 5 causes the rotation to be hindered, affecting the self-locking.

[0041] In order to make the rotation of the rotating screw 1 more stable, Figure 4 and Figure 5 As shown, in this embodiment, the gear 2 and the rotating screw 1 are preferably connected by a spline 6. Compared with the ordinary key connection, the spline 6 connection makes the circumferential fixation of the gear 2 and the rotating screw 1 more stable, thereby making the rotation of the rotating screw 1 more stable. A flat hole is provided inside the spline 6, and the rotating screw 1 is inserted into the flat hole of the spline 6, so that the rotating screw 1 and the spline 6 are circumferentially positioned.

[0042] In order to make the mechanism able to withstand a certain axial tension and prevent the rotating screw 1 from being pulled out in the axial direction, Figure 6 and Figure 7 As shown, in this embodiment, a pin 7 is preferably used to position the spline 6 and the rotating screw 1. A through hole is provided on the rotating screw 1, and the pin 7 is inserted into the through hole. A mounting groove is provided on the spline 6, and the pin 7 is inserted into the mounting groove. The rotating screw 1 is positioned along its extending direction, so that when the rotating screw 1 is subjected to axial tension along its extending direction, it is not pulled out by external force.

[0043] In order to further optimize the structure, the linear actuator of this embodiment preferably also includes a housing, and the friction member and the housing are an integral structure or the friction member and the housing are fixedly connected, and friction is achieved by utilizing the housing or a friction member is provided to achieve friction. The friction member can be a friction plate 10, and one end of the friction plate 10 is relatively fixed to the housing, and the other end is clearance-fitted with the first torsion spring seat 3. Under the action of the axial force, the first torsion spring seat 3 contacts the friction plate 10, thereby achieving friction self-locking.

[0044] Embodiment 2:

[0045] The difference between this embodiment and the first embodiment is that, in this embodiment, when the rotating screw 1 is unloaded in the axial direction, there is a floating gap between the first torsion spring seat 3 and the friction member in the axial direction of the transmission screw 1. With this structure, when the rotating screw 1 is normally extended and retracted and there is no axial force, there is no contact between the first torsion spring seat 3 and the friction member, so that the rotating screw 1 does not need to overcome the friction force between the first torsion spring seat 3 and the friction member when extending and retracting. This embodiment can also achieve the technical effect of the first embodiment.

[0046] Embodiment three:

[0047] The third embodiment is a linear actuator, and the brake device described in the first embodiment is used to be installed in the linear actuator of the present embodiment. Figure 8 and Fig. 9As shown, the preferred structure of this embodiment mainly includes a first sleeve, a second sleeve, a rotating screw 1, a transmission nut, a transmission gear 2 and a driving motor. The driving motor drives the rotating screw 1 to rotate by driving the transmission gear 2. When the rotating screw 1 rotates, it drives the transmission nut to move axially. The transmission nut moves to drive the first sleeve and the second sleeve to retract relative to each other.

[0048] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes but is not limited to the contents described in the drawings and the above specific embodiments. Any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims

1. A brake device for a linear actuator, characterized in that: The brake device comprises a first torsion spring seat (3), a torsion spring (4), a second torsion spring seat (5) and a friction member, wherein the second torsion spring seat (5) is used to be fixed relative to the rotating screw (1) of the linear actuator. In a free state, the torsion spring (4) and the first torsion spring seat (3) and the second torsion spring seat (5) are all interference fits. When the rotating screw (1) rotates in a positive direction, the first torsion spring seat (3) does not rotate. When the rotating screw (1) rotates in a reverse direction, the torsion spring (4) is tightly held, and the second torsion spring seat (5), the torsion spring (4) and the first torsion spring seat (3) rotate synchronously. The first torsion spring seat (3) and the friction member are in contact to generate friction force. When the rotating screw (1) is unloaded in the axial direction, the first torsion spring seat (3) and the friction member are in contact with each other. The second torsion spring seat (5) comprises a flat hole (8), and the rotating screw (1) is inserted into the flat hole (8).

2. The brake device of the linear actuator according to claim 1, characterized in that: A plane bearing (9) is provided between the first torsion spring seat (3) and the second torsion spring seat (5).

3. The brake device of the linear actuator according to claim 1, characterized in that: There is a gap between the first torsion spring seat (3) and the second torsion spring seat (5) in the axial direction of the rotating screw rod (1).

4. A brake device for a linear actuator, characterized in that: The brake device comprises a first torsion spring seat (3), a torsion spring (4), a second torsion spring seat (5) and a friction member, wherein the second torsion spring seat (5) is used to be fixed relative to the rotating screw (1) of the linear actuator. In a free state, the torsion spring (4) and the first torsion spring seat (3) and the second torsion spring seat (5) are all interference fits. When the rotating screw (1) rotates in a positive direction, the first torsion spring seat (3) does not rotate. When the rotating screw (1) rotates in a reverse direction, the torsion spring (4) is tightly held, and the second torsion spring seat (5), the torsion spring (4) and the first torsion spring seat (3) rotate synchronously. The first torsion spring seat (3) and the friction member are in contact to generate friction force. When the rotating screw (1) is unloaded in the axial direction, there is a floating gap between the first torsion spring seat (3) and the friction member in the axial direction of the rotating screw (1). The second torsion spring seat (5) comprises a flat hole (8), and the rotating screw (1) is inserted into the flat hole (8).

5. A linear actuator, comprising a first sleeve, a second sleeve, a rotating screw (1), a transmission nut, a transmission gear (2) and a driving motor, wherein the driving motor drives the rotating screw (1) to rotate by driving the transmission gear (2), and when the rotating screw (1) rotates, the transmission nut is driven to move axially, and the transmission nut moves to drive the first sleeve and the second sleeve to extend and retract relative to each other, characterized in that: The rotating screw rod (1) is provided with a brake device as claimed in any one of claims 1 to 4.

6. The linear actuator according to claim 5, characterized in that: The transmission gear (2) and the rotating screw rod (1) are connected by a spline (6).

7. The linear actuator according to claim 6, characterized in that: The spline (6) and the rotating screw rod (1) are positioned by a pin (7).

8. The linear actuator according to claim 5, characterized in that: The linear actuator further comprises a housing, and the friction member and the housing are an integral structure or the friction member and the housing are fixedly connected.

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