Ball screw device and electromechanical brake

Abstract

The utility model relates to the technical field of mechanical transmission, and provides a ball screw device, which comprises a screw, a nut, a ball and at least one ball return device arranged on the screw, each ball return device comprises a ball return groove, the downstream side and the upstream side of a thread groove of the screw are communicated, and a ball circulating raceway which returns to the upstream side from the downstream side through the ball return groove is formed; and the blocking tongue is connected with the ball return groove, and the inner surface of the blocking tongue and the ball return groove jointly define a ball return raceway. The ball return groove and the blocking tongue are matched to jointly define the ball return raceway, the ball return raceway is not in contact with the nut, friction self-locking caused by joint extrusion of the lead screw and the nut in the ball return process of the ball is effectively avoided, and accordingly the problems of clamping stagnation, efficiency reduction, abnormal abrasion and the like of the ball screw device are avoided. And the transmission stability and the service life of the ball screw device are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of mechanical transmission, in particular to a ball screw device. Background Art

[0002] Ball screws are widely used mechanical transmission devices for converting rotary motion into linear motion. They consist of a screw, a nut that meshes with the screw thread, balls that roll in the threaded raceway formed by the meshing screw and nut, and a ball return mechanism. Ball screws utilize the rolling motion of balls between the screw and nut to reduce friction and improve transmission efficiency. The balls circulate through the ball return mechanism, preventing them from rolling out and ensuring continuous operation within the threaded raceway.

[0003] In applications such as electromechanical brakes, a ball return structure is provided on the lead screw in order to reduce axial space. Figure 1 The structure of a current ball screw is shown in FIG. Figure 2 The structure of the ball of the current ball screw when returning to the ball is shown; combined with Figure 1 and Figure 2 As shown, the current ball screw has an S-shaped groove 11 machined on the screw 10 as a ball return structure. When the ball 30 is located at the turning point of the groove 11, the ball 30 is squeezed by the screw 10 and the nut 20. The contact angle θ between the ball 30 and the groove 11 and the nut 20 is close to the friction self-locking angle, resulting in a one-way self-locking structure at this time, which prevents the ball 30 from further entering the groove 11, thereby causing the ball screw to get stuck, reducing the transmission efficiency, and causing abnormal wear.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Utility Model Content

[0005] In view of this, the utility model provides a ball screw device, which effectively avoids friction self-locking during the ball return process, thereby avoiding the problems of ball screw device jamming, reduced efficiency, abnormal wear and other problems caused by this, and improves the transmission stability and life of the ball screw device.

[0006] According to one aspect of the utility model, a ball screw device is provided, comprising a screw, a nut threadedly engaged with the screw, and a ball limited between the screw and the nut; the ball screw device also includes at least one ball return device arranged on the screw, wherein each ball return device includes: a ball return groove, connecting the downstream side and the upstream side of the thread groove of the screw, forming a ball circulation track from the downstream side through the ball return groove to the upstream side; a tongue, connected to the ball return groove, and the inner surface of the tongue and the ball return groove jointly define a ball return track.

[0007] The ball screw assembly of this utility model utilizes a ball return device mounted on the screw to form a ball screw structure that prevents the balls from leaving the screw surface during operation. The ball return device utilizes a ball return groove to connect the downstream and upstream sides of the screw's thread groove, forming a ball circulation track that traverses upstream → downstream → ball return groove → upstream, allowing the balls to circulate within the ball circulation track. The ball return device also defines the ball return track through the cooperation of the ball return groove and the retaining tongue, providing space for the balls to smoothly return. During the ball return process, if there is no shielding effect of the tongue, the ball located at the connection between the ball return groove and the thread groove, that is, the first ball entering the ball return groove, is likely to get stuck due to the squeezing of the nut and the lead screw; the utility model utilizes the inner surface of the tongue and the ball return groove to jointly define a ball return raceway, and the ball return raceway does not contact the nut, thus avoiding the friction self-locking caused by the lead screw and the nut squeezing the balls during the ball return process, effectively solving the problem of the balls getting stuck during the ball return process, and thus avoiding the problems of the ball screw device getting stuck, reduced efficiency, abnormal wear and other problems caused thereby, thereby improving the transmission stability and life of the ball screw device.

[0008] In some embodiments, the outer surface of the tongue is loosely matched with the nut and operates with the ball screw device: the balls located in the threaded groove of the screw are squeezed by the nut and the screw to form load-bearing balls, and the balls located in the return ball raceway do not contact the nut and form non-load-bearing balls, and the load-bearing balls drive the non-load-bearing balls in and out of the return ball raceway.

[0009] The outer surface of the retaining tongue is loosely matched with the nut, preventing the nut from self-locking due to friction caused by the nut and the screw squeezing the balls during the ball return process. This effectively solves the problem of ball jamming during the ball return process, further avoiding the resulting jamming, reduced efficiency, and abnormal wear of the ball screw device, further improving the transmission stability and lifespan of the ball screw device. During the operation of the ball screw device, the balls entering the ball return raceway do not contact the nut, forming non-load-bearing balls, effectively avoiding the problem of friction self-locking caused by the screw and nut squeezing the balls during the ball return process; the non-load-bearing balls roll in and out of the ball return raceway driven by the load-bearing balls, realizing ball circulation.

[0010] In some embodiments, the ball return groove is recessed relative to the thread groove of the lead screw and is transitionally connected to the thread groove of the lead screw in a circular arc.

[0011] The ball return groove is recessed relative to the thread groove of the lead screw, leaving enough space for the ball to return; the ball return groove and the thread groove of the lead screw are connected in an arc transition to avoid problems such as jamming and wear of the first ball entering the ball return groove.

[0012] In some embodiments, the ball return device and the thread groove of the screw are integrally formed or separately formed.

[0013] Considering factors such as processing cost, demoulding convenience, and number of parts, the ball return device can be designed to be integrally formed with the thread groove of the screw or to be separately formed.

[0014] In some embodiments, when the bead return device and the thread groove of the screw are formed separately, the bead return device includes: a groove platform connecting the downstream side and the upstream side of the thread groove of the screw; a bead return component installed on the groove platform, and the bead return component is provided with the bead return groove and the retaining tongue.

[0015] The groove platform and the thread groove of the lead screw are integrally formed, and the ball return part and the groove platform are separately formed, so as to process the structure of the ball return groove and the structure of the tongue.

[0016] In some embodiments, the bead return member is an integral component, or the bead return member is formed by assembling a pair of separate components.

[0017] Considering factors such as assembly convenience and demoulding convenience, the bead return piece can be designed as an integral component or a split component. In the case where the bead return piece is assembled from a pair of split components, each split component is provided with half a bead return groove and half a tongue, which facilitates demoulding.

[0018] In some embodiments, the bead return piece is fixed to the groove platform by screwing, riveting, welding or interference fitting.

[0019] For example, the groove platform and the bead return piece are provided with matching screw holes, and the bead return piece is screwed onto the groove platform by screws, but the present invention is not limited thereto.

[0020] In some embodiments, the retaining tongue and the ball return groove are integrally formed or separately formed.

[0021] Taking factors such as assembly convenience and demoulding convenience into consideration, the tongue and the bead return groove can be designed as an integral component or a separate component.

[0022] In some embodiments, the bead returner is made of metal or plastic.

[0023] Specifically, suitable materials can be selected to make the bead return device based on factors such as cost, structural strength, and processing convenience.

[0024] In some embodiments, the at least one bead return device is staggered or concentrated in the circumferential direction.

[0025] According to the design requirements, the bead return devices can be evenly or unevenly distributed in the circumferential direction.

[0026] According to another aspect of the present invention, an electromechanical brake is provided. The electromechanical brake is equipped with the ball screw device as described in any of the above embodiments.

[0027] Utilizing the above-mentioned ball screw device, the ball return groove and the tongue cooperate to define a ball return track, and the ball return track does not contact the nut. This avoids the screw and nut jointly squeezing the balls during the ball return process and causing friction self-locking, effectively solving the problem of ball jamming during the ball return process, making the ball screw device run smoothly and steadily, thereby improving the stability and braking performance of the electronic mechanical brake.

[0028] Compared with the prior art, the beneficial effects of the present invention include at least:

[0029] The ball screw device of the present invention defines a ball return track through the cooperation of the tongue and the ball return groove. The ball return track does not contact the nut, effectively avoiding friction self-locking caused by the joint extrusion of the screw and the nut during the ball return process, thereby avoiding the problems of sticking, reduced efficiency, abnormal wear and other problems of the ball screw device caused by this, improving the transmission stability and life of the ball screw device, and enhancing the stability and transmission performance of the products used in the ball screw device.

[0030] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory and are not restrictive of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present invention, and together with the specification, are used to explain the principles of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0032] Figure 1 Shown is a schematic structural diagram of a current ball screw;

[0033] Figure 2 A schematic diagram showing the structure of the balls of a conventional ball screw during ball return;

[0034] Figure 3 A schematic diagram of the assembly structure of the ball screw device in the embodiment of the present utility model is shown;

[0035] Figure 4 A schematic diagram showing the structure of the balls of the ball screw device in the embodiment of the present invention when returning to the ball state;

[0036] Figure 5 A schematic diagram of the exploded structure of the ball screw device in the embodiment of the present invention is shown;

[0037] Figure 6 A schematic structural diagram of a ball screw device in an embodiment of the present invention is shown;

[0038] Figure 7 A schematic structural diagram of the ball return member of the ball screw device in an embodiment of the present utility model is shown. DETAILED DESCRIPTION

[0039] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to make this disclosure more comprehensive and complete and to fully convey the concepts of the example embodiments to those skilled in the art.

[0040] The accompanying drawings are only schematic diagrams of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings represent the same or similar structures, and their repeated description will be omitted.

[0041] The terms "first," "second," and similar terms used in the specific description do not indicate any order, quantity, or importance, but are simply used to distinguish different components. Terms such as "clockwise" and "counterclockwise" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are intended solely for ease of description and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, in the description of the present invention, when a device is said to be "connected" to another device, this includes not only direct connections but also indirect connections through other components.

[0042] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in different embodiments may be combined with each other.

[0043] Figure 3 The exploded structure of the ball screw device is shown. Figure 4 The assembly structure of the ball screw device is shown in FIG. Figure 5 The exploded structure of the ball screw device is shown; combined with Figures 3 to 5 As shown, the ball screw device provided by the embodiment of the present invention includes a screw 100, a nut 200 threadedly engaged with the screw 100, a ball 300 limited between the screw 100 and the nut 200, and at least one ball return device 400 provided on the screw 100, wherein each ball return device 400 includes:

[0044] The ball return groove 410 connects the downstream side and the upstream side of the thread groove 110 of the screw 100 to form a ball circulation track that returns from the downstream side to the upstream side through the ball return groove 410;

[0045] The retaining tongue 420 is connected to the ball return groove 410 , and the inner surface of the retaining tongue 420 and the ball return groove 410 together define a ball return raceway 440 .

[0046] The ball screw device of the present invention utilizes a ball return device 400 provided on the screw 100 to form a ball screw structure in which the balls 300 do not leave the surface of the screw 100 during operation. The number of ball return devices 400 is determined according to the requirements for the fit between the screw 100 and the nut 200. Each time a ball return device 400 is provided, a ball circulation track is formed on the surface of the screw 100. The ball return device 400 connects the downstream side and the upstream side of the thread groove 110 of the screw 100 via the ball return groove 410, for example Figure 3 The downstream side 110b and upstream side 110a, indicated in the middle, form a ball circulation track from upstream side 110a → downstream side 110b → ball return groove 410 → upstream side 110a, allowing balls 300 to circulate in the ball circulation track. It should be noted that the upstream side 110a and downstream side 110b are not absolute; when the kinematic relationship between the screw 100 and the nut 200 changes, the upstream side 110a may become the downstream side, and the downstream side 110b may correspondingly become the upstream side.

[0047] The ball return device 400 also defines a ball return track 440 through the cooperation of the ball return groove 410 and the retaining tongue 420, providing space for the smooth return of the ball 300. During the ball return process, if there is no shielding effect of the retaining tongue 420, the ball located at the connection between the ball return groove 410 and the thread groove 110, that is, the first ball to enter the ball return groove 410, is likely to get stuck due to the squeezing of the nut 200 and the screw 100; the utility model uses the inner surface of the retaining tongue 420 and the ball return groove 410 to define the ball return track 440, and the ball return track 440 does not contact the nut 200, thus avoiding the friction self-locking caused by the screw 100 and the nut 200 squeezing the ball 300 during the ball return process, effectively solving the problem of the ball 300 getting stuck during the ball return process, thereby avoiding the problems of the ball screw device getting stuck, reduced efficiency, abnormal wear, etc. caused by this, and improving the transmission stability and life of the ball screw device.

[0048] In some embodiments, the outer surface of the tongue 420 is loosely matched with the nut 200; as the ball screw device operates: the balls 300 located in the threaded groove 110 of the screw 100 are squeezed by the nut 200 and the screw 100 to form load-bearing balls, and the balls 300 located in the return ball raceway 440 do not contact the nut 200 and form non-load-bearing balls, and the load-bearing balls drive the non-load-bearing balls in and out of the return ball raceway 440.

[0049] Among them, the fitting gap between the outer surface of the tongue 420 and the nut 200 can be set as needed, as long as the gap is not too large to affect the stable fit between the nut 200 and the screw 100 and the structural strength of the screw 100 itself, and the gap is not too small to increase the friction between the nut 200 and the screw 100.

[0050] The outer surface of the tongue 420 is in clearance with the nut 200, thus preventing the nut 200 from squeezing the ball 300 through the tongue 420 and the screw 100 during the ball return process, causing frictional self-locking. This effectively solves the problem of the ball 300 getting stuck during the ball return process, further avoiding the problems of the ball screw device getting stuck, reduced efficiency, abnormal wear, etc. caused by this, and further improving the transmission stability and life of the ball screw device. During the operation of the ball screw device, the ball 300 entering the ball return raceway 440 does not contact the nut 200, forming a non-load-bearing ball, effectively avoiding the problem of the ball 300 being squeezed by the screw 100 and the nut 200 during the ball return process, causing frictional self-locking. The non-load-bearing ball rolls in and out of the ball return raceway 440 driven by the load-bearing ball, realizing the circulation of the ball 300.

[0051] Specifically, refer to Figure 4 As shown, during the operation of the ball screw device, assuming that the screw 100 is fixed and the nut 200 rotates counterclockwise, the load-bearing ball 300a is driven to rotate counterclockwise; the non-load-bearing ball entering the return ball raceway 440 will no longer be in contact with the nut 200. When the first non-load-bearing ball 300b entering the return ball raceway 440 is in contact with the return ball raceway 440 and the load-bearing ball 300a at the same time, the first non-load-bearing ball 300b rotates clockwise under the drive of the load-bearing ball 300a, rolls into the return ball raceway 440, and drives other non-load-bearing balls located in the return ball raceway 440 to roll along the return ball raceway 440, thereby realizing the circulation of the balls. According to experimental measurements, due to the shielding effect of the tongue 420, the joint extrusion of the screw 100 and the nut 200 is avoided, and the maximum contact angle between the first non-load-bearing ball 300b and the return ball raceway 440 is much smaller than the self-locking angle, thereby effectively avoiding the one-way self-locking of the structure, making the movement of the ball between the screw 100 and the nut 200 smooth and stable.

[0052] In some embodiments, the tongue 420 is sufficiently rigid and has a lubricated outer surface, and the tongue 420 and the nut 200 can also be in sliding contact, thereby preventing the nut 200 from squeezing the tongue 420 and then squeezing the ball 300.

[0053] Continue to refer to Figure 4As shown, in some embodiments, the ball return groove 410 is recessed relative to the thread groove 110 of the lead screw 100 to reserve sufficient space for the balls to return. The ball return groove 410 and the thread groove 110 of the lead screw 100 are connected in a circular arc to prevent the first ball to enter the ball return groove 410 from getting stuck or wearing out. This design of the ball return groove 410, combined with the shielding effect of the tongue 420, can effectively ensure smooth rolling of the balls between the lead screw 100 and the nut 200, thereby improving the transmission stability and lifespan of the ball screw device.

[0054] Continue to combine Figures 3 to 5 As shown, in some embodiments, the bead return device 400 is integrally formed with or separately formed from the thread groove 110 of the lead screw 100. Considering factors such as processing cost, demoulding convenience, and number of parts, the bead return device 400 can be designed to be integrally formed with or separately formed from the thread groove 110 of the lead screw 100.

[0055] Figure 6 The structure of the ball screw device is shown in figure. Figure 7 The structure of the ball return part of the ball screw device is shown in figure. Figures 3 to 7 As shown:

[0056] In some embodiments, when the bead return device 400 and the thread groove 110 of the screw 100 are formed separately, the bead return device 400 includes: a groove platform 460, connecting the downstream side and the upstream side of the thread groove 110 of the screw 100; a bead return component 470, installed on the groove platform 460, and the bead return component 470 is provided with a bead return groove 410 and a tongue 420.

[0057] The groove platform 460 and the thread groove 110 of the lead screw 100 are integrally formed, and the ball return member 470 and the groove platform 460 are separately formed so as to process the structure of the ball return groove 410 and the structure of the retaining tongue 420.

[0058] In some embodiments, the bead return member 470 is a unitary member; alternatively, the bead return member 470 is formed by assembling a pair of separate members 470 ′.

[0059] The bead return member 470 can be designed as an integral component or a split component for ease of assembly and demolding. When the bead return member 470 is assembled from a pair of split components 470', each split component 470' is provided with half a bead return groove and half a retaining tongue, which facilitates demolding.

[0060] In some embodiments, the bead 470 is fixed to the slot platform 460 by screwing, riveting, welding, or interference fit. For example, the slot platform 460 and the bead 470 are provided with matching screw holes 480, and the bead 470 is screwed to the slot platform 460 by screws 190, but the present invention is not limited thereto.

[0061] In some embodiments, the tongue 420 and the bead return groove 410 are integrally formed or separately formed. Considering factors such as assembly convenience and demoulding convenience, the tongue 420 and the bead return groove 410 can be designed as an integral component or a separate component.

[0062] In the accompanying drawings of the present invention, Figure 7 As shown, the bead return member 470 is assembled by a pair of split components 470', each split component 470' is configured to assemble a groove portion 410' (i.e., half of the bead return groove) to form the bead return groove 410 and a tongue portion 420' (i.e., half of the tongue) to form the tongue 420, and the tongue portion 420' and the groove portion 410' are integrally formed, but not limited to this.

[0063] Continue to combine Figures 3 to 7 As shown, in some embodiments, the bead return device 400 is made of metal or plastic. Specifically, the bead return device 400 can be made of a suitable material based on factors such as cost, structural strength, and processing convenience.

[0064] In some embodiments, the bead return devices 400 are staggered or concentrated in the circumferential direction. According to design requirements, the bead return devices 400 can be evenly or unevenly distributed in the circumferential direction.

[0065] The present invention also provides an electronic mechanical brake equipped with a ball screw assembly as described in any of the above embodiments. The ball screw assembly comprises a ball return groove 410 and a retaining tongue 420, which cooperate to define a ball return track 440. The ball return track 440 does not contact the nut 200. This prevents the screw 100 and nut 200 from jointly squeezing the balls 300 during the ball return process, thereby preventing frictional self-locking caused by the balls 300 being stuck during the ball return process. This effectively solves the problem of the balls 300 becoming stuck during the ball return process, ensuring smooth and stable operation of the ball screw assembly, and thereby improving the stability and braking performance of the electronic mechanical brake.

[0066] The ball screw device of the present invention can also be applied to other mechanical transmission products, not just electronic mechanical brakes. Utilizing the ball screw device of the present invention, the tongue 420 cooperates with the ball return groove 410 to define a ball return track 440, effectively preventing the balls 300 from being squeezed by the screw 100 and nut 200 during their return, causing frictional self-locking. This, in turn, prevents problems such as ball screw device jamming, reduced efficiency, and abnormal wear, thereby improving the transmission stability and lifespan of the ball screw device and enhancing the stability and transmission performance of the products to which the ball screw device is applied.

[0067] The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention cannot be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A ball screw device comprising a screw, a nut threadedly engaged with the screw, and a ball positioned between the screw and the nut; It is characterized by: The ball screw device further comprises at least one ball return device provided on the screw, wherein each ball return device comprises: a ball return groove connecting the downstream side and the upstream side of the thread groove of the lead screw to form a ball circulation track that returns from the downstream side to the upstream side through the ball return groove; A retaining tongue is connected to the ball return groove, and the inner surface of the retaining tongue and the ball return groove jointly define a ball return raceway.

2. The ball screw device according to claim 1, wherein: The outer surface of the tongue is in clearance fit with the nut; As the ball screw device operates, the balls located in the threaded groove of the screw are squeezed by the nut and the screw to form load-bearing balls, and the balls located in the return ball raceway do not contact the nut to form non-load-bearing balls. The load-bearing balls drive the non-load-bearing balls in and out of the return ball raceway.

3. The ball screw device according to claim 1, wherein: The ball return groove is recessed relative to the thread groove of the lead screw and is transitionally connected to the thread groove of the lead screw in a circular arc.

4. The ball screw device according to claim 1, wherein: The bead return device and the thread groove of the lead screw are integrally formed or separately formed.

5. The ball screw device according to claim 4, wherein: In the case where the bead return device and the thread groove of the lead screw are formed separately, the bead return device includes: a groove platform connecting the downstream side and the upstream side of the thread groove of the lead screw; The bead return piece is installed on the groove platform, and the bead return piece is provided with the bead return groove and the blocking tongue.

6. The ball screw device according to claim 5, wherein: The bead return piece is an integral component, or the bead return piece is formed by assembling a pair of split components.

7. The ball screw device according to claim 5, wherein: The return bead piece is fixed on the groove platform by screwing, riveting, welding or interference fitting.

8. The ball screw device according to claim 1, wherein: The retaining tongue and the ball return groove are integrally formed or separately formed.

9. The ball screw device according to claim 1, wherein: The bead return device is made of metal or plastic.

10. The ball screw device according to any one of claims 1 to 9, characterized in that: The at least one bead return device is staggered or concentrated in the circumferential direction.

11. An electromechanical brake, characterized in that: The electromechanical brake is equipped with a ball screw device according to any one of claims 1 to 10.

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