Internal circulation lead screw nut structure and transmission system

Abstract

The utility model discloses an internal circulation lead screw nut structure and transmission system, including ball screw, lead screw nut and steel ball, ball screw peripheral surface is equipped with the spiral outer channel, the inner surface of lead screw nut is equipped with the spiral inner channel, the steel ball is equipped with the spiral outer channel. The outer channel and the inner channel are matched to form a working raceway for the steel balls to roll, four ball return channels are evenly distributed in the screw nut in the radial direction, and two ports of each ball return channel are in butt joint with the corresponding inner channel to form a closed loop. And two end openings of the four ball return channels span the crests of the two corresponding adjacent outer channels. Internal circulation of steel balls of the ball screw is completed without relying on a reverser, the NVH performance of an internal circulation ball screw assembly of the electric power steering gear is improved, the arrangement mode of a ball return raceway is changed, the bearing capacity of the screw nut is optimized, and cost is saved.

Description

Technical Field

[0001] The utility model relates to the technical field of ball screws, in particular to an internal circulation screw nut structure and a transmission system. Background Art

[0002] With the widespread use of R-EPS electric power steering in the steering field, internal circulation ball screw assemblies are increasingly used in the steering field. The ball screw assembly is used to transmit and bear the rack force. The traditional internal circulation ball screw nut controls the return of the steel ball through a metal / plastic reverser. There will inevitably be steps at the transition position between the ball return channel carried by the reverser and the screw nut. The steel ball needs to cross the steps in the process of returning the ball through the reverser. In the process of returning the ball, the noise generated by the collision and friction between the steel ball and the raceway, the steel ball and the steel ball, and the steel ball and the reverser will be directly transmitted to the driving seat, seriously affecting the driving experience. According to analysis, when the steel ball passes through reversers made of different materials, the metal reverser will be better than the plastic reverser in terms of noise generation. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide an internal circulation screw nut structure, which completes the internal circulation of the ball screw steel ball without relying on a reverser, improves the NVH performance of the internal circulation ball screw assembly of the electric power steering gear, changes the arrangement of the return ball raceway to optimize the bearing capacity of the screw nut, and saves costs.

[0004] The utility model provides a technical solution to the above-mentioned technical problems as follows: an internal circulation lead screw nut structure, comprising a ball screw, a lead screw nut and a steel ball, the outer peripheral surface of the ball screw being provided with a spiral outer groove, the inner surface of the lead screw nut being provided with a spiral inner groove, the outer groove cooperating with the inner groove forming a working raceway for the steel ball to roll, four ball return grooves being evenly distributed radially inside the lead screw nut, the two ends of the four ball return grooves being respectively connected with the corresponding inner grooves to form a closed loop, the two ends of the four ball return grooves spanning the tooth tops of the corresponding two adjacent outer grooves.

[0005] The beneficial effects of adopting the above technical solution are:

[0006] The ball of the ball screw is not required to be circulated internally, which improves the NVH performance of the internal circulation ball screw assembly of the electric power steering gear. The arrangement of the ball return raceway is changed to optimize the bearing capacity of the screw nut and save costs.

[0007] On the basis of the above technical solution, the present invention can also be improved as follows.

[0008] Furthermore, the ball return channel is S-shaped.

[0009] The beneficial effect of adopting the above further solution is that it can be docked with the inner channel in the screw nut to form a closed loop.

[0010] Furthermore, the ball-returning channel includes two variable diameter channels and a maximum diameter channel, wherein the small diameter end of one of the variable diameter channels is connected to one end of the inner channel, and the large diameter end thereof is connected to one end of the maximum diameter channel, the other end of the maximum diameter channel is connected to the large diameter end of another variable diameter channel, and the small diameter end of another variable diameter channel is connected to the other end of the inner channel.

[0011] The beneficial effect of adopting the above further solution is to ensure that there is no jamming or abnormal sound during the ball return process.

[0012] Furthermore, the maximum diameter groove is 0.1-0.2 mm larger than the diameter of the working raceway.

[0013] The beneficial effect of adopting the above further solution is smooth transition.

[0014] Furthermore, both sides of the variable diameter channel are inclined by 10-15 degrees in the vertical direction.

[0015] The beneficial effect of adopting the above further solution is that it is easy to process the variable diameter groove.

[0016] Furthermore, one end of the screw nut is provided with a bearing for connecting to an external device.

[0017] The beneficial effect of adopting the above further solution is that it is convenient to install other equipment.

[0018] The utility model also provides a transmission system, comprising the internal circulation screw rod and nut structure as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural sectional view of the utility model;

[0020] Figure 2 This is a schematic diagram of the installation position of the ball return channel;

[0021] Figure 3 It is the plane diagram of the ball return curve XOZ;

[0022] Figure 4 It is the XOY plane diagram of the ball return curve;

[0023] Figure 5 It is a normal cross-sectional view of the ball return channel at point C of the utility model;

[0024] Figure 6 This is a position distribution diagram of the ball return channel of the utility model;

[0025] Figure 7 It is a structural schematic diagram of the prior art;

[0026] Figure 8 This is a distribution diagram of the inverter positions in the prior art.

[0027] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0028] 1. Ball screw; 2. Screw nut; 3. Steel ball; 4. Bearing; 5. Return ball groove; 6. Working raceway; 7. Reverser mounting hole. DETAILED DESCRIPTION

[0029] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0030] Further, if Figure 7-8 As shown, the prior art is to return the ball through a reverser. A reverser connected to the adjacent raceway is installed in the reverser mounting hole 7 on the side of the nut. The reverser is used to guide the ball to pass over the spiral top of the screw rod and enter the adjacent raceway to form a circulation loop. Generally, four reversers for balls are installed on the same nut and are evenly distributed at intervals of 120° on the XOZ plane along the circumference of the nut. The disadvantages are as follows:

[0031] 1) When the steel ball enters the reverser from the lead screw nut and enters the lead screw nut from the reverser return ball raceway, it passes through the steps, which will produce noise and slight jamming, affecting the performance of the electric power steering assembly.

[0032] 2) The noise generated when the steel ball passes through the reverser of different materials is different. The noise generated when passing through the reverser is one of the main noise sources of the ball screw assembly.

[0033] 3) In order to shorten the length of the screw nut, the reverser is generally evenly distributed at 120° on the XOZ plane, so the load-bearing capacity of the ball screw is not evenly distributed, and the center of gravity is not on the screw axis.

[0034] Embodiment 1:

[0035] like Figure 1-6 As shown, in the present embodiment, an internal circulation screw nut structure includes a ball screw 1, a screw nut 2 and a steel ball 3. The outer peripheral surface of the ball screw 1 is provided with a spiral outer groove, and the inner surface of the screw nut 2 is provided with a spiral inner groove. The outer groove cooperates with the inner groove to form a working raceway 6 for the steel ball 3 to roll. Four ball return grooves 5 are evenly distributed radially in the screw nut 2, and the two ends of the four ball return grooves 5 are respectively connected with the corresponding inner grooves to form a closed loop, and the two ends of the four ball return grooves 5 span the tooth tops of the corresponding two adjacent outer grooves.

[0036] The beneficial effects of this embodiment are: the internal circulation of the ball screw steel ball is completed without relying on the reverser, the NVH performance of the internal circulation ball screw assembly of the electric power steering is improved, the arrangement of the return ball raceway 5 is changed to optimize the bearing capacity of the screw nut, and the cost is saved.

[0037] Further, if Figure 1 As shown, the screw nut 2 and the ball return channel 5 can be integrally formed.

[0038] Example 2

[0039] Preferably, based on Example 1, the ball return channel 5 is S-shaped.

[0040] The beneficial effect of this embodiment is that it can dock with the inner channel in the screw nut 2 to form a closed loop.

[0041] Example 3

[0042] Preferably, on the basis of Example 2, the ball-returning groove 5 includes two variable diameter grooves and a maximum diameter groove, wherein the small diameter end of one of the variable diameter grooves is connected to one end of the inner groove, and the large diameter end thereof is connected to one end of the maximum diameter groove, and the other end of the maximum diameter groove is connected to the large diameter end of another variable diameter groove, and the small diameter end of another variable diameter groove is connected to the other end of the inner groove.

[0043] The beneficial effect of this embodiment is: ensuring that there is no stagnation or abnormal sound during the ball return process.

[0044] It should be noted that the diameter of the large diameter end of the variable diameter channel is equal to the diameter of the maximum diameter channel.

[0045] Example 4

[0046] Preferably, based on Embodiment 3, the maximum diameter groove is 0.1-0.2 mm larger than the diameter of the working raceway 6 .

[0047] The beneficial effect of this embodiment is: smooth transition.

[0048] Example 5

[0049] Preferably, based on Embodiment 3-4, both sides of the variable diameter channel are inclined by 10-15 degrees in the vertical direction.

[0050] The beneficial effect of this embodiment is that it is easy to process the variable diameter groove.

[0051] Further, if Figure 5 As shown, both sides of the variable diameter channel are inclined 10° along the vertical direction.

[0052] Example 6

[0053] Preferably, on the basis of embodiments 1-5, one end of the screw nut 2 is provided with a bearing 4 for connecting to an external device.

[0054] The beneficial effect of this embodiment is that it is convenient to install other equipment.

[0055] Example 7

[0056] Preferably, based on Examples 1-6, a transmission system includes the internal circulation screw nut structure as described above.

[0057] The beneficial effects of this embodiment are: good transmission effect, low noise, and easy manufacturing.

[0058] It should be noted that 1) the inner ring of the screw nut 2 along the inner circulation curve of the steel ball 3 ( Figure 3 and Figure 4 ) The groove is processed, the curve of the steel ball return channel 4 is a quintic parabola equation, the return ball working diameter is φ22mm, the ball diameter of the steel ball 3 is φ5.556mm, and the contact angle is 42°. 2) The ball return channel of the screw nut 2 is a variable diameter channel from the starting point A to the transition end point B, and is the maximum diameter channel from the transition end point B to the return ball center C. The maximum diameter of the ball return channel 5 is 0.1-0.2mm larger than the working channel diameter, and the variable diameter channel has a smooth transition to ensure that there is no jamming or abnormal noise during the ball return process. 3) Taking into account the feasibility of raceway processing, in order to reduce the difficulty of tool processing, the closer the ball return channel of the screw nut is to the center groove, the deeper it is. The ball return channel is as follows Figure 5 The two sides of the raceway are tilted outwards by 10-15° for easy processing. 4) The lead of the ball screw is 8mm, and the raceway of the screw nut is as follows Figure 6 As shown from right to left, the center of the second raceway ball return groove rotates 180° in the CW direction (clockwise) of the first raceway, offset by 1.5 times the lead, the third raceway rotates 90° clockwise compared to the first raceway, the ball return center offset by 2.75 times the lead, the fourth raceway rotates 90° counterclockwise compared to the first raceway, and the ball return center offset by 4.25 times the lead. The raceway is arranged as close to one side of the bearing as possible to reduce the overall length and save materials.

[0059] The beneficial effects of the utility model are:

[0060] 1) Optimize the screw nut structure, complete the internal circulation of the ball screw without relying on the reverser, and improve the NVH performance of the internal circulation ball screw assembly of the electric power steering gear.

[0061] 2) Optimize the bearing capacity of the screw nut by changing the arrangement of the ball return track.

[0062] 3) By optimizing the screw nut structure, materials and processes can be saved and economy can be improved.

[0063] In the description of the present invention, it should be understood that the terms "center", "length", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "inside", "outside", "peripheral", "circumferential" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred system or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0064] In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0065] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0066] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An internal circulation lead screw nut structure, characterized in that: The invention comprises a ball screw (1), a screw nut (2) and a steel ball (3); the outer peripheral surface of the ball screw (1) is provided with a spiral outer groove; the inner surface of the screw nut (2) is provided with a spiral inner groove; the outer groove cooperates with the inner groove to form a working raceway (6) for the steel ball (3) to roll; four ball return grooves (5) are evenly distributed radially inside the screw nut (2); two ends of the four ball return grooves (5) are respectively connected with the corresponding inner grooves to form a closed loop; the two ends of the four ball return grooves (5) span the tooth tops of the corresponding two adjacent outer grooves.

2. An internal circulation lead screw nut structure according to claim 1, characterized in that: The ball return channel (5) is S-shaped.

3. An internal circulation lead screw nut structure according to claim 2, characterized in that: The ball return channel (5) comprises two variable diameter channels and a maximum diameter channel, wherein the small diameter end of one of the variable diameter channels is connected to one end of the inner channel, and the large diameter end thereof is connected to one end of the maximum diameter channel, the other end of the maximum diameter channel is connected to the large diameter end of another variable diameter channel, and the small diameter end of another variable diameter channel is connected to the other end of the inner channel.

4. An internal circulation lead screw nut structure according to claim 3, characterized in that: The maximum diameter groove is 0.1-0.2 mm larger than the diameter of the working raceway (6).

5. The internal circulation lead screw nut structure according to claim 3, characterized in that: Both sides of the variable diameter channel are inclined by 10-15 degrees in the vertical direction.

6. An internal circulation lead screw nut structure according to any one of claims 1 to 5, characterized in that: One end of the screw nut (2) is provided with a bearing (4) for connecting to an external device.

7. A transmission system, characterized in that: It comprises an internal circulation lead screw nut structure as described in any one of claims 1 to 5.

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