Planetary roller screw with concave-convex contact point contact

Abstract

The invention relates to a planetary roller screw with contact of concave and convex contact points, and relates to the technical field of planetary roller screws. A roller working tooth profile of the planetary roller lead screw adopts a convex arc tooth profile, a lead screw working tooth profile of the planetary roller lead screw adopts a concave arc tooth profile, and a nut working tooth profile of the planetary roller lead screw adopts a concave arc tooth profile; in the movement process of the planetary roller screw, the roller convex tooth profile surface is in contact with the screw concave tooth profile surface and the nut concave tooth profile surface, the convex tooth profile surface is a working tooth profile surface formed by a convex arc tooth profile curve section, and the concave tooth profile surface is a working tooth profile surface formed by a concave arc tooth profile curve section. The lubricating device has the characteristics of high contact strength, large bearing capacity, high transmission efficiency and good lubricating effect.

Description

Technical Field

[0001] The invention relates to the technical field of planetary roller screws, in particular to a planetary roller screw with concave and convex contact points. Background Art

[0002] In the roller screw transmission process, the plane profile has many thread contact points, but it cannot guarantee that the diameter at the contact point between the roller and the thread (nut) remains constant. In order to obtain accurate lead, the stability and accuracy of the thread contact point must be guaranteed, and at least one of the thread tooth profiles of the roller and the screw (nut) should be a curved surface. In previous designs, the screw and the nut are triangular threads with the same number of heads. For this type of planetary roller screw, the radius of curvature of the arc is fixed for the thread teeth, but according to Hertz contact theory, the contact of this planetary roller screw pair can be regarded as convex contact, which will result in a large contact stress at the meshing point, thereby reducing its load-bearing capacity.

[0003] Therefore, how to provide a planetary roller screw with concave and convex contact points with high contact strength and large load-bearing capacity has become a technical problem that technical personnel in this field need to solve urgently. Summary of the invention

[0004] In order to solve at least one technical problem in the background technology, the present invention provides a planetary roller screw with concave and convex contact points, which has the characteristics of high contact strength, large load-bearing capacity, high transmission efficiency and good lubrication effect.

[0005] To achieve the above-mentioned purpose, the present invention provides a planetary roller screw with concave-convex contact points, wherein the roller working tooth profile of the planetary roller screw adopts a convex arc tooth profile, the screw working tooth profile of the planetary roller screw adopts a concave arc tooth profile, and the nut working tooth profile of the planetary roller screw adopts a concave arc tooth profile;

[0006] During the movement of the planetary roller screw, the convex tooth profile surface of the roller contacts the concave tooth profile surface of the screw and the concave tooth profile surface of the nut respectively, the convex tooth profile surface is a working tooth profile surface formed by a convex circular arc tooth profile curve segment, and the concave tooth profile surface is a working tooth profile surface formed by a concave circular arc tooth profile curve segment.

[0007] Furthermore, the center of the convex circular arc tooth profile curve segment is set below the median diameter line, and the center of the concave circular arc tooth profile curve segment is set below the median diameter line.

[0008] Furthermore, the equation C1 of the convex arc tooth profile curve segment and the equation C2 of the concave arc tooth profile curve segment are respectively:

[0009]

[0010] Among them, r s is the coordinate vector of the tooth profile curve, x sis the projection of the coordinate vector on the x-axis, y s is the projection of the coordinate vector on the y-axis, z s is the projection of the coordinate vector on the z-axis, ρ and ρ f are the arc radii of curve segments C1 and C2 respectively; α is the independent variable parameter of the curve segment; at z s In the formula, the upper symbol in “±” represents the left dental profile curve segment, and the lower symbol represents the right dental profile curve segment; (l,e) and (l f ,e f ) are the coordinates of the centers of the curve segments C1 and C2 respectively; wa and wf are the tooth widths of the roller and the screw nut respectively.

[0011] Furthermore, the equation Σ of the working tooth profile surface is:

[0012]

[0013] Among them, r i is the coordinate vector of the roller, nut or screw tooth profile curve, x i is the projection of the coordinate vector of the roller, nut or screw tooth profile curve in the x-axis direction, y i is the projection of the coordinate vector of the roller, nut or screw tooth profile curve in the y-axis direction, z i is the projection of the coordinate vector of the roller or nut or screw tooth profile curve in the z-axis direction, d is the mean diameter of the roller or nut or screw; φ is the rotation angle of the roller or nut or screw; when i=1, the expression is the equation of the roller working tooth profile surface formed by the convex circular arc tooth profile curve segment; when i=2, the expression is the equation of the screw working tooth profile surface formed by the concave circular arc tooth profile curve segment; when i=3, the expression is the equation of the nut working tooth profile surface formed by the concave circular arc tooth profile curve segment.

[0014] The beneficial effects of the present invention are:

[0015] The circular arc concave-convex point contact planetary roller screw of the present invention has concave-convex point contact when in motion, which reduces the average load at each point. The screw has high contact strength, large load-bearing capacity, high transmission efficiency and good lubrication effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic structural diagram of the planetary roller screw of the present invention;

[0017] Figure 2 It is a schematic diagram of the tooth profile of the roller and the nut or the lead screw of the present invention.

[0018] Among them, in the figure: 1-convex arc tooth profile; 2-concave arc tooth profile; 3-roller convex tooth profile surface; 4-screw concave tooth profile surface; 5-nut concave tooth profile surface. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0021] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0022] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0023] In addition, the terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0024] To achieve the above purpose, Figure 1-2As shown, the present invention provides a planetary roller screw with concave-convex contact points, the roller working tooth profile of the planetary roller screw adopts a convex arc tooth profile, the screw working tooth profile of the planetary roller screw adopts a concave arc tooth profile, and the nut working tooth profile of the planetary roller screw adopts a concave arc tooth profile;

[0025] During the movement of the planetary roller screw, the roller convex tooth profile surface contacts the screw concave tooth profile surface and the nut concave tooth profile surface respectively, the convex tooth profile surface is a working tooth profile surface formed by a convex circular tooth profile curve segment, and the concave tooth profile surface is a working tooth profile surface formed by a concave circular tooth profile curve segment. The tooth profile of the concave-convex contact gear is designed to be concave-convex meshing. This design makes the gear have a load-bearing capacity of about 1.5 to 2 times that of the involute gear under the same size and material.

[0026] To further optimize the technical solution, the center of the convex circular arc tooth profile curve segment is set below the median diameter line, and the center of the concave circular arc tooth profile curve segment is set below the median diameter line.

[0027] To further optimize the technical solution, the equation C1 of the convex arc tooth profile curve segment and the equation C2 of the concave arc tooth profile curve segment are respectively:

[0028]

[0029] Among them, r s is the coordinate vector of the tooth profile curve, x s is the projection of the coordinate vector on the x-axis, y s is the projection of the coordinate vector on the y-axis, z s is the projection of the coordinate vector on the z-axis, ρ and ρ f are the arc radii of curve segments C1 and C2 respectively; α is the independent variable parameter of the curve segment; at z s In the formula, the upper symbol in “±” represents the left dental profile curve segment, and the lower symbol represents the right dental profile curve segment; (l,e) and (l f ,e f ) are the coordinates of the centers of the curve segments C1 and C2 respectively; wa and wf are the tooth widths of the roller and the screw nut respectively.

[0030] To further optimize the technical solution, the equation Σ of the working tooth profile surface is:

[0031]

[0032] Among them, r i is the coordinate vector of the roller, nut or screw tooth profile curve, x i is the projection of the coordinate vector of the roller, nut or screw tooth profile curve in the x-axis direction, y i is the projection of the coordinate vector of the roller, nut or screw tooth profile curve in the y-axis direction, zi is the projection of the coordinate vector of the roller or nut or screw tooth profile curve in the z-axis direction, d is the mean diameter of the roller or nut or screw; φ is the rotation angle of the roller or nut or screw; when i=1, the expression is the equation of the roller working tooth profile surface formed by the convex circular arc tooth profile curve segment; when i=2, the expression is the equation of the screw working tooth profile surface formed by the concave circular arc tooth profile curve segment; when i=3, the expression is the equation of the nut working tooth profile surface formed by the concave circular arc tooth profile curve segment.

[0033] When the planetary roller screw of the present invention is working, the convex arc of the roller and the concave arc of the screw and the nut are in concave-convex point contact, and the concave-convex contact can reduce the contact stress of the screw, nut and roller at the contact point, and has the characteristics of high contact strength, large load-bearing capacity, high transmission efficiency and good lubrication effect. The concave-convex contact of the present invention can reduce the contact stress, thereby improving its load-bearing capacity, and fundamentally solves the problem that the contact of the planetary roller screw pair is convex-flat contact, which will cause the contact stress at the meshing point position to be large, thereby causing its load-bearing capacity to decrease.

[0034] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A planetary roller screw with concave and convex contact points, characterized in that: The roller working tooth profile of the planetary roller screw adopts a convex arc tooth profile, the screw working tooth profile of the planetary roller screw adopts a concave arc tooth profile, and the nut working tooth profile of the planetary roller screw adopts a concave arc tooth profile; During the movement of the planetary roller screw, the convex tooth profile surface of the roller contacts the concave tooth profile surface of the screw and the concave tooth profile surface of the nut respectively, the convex tooth profile surface is a working tooth profile surface formed by a convex circular arc tooth profile curve segment, and the concave tooth profile surface is a working tooth profile surface formed by a concave circular arc tooth profile curve segment.

2. A planetary roller screw with concave-convex contact points according to claim 1, characterized in that: The center of the convex circular arc tooth profile curve segment is set below the median diameter line, and the center of the concave circular arc tooth profile curve segment is set below the median diameter line.

3. A planetary roller screw with concave-convex contact points according to claim 1 or 2, characterized in that: The equations C1 and C2 of the convex arc tooth profile curve segment and the concave arc tooth profile curve segment are respectively: Among them, r s is the coordinate vector of the tooth profile curve, x s is the projection of the coordinate vector on the x-axis, y s is the projection of the coordinate vector on the y-axis, z s is the projection of the coordinate vector on the z-axis, ρ and ρ f are the arc radii of curve segments C1 and C2 respectively; α is the independent variable parameter of the curve segment; at z s In the formula, the upper symbol in "±" represents the left dental profile curve segment, and the lower symbol represents the right dental profile curve segment; (l,e) and (l f ,e f ) are the coordinates of the centers of the curve segments C1 and C2 respectively; wa and wf are the tooth widths of the roller and the screw nut respectively.

4. A planetary roller screw with concave-convex contact points according to claim 3, characterized in that: The equation of the working tooth profile Σ is: Among them, r i is the coordinate vector of the roller, nut or screw tooth profile curve, x i is the projection of the coordinate vector of the roller, nut or screw tooth profile curve in the x-axis direction, y i is the projection of the coordinate vector of the roller, nut or screw tooth profile curve in the y-axis direction, z i is the projection of the coordinate vector of the roller or nut or screw tooth profile curve in the z-axis direction, d is the mean diameter of the roller or nut or screw; φ is the rotation angle of the roller or nut or screw; when i=1, the expression is the equation of the roller working tooth profile surface formed by the convex circular arc tooth profile curve segment; when i=2, the expression is the equation of the screw working tooth profile surface formed by the concave circular arc tooth profile curve segment; when i=3, the expression is the equation of the nut working tooth profile surface formed by the concave circular arc tooth profile curve segment.

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