Electric steering gear with roller screw assembly

Abstract

The invention relates to an electric steering gear with a roller screw assembly. Comprising a shell, the two ends of the shell are detachably connected with a bottom cover and an upper cover respectively, bearings are installed in the bottom cover and the upper cover, and the two ends of a roller lead screw assembly are installed between the bottom cover and the upper cover through the bearings. The roller lead screw assembly is composed of a lead screw, a nut and a flat key, the nut is in threaded connection with the lead screw, a key groove is formed in the periphery of the nut, the flat key is arranged in the key groove, the roller lead screw assembly is inserted into an inner hole of the rack piston, the outer portion of the flat key is arranged in the key groove of the rack piston, the lead screw is sleeved with the locking nut, and the locking nut is arranged in the inner hole of the rack piston. And the locking nut is in threaded and glue locking connection with the rack piston. And the rocker arm shaft is meshed with the rack piston. According to the invention, the structure is simple, the output torque is large, safety and reliability are realized, the manufacturability of part processing is strong, the assembly method is simple, the adaptability of vehicle selection and assembly is improved, and the requirements of different vehicle types are widely met.

Description

Technical Field

[0001] The invention relates to an electric steering gear in the technical field of automobiles, in particular to an electric steering gear with a roller screw assembly. Background Art

[0002] With the gradual promotion of new energy vehicles, the integral recirculating ball electric steering gear has been widely used in various commercial vehicles. The existing structure has the following shortcomings during product assembly and use: 1. The existing electric steering gear screw adopts a recirculating ball structure, and the output torque of the assembly is only 1500-1800N.m, and the instantaneous output can only reach 2000N.m; 2. The bearings at both ends of the screw use thrust angular contact ball bearings with a rated load of less than 70KN; 3. The screw in the steering gear and the output shaft in the reducer are made into an integral type, which is complex and inefficient during the parts processing process; the components and assembly are large in size, heavy in weight, and inconvenient to operate during assembly. Due to its shortcomings such as small output torque, weak load-bearing capacity, large in size, and heavy in weight, it has limitations in the use of medium and heavy commercial vehicles and passenger cars with a load of more than 2000N.m. Therefore, according to market demand, we developed this electric steering gear assembly with a roller screw assembly to fill the market gap. Summary of the invention

[0003] The object of the present invention is to provide an electric steering gear with a roller screw assembly, which has a simple structure, strong adaptability, large output torque, and is safer and more reliable.

[0004] The technical solution of the present invention: An electric steering gear with a roller screw assembly comprises a housing, a bottom cover, an upper cover, a roller screw assembly, a rack piston, a locking nut, a bearing and a rocker shaft; The two ends of the housing are respectively connected to the bottom cover and the upper cover in a detachable manner, the bottom cover and the upper cover are provided with bearings, and the two ends of the roller screw are installed between the bottom cover and the upper cover through the bearings; The roller screw is composed of a screw rod, a nut and a flat key. The screw rod is threadedly connected with a nut, a keyway is opened on the outer periphery of the nut, and the flat key is placed in the keyway. The roller screw assembly is inserted into the inner hole of the rack piston, and the outer part of the flat key is placed in the keyway of the rack piston. The locking nut is sleeved on the screw rod and placed in the inner hole of the rack piston. The locking nut and the rack piston are locked and connected by threads and glue. The rocker arm shaft is meshed with the rack piston.

[0005] Beneficial effects of the present invention: 1. The steering gear of the present invention has a simple structure, large output torque, safety and reliability, strong processability of parts processing, and a simple assembly method, which improves the adaptability of vehicle selection and widely meets the needs of different models.

[0006] 2. The steering gear of the present invention adopts a roller screw assembly structure, and the rack piston is connected to the roller screw assembly through a flat key. Because the bearing capacity of the ball screw assembly is strong, this product can provide a large output torque, ultimately meeting the needs of medium and heavy commercial vehicles and passenger cars above 2 tons.

[0007] 3. The steering gear assembly of the present invention adopts a split design, which is small in size and light in weight. The output shaft in the reducer is processed with an internal spline, which matches with the external spline of the screw rod of the roller screw assembly to transmit force and torque; the bottom of the housing in the reducer is processed with an inner hole, which matches with the stopper of the outer circle of the steering gear housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0009] Figure 1 This is a schematic diagram of the structure of an electric steering gear with a roller screw assembly for this application.

[0010] Figure 2 This is a schematic diagram of the roller screw assembly and rack piston assembly of the steering gear of this application.

[0011] Figure 3 This is a schematic diagram of a double-row tapered roller bearing in the product of this application.

[0012] Figure 4 This is a schematic diagram of the reducer structure used in the steering gear assembly of this application.

[0013] Figure 5 This is a schematic diagram of the assembly of the steering gear and reducer for this application.

[0014] Reference numerals: Housing 1, bottom cover 2, bearing 3, roller screw assembly 4, locking nut 5, rack piston 6, upper cover 7, dustproof oil seal 8, anti-loosening nut 9, rocker shaft 10, oil filling hole 11, stopper 12, oil drain hole 21, O-ring 22, flange bolt 23, outer ring 31, tapered roller 32, inner ring 33, screw 41, nut 42, flat key 43, electric steering gear 100 with roller screw assembly, reducer 200, input shaft 201, output shaft spline hole 202, inner hole 203, positioning optical axis 411, threaded screw 412, transition shaft 413, spline shaft 414. Specific implementation plan

[0015] In order to solve the problems in the background technology, an electric steering gear with a roller screw assembly is invented.

[0016] It should be noted that the specific embodiments described herein are only used to explain the relevant inventions, rather than to limit the invention. It should also be noted that, for the convenience of description, only the parts related to the invention are shown in the drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. Unless otherwise clearly specified and limited, the terms "install", "connect", "press-fit", and "connect" should be understood in a broad sense. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood in specific circumstances. Multiple technical solutions in the same embodiment, as well as multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions that do not have contradictions or conflicts, all within the scope of protection required by the present invention.

[0017] An electric steering gear with a roller screw assembly comprises a housing, a bottom cover, an upper cover, a roller screw assembly, a rack piston, a locking nut, a bearing and a rocker shaft. The bearing is a single-row tapered roller bearing or a double-row tapered roller bearing. The two ends of the housing are respectively connected to the bottom cover and the upper cover in a detachable manner, and the bottom cover and the upper cover are provided with bearings. The two ends of the roller screw assembly are installed between the bottom cover and the upper cover through bearings. The roller screw assembly consists of a screw rod, a nut and a flat key. The screw rod is threadedly connected with a nut, and a keyway is provided on the outer periphery of the nut. The flat key is placed in the keyway. The roller screw assembly is inserted into the inner hole of the rack piston, and the outer part of the flat key is placed in the keyway of the rack piston. The locking nut is sleeved on the screw rod and placed in the inner hole of the rack piston. The locking nut is locked and connected to the rack piston by threads and glue. The rocker shaft is meshed with the rack piston.

[0018] The connection between the locking nut and the rack piston is as follows: The locking nut has an external thread, the rack piston has an internal thread, the locking nut is threadedly connected to the rack piston, and glue is applied at the threaded connection between the locking nut and the rack piston so that the locking nut and the rack piston are glue-locked and connected, and the inner side of the locking nut fits with the nut.

[0019] The application is described in detail below with reference to the accompanying drawings: like Figure 1 , 2As shown, the electric steering gear with roller screw assembly of the present application mainly includes housing 1, bottom cover 2, double-row tapered roller bearing (referred to as: bearing 3), roller screw assembly 4, locking nut 5, rack piston 6, upper cover 7, dustproof oil seal 8, anti-loosening nut 9, rocker shaft 10, O-ring 22, flange bolt 23. The inner hole of the bottom cover 2 is pressed with bearing 3, the bottom is provided with oil drain hole 21, and the outer circle is provided with O-ring 22. The inner hole of the upper cover 7 is pressed with bearing 3 and dustproof oil seal 8, and O-ring 22 is installed between the outer circle of the upper cover and the housing. The flat key is placed in the keyway of the nut and the keyway of the rack piston. The roller screw assembly 4 is connected to the rack piston 6 through the flat key 43, and the rack piston and the nut of the roller screw assembly are connected into a whole by using the locking nut 5. The bottom cover and the housing are connected together by flange bolts 23; the roller screw assembly equipped with the rack piston is installed into the housing from the upper end; the upper end of the housing is processed with an internal thread, which is screwed and installed together with the external thread of the upper cover, and the upper cover is locked and fixed to the upper end of the housing by using a locking nut 9. A stopper is processed on the outer periphery of the housing at one end of the upper cover. The bearings pre-pressed in the bottom cover and the upper cover are arranged at both ends of the screw of the roller screw assembly respectively, which are used to limit the axial displacement of the screw and bear the axial and radial loads. An oil filling hole 11 is processed on the side of the housing. The rocker shaft is installed inside the housing and meshes with the rack piston.

[0020] like Figure 2 As shown, the roller screw assembly and the rack piston are assembled as shown, which are composed of a screw 41, a nut 42, and a flat key 43. The screw is spirally connected to the nut, and the flat key is installed in the keyway of the nut to assemble the roller screw assembly. The roller screw assembly is installed into the rack piston 6 from the left side (in the figure), and finally, after applying thread locking glue on the outer thread of the locking nut, it is screwed in from the left side of the rack piston and locked, and the nut is fixed in the inner hole of the rack piston. The nut, locking nut and rack piston are connected as a whole, so that the rack piston performs reciprocating linear motion on the screw.

[0021] like Figure 1 , 3 As shown in the figure, the double-row tapered roller bearings pre-pressed into the bottom cover and the upper cover are arranged at both ends of the screw of the roller screw assembly in the product assembly to limit the axial displacement of the screw and simultaneously bear the axial load in the direction of the screw axis and the radial load in the diameter direction of the bottom cover and the upper cover. Compared with traditional angular contact ball bearings, it has a greater load-bearing capacity. The double-row tapered roller bearing consists of an inner ring 33 with a conical ring groove, an outer ring 31 with a tapered surface, and a tapered roller 32 with a cage. The tapered roller with a cage is arranged between the inner ring and the outer ring. See Figure 2The screw 41 is composed of a positioning optical axis 411, a threaded screw 412, a positioning optical axis 411, a transition shaft 413 and a spline shaft 414. There is a shaft shoulder between the threaded screw and the positioning optical axis on one side, and a guide angle between the threaded screw and the positioning optical axis on the other side. The outer ring of the double-row tapered roller bearing is pressed into one piece with the inner hole of the upper cover or the bottom cover by interference fit. The inner ring and the positioning optical axis are made into a small gap or overfit, and are respectively installed into the positioning optical axis from both sides of the screw, and are matched with the inner ring through the shaft shoulder and the end face on the guide angle side to limit the displacement of the inner ring of the bearing.

[0022] An electric steering gear assembly includes a steering gear and a reducer 200. The reducer is a commonly used reducer in the prior art, and the reducer is driven by a motor. The steering gear is the electric steering gear 100 with a roller screw assembly as described above, and the screw rod of the electric steering gear 100 with a roller screw assembly extends out of the spline shaft 414 at one end of the upper cover and is matched with the inner spline hole 202 opened at the bottom of the output shaft of the reducer. The housing of the reducer is machined with an inner hole 203, and the outer circle of the upper cover end of the housing of the electric steering gear with a roller screw assembly is provided with a stopper 12, and the inner hole 203 and the stopper 12 are plugged and connected through flange bolts 23.

[0023] When in use, the spline shaft of the screw rod of the steering gear of the present application extends out of the upper cover and is connected to the spline hole of the output shaft of the reducer, and the input shaft 201 in the reducer is connected to the steering wheel of the vehicle. The bottom of the output shaft is processed with an internal spline, and the top of the screw rod is processed with an external spline. The internal and external splines cooperate to transmit force and torque. The present application separates the steering gear and the reducer of the existing steering gear assembly and connects them with splines. In the process of parts processing, the process is simple and efficient.

[0024] The above schematically describes the present invention and its implementation methods, which are not restrictive. The drawings show only one implementation method of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by it and does not deviate from the technical solution of the present invention, and designs a structure and implementation similar to the technical solution based on the above implementation examples without creativity according to the technical essence of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. An electric steering gear with a roller screw assembly, characterized in that: It includes a housing, a bottom cover, an upper cover, a roller screw assembly, a rack piston, a locking nut, a bearing and a rocker shaft; The two ends of the housing are respectively connected to the bottom cover and the upper cover in a detachable manner, the bottom cover and the upper cover are provided with bearings, and the two ends of the roller screw assembly are installed between the bottom cover and the upper cover through the bearings; The roller screw assembly is composed of a screw rod, a nut and a flat key. The screw rod is threadedly connected with a nut, a keyway is opened on the outer periphery of the nut, and the flat key is placed in the keyway. The roller screw assembly is inserted into the inner hole of the rack piston, and the outer part of the flat key is placed in the keyway of the rack piston. The locking nut is sleeved on the screw rod and placed in the inner hole of the rack piston. The locking nut and the rack piston are locked and connected by threads and glue. The rocker arm shaft is meshed with the rack piston.

2. The electric steering gear with a roller screw assembly according to claim 1, characterized in that: The locking nut has an external thread, the rack piston has an internal thread, the locking nut is threadedly connected to the rack piston, and glue is applied at the threaded connection between the locking nut and the rack piston so that the locking nut and the rack piston are locked and connected by glue, and the inner side of the locking nut fits with the nut.

3. The electric steering gear with a roller screw assembly according to claim 1, characterized in that: The bearing is a single-row tapered roller bearing or a double-row tapered roller bearing.

4. A steering gear assembly, characterized in that: It comprises a steering gear and a reducer, wherein the steering gear is an electric steering gear with a roller screw assembly as claimed in claim 1, wherein the screw rod of the electric steering gear with a roller screw assembly extends out of one end of the upper cover and has an external spline, and an internal spline hole is opened at the bottom of the output shaft of the reducer, and the internal and external splines are matched and connected; an inner hole is processed at the bottom of the reducer shell, and a stop is provided on the outer circle of the upper cover end of the electric steering gear with a roller screw assembly shell, and the inner hole and the stop are plugged in and connected by flange bolts.

Images