Lightweight electric power steering gear

Abstract

A first eccentric bearing is provided with a first adjusting hole, a second eccentric bearing is provided with a second adjusting hole, the first adjusting hole and the second adjusting hole are formed in the same axis, and at the beginning of assembly, the small diameter of the first eccentric bearing and the small diameter of the second eccentric bearing both face the top of a shell; the first eccentric bearing and the second eccentric bearing are rotated synchronously, so that the steering nut abuts against the inner circumferential wall of the shell. The first eccentric bearing is rotated through the first adjusting hole, the second eccentric bearing is rotated through the second adjusting hole, the large diameter of the first eccentric bearing and the large diameter of the second eccentric bearing both face the top of the shell, then the radial gap between the steering nut and the shell is adjusted, and an eccentric bearing or a lead screw nut on the rocker arm shaft is omitted; the weight of the electric power steering gear can be effectively reduced, cost is saved, and meanwhile the purposes of saving energy and improving efficiency are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of automobiles, and in particular to a lightweight electric power steering device. Background Art

[0002] Modern automobile technology pursues three goals: high efficiency and energy saving, high comfort and high safety. As one of the most important subsystems of automobiles, the development of steering systems has also been striving to achieve these goals. Compared with the traditional hydraulic power steering system (HPS), the electric power steering system (EPS) can save about 3% to 5% of fuel consumption, has the advantages of exquisite structure, energy saving and environmental protection, safety and comfort, etc., and is the development direction of automobile power steering system. However, the steering device has a large output torque, high integration requirements, and great overall design difficulty. The existing electric power steering gear is generally provided with a clearance adjustment structure, which mainly refers to the radial clearance adjustment structure of the rocker shaft. The steering gear gear kinematic pair is composed of a rocker shaft and a rack piston. The radial clearance of the rocker shaft is achieved by synchronously adjusting the eccentric bearings at both ends. However, because the length of the vertical arm connecting the steering gear rocker shaft is long, and the steering gear output torque is large, when the steering wheel is turned, it is very easy to cause the eccentric bearing and the rocker shaft to rotate synchronously. In order to solve this problem, Chinese patent CN202011009669.9 discloses an electric power steering device, in which a steering nut is provided on the outer peripheral wall of the screw nut, and the radial clearance of the rocker arm shaft is adjusted by the gap between the screw nut and the steering nut. However, the setting of the steering nut + screw nut also increases the overall weight of the steering device, thereby increasing the energy consumption. Summary of the invention

[0003] In order to solve the technical problem in the prior art that the setting of a steering nut + a lead screw nut increases the overall weight of the steering device, the present invention proposes a lightweight electric power steering device, which eliminates the setting of an eccentric bearing or a lead screw nut on the rocker shaft, thereby effectively reducing the weight of the electric power steering device and saving costs.

[0004] The technical solution adopted by the present invention is as follows: A lightweight electric power steering gear comprises a housing, a worm gear, a screw, a steering nut and a rocker shaft, the worm gear and the screw have an interference fit, the steering nut is sleeved on the outer peripheral wall of the screw, the rocker shaft is meshed with the steering nut, a first eccentric bearing is provided at one end of the screw, and a second eccentric bearing is provided at the other end of the screw, the worm gear and the steering nut are both arranged between the first eccentric bearing and the second eccentric bearing, the first eccentric bearing is provided with a first adjustment hole, the second eccentric bearing is provided with a second adjustment hole, the first adjustment hole and the second adjustment hole are arranged on the same axis, at the beginning of assembly, the small diameter of the first eccentric bearing and the small diameter of the second eccentric bearing are both facing the top of the housing, the first eccentric bearing and the second eccentric bearing are rotated synchronously, so that the steering nut is against the inner peripheral wall of the housing.

[0005] Optionally, both ends of the steering nut are provided with supporting protrusions that are movably abutted against the shell, one side of the outer wall of the steering nut is provided with a rack that meshes with the fan teeth of the rocker arm shaft, and the inner wall of the steering nut is provided with a flat groove for installing a ball return device and a raceway for rolling balls.

[0006] Optionally, the free end of the rack protrudes from the supporting protrusion ring, and a groove is formed between the two supporting protrusion rings.

[0007] Optionally, a sealing plate is provided on the side of the second eccentric bearing facing the steering nut, one end of the sealing plate is interference fit with the inner ring of the second eccentric bearing, and the other end of the sealing plate is press-fitted with the inner wall of the outer ring of the second eccentric bearing by chamfering.

[0008] Optionally, the inner wall of the shell is provided with a cylindrical protrusion that cooperates with the steering nut, the shell is provided with a through hole for the sector teeth of the rocker arm shaft to pass through, and notches are respectively provided at the axial ends of the cylindrical protrusion and the connection with the through hole.

[0009] Optionally, the shell is provided with an oil inlet pipe, and the oil inlet pipe is connected to a sealing assembly, the sealing assembly includes an end cover and a connecting pipe with a hollow hole, one end of the connecting pipe is provided with a first boss which matches the end cover gap, and the other end of the connecting pipe is provided with a second boss which is tightly connected to the oil inlet pipe, and the first boss is provided with a breathable and waterproof membrane inside.

[0010] Optionally, a plurality of water flow grooves are provided at intervals along the circumferential direction at the free end of the first boss, and the breathable and waterproof membrane is flush with the lowest point of the water flow grooves.

[0011] Optionally, a plurality of elastic ridges are provided at intervals on the inner circumferential wall of the end cover, the elastic ridges correspond to the water flow grooves in an alternating manner, the elastic ridges are interference fit with the outer circumferential wall of the first boss, the outer circumferential wall of the first boss is provided with an annular groove, and the elastic ridges and the annular groove are arranged perpendicular to each other.

[0012] Optionally, the connecting pipe is provided with a cover plate, the bottom surface of the cover plate is provided with an elastic ring bulge that abuts against the free end of the oil inlet pipe, the free end of the oil inlet pipe is provided with a limiting groove that cooperates with the cover plate, the outer peripheral wall of the second boss is provided with an external thread, the oil inlet pipe is provided with an internal thread that cooperates with the external thread, and the inner diameter of the hollow hole of the connecting pipe is 8~9cm.

[0013] Optionally, it also includes an input shaft connected to the screw rod, the outer peripheral wall of the input shaft is sleeved with a valve cover and a dust cover, one end of the dust cover is interference fit with the input shaft, and the other end of the dust cover covers a portion of the outer peripheral wall of the valve cover, and the valve cover is connected to the shell.

[0014] The beneficial effects of the present invention are: (1) by rotating the first eccentric bearing through the first adjusting hole and the second eccentric bearing through the second adjusting hole, the major diameter of the first eccentric bearing and the major diameter of the second bearing are both directed toward the top of the housing, thereby adjusting the radial clearance between the steering nut and the housing, eliminating the need for an eccentric bearing or a lead screw nut on the rocker shaft, and effectively reducing the weight of the electric power steering device, saving costs, and achieving the purpose of energy saving and efficiency improvement.

[0015] (2) Since iron filings generated by the meshing friction between the worm wheel and the worm, and between the steering nut and the screw, will enter the second eccentric bearing, causing the steel balls in the second eccentric bearing to get stuck, thereby affecting the normal operation of the steering gear, the setting of the sealing plate can prevent iron filings from entering the second eccentric bearing and extend the service life of the second eccentric bearing. Both the first eccentric bearing and the second eccentric bearing are thrust angular contact bearings.

[0016] (3) The free end of the rack protrudes from the supporting convex ring, which can increase the strength of the rack itself and increase the convenience of meshing and assembling the rack and the rocker shaft. The cylindrical protrusion limits the supporting convex ring of the steering nut. The setting of the notch prevents the rack protruding from the supporting convex ring from interfering with the cylindrical protrusion during reciprocating movement. At the same time, it also plays a role in reducing the overall weight of the housing, reducing costs and increasing efficiency.

[0017] (4) The oil inlet pipe is used to add lubricating oil to the inside of the steering gear. In the prior art, the oil inlet pipe is generally sealed with a nut. When the air pressure inside the steering gear increases, the oil seal or shell of the steering gear is very likely to cause oil leakage due to the high pressure. The setting of the breathable waterproof membrane enables the steering gear to maintain internal and external pressure balance while preventing moisture from entering the steering gear. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A cross-sectional view of a lightweight electric power steering device according to an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of a steering nut of a lightweight electric power steering device provided in an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of a housing of a lightweight electric power steering device provided in an embodiment of the present invention;

[0021] Figure 4 A schematic diagram of a second eccentric bearing provided in an embodiment of the present invention;

[0022] Figure 5 A schematic diagram of a cover assembly according to an embodiment of the present invention;

[0023] Figure 6 A schematic diagram of the elastic convex strip and the annular groove of the cover assembly proposed in an embodiment of the present invention;

[0024] Figure 7 A schematic diagram of a dust cover provided in an embodiment of the present invention.

[0025] The marks in the drawings are: 1, housing; 11, cylindrical protrusion; 12, through hole; 13, notch; 14, oil inlet pipe; 141, limit groove; 2, worm gear; 3, screw; 4, steering nut; 41, supporting protrusion; 42, rack; 43, groove; 5, rocker shaft; 6, first eccentric bearing; 7, second eccentric bearing; 71, sealing plate; 8, cover assembly; 81, end cover; 811, elastic Raised strip; 82, connecting pipe; 821, first boss; 822, second boss; 823, water flow groove; 824, ring groove; 825, cover plate; 826, elastic ring convex; 827, hollow hole; 828, external thread; 83, breathable waterproof membrane; 9, input shaft; 91, dust cover; 911, dustproof surface; 912, ring cover; 92, valve cover; 921, convex cover; 922, cover body; 93, oil seal. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0027] like Figure 1 and Figure 4 As shown, it includes a housing 1, a worm gear 2, a screw rod 3, a steering nut 4 and a rocker shaft 5. The worm gear 2 and the screw rod 3 are interference fit, the steering nut 4 is sleeved on the outer peripheral wall of the screw rod 3, the rocker shaft 5 is meshed with the steering nut 4, one end of the screw rod 3 is provided with a first eccentric bearing 6, and the other end of the screw rod 3 is provided with a second eccentric bearing 7. The worm gear 2 and the steering nut 4 are both arranged between the first eccentric bearing 6 and the second eccentric bearing 7. The first eccentric bearing 6 is provided with a first adjustment hole, and the second eccentric bearing 7 is provided with a second adjustment hole. The first adjustment hole and the second adjustment hole are arranged on the same axis. At the beginning of assembly, the small diameter of the first eccentric bearing 6 and the small diameter of the second eccentric bearing 7 are both toward the top of the housing 1, and the first eccentric bearing 6 and the second eccentric bearing 7 are rotated synchronously to make the steering nut 4 abut against the inner peripheral wall of the housing 1. The first eccentric bearing 6 is rotated through the first adjusting hole, and the second eccentric bearing 7 is rotated through the second adjusting hole, so that the major diameter of the first eccentric bearing 6 and the major diameter of the second bearing are both toward the top of the housing 1, thereby adjusting the radial clearance between the steering nut 4 and the housing 1, eliminating the need for an eccentric bearing or a lead screw nut on the rocker shaft 5, which can effectively reduce the weight of the electric power steering device, save costs, and achieve the purpose of energy saving and efficiency improvement.

[0028] In this embodiment, if Figure 2As shown, both ends of the steering nut 4 are provided with supporting protruding rings 41 that are movably abutted against the housing 1, one side of the outer peripheral wall of the steering nut 4 is provided with a rack 42 that meshes with the fan teeth of the rocker shaft 5, and the inner peripheral wall of the steering nut 4 is provided with a flat groove for installing a ball return device and a raceway for ball rolling. The raceway on the inner peripheral wall of the steering nut 4 and the raceway on the outer peripheral wall of the screw 3 correspond to form a channel for ball rolling, and the ball return device causes the balls to reciprocate and circulate. The free end of the rack 42 protrudes from the supporting protruding ring 41, and a groove 43 is formed between the two supporting protruding rings 41. The free end of the rack 42 protrudes from the supporting protruding ring 41, which can increase the strength of the rack 42 itself and increase the convenience of the rack 42 and the rocker shaft 5 when meshing and assembling.

[0029] like Figure 4 As shown, a sealing plate 71 is provided on the side of the second eccentric bearing 7 facing the steering nut 4. One end of the sealing plate 71 is interference fit with the inner ring of the second eccentric bearing 7, and the other end of the sealing plate 71 is press-fitted with the inner wall of the outer ring of the second eccentric bearing 7 through chamfering. Since the iron filings generated by the meshing friction between the worm wheel 2 and the worm, and the steering nut 4 and the screw 3 will enter the second eccentric bearing 7, causing the steel balls in the second eccentric bearing 7 to get stuck, thereby affecting the normal operation of the steering gear, the setting of the sealing plate 71 can prevent the iron filings from entering the second eccentric bearing 7, thereby extending the service life of the second eccentric bearing 7. The first eccentric bearing 6 and the second eccentric bearing 7 are both thrust angular contact bearings. The first adjustment hole is provided on the outer ring of the first eccentric shaft, and the second adjustment hole is provided on the outer ring of the second eccentric bearing.

[0030] like Figure 3 As shown, the inner circumferential wall of the housing 1 is provided with a cylindrical protrusion 11 that cooperates with the steering nut 4, and the housing 1 is provided with a through hole 12 for the sector teeth of the rocker arm shaft 5 to pass through. Notches 13 are respectively provided at the connection between the axial ends of the cylindrical protrusion 11 and the through hole 12. The cylindrical protrusion 11 limits the support protrusion 41 of the steering nut 4. The provision of the notch 13 avoids the interference between the support protrusion 41 located on both sides of the rack 42 and the cylindrical protrusion 11 during the reciprocating movement, and also plays a role in reducing the overall weight of the housing 1, reducing costs and increasing efficiency.

[0031] like Figure 3-6As shown, the housing 1 is provided with an oil inlet pipeline 14, and the oil inlet pipeline 14 is connected to a sealing assembly 8, and the sealing assembly 8 includes an end cover 81 and a connecting pipe 82 with a hollow hole 827, and one end of the connecting pipe 82 is provided with a first boss 821 that is loosely matched with the end cover 81, and the other end of the connecting pipe 82 is provided with a second boss 822 that is tightly connected to the oil inlet pipeline 14, and a breathable waterproof membrane 83 is provided inside the first boss 821. The oil inlet pipeline 14 is used to add lubricating oil to the inside of the steering gear. The oil inlet pipeline 14 in the prior art is generally sealed with a nut. When the air pressure inside the steering gear increases, the oil seal or housing 1 of the steering gear is very likely to cause oil leakage due to the high pressure. The provision of the breathable waterproof membrane 83 enables the steering gear to maintain internal and external pressure balance, while preventing moisture from entering the inside of the steering gear.

[0032] In this embodiment, if Figure 5 and 6 As shown, the free end of the first boss 821 is provided with a plurality of water flow grooves 823 at intervals along the circumferential direction, and the breathable waterproof membrane 83 is flush with the lowest point of the water flow groove 823. Water isolated by the breathable waterproof membrane 83 can flow out from the water flow groove 823 and out from the gap between the end cover 81 and the first boss 821. The inner peripheral wall of the end cover 81 is provided with a plurality of elastic convex strips 811 at intervals, and the elastic convex strips 811 correspond to the water flow grooves 823 in an interlaced manner, and the elastic convex strips 811 are interference fit with the outer peripheral wall of the first boss 821, and the outer peripheral wall of the first boss 821 is provided with an annular groove 824, and the elastic convex strips and the annular groove 824 are arranged perpendicular to each other. The end cap 81 is interference fit with the outer wall of the first boss 821 through the elastic convex strip 811 on the inner wall, and water and gas flow out from the gap between the inner wall of the end cap 81 and the outer wall of the first boss 821. The setting of the annular groove 824 increases the pulling force of the end cap 81, making it difficult for the end cap 81 to be pulled out. The connecting pipe 82 is provided with a cover plate 825, and the bottom surface of the cover plate 825 is provided with an elastic annular protrusion 826 that abuts against the free end of the oil inlet pipeline 14. The free end of the oil inlet pipeline 14 is provided with a limiting groove 141 that cooperates with the cover plate 825. The outer wall of the second boss 822 is provided with an external thread 828, and the oil inlet pipeline 14 is provided with an internal thread that cooperates with the external thread 828. When the first boss 821 and the oil inlet pipeline 14 are tightly matched through the external thread 828 and the internal thread, the cover plate 825 blocks the oil inlet pipeline 14, and the elastic annular protrusion 826 further plays a sealing effect. The inner diameter of the hollow hole 827 of the connecting pipe 82 is 8 to 9 cm. If the diameter of the hollow hole 827 is less than 8 cm, the lubricating oil is easily stagnated on the inner wall of the hollow hole 827, resulting in blockage of the hollow hole 827 and affecting the exhaust effect. If the hollow hole 827 is larger than 9 cm, the size of the connecting pipe 82 and the breathable waterproof membrane 83 also needs to be increased accordingly, increasing the processing cost.

[0033] like Figure 7As shown, it also includes an input shaft 9 connected to the screw rod, and the outer peripheral wall of the input shaft 9 is sleeved with a valve cover 92 and a dust cover 91, one end of the dust cover 91 is interference fit with the input shaft 9, and the other end of the dust cover 91 covers part of the outer peripheral wall of the valve cover 92, and the valve cover 92 is connected to the housing. An oil seal 93 is provided on the outer peripheral wall of the input shaft 9, and the valve cover 92 is arranged on the outer peripheral wall of the oil seal 93. The valve cover 92 and the oil seal 93 protect the sensor inside. Since the input shaft 9 and the oil seal 93 are exposed to the outside, when this part contacts mud or water, this part will rust, and the rust will continue, causing the shaft inside the oil seal 93 to rust, and the lip of the oil seal 93 will be deformed and abnormally worn due to the rust of the shaft, resulting in premature failure. The dust cover 91 includes a dust cover surface 911 and a ring cover 912 connected to the dust cover surface 911 at an angle. The valve cover 92 includes a convex cover 921 and a cover body 922 connected to the convex cover 921 at an angle. The dust cover surface 911 has an inner hole that is an interference fit with the input shaft 9, so that the dust cover 91 rotates together with the input shaft 9. The ring cover 912 has a gap covering the outer peripheral wall of the convex cover 921 to prevent water or mud from entering the oil seal 93. The inner wall of the ring cover 912 may be provided with a ring convex, and the outer peripheral wall of the convex cover 921 may be provided with a ring groove that matches the gap with the ring convex. A labyrinth design is used to further prevent the entry of water or mud. In addition, the ring cover 912 and the cover body 922 of the dust cover 91 can be arranged at an angle. Since the steering gear is arranged vertically and is very high from the ground, it is difficult for water to enter from below. Only when the car is moving on rainy days, some water and mud may enter the inside of the valve cover 92. The inclined arrangement of the dust cover 91 and the valve cover 92 avoids the accumulation of water or mud, and can further prevent water or mud from entering the oil seal 93 and the inner wall of the valve cover 92.

[0034] It is understandable that the specific embodiments described above are only used to explain the relevant inventions, rather than to limit the inventions. It should also be noted that, for ease of description, only the parts related to the invention are shown in the drawings. 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 without contradictions or conflicts. All equivalent structural transformations made using the contents of the specification and drawings of the present invention, directly or indirectly used in other related technical fields, are similarly included in the protection scope of the present invention.

Claims

1. A lightweight electric power steering gear, characterized in that: It includes a shell, a worm gear, a screw, a steering nut and a rocker shaft. The worm gear and the screw are interference fit, the steering nut is sleeved on the outer peripheral wall of the screw, the rocker shaft is meshed with the steering nut, a first eccentric bearing is provided at one end of the screw, and a second eccentric bearing is provided at the other end of the screw. The worm gear and the steering nut are both arranged between the first eccentric bearing and the second eccentric bearing. The first eccentric bearing is provided with a first adjusting hole, and the second eccentric bearing is provided with a second adjusting hole. The first adjusting hole and the second adjusting hole are arranged on the same axis. At the beginning of assembly, the small diameter of the first eccentric bearing and the small diameter of the second eccentric bearing are both facing the top of the shell, and the first eccentric bearing and the second eccentric bearing are rotated synchronously to make the steering nut abut against the inner peripheral wall of the shell.

2. The lightweight electric power steering device according to claim 1, characterized in that: Both ends of the steering nut are provided with supporting convex rings that are movably abutted against the shell, one side of the outer peripheral wall of the steering nut is provided with a rack that meshes with the fan teeth of the rocker arm shaft, and the inner peripheral wall of the steering nut is provided with a flat groove for installing a ball return device and a raceway for rolling balls.

3. The lightweight electric power steering device according to claim 2, characterized in that: The free end of the rack protrudes from the supporting convex ring, and a groove is formed between the two supporting convex rings.

4. The lightweight electric power steering device according to claim 1, characterized in that: A sealing plate is provided on the side of the second eccentric bearing facing the steering nut. One end of the sealing plate is interference fit with the inner ring of the second eccentric bearing, and the other end of the sealing plate is press-fitted with the inner wall of the outer ring of the second eccentric bearing through chamfering.

5. The lightweight electric power steering device according to claim 2, characterized in that: The inner peripheral wall of the shell is provided with a cylindrical protrusion matched with the steering nut, the shell is provided with a through hole for the sector teeth of the rocker arm shaft to pass through, and notches are respectively provided at the axial ends of the cylindrical protrusion and the connection with the through hole.

6. The lightweight electric power steering device according to claim 1, characterized in that: The shell is provided with an oil inlet pipeline, and the oil inlet pipeline is connected to a sealing cover assembly, which includes an end cover and a connecting pipe with a hollow hole. One end of the connecting pipe is provided with a first boss that matches the end cover gap, and the other end of the connecting pipe is provided with a second boss that is tightly connected to the oil inlet pipeline. A breathable and waterproof membrane is provided inside the first boss.

7. The lightweight electric power steering device according to claim 6, characterized in that: The free end of the first boss is provided with a plurality of water flow grooves at intervals along the circumferential direction, and the breathable and waterproof membrane is flush with the lowest point of the water flow grooves.

8. The lightweight electric power steering device according to claim 7, characterized in that: The inner wall of the end cover is provided with a plurality of elastic ridges at intervals, the elastic ridges correspond to the water flow grooves in an alternating manner, the elastic ridges are interference fit with the outer wall of the first boss, the outer wall of the first boss is provided with an annular groove, and the elastic ridges and the annular groove are arranged perpendicular to each other.

9. The lightweight electric power steering device according to claim 6, characterized in that: The connecting pipe is provided with a cover plate, the bottom surface of the cover plate is provided with an elastic ring convexity abutting against the free end of the oil inlet pipe, the free end of the oil inlet pipe is provided with a limiting groove cooperating with the cover plate, the outer peripheral wall of the second boss is provided with an external thread, the oil inlet pipe is provided with an internal thread cooperating with the external thread, and the inner diameter of the hollow hole of the connecting pipe is 8~9cm.

10. The lightweight electric power steering device according to claim 1, characterized in that: It also includes an input shaft connected to the screw rod, wherein the outer peripheral wall of the input shaft is sleeved with a valve cover and a dust cover, one end of the dust cover is interference fit with the input shaft, and the other end of the dust cover covers a portion of the outer peripheral wall of the valve cover, and the valve cover is connected to the housing.

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