Lightweight Electric Power Steering Gear

Abstract

The present invention discloses a lightweight electric power steering gear. The first eccentric bearing is provided with a first adjustment hole, and 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 diameters of both the first eccentric bearing and the second eccentric bearing face the top of the housing. Rotate the first eccentric bearing and the second eccentric bearing synchronously to make the steering nut abut against the inner peripheral wall of the housing. By rotating the first eccentric bearing through the first adjustment hole and the second eccentric bearing through the second adjustment hole, the large diameters of both the first eccentric bearing and the second bearing face the top of the housing, thereby adjusting the radial clearance between the steering nut and the housing, eliminating the need for the eccentric bearing on the rocker shaft or the screw nut, effectively reducing the weight of the electric power steering gear, saving costs, and achieving the purpose of energy conservation and efficiency improvement at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of automobiles, and particularly to a lightweight electric power steering gear. Background Art

[0002] Modern automotive technology pursues three major goals: high efficiency and energy conservation, high comfort, and high safety. As one of the most important subsystems of an automobile, the development of the steering system 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% - 5% of fuel consumption, and has the advantages of delicate structure, energy conservation and environmental protection, safety and comfort, etc. It is the development direction of the automotive power steering system. However, the steering device has a large output torque, high integration requirements, and great overall design difficulty. Existing electric power steering gears generally have a clearance adjustment structure, which mainly refers to the radial clearance adjustment structure of the rocker shaft. The steering gear gear 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, due to the long length of the pitman arm connected to the rocker shaft of the steering gear and the large output torque of the steering gear, when the steering wheel is rotated, it is very easy to cause the eccentric bearings to rotate synchronously with the rocker shaft. 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 lead screw nut, and the radial clearance of the rocker shaft is adjusted through the gap between the lead screw nut and the steering nut. However, the setting of the steering nut + lead screw nut also increases the overall weight of the steering device, thereby increasing energy consumption. Summary of the Invention

[0003] Aiming at the technical problem that the setting of the steering nut + lead screw nut in the prior art increases the overall weight of the steering device, the present invention proposes a lightweight electric power steering gear, which omits the setting of the eccentric bearing or the lead screw nut on the rocker shaft, and can effectively reduce the weight of the electric power steering gear and save costs.

[0004] The technical solution adopted by the present invention is as follows: A lightweight electric power steering gear includes a housing, a worm gear, a screw, a steering nut, and a rocker shaft. The worm gear is in interference fit with the screw. The steering nut is sleeved on the outer peripheral wall of the screw. The rocker shaft is meshed with the steering nut. One end of the screw is provided with a first eccentric bearing, and the other end of the screw is provided with a second eccentric bearing. 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, and 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 diameters of the first eccentric bearing and the second eccentric bearing both face the top of the housing. The first eccentric bearing and the second eccentric bearing are synchronously rotated so that the steering nut abuts against the inner peripheral wall of the housing.

[0005] Optionally, support convex rings that are movably abutted against the housing are provided at both ends of the steering nut. A rack that meshes with the sector gear of the rocker arm shaft is provided on one side of the outer peripheral wall of the steering nut. A flat groove for installing a ball returner and a raceway for the rolling of the balls are provided on the inner peripheral wall of the steering nut.

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

[0007] Optionally, a sealing plate is provided on the surface of the second eccentric bearing facing the steering nut. One end of the sealing plate is in 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 a chamfer.

[0008] Optionally, a cylindrical protrusion that cooperates with the steering nut is provided on the inner peripheral wall of the housing. The housing is provided with a through hole for the sector gear of the rocker arm shaft to pass through, and notches are respectively provided at the joints of the axial two ends of the cylindrical protrusion and the through hole.

[0009] Optionally, the housing is provided with an oil inlet pipe, and the oil inlet pipe is connected with a cover assembly. The cover 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 that is in clearance fit with the end cover, and the other end of the connecting pipe is provided with a second boss that is tightly connected with the oil inlet pipe. A breathable and waterproof film is provided inside the first boss.

[0010] Optionally, a plurality of water flow grooves are circumferentially spaced at the free end of the first boss, and the breathable and waterproof film is flush with the lowest point of the water flow grooves.

[0011] Optionally, a plurality of elastic convex strips are spaced on the inner peripheral wall of the end cover. The elastic convex strips are staggered and corresponding to the water flow grooves. The elastic convex strips are in interference fit with the outer peripheral wall of the first boss. A ring groove is provided on the outer peripheral wall of the first boss, and the elastic convex strips and the ring groove are arranged perpendicular to each other.

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

[0013] Optionally, it further includes an input shaft connected to the screw rod. A valve cover and a dust cover are sleeved on the outer peripheral wall of the input shaft. One end of the dust cover is in interference fit with the input shaft, and the other end of the dust cover covers part of the outer peripheral wall of the valve cover. The valve cover is connected to the housing.

[0014] The beneficial effects of the present invention are as follows: (1) By rotating the first eccentric bearing through the first adjustment hole and the second eccentric bearing through the second adjustment hole, the large diameters of both the first eccentric bearing and the second bearing face the top of the housing, thereby adjusting the radial clearance between the steering nut and the housing, eliminating the need for an eccentric bearing on the rocker shaft or a lead screw nut, effectively reducing the weight of the electric power steering gear, saving costs, and achieving the purpose of energy conservation and efficiency improvement.

[0015] (2) Since the iron filings generated by the meshing friction between the worm wheel and the worm, and between the steering nut and the screw rod will enter the second eccentric bearing, causing the steel balls in the second eccentric bearing to jam, thereby affecting the normal operation of the steering gear. The setting of the sealing plate can prevent the iron filings from entering the interior of the second eccentric bearing, extending 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 support convex ring, which can not only increase the strength of the rack itself but also enhance the convenience of the meshing assembly between the rack and the rocker shaft. The cylindrical protrusion limits the support convex ring of the steering nut. The notch is provided to avoid interference between the rack protruding from the support convex ring and the cylindrical protrusion during reciprocating movement, and 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 interior of the steering gear. In the prior art, the oil inlet pipe is generally sealed with a nut. When the internal pressure of the steering gear increases, the oil seal or the housing of the steering gear is extremely likely to leak oil due to high pressure. The setting of the breathable waterproof film keeps the internal and external pressures of the steering gear balanced and prevents moisture from entering the interior of the steering gear. Brief Description of the Drawings

[0018] Figure 1 It is a cross-sectional view of the lightweight electric power steering gear proposed in the embodiment of the present invention;

[0019] Figure 2 It is a schematic diagram of the steering nut of the lightweight electric power steering gear proposed in the embodiment of the present invention;

[0020] Figure 3 It is a schematic diagram of the housing of the lightweight electric power steering gear proposed in the embodiment of the present invention;

[0021] Figure 4 It is a schematic diagram of the second eccentric bearing proposed in the embodiment of the present invention;

[0022] Figure 5 It is a schematic diagram of the cover assembly proposed in the embodiment of the present invention;

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

[0024] Figure 7 Schematic diagram of the dust cover proposed in the embodiment of the present invention.

[0025] The reference numerals in each drawing 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 convex ring; 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 convex strip; 82, connecting pipe; 821, first boss; 822, second boss; 823, water chute; 824, annular groove; 825, cover plate; 826, elastic ring convex; 827, hollow hole; 828, external thread; 83, breathable and waterproof membrane; 9, input shaft; 91, dust cover; 911, dust-proof surface; 912, ring cover; 92, valve cover; 921, convex cover; 922, cover body; 93, oil seal. Detailed implementation manners

[0026] The present invention will be further described in detail below with reference to the drawings and embodiments.

[0027] As Figure 1 and Figure 4 shown, it includes a housing 1, a worm gear 2, a screw 3, a steering nut 4 and a rocker shaft 5. The worm gear 2 is in interference fit with the screw 3. The steering nut 4 is sleeved on the outer peripheral wall of the screw 3. The rocker shaft 5 is meshed with the steering nut 4. One end of the screw 3 is provided with a first eccentric bearing 6, and the other end of the screw 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 diameters of the first eccentric bearing 6 and the second eccentric bearing 7 both face the top of the housing 1. 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. By rotating the first eccentric bearing 6 through the first adjustment hole and rotating the second eccentric bearing 7 through the second adjustment hole, the large diameters of the first eccentric bearing 6 and the second bearing both face the top of the housing 1, thereby adjusting the radial clearance between the steering nut 4 and the housing 1, eliminating the setting of the eccentric bearing or the screw nut on the rocker shaft 5, effectively reducing the weight of the electric power steering gear, saving costs, and achieving the purpose of energy conservation and efficiency improvement at the same time.

[0028] In this embodiment, as Figure 2As shown, support convex rings 41 that are movably abutted against the housing 1 are provided at both ends of the steering nut 4. A rack 42 that meshes with the sector gear of the rocker arm shaft 5 is provided on one side of the outer peripheral wall of the steering nut 4. A flat groove for installing a ball returner and a raceway for the balls to roll are provided on the inner peripheral wall of the steering nut 4. The raceway on the inner peripheral wall of the steering nut 4 and the raceway on the outer peripheral wall of the screw rod 3 are correspondingly matched to form a channel for the balls to roll, and the ball returner enables the balls to roll reciprocally in a cycle. The free end of the rack 42 protrudes from the support convex ring 41, and a groove 43 is formed between the two support convex rings 41. The fact that the free end of the rack 42 protrudes from the support convex ring 41 can not only increase the strength of the rack 42 itself but also increase the convenience of the meshing and assembly of the rack 42 and the rocker arm shaft 5.

[0029] As Figure 4 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 in 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 a chamfer. Since iron filings generated by the meshing friction between the worm gear 2 and the worm, and between the steering nut 4 and the screw rod 3 will enter the second eccentric bearing 7, causing the steel balls in the second eccentric bearing 7 to jam, thus affecting the normal operation of the steering gear. The setting of the sealing plate 71 can prevent the iron filings from entering the interior of the second eccentric bearing 7 and extend the service life of the second eccentric bearing 7. Both the first eccentric bearing 6 and the second eccentric bearing 7 are thrust angular contact bearings. The first adjustment hole is provided on the outer ring in the first eccentric axial direction, and the second adjustment hole is provided on the outer ring of the second eccentric bearing.

[0030] As Figure 3 shown, a cylindrical protrusion 11 that cooperates with the steering nut 4 is provided on the inner peripheral wall of the housing 1. The housing 1 is provided with a through hole 12 for the sector gear of the rocker arm shaft 5 to pass through. Notches 13 are respectively provided at the joints of the axial two ends of the cylindrical protrusion 11 and the through hole 12. The cylindrical protrusion 11 limits the support convex ring 41 of the steering nut 4. The setting of the notches 13 avoids the interference between the support convex rings 41 on both sides of the rack 42 and the cylindrical protrusion 11 during the reciprocating movement, and at the same time plays the role of the overall weight of the housing 1, reducing costs and increasing efficiency.

[0031] As Figure 3-6As shown, the housing 1 is provided with an oil inlet pipe 14, and the oil inlet pipe 14 is connected with a cover assembly 8. The cover assembly 8 includes an end cover 81 and a connecting pipe 82 with a hollow hole 827. One end of the connecting pipe 82 is provided with a first boss 821 which is in clearance fit with the end cover 81, and the other end of the connecting pipe 82 is provided with a second boss 822 which is tightly connected with the oil inlet pipe 14. An air-permeable and waterproof membrane 83 is arranged inside the first boss 821. The oil inlet pipe 14 is used to add lubricating oil to the inside of the steering gear. In the prior art, the oil inlet pipe 14 is generally sealed with a nut. When the internal air pressure of the steering gear increases, the oil seal or the housing 1 of the steering gear is extremely likely to leak oil due to high pressure. The setting of the air-permeable and waterproof membrane 83 keeps the internal and external pressures of the steering gear balanced and at the same time prevents water from entering the inside of the steering gear.

[0032] In this embodiment, as Figure 5 and 6 shown, a plurality of water channels 823 are arranged at intervals along the circumferential direction at the free end of the first boss 821, and the air-permeable and waterproof membrane 83 is flush with the lowest point of the water channels 823. The water isolated by the air-permeable and waterproof membrane 83 can flow out from the water channels 823 and flow out through the gap between the end cover 81 and the first boss 821. A plurality of elastic ridges 811 are arranged at intervals on the inner peripheral wall of the end cover 81. The elastic ridges 811 are staggered and corresponding to the water channels 823. The elastic ridges 811 are in interference fit with the outer peripheral wall of the first boss 821. An annular groove 824 is arranged on the outer peripheral wall of the first boss 821, and the elastic ridges and the annular groove 824 are arranged perpendicular to each other. The end cover 81 is in interference fit with the outer peripheral wall of the first boss 821 through the elastic ridges 811 on the inner peripheral wall. Water and gas flow out through the gap between the inner peripheral wall of the end cover 81 and the outer peripheral wall of the first boss 821. The setting of the annular groove 824 increases the pulling force of the end cover 81 and makes the end cover 81 not easy to be pulled out. The connecting pipe 82 is provided with a cover plate 825. An elastic ring protrusion 826 which abuts against the free end of the oil inlet pipe 14 is arranged on the bottom surface of the cover plate 825. A limit groove 141 which cooperates with the cover plate 825 is arranged at the free end of the oil inlet pipe 14. An external thread 828 is arranged on the outer peripheral wall of the second boss 822, and an internal thread which cooperates with the external thread 828 is arranged on the oil inlet pipe 14. When the first boss 821 and the oil inlet pipe 14 are tightly fitted through the external thread 828 and the internal thread, the cover plate 825 seals the oil inlet pipe 14, and the elastic ring protrusion 826 further plays a sealing role. The inner diameter of the hollow hole 827 of the connecting pipe 82 is 8 - 9 cm. If the diameter of the hollow hole 827 is less than 8 cm, lubricating oil is likely to stagnate on the inner wall of the hollow hole 827, resulting in the blockage of the hollow hole 827 and affecting the exhaust effect. If the hollow hole 827 is greater than 9 cm, the sizes of the connecting pipe 82 and the air-permeable and waterproof membrane 83 also need to be made larger accordingly, increasing the processing cost.

[0033] As Figure 7As shown, it further includes an input shaft 9 connected to the screw. A valve cover 92 and a dust cover 91 are sleeved on the outer peripheral wall of the input shaft 9. One end of the dust cover 91 is in interference fit with the input shaft 9, and the other end of the dust cover 91 covers a part of the outer peripheral wall of the valve cover 92. 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 part between the input shaft 9 and the oil seal 93 is exposed outside, when this part comes into contact with sediment or water for a long time, this part will rust, and the rust will spread, resulting in the rusting of the shaft inside the oil seal 93. The lip of the oil seal 93 will be deformed and abnormally worn due to the rusting of the shaft, leading to premature failure. The dust cover 91 includes a dust-proof surface 911 and a ring cover 912 connected to the dust-proof 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-proof surface 911 has an inner hole that is in interference fit with the input shaft 9, so that the dust cover 91 rotates together with the input shaft 9. The ring cover 912 covers the outer peripheral wall of the convex cover 921 with a gap to prevent water or sediment from entering the oil seal 93. A ring protrusion can be provided on the inner wall of the ring cover 912, and a ring groove that is in clearance fit with the ring protrusion can be provided on the outer peripheral wall of the convex cover 921. The labyrinth design is adopted to further prevent water or sediment from entering. In addition, the ring cover 912 and the cover body 922 of the dust cover 91 can be inclined. 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 vehicle is moving on a rainy day, some water and sediment may enter the inside of the valve cover 92. The inclined settings of the dust cover 91 and the valve cover 92 avoid the accumulation of water or sediment, and can further prevent water or sediment from entering the oil seal 93 and the inner wall of the valve cover 92.

[0034] It can be understood that the specific embodiments described above are only used to explain the related invention, rather than limiting the invention. In addition, it should be noted that for the convenience 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 contradiction or conflict. Any equivalent structural transformation made by using the content of the specification and drawings of the present invention, directly or indirectly applied in other related technical fields, shall be included in the protection scope of the present invention by the same token.

Claims

1. A lightweight electric power steering gear, characterized in that, It includes a housing, a worm gear, a screw rod, a steering nut and a rocker arm shaft. The worm gear is in interference fit with the screw rod. The steering nut is sleeved on the outer peripheral wall of the screw rod. The rocker arm shaft meshes with the steering nut. One end of the screw rod is provided with a first eccentric bearing, and the other end of the screw rod is provided with a second eccentric bearing. 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, and 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 diameters of both the first eccentric bearing and the second eccentric bearing face the top of the housing. Rotate the first eccentric bearing and the second eccentric bearing synchronously to make the steering nut abut against the inner peripheral wall of the housing; The housing is provided with an oil inlet pipe, and the oil inlet pipe is connected with a cover assembly. The cover 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 in clearance fit with the end cover, and the other end of the connecting pipe is provided with a second boss tightly connected with the oil inlet pipe. The inside of the first boss is provided with a breathable and waterproof film; The free end of the first boss is circumferentially provided with a plurality of water channels at intervals, and the breathable and waterproof film is flush with the lowest point of the water channels; The inner peripheral wall of the end cover is provided with a plurality of elastic ridges at intervals. The elastic ridges and the water channels are staggered and corresponding. The elastic ridges are in interference fit with the outer peripheral wall of the first boss. The outer peripheral 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.

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

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

4. The lightweight electric power steering gear according to claim 1, characterized in that, One side of the second eccentric bearing facing the steering nut is provided with a sealing plate. One end of the sealing plate is in 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 a chamfer.

5. The lightweight electric power steering gear according to claim 2, characterized in that, The inner peripheral wall of the housing is provided with a cylindrical protrusion that cooperates with the steering nut. The housing is provided with a through hole for the sector teeth of the rocker arm shaft to pass through. Notches are respectively provided at the joints of the axial two ends of the cylindrical protrusion and the through hole.

6. The lightweight electric power steering gear according to claim 1, wherein The connecting pipe is provided with a cover plate. The bottom surface of the cover plate is provided with an elastic ring protrusion that abuts against the free end of the oil inlet pipe. The free end of the oil inlet pipe is provided with a limit groove that cooperates with the cover plate. The outer peripheral wall of the second boss is provided with an external thread, and the oil inlet pipe is provided with an internal thread that cooperates with the external thread. The inner diameter of the hollow hole of the connecting pipe is 8 - 9 cm.

7. The lightweight electric power steering gear according to claim 1, characterized in that, It further 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 in interference fit with the input shaft, and the other end of the dust cover covers part of the outer peripheral wall of the valve cover. The valve cover is connected to the housing.

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