Gear and rack pre-tightening mechanism for double-pinion steering machine
Through the pretension mechanism controlled by the pendulum bearing, the problem of stiffness attenuation and gap increase after durability of the gear rack and rack pretension mechanism is solved, which improves NVH performance and reduces manufacturing costs.
Patent Information
- Application Number
- CN202421321715.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-12
- Publication Date
- 2025-02-11
- Estimated Expiration
- 2034-06-12
AI Technical Summary
After durability, the preloading mechanism has a deterioration of the stiffness of the preloading mechanism, larger gaps, reduced NVH performance, and high assembly complexity and high cost.
The pendulum bearing clearance control complete set of pretension mechanisms is adopted to reduce parts use and reduce assembly complexity and cost.
It effectively solves the problem of stiffness attenuation and gap of preloading mechanism after durability, improves NVH performance, and reduces the manufacturing cost of the steering machine.
Smart Images
Figure CN222452331U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of steering systems, in particular to a gear rack pre-tightening mechanism for a double pinion steering machine. Background Art
[0002] Currently, the mainstream R-EPS steering gears on the market are divided into three types: 1. Single pinion steering gear; 2. Double pinion steering gear; 3. Ball screw recirculating ball steering gear.
[0003] At present, the mainstream gear rack meshing positions all use a pressure block pre-tightening adjustment mechanism to achieve the vibration caused by the gear rack meshing during the switching process.
[0004] The preload force of the pressure block preload adjustment mechanism is mainly achieved through the change of the diaphragm spring stiffness curve, which realizes the movement of the pressure block subassembly on the inner wall of the housing during the gear rack meshing process, thereby achieving smooth movement of the steering mechanism. The design of the pressure block preload adjustment mechanism has the following problems: 1. The stiffness design of the diaphragm spring, the core preload source, is complex. Excessive stiffness will lead to an increase in preload, thereby increasing the rack moving force and reducing transmission efficiency; too small stiffness will lead to insufficient preload, and the impact energy generated during the gear rack meshing process cannot be effectively absorbed; 2. During the steering endurance process, the stiffness of the diaphragm spring will continue to decay, and the preload effect will deteriorate after the stiffness is reduced, and the structure cannot provide stiffness compensation function; 3. At the same time, after endurance, the gear rack meshing wear and the wear between the lining and the tooth back will cause the pressure block gap to increase, and the NVH performance after the increase will be significantly reduced; 4. The design of the structure has high requirements on the roughness of the inner wall of the shell and the dimensional tolerance accuracy, which invisibly increases the manufacturing cost of parts; 5. Since the structure needs to slide for a long time on the inner wall of the shell and uses the same material, different surface treatment methods are required for the sliding pair mechanism to avoid material sintering after micro-wear. Different surface treatment processes increase the complexity of part manufacturing. Summary of the invention
[0005] In order to overcome the deficiencies of the prior art, the utility model provides a gear rack preload mechanism for a double pinion steering gear, reduces assembly complexity; solves the problem of stiffness attenuation of the preload mechanism after durability; solves the problem of increased clearance due to wear of different mating parts after durability; eliminates the gap adjustment process of the production line pressure block, and controls the entire preload mechanism by the clearance of a pendulum bearing; and reduces the cost of the steering gear by reducing the use of parts.
[0006] To achieve the above-mentioned purpose, a gear rack preload mechanism for a double pinion steering gear is designed, comprising a rack and a long housing, and characterized in that: a long housing is provided on the outer side of the rack, and a steering wheel side bearing installation area and a motor end bearing installation area are respectively provided at both ends of the rack; the steering wheel side bearing installation area comprises a needle bearing and a first pendulum bearing, one end of the rack is sleeved with the first pendulum bearing, and the rack located above the first pendulum bearing is sleeved with a needle bearing; the motor end bearing installation area comprises a ball bearing and a second pendulum bearing, the other end of the rack is sleeved with the second pendulum bearing, and the rack located above the second pendulum bearing is sleeved with a ball bearing.
[0007] The first pendulum bearing and the second pendulum bearing have the same structure. The first pendulum bearing comprises an outer ring, a middle ring, a sealing ring, a retainer, a steel ball and an inner ring. A groove for placing the steel ball is provided in the middle of the inner ring. A plurality of steel balls are evenly distributed in the groove in the middle of the inner ring. One side of the steel ball is fixed by a retainer. The middle ring is sleeved on the outer edge of the steel ball, and the outer ring is sleeved on the outer side of the middle ring. The front and rear sides of the middle ring are sealed respectively by an inner sealing ring and an outer sealing ring.
[0008] The needle bearing is located on the rack near the sensor end.
[0009] The first pendulum bearing and the needle bearing form a hard limit at one end of the rack.
[0010] The ball bearing is located on the rack near the motor end.
[0011] The second pendulum bearing and the ball bearing form a hard limit at the other end of the rack.
[0012] Compared with the prior art, the utility model provides a gear rack preload mechanism for a double pinion steering gear, which reduces assembly complexity; solves the problem of stiffness attenuation of the preload mechanism after durability; solves the problem of increased clearance due to wear of different mating parts after durability; eliminates the gap adjustment process of the production line pressure block, and controls the entire preload mechanism by the clearance of a pendulum bearing; and reduces the cost of the steering gear by reducing the use of parts. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 Schematic diagram of the double pinion steering gear assembly.
[0014] Figure 2 Schematic diagram of the bearing installation area on the steering wheel side of the double pinion steering gear assembly.
[0015] Figure 3 Schematic diagram of the motor-end bearing installation area of the double pinion steering gear assembly.
[0016] Figure 4 This is a three-dimensional diagram of the pendulum bearing structure.
[0017] Figure 5 This is a partial cross-sectional view of the pendulum bearing.
[0018] Figure 6 This is an exploded diagram of the pendulum bearing.
[0019] Figure 7 , Figure 8 Schematic diagram of the pendulum bearing load angle.
[0020] Fig. 9 This is a schematic diagram of the installation of the first pendulum bearing and needle roller bearing.
[0021] Fig.10 This is a schematic diagram of the installation of the second pendulum bearing.
[0022] Fig.11 This is a schematic diagram of the rack installation.
[0023] Fig.12 Schematic diagram of sensor installation.
[0024] Fig.13 This is a schematic diagram of the drive gear shaft installation.
[0025] Fig.14 Schematic diagram of the moving state of the pendulum bearing. DETAILED DESCRIPTION
[0026] The utility model is further described below with reference to the accompanying drawings.
[0027] like Figures 1 to 6 As shown, a long housing 2 is provided on the outer side of the rack 1, and a steering wheel side bearing installation area and a motor end bearing installation area are respectively provided at both ends of the rack 1; the steering wheel side bearing installation area includes a needle bearing and a first pendulum bearing, one end of the rack 1 is sleeved with a first pendulum bearing 3, and the rack 1 above the first pendulum bearing 3 is sleeved with a needle bearing 4; the motor end bearing installation area includes a ball bearing and a second pendulum bearing, the other end of the rack 1 is sleeved with a second pendulum bearing 5, and the rack 1 above the second pendulum bearing 5 is sleeved with a ball bearing 6.
[0028] The first pendulum bearing 3 and the second pendulum bearing 5 have the same structure. The first pendulum bearing includes an outer ring, a middle ring, a sealing ring, a retainer, a steel ball, and an inner ring. A groove for placing the steel ball 5-5 is provided in the middle of the inner ring 5-6. A number of steel balls 5-5 are evenly distributed in the groove in the middle of the inner ring 5-6. One side of the steel ball 5-5 is fixed by a retainer 5-4. The middle ring 5-2 is sleeved on the outer edge of the steel ball 5-5, and the outer side of the middle ring 5-2 is sleeved on the outer side; the front and rear sides of the middle ring 5-2 are sealed by an inner sealing ring 5-3 and an outer sealing ring 5-7 respectively.
[0029] The pendulum bearing is in the assembly, such as Figure 7 , Figure 8 As shown, the gear rack meshing position conversion motion mode: At the same time, according to the calculation of the rated dynamic load of the pendulum bearing can meet: C r =b m f c (icosα )0.7 Z 2 / 3 D W 1.8 =8500N.
[0030] Rated static load: C 0r =f0iZD W 2 cosα=5300N, which can currently meet the F of the meshing point between the drive gear and the rack. x ,F y ,F z , components of force in three directions.
[0031] The needle bearing 4 is located on the rack 1 near the sensor end.
[0032] The first pendulum bearing 3 and the needle bearing 4 form a hard limit at one end of the rack 1 .
[0033] The ball bearing 6 is located on the rack 1 near the motor end.
[0034] The second pendulum bearing 5 and the ball bearing 6 form a hard limit for the other end of the rack 1 .
[0035] The assembly sequence of the utility model structure is as follows:
[0036] 1. Install the bearings of the long housing. First, install the bearings on the steering wheel side. Press the first pendulum bearing 3 and the needle bearing 4 into the hard limit position of the long housing 1. Fig. 9 As shown;
[0037] 2. Next, install the bearing at the motor end and press the second pendulum bearing 5 into the hard limit position of the long housing 1. Fig.10 As shown;
[0038] 3. Assemble the rack 1 into the long housing 1, and assemble the related components of the sensor unit subassembly. Place the rack 1 at the nominal length of the stroke, and then insert the sensor unit subassembly component so that the steering shaft tooth profile meshes with the tooth profile of the rack 1, as shown in the figure. Fig.11 , Fig.12 As shown;
[0039] 4. Assemble the SCU subassembly into the long housing 1, and push the drive gear shaft to the hard limit surface of the inner ring of the second pendulum bearing 5, as shown in the figure. Fig.13 As shown;
[0040] 5. Assemble the left and right ball head tie rods and dust covers.
[0041] During the meshing of the gear rack, the pendulum bearing will produce a small swing displacement with the fluctuation of the tooth meshing to convert the fluctuation caused by the meshing. The floating bearing at the upper end and the steering shaft adopt a clearance fit to achieve the balance of the freedom of the entire small assembly. The movement range of the pendulum bearing is as follows Fig.14 shown.
[0042] In summary, the utility model mainly solves the following structural difficulties:
[0043] 1. The gear rack preload mechanism is changed to a pendulum bearing structure controlled by clearance, which reduces the assembly manufacturing cost of the original pressure block assembly consisting of 7 parts and greatly reduces the complexity of process assembly;
[0044] 2. The radial swing of the gear shaft is controlled by the pendulum bearing, and the long housing is processed into a closed hole, avoiding the subsequent remedial measures for the sealing performance of the long assembly;
[0045] 3. The change in clearance after the pendulum bearing is much smaller than that of the traditional pressure block small assembly structure, including lining, pressure block and adjustment nut, which generally improves the NVH performance after the bearing.
[0046] 4. Due to the excellent NVH performance of the pendulum bearing itself, the knocking noise between the new pressure block and the long housing, the pressure block and the adjusting nut, or the pressure block and the diaphragm spring is greatly reduced.
Claims
1. A gear rack preload mechanism for a double pinion steering gear, comprising a rack and a long housing, characterized in that: A long housing (2) is provided on the outer side of the rack (1), and a steering wheel side bearing installation area and a motor end bearing installation area are respectively provided at both ends of the rack (1); the steering wheel side bearing installation area comprises a needle bearing and a first pendulum bearing, one end of the rack (1) is sleeved with a first pendulum bearing (3), and a needle bearing (4) is sleeved on the rack (1) above the first pendulum bearing (3); the motor end bearing installation area comprises a ball bearing and a second pendulum bearing, the other end of the rack (1) is sleeved with a second pendulum bearing (5), and a ball bearing (6) is sleeved on the rack (1) above the second pendulum bearing (5).
2. The rack and pinion preload mechanism for a double pinion steering gear according to claim 1, characterized in that: The first pendulum bearing (3) and the second pendulum bearing (5) have the same structure. The first pendulum bearing comprises an outer ring, a middle ring, a sealing ring, a retainer, a steel ball, and an inner ring. A groove for placing the steel ball (5-5) is provided in the middle of the inner ring (5-6). A plurality of steel balls (5-5) are evenly distributed in the groove in the middle of the inner ring (5-6). One side of the steel ball (5-5) is fixed by a retainer (5-4). The middle ring (5-2) is sleeved on the outer edge of the steel ball (5-5), and the outer ring (5-1) is sleeved on the outer side of the middle ring (5-2). The front and rear sides of the middle ring (5-2) are sealed respectively by an inner sealing ring (5-3) and an outer sealing ring (5-7).
3. The rack and pinion preload mechanism for a double pinion steering gear according to claim 1, characterized in that: The needle roller bearing (4) is located on the rack (1) close to the sensor end.
4. The rack and pinion preload mechanism for a double pinion steering gear according to claim 1, characterized in that: The first pendulum bearing (3) and the needle bearing (4) form a hard stop at one end of the rack (1).
5. The rack and pinion preload mechanism for a double pinion steering gear according to claim 1, characterized in that: The ball bearing (6) is located on the rack (1) close to the motor end.
6. The rack and pinion preload mechanism for a double pinion steering gear according to claim 1, characterized in that: The second pendulum bearing (5) and the ball bearing (6) form a hard limit stop at the other end of the rack (1).