High-sensitivity electric recirculating ball steering gear

Abstract

The invention discloses a high-sensitivity electric recirculating ball steering gear and aims to solve the problems that the radial force of a ball screw in an existing steering gear cannot be completely offset, friction is increased and sensitivity is insufficient. According to the invention, an innovative combination design of hydraulic active radial force balance, a self-adaptive piston piece and a closed-loop hydraulic control system is adopted; the high-pressure liquid in the oil storage tank acts on the piston piece, so that the piston piece slides in the guide groove to balance the radial force generated by the nut tooth shape, and the stress of the ball screw is effectively reduced; the self-adaptive piston piece is of a double-layer structure, a miniature spring piece is embedded in the middle, contact pressure can be adjusted in real time according to hydraulic pressure changes, friction is reduced, and durability is enhanced. In addition, torque signals of the input shaft are detected through the sensor, the electric control pump dynamically adjusts the hydraulic oil pressure, and real-time radial force balance is achieved. The invention has the advantages of high sensitivity, low friction and high durability, and is particularly suitable for commercial vehicle markets with higher requirements on high-precision steering control.

Description

Technical Field

[0001] The invention relates to the technical field of steering gears, in particular to a high-sensitivity electric circulating ball steering gear. Background Art

[0002] Electric recirculating ball steering gears are widely used in the steering systems of commercial vehicles, which mainly rely on mechanical force transmission. In traditional designs, ball screws often bear large axial and radial forces, especially as the number of steering wheel circles of the whole vehicle is reduced to improve steering sensitivity. This force situation is more obvious. After long-term use, the ball screw may be pitted and damaged, reducing the durability of the system.

[0003] In the prior art, Chinese patent application No. 202011009669.9 discloses an electric power steering device that attempts to reduce part of the radial force through direct dry friction between the nut and the housing. However, this design has the following shortcomings: 1. Incomplete radial force offset: Since the radial force cannot be completely offset, the ball screw still bears residual radial force, affecting its performance and life; 2. Increased friction: As the use time increases, the contact surface between the nut and the housing may wear, resulting in a decrease in contact force and an increase in radial force, which in turn affects the steering accuracy and durability. It cannot meet the needs of actual use, so there is an urgent need for improved technology on the market to solve the above problems. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the existing defects and provide a high-sensitivity electric circulating ball steering gear, which completely changes the traditional steering gear structure and innovatively designs the structure of the oil storage tank and the piston guide, and uses the hydraulic oil pressure to offset the radial force generated by the nut, thereby reducing the burden on the ball screw. At the same time, this structure will not increase the size of the steering gear, will not change the original structure, will not cause the problem of incompatibility with the traditional steering gear, and can effectively solve the problems in the background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a highly sensitive electric circulating ball steering gear, comprising a housing, an electronically controlled pump and a screw rod, the screw rod being installed in the housing through a bearing, a nut being arranged on the screw rod, an oil storage tank being arranged on the outer side of the nut, a sealing gasket and a piston plate being arranged on the left end of the oil storage tank, a guide groove being arranged on the inner wall of the housing, the guide groove being in sliding contact with the piston plate, an oil outlet and an oil inlet being arranged at the lower part of the guide groove, the oil outlet being connected with the telescopic oil pipe through a telescopic oil pipe, the electronically controlled pump being arranged on the outer side of the housing, the inlet and the outlet of the electronically controlled pump being connected with the oil inlet and the oil outlet respectively, a sensor being arranged above the screw rod, and the sensor being electrically connected with the electronically controlled pump through a sensor harness.

[0006] Furthermore, the piston plate is configured as a double-layer structure, the double-layer structure comprises an outer layer plate and an inner layer plate, a spring plate is arranged between the outer layer plate and the inner layer plate, the spring plate, the outer layer plate and the inner layer plate constitute an adaptive piston structure, and the inner layer plate is fixedly connected to the sealing gasket.

[0007] Furthermore, the outer layer sheet is in contact with the guide groove, the outer surface of the outer layer sheet is provided with a silicon nitride coating, the outer layer sheet is arranged in a concave structure, and the spring sheet is located in the groove of the outer layer sheet.

[0008] Furthermore, the oil storage tank is connected to the electronically controlled pump via a retractable oil pipe for receiving high-pressure oil, and the oil outlet is connected to the inner cavity of the shell to form a closed-loop hydraulic circuit.

[0009] Furthermore, the retractable oil pipe is made of a flexible hose and is provided with a metal mesh reinforcement layer.

[0010] Furthermore, the upper end of the screw rod is connected to an input shaft through a torsion bar, the input shaft is connected to a main driving shaft of the steering wheel, and the sensor is mounted on the input shaft.

[0011] Furthermore, a worm gear is provided on the lead screw, and the lead screw is connected to an external motor via the worm gear.

[0012] Furthermore, the nut is fixed to the oil storage tank by welding, and the meshing teeth on the outer side of the nut mesh with the output shaft.

[0013] Furthermore, the spring sheets are stainless steel micro spring sheets, and the spring sheets are arranged in a ring shape, with one spring sheet arranged every 30 degrees.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention realizes that the ball screw can still meet the load-bearing capacity requirements and maintain a highly sensitive steering response when the number of steering wheel turns of the whole vehicle is controlled within 4 turns through the design of hydraulic active radial force balance and adaptive piston plate; this technical improvement meets the strict requirements of commercial vehicles for high-precision steering control and ensures the vehicle's precise control capability under complex working conditions.

[0015] 2. The adaptive piston plate adopts a double-layer structure and dynamically adjusts the contact area through a micro spring plate, effectively reducing the friction between the piston plate and the guide groove; the use of the designed coating further reduces the sliding friction coefficient and reduces energy loss, thereby improving the overall operating efficiency of the system and significantly extending the service life of the ball screw and piston plate.

[0016] 3. The hydraulic pressure generated by the high-pressure hydraulic oil in the oil tank forms a dynamic balance with the radial force generated by the nut tooth shape, effectively avoiding abnormal wear and pitting of the ball screw due to uneven force; this design significantly improves the durability and reliability of the ball screw, and is particularly suitable for vehicles that are used for a long time and at high intensity.

[0017] 4. The closed-loop hydraulic control system formed by the sensor and the electronically controlled pump can monitor and adjust the hydraulic oil pressure in real time to ensure that the radial force of the ball screw remains balanced under various working conditions. In addition, the device improves the radial force balancing method without increasing the overall size, and can directly replace the existing electric recirculating ball steering gear, with strong market adaptability and installation convenience. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the guide groove structure of the present invention; Figure 3 This is a schematic diagram of the structure of an oil storage tank provided on a nut of the present invention; Figure 4 This is a schematic diagram of the adaptive piston structure of the present invention.

[0019] In the figure: 1 input shaft, 2 torsion bar, 3 sensor, 4 worm gear, 5 lead screw, 6 nut, 7 sealing gasket, 8 piston plate, 9 telescopic oil pipe, 10 sensor harness, 11 electronically controlled pump, 12 housing, 13 output shaft, 121 guide groove, 122 oil outlet, 123 oil inlet, 601 oil storage tank, 602 meshing teeth, 801 outer layer plate, 802 spring plate, 803 inner layer plate. DETAILED DESCRIPTION

[0020] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0021] See also Figure 1-4The present invention provides a technical solution: a highly sensitive electric circulating ball steering gear, comprising a housing 12, an electronically controlled pump 11 and a screw rod 5, the screw rod 5 being installed in the housing 12 through a bearing, a nut 6 being arranged on the screw rod 5, an oil storage tank 601 being arranged on the outer side of the nut 6 for storing high-pressure hydraulic oil, a sealing gasket 7 and a piston plate 8 being arranged on the left end of the oil storage tank 601, a guide groove 121 being arranged on the inner wall of the housing 12, the guide groove 121 being in sliding contact with the piston plate 8, and the oil storage tank 601 generating a radial pressure through the high-pressure oil The radial force generated by the meshing teeth 602 of the nut 6 is offset by the radial force, thereby reducing the force on the screw rod 5. An oil outlet 122 and an oil inlet 123 are provided at the lower part of the guide groove 121. The oil outlet 122 is connected with the telescopic oil pipe 9 through the telescopic oil pipe 9. The electronically controlled pump 11 is arranged on the outer side of the housing 12. The inlet and outlet of the electronically controlled pump 11 are respectively connected with the oil inlet 123 and the oil outlet 122. A sensor 3 is provided above the screw rod 5, and the sensor 3 is electrically connected with the electronically controlled pump 11 through the sensor harness 10.

[0022] Force balance analysis: the forces in the system need to satisfy the following balance conditions: Ftotal radial force = Ftooth force - Fliquid pressure = 0.

[0023] Actual stress state: F tooth force>F hydraulic pressure, radial force is not completely offset, and residual radial force still exists; F tooth force<F hydraulic pressure, radial force is over-compensated, which may cause the screw to deviate in the opposite direction; the torque change generated by the input shaft is monitored in real time by sensor 3, and the signal is transmitted to the electronically controlled pump 11; the electronically controlled pump 11 adjusts the oil pressure: the electronically controlled pump 11 adjusts the oil pressure according to the sensor signal to ensure the oil pressure and the real-time tooth stress match; the piston plate 8 is set to a double-layer structure, the double-layer structure is an outer plate 801 and an inner plate 803, and the outer plate 801 and the inner plate 803 are respectively A spring sheet 802 is arranged in the middle, and the spring sheet 802, the outer sheet 801 and the inner sheet 803 constitute an adaptive piston structure, which is used to adaptively adjust the contact pressure between the piston sheet 8 and the guide groove 121 according to the change of hydraulic oil pressure, and has a dynamic balance effect: the spring sheet 802 can be adjusted in real time according to the fluctuation of hydraulic oil, thereby improving the sensitivity and reliability of the steering gear. When the hydraulic pressure decreases, the micro spring sheet 802 rebounds to reduce the contact area, thereby restoring the initial state and maintaining force balance. The inner sheet 803 is fixedly connected to the sealing gasket 7, and the oil storage tank 601 is sealed by the sealing gasket 7.

[0024] In addition, the adaptive piston structure has a double-layer structure and the innovative design of the spring sheet 802, which achieves a more efficient radial force balance and friction reduction effect. It is particularly suitable for the needs of high-sensitivity electric recirculating ball steering gears, and effectively improves the durability and performance stability of the system.

[0025] The outer layer 801 is in contact with the guide groove 121. The outer surface of the outer layer 801 is provided with a silicon nitride coating, which significantly improves the wear resistance and reduces the friction coefficient, making the piston structure more sensitive. The outer layer 801 is arranged into a concave structure, and the spring sheet 802 is located in the groove of the outer layer 801, which restricts the spring sheet 802, facilitates installation, and improves the stability of the structure.

[0026] The oil storage tank 601 is connected to the electronically controlled pump 11 through the retractable oil pipe 9 for receiving high-pressure oil, and the oil outlet 122 is connected to the inner cavity of the housing 12 to form a closed-loop hydraulic circuit.

[0027] The telescopic oil pipe 9 is made of a flexible hose and is provided with a metal mesh reinforcement layer to improve the pressure resistance and service life.

[0028] The upper end of the screw rod 5 is connected to the input shaft 1 through the torsion bar 2. The torsion bar 2 is torsionally deformed when the input shaft 1 rotates. The input shaft 1 is connected to the main drive shaft of the steering wheel for receiving the driver's steering input. The sensor 3 is installed on the input shaft 1. The sensor 3 is used to detect the deformation of the torsion bar 2.

[0029] A worm gear 4 is disposed on the lead screw 5 , and the lead screw 5 is connected to an external motor via the worm gear 4 .

[0030] The nut 6 is fixed to the oil storage tank 601 by welding, and the meshing teeth 602 on the outer side of the nut 6 mesh with the output shaft 13 .

[0031] The spring sheet 802 adopts an integral butterfly spring. The spring sheet 802 can also adopt a stainless steel micro spring sheet. When using a stainless steel micro spring sheet, the spring sheet 802 is arranged in a ring, with a spring sheet 802 arranged every 30°. The stiffness can be adjusted by changing the thickness and material of the spring sheet 802 according to different hydraulic requirements.

[0032] The high-sensitivity electric recirculating ball steering gear of the present invention effectively solves the problems that the radial force of the ball screw 5 cannot be completely offset, the friction is increased, and the sensitivity is insufficient through hydraulic active radial force balance and adaptive piston plate structure.

[0033] The basic principles, main features and advantages of the present invention are shown and described above. Without departing from the spirit and scope of the present invention, the present invention may also be subject to various changes and improvements, which all fall within the scope of the present invention to be protected.

Claims

1. A highly sensitive electric recirculating ball steering gear, comprising a housing (12), an electronically controlled pump (11) and a screw (5), characterized in that: The screw rod (5) is installed in the housing (12) via a bearing. A nut (6) is provided on the screw rod (5). An oil storage tank (601) is provided on the outer side surface of the nut (6). A sealing gasket (7) and a piston plate (8) are provided at the left end of the oil storage tank (601). A guide groove (121) is provided on the inner wall of the housing (12). The guide groove (121) is in sliding contact with the piston plate (8). An oil outlet (122) and an oil inlet (123) are provided at the lower part of the guide groove (121). The oil outlet (122) is connected to the telescopic oil pipe (9) via a telescopic oil pipe (9). An electric control pump (11) is provided on the outer side of the housing (12). An inlet and an outlet of the electric control pump (11) are connected to the oil inlet (123) and the oil outlet (122) respectively. A sensor (3) is provided above the screw rod (5). The sensor (3) is electrically connected to the electric control pump (11) via a sensor harness (10).

2. A highly sensitive electric recirculating ball steering gear according to claim 1, characterized in that: The piston plate (8) is configured as a double-layer structure, wherein the double-layer structure comprises an outer layer plate (801) and an inner layer plate (803), a spring plate (802) is provided between the outer layer plate (801) and the inner layer plate (803), the spring plate (802), the outer layer plate (801) and the inner layer plate (803) constitute an adaptive piston structure, and the inner layer plate (803) is fixedly connected to the sealing gasket (7).

3. The high-sensitivity electric recirculating ball steering gear according to claim 1, characterized in that: The outer layer sheet (801) is in contact with the guide groove (121), the outer surface of the outer layer sheet (801) is provided with a silicon nitride coating, the outer layer sheet (801) is arranged in a concave structure, and the spring sheet (802) is located in the groove of the outer layer sheet (801).

4. The high-sensitivity electric recirculating ball steering gear according to claim 1, characterized in that: The oil storage tank (601) is connected to the electric control pump (11) via a retractable oil pipe (9) and is used to receive high-pressure oil. The oil outlet (122) is connected to the inner cavity of the housing (12) to form a closed hydraulic circuit.

5. The high-sensitivity electric recirculating ball steering gear according to claim 4, characterized in that: The telescopic oil pipe (9) is made of a flexible hose and is provided with a metal mesh reinforcement layer.

6. The high-sensitivity electric recirculating ball steering gear according to claim 1, characterized in that: The upper end of the screw rod (5) is connected to an input shaft (1) via a torsion bar (2), the input shaft (1) is connected to a main drive shaft of a steering wheel, and the sensor (3) is mounted on the input shaft (1).

7. The high-sensitivity electric recirculating ball steering gear according to claim 1, characterized in that: A worm gear (4) is arranged on the lead screw (5), and the lead screw (5) is connected to an external motor via the worm gear (4).

8. The high-sensitivity electric recirculating ball steering gear according to claim 1, characterized in that: The nut (6) and the oil storage tank (601) are fixed by welding, and the meshing teeth (602) on the outer side of the nut (6) mesh with the output shaft (13).

9. The high-sensitivity electric recirculating ball steering gear according to claim 2, characterized in that: The spring sheets (802) are stainless steel micro spring sheets, and the spring sheets (802) are arranged in a ring shape, with one spring sheet (802) arranged every 30°.

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