A highly sensitive electric recirculating ball steering gear

Abstract

The present invention discloses a highly sensitive electric recirculating ball steering gear, aiming to solve the problems in existing steering gears such as the inability to completely cancel the radial force of the ball screw, increased friction, and insufficient sensitivity. The present invention adopts an innovative combined design of hydraulic active radial force balance, adaptive piston plates, and a closed-loop hydraulic control system; by the action of high-pressure liquid in the oil storage tank on the piston plates, the piston plates slide in the guide grooves to balance the radial force generated by the nut teeth, thereby effectively reducing the force on the ball screw; the adaptive piston plates adopt a double-layer structure with a micro spring plate embedded in the middle, which can adjust the contact pressure in real time according to the change of hydraulic pressure to reduce friction and enhance durability; in addition, by detecting the torque signal of the input shaft through a sensor, the electric control pump dynamically adjusts the hydraulic oil pressure to achieve real-time radial force balance; the present invention has high sensitivity, low friction, and high durability, and is particularly suitable for the commercial vehicle market with high requirements for high-precision steering control.

Description

Technical Field

[0001] The present invention relates to the technical field of steering gears, and particularly to a highly sensitive electric recirculating ball steering gear. Background Technique

[0002] Electric recirculating ball steering gears are widely used in the steering systems of commercial vehicles, and mainly rely on mechanical force transmission inside. In traditional designs, the ball screw often bears large axial and radial forces. Especially with the trend of reducing the number of turns of the vehicle steering wheel to improve steering sensitivity, this force-bearing situation is more obvious. After long-term use, pitting and damage may occur to the ball screw, 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 deficiencies: First, the radial force is not completely offset: Since the radial force is not completely offset, the ball screw still bears the residual radial force, affecting its performance and life; Second, the friction increases: As the use time increases, the contact surface between the nut and the housing may wear, resulting in a decrease in the contact force and an increase in the radial force, thereby affecting the steering accuracy and durability. It cannot meet the actual use requirements, so there is an urgent need for improved technologies in 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, provide a highly sensitive electric recirculating ball steering gear, which completely changes the traditional steering gear structure, innovatively designs the structure of the oil storage tank and piston guide, uses the hydraulic oil pressure to offset the radial force generated by the nut, reduces the burden on the ball screw, and at the same time, this structure will not increase the size of the steering gear, will not change the original structure, and will not cause problems of incompatibility with traditional steering gears, and can effectively solve the problems in the background technique.

[0005] To achieve the above object, the present invention provides the following technical solution: A highly sensitive electric recirculating ball steering gear, including a housing, an electric control pump, and a screw. The screw is installed in the housing through bearings. A nut is provided on the screw. An oil storage tank is provided on the outer side of the nut. A sealing gasket and a piston piece are provided at the left end of the oil storage tank. A guide groove is provided on the inner wall of the housing. The guide groove is in sliding contact with the piston piece. An oil outlet and an oil inlet are provided at the lower part of the guide groove. The oil outlet is communicated with the oil inlet through a telescopic oil pipe. The electric control pump is provided outside the housing. The inlet and outlet of the electric control pump are respectively communicated with the oil inlet and the oil outlet. A sensor is provided above the screw. The sensor is electrically connected to the electric control pump through a sensor wire harness.

[0006] Furthermore, the piston piece is arranged in a double-layer structure, which are respectively an outer layer piece and an inner layer piece. A spring piece is arranged between the outer layer piece and the inner layer piece. The spring piece, the outer layer piece and the inner layer piece form an adaptive piston structure, and the inner layer piece is fixedly connected to the gasket.

[0007] Furthermore, the outer layer piece contacts with the guide groove. A silicon nitride coating is arranged on the outer surface of the outer layer piece. The outer layer piece is arranged in a concave structure, and the spring piece is located in the groove of the outer layer piece.

[0008] Furthermore, the oil storage tank is communicated with the electric control pump through a telescopic oil pipe, which is used to receive high-pressure oil fluid. The oil outlet is communicated with the inner cavity of the housing to form a closed-loop hydraulic circuit.

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

[0010] Furthermore, the upper end of the lead screw is connected to an input shaft through a torsion bar. The input shaft is connected to the main drive shaft of the steering wheel, and the sensor is installed on the input shaft.

[0011] Furthermore, a worm and worm gear are arranged on the lead screw. The lead screw is connected to an external motor through the worm and worm gear.

[0012] Furthermore, the nut and the oil storage tank are fixed by welding. The meshing teeth on the outside of the nut are meshed with the output shaft.

[0013] Furthermore, the spring piece is made of a stainless steel micro spring piece. The spring pieces are arranged in a ring shape, and one spring piece is arranged every 30°.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] 1. Through the design of hydraulic active radial force balance and adaptive piston piece, the present invention realizes that when the steering wheel turns of the whole vehicle are controlled within 4 turns, the ball screw still meets the bearing capacity requirement and maintains a highly sensitive steering response. This technical improvement meets the strict requirements of commercial vehicles for high-precision steering control and ensures the accurate control ability of the vehicle under complex working conditions.

[0016] 2. The adaptive piston piece adopts a double-layer structure, and the contact area is dynamically adjusted through the micro spring piece, effectively reducing the friction between the piston piece and the guide groove. The use of the designed coating further reduces the sliding friction coefficient, reduces the energy consumption loss, thereby improving the overall operation efficiency of the system and significantly extending the service life of the ball screw and the piston piece.

[0017] 3. The hydraulic pressure generated by the high-pressure hydraulic oil in the oil storage tank forms a dynamic balance with the radial force generated by the nut teeth, effectively avoiding abnormal wear and pitting of the ball screw due to uneven stress; this design significantly improves the durability and reliability of the ball screw and is especially suitable for vehicles with long-term high-intensity use.

[0018] 4. The closed-loop hydraulic control system formed by the sensor and the electronic control 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, without increasing the overall size, this device improves the radial force balance method and can directly replace the existing electric recirculating ball steering gear, with strong market adaptability and installation convenience. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of the present invention;

[0020] Figure 2 is a schematic structural diagram of the guiding groove of the present invention;

[0021] Figure 3 is a schematic structural diagram of the oil storage tank arranged on the nut of the present invention;

[0022] Figure 4 is a schematic structural diagram of the adaptive piston of the present invention.

[0023] In the figure: 1 input shaft, 2 torsion bar, 3 sensor, 4 worm and worm gear, 5 screw rod, 6 nut, 7 gasket, 8 piston piece, 9 telescopic oil pipe, 10 sensor wire harness, 11 electronic control pump, 12 housing, 13 output shaft, 121 guiding groove, 122 oil outlet, 123 oil inlet, 601 oil storage tank, 602 meshing teeth, 801 outer layer piece, 802 spring piece, 803 inner layer piece. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0025] Please refer to Figures 1-4, the present invention provides a technical solution: a highly sensitive electric recirculating ball steering gear, including a housing 12, an electric control pump 11 and a lead screw 5. The lead screw 5 is installed in the housing 12 through bearings. A nut 6 is arranged on the lead screw 5. An oil storage tank 601 is arranged on the outer side of the nut 6 for storing high-pressure hydraulic oil. A gasket 7 and a piston piece 8 are arranged at the left end of the oil storage tank 601. A guide groove 121 is arranged on the inner wall of the housing 12. The guide groove 121 is in sliding contact with the piston piece 8. The oil storage tank 601 generates a radial force through high-pressure hydraulic oil, and the generated radial force cancels out the radial force generated by the meshing teeth 602 of the nut 6, thereby reducing the force on the lead screw 5. An oil outlet 122 and an oil inlet 123 are arranged at the lower part of the guide groove 121. The oil outlet 122 is communicated with the retractable oil pipe 9 through the retractable oil pipe 9. The electric control pump 11 is arranged outside the housing 12. The inlet and outlet of the electric control pump 11 are respectively communicated with the oil inlet 123 and the oil outlet 122. A sensor 3 is arranged above the lead screw 5. The sensor 3 is electrically connected to the electric control pump 11 through a sensor wire harness 10.

[0026] Force balance analysis, the forces in the system need to satisfy the following balance condition: F total radial force = F tooth force - F hydraulic pressure = 0.

[0027] Actual force state: F tooth force > F hydraulic pressure, the radial force is not completely cancelled, and there is still residual radial force; F tooth force < F hydraulic pressure, the radial force is over-compensated, which may cause the lead screw to deflect in the opposite direction; the torque change generated by the input shaft is monitored in real time through the sensor 3, and the signal is transmitted to the electric control pump 11; the electric control pump 11 adjusts the oil pressure: the electric control pump 11 adjusts the oil pressure according to the sensor signal to ensure the oil pressure and ensure the real-time matching of the tooth force; the piston piece 8 is set as a double-layer structure, the double-layer structure is respectively an outer layer piece 801 and an inner layer piece 803, and a spring piece 802 is arranged between the outer layer piece 801 and the inner layer piece 803. The spring piece 802, the outer layer piece 801 and the inner layer piece 803 form an adaptive piston structure for adaptively adjusting the contact pressure between the piston piece 8 and the guide groove 121 according to the change of the hydraulic oil pressure, and has the effect of dynamic balance: the spring piece 802 can be adjusted in real time according to the hydraulic oil fluctuation, improving the sensitivity and reliability of the steering gear. When the hydraulic pressure decreases, the micro spring piece 802 rebounds, reducing the contact area, thereby restoring the initial state and maintaining the force balance. The inner layer piece 803 is fixedly connected to the gasket 7, and the oil storage tank 601 is sealed through the gasket 7.

[0028] The additionally provided adaptive piston structure realizes more efficient radial force balance and anti-friction effect through the innovative design of the double-layer structure and the spring piece 802, is particularly suitable for the requirements of a highly sensitive electric recirculating ball steering gear, and effectively improves the durability and performance stability of the system.

[0029] The outer layer piece 801 contacts with the guiding groove 121. A silicon nitride coating is provided on the outer surface of the outer layer piece 801, which significantly improves wear resistance and reduces the friction coefficient, making the piston structure more sensitive. The outer layer piece 801 is arranged in a concave structure. The spring piece 802 is located in the groove of the outer layer piece 801 to restrict the spring piece 802, which is convenient for installation and improves the structural stability.

[0030] The oil storage tank 601 is communicated with the electric control pump 11 through the telescopic oil pipe 9, and is used for receiving high-pressure oil fluid. The oil outlet 122 is communicated with the inner cavity of the housing 12 to form a closed-loop hydraulic circuit.

[0031] 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.

[0032] The upper end of the lead screw 5 is connected with an input shaft 1 through a torsion bar 2. The torsion bar 2 generates torsional deformation when the input shaft 1 rotates. The input shaft 1 is connected with the main drive shaft of the steering wheel and is used for receiving the steering input of the driver. The sensor 3 is installed on the input shaft 1, and the sensor 3 is used for detecting the deformation amount of the torsion bar 2.

[0033] A worm and worm gear 4 is arranged on the lead screw 5, and the lead screw 5 is connected with an external motor through the worm and worm gear 4.

[0034] The nut 6 and the oil storage tank 601 are fixed by welding. The meshing teeth 602 on the outer side of the nut 6 are meshed with the output shaft 13.

[0035] The spring piece 802 adopts an integral disc spring. The spring piece 802 can also adopt a stainless steel micro spring piece. When using the stainless steel micro spring piece, the spring pieces 802 are arranged in a ring shape, and one spring piece 802 is arranged every 30°. According to different hydraulic requirements, the stiffness can be adjusted by changing the thickness and material of the spring piece 802.

[0036] The highly sensitive electric recirculating ball steering gear of the present invention effectively solves the problems of incomplete cancellation of the radial force of the ball screw 5, increased friction and insufficient sensitivity through hydraulic active radial force balance and an adaptive piston piece structure.

[0037] The above shows and describes the basic principles, main features and advantages of the present invention. Without departing from the spirit and scope of the present invention, the present invention has various changes and improvements, and these changes and improvements all fall into the scope of the present invention claimed.

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 oil storage tank (601) via a telescopic oil pipe (9). The electric control pump (11) is provided on the outer side of the housing (12). The inlet and outlet of the electric control pump (11) are respectively connected to the oil inlet (123) and the oil outlet (122); a sensor (3) is arranged above the screw rod (5); the sensor (3) is electrically connected to the electric control pump (11) through a sensor harness (10); the piston plate (8) is arranged to have a double-layer structure, the double-layer structure comprises an outer layer plate (801) and an inner layer plate (803); a spring plate (802) is arranged 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) form an adaptive piston structure; the inner layer plate (803) is fixedly connected to the sealing gasket (7).

2. A highly sensitive 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).

3. 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.

4. A highly sensitive electric recirculating ball steering gear according to claim 3, characterized in that: The telescopic oil pipe (9) is made of a flexible hose and is provided with a metal mesh reinforcement layer.

5. 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).

6. 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).

7. 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).

8. 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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