CN114261443A - Electro-hydraulic steering system and control method - Google Patents
Electro-hydraulic steering system and control method Download PDFInfo
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- CN114261443A CN114261443A CN202210012388.1A CN202210012388A CN114261443A CN 114261443 A CN114261443 A CN 114261443A CN 202210012388 A CN202210012388 A CN 202210012388A CN 114261443 A CN114261443 A CN 114261443A
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- 238000000034 method Methods 0.000 title claims abstract description 14
- 230000002457 bidirectional effect Effects 0.000 claims abstract description 41
- 238000009434 installation Methods 0.000 abstract description 5
- 230000010354 integration Effects 0.000 abstract description 2
- 239000003921 oil Substances 0.000 description 40
- 230000000694 effects Effects 0.000 description 2
- 239000010720 hydraulic oil Substances 0.000 description 2
- 230000003134 recirculating effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
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Abstract
The invention discloses an electro-hydraulic steering system and a control method thereof, wherein the electro-hydraulic steering system comprises a steering mechanism and a hydraulic power-assisted mechanism, the steering mechanism comprises a steering wheel, a steering shaft, a torsion angle sensor and a steering gear which are sequentially connected, and the hydraulic power-assisted mechanism comprises a controller, a servo motor, a bidirectional gear pump, a valve block and a closed oil tank which are sequentially connected. The electro-hydraulic system adopts a closed system, has simple structure and high integration level, saves installation space, reduces the problem of hydraulic leakage, leakage and leakage, avoids a rotating speed interval with poor low-speed characteristic of the bidirectional gear pump, solves the problem of poor low-speed characteristic of the bidirectional gear pump by controlling the shunting of the electromagnetic directional valve when the steering speed is very low, can actively control the servo motor, realizes the auxiliary driving function, and has better operation stability and driving comfort.
Description
Technical Field
The invention relates to the technical field of electro-hydraulic steering systems, in particular to an electro-hydraulic steering system and a control method.
Background
At present, an electro-hydraulic steering gear used on a large-scale commercial vehicle is an electric power-assisted mechanism with a worm and gear type at the input end of a hydraulic steering gear, and both an electric power-assisted part and a hydraulic power-assisted part are provided with a torsion bar, so that the stability of operation and the driving comfort can be improved to a certain extent, and the driving assisting function can be realized, but the effect is not as good as that of a single torsion bar. Due to the fact that the electric power assisting part is added, the size of the product structure is increased, when the existing vehicle hydraulic steering gear is upgraded and replaced, strict requirements are placed on installation space, and upgrading and replacement cannot be achieved for vehicles with limited installation space; and the power source of the hydraulic power-assisted part is driven by the engine, so that the hydraulic pump is always in a working state, thereby shortening the service life of each component of the hydraulic system and seriously wasting energy.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides the electro-hydraulic steering system and the control method, the electro-hydraulic steering system and the control method can save the installation space, and simultaneously can well avoid the rotating speed interval with poor low-speed characteristics of the bidirectional gear pump and solve the problem of poor low-speed characteristics of the bidirectional gear pump.
In order to solve the technical problems, the invention provides the following technical scheme: an electro-hydraulic steering system and a control method thereof comprise a steering mechanism and a hydraulic power-assisted mechanism, wherein the steering mechanism comprises a steering wheel, a steering shaft, a torsion angle sensor and a steering gear which are sequentially connected, and the hydraulic power-assisted mechanism comprises a controller, a servo motor, a bidirectional gear pump, a valve block and a closed oil tank which are sequentially connected.
As a preferable technical scheme of the invention, the steering gear adopts a recirculating ball type structure.
As a preferred technical scheme of the invention, the servo motor, the bidirectional gear pump, the valve block and the closed oil tank are sequentially connected through a connecting piece, and the connecting piece comprises a first bolt and a second bolt.
As a preferable technical solution of the present invention, the valve block includes a first control valve, a second control valve, and an electromagnetic proportional valve, the first control valve is composed of a first pilot operated check valve and a second pilot operated check valve, and the second control valve is composed of a first overflow valve and a second overflow valve.
As a preferable technical scheme of the invention, the first hydraulic control one-way valve, the second hydraulic control one-way valve, the first overflow valve, the second overflow valve and the electromagnetic proportional valve are all of plug-in mounting type structures.
As a preferred technical scheme of the invention, the bidirectional gear pump is provided with an oil inlet, an oil outlet and an oil drainage port.
Compared with the prior art, the invention can achieve the following beneficial effects:
1. the electro-hydraulic system adopts a closed system, has simple structure and high integration level, saves installation space and reduces the problems of hydraulic pressure leakage and leakage;
2. in the invention, the servo motor sets the lowest working rotating speed (+/-500 r/min), avoids the rotating speed interval with poor low-speed characteristics of the bidirectional gear pump, and solves the problem of poor low-speed characteristics of the bidirectional gear pump by controlling the shunting of the electromagnetic directional valve when the steering speed is very low;
3. in the invention, the servo motor drives the bidirectional gear pump to work only when the steering is carried out, thus realizing the high efficiency and energy saving of the system;
4. in the invention, the auxiliary driving function can be realized by actively controlling the servo motor;
5. according to the invention, only one torsion bar is arranged at the torsion angle sensor, so that the steering mechanism has better operation stability and driving comfort.
Drawings
FIG. 1 is a schematic view of the steering system of the present invention;
FIG. 2 is a schematic structural view of a hydraulic assist mechanism according to the present invention;
wherein: 1. a steering wheel; 2. a steering shaft; 3. a torsion angle sensor; 4. a diverter; 5. a servo motor; 6. a bidirectional gear pump; 61. an oil inlet; 62. an oil outlet; 63. an oil drainage port; 7. sealing the oil tank; 8. a first control valve; 81. a first hydraulic control check valve; 82. a second hydraulic control one-way valve; 9. a second control valve; 91. a first overflow valve; 92. a second overflow valve; 10. an electromagnetic proportional valve; 11. a valve block; 12. a controller; 13. a connecting member; 131. a first bolt; 132. and a second bolt.
Detailed Description
The present invention will be further described with reference to specific embodiments for the purpose of facilitating an understanding of technical means, characteristics of creation, objectives and functions realized by the present invention, but the following embodiments are only preferred embodiments of the present invention, and are not intended to be exhaustive. Based on the embodiments in the implementation, other embodiments obtained by those skilled in the art without any creative efforts belong to the protection scope of the present invention. The experimental methods in the following examples are conventional methods unless otherwise specified, and materials, reagents and the like used in the following examples are commercially available unless otherwise specified.
Example (b):
as shown in fig. 1-2, an electro-hydraulic steering system and a control method thereof include a steering mechanism and a hydraulic power-assisted mechanism, wherein the steering mechanism includes a steering wheel 1, a steering shaft 2, a torsion angle sensor 3 and a steering gear 4 which are connected in sequence, and the hydraulic power-assisted mechanism includes a controller 12, a servo motor 5, a bidirectional gear pump 6, a valve block 11 and a closed oil tank 7 which are connected in sequence.
In other embodiments, the diverter 4 is of recirculating ball type construction;
in other embodiments, the servo motor 5, the bidirectional gear pump 6, the valve block 11 and the closed oil tank 7 are sequentially connected through a connecting piece 13, and the connecting piece 13 comprises a first bolt 131 and a second bolt 132;
in other embodiments, the valve block 11 includes a first control valve 8, a second control valve 9, and an electromagnetic proportional valve 10, the first control valve 8 is composed of a first pilot operated check valve 81 and a second pilot operated check valve 82, and the second control valve 9 is composed of a first overflow valve 91 and a second overflow valve 92;
the first hydraulic control check valve 81 and the second hydraulic control check valve 82 have an oil supplementing effect, and the first overflow valve 91 and the second overflow valve 92 have a pressure limiting protection effect on the system.
In other embodiments, the first pilot-operated check valve 81, the second pilot-operated check valve 82, the first overflow valve 91, the second overflow valve 92 and the electromagnetic proportional valve 10 are all of cartridge type structures;
in other embodiments, the bidirectional gear pump 6 is provided with an oil inlet 61, an oil outlet 62 and an oil drainage port 63;
in the graph 1, the mark F is a load, the set lowest working rotating speed of the servo motor 5 is +/-500 r/min, a rotating speed interval with poor low-speed characteristics of the bidirectional gear pump 6 is avoided, when the steering speed is very low and the flow of the boosting pressure oil required by the steering of the steering gear 4 is smaller than the flow of the pressure oil provided by the lowest working rotating speed of the bidirectional gear pump 6, the controller 12 controls the electromagnetic proportional valve 10 to open for a certain opening, so that the redundant flow of the pressure oil flows back to the oil inlet 61 of the bidirectional gear pump 6 through the electromagnetic proportional valve 10, and the problem of poor low-speed characteristics of the bidirectional gear pump 6 is solved; the electromagnetic proportional valve 10 can be controlled by the controller 12 to be completely opened under the non-power-assisted emergency working condition, so that the upper cavity and the lower cavity of the steering gear 4 are communicated, the steering gear 4 is directly driven by the steering wheel 1 to realize steering, and the safety under the emergency working condition is improved.
Basic working principle; taking the clockwise rotation of the steering wheel 1 as an example: when the steering wheel 1 is rotated clockwise, the steering torque is transmitted to the steering gear 4 through the steering shaft 2 and the torsion angle sensor 3 in sequence; wherein the torsion angle sensor 3 transmits a detected torque signal to the controller 12, the controller 12 controls the servo motor 5 to rotate clockwise, an oil outlet 62 of the bidirectional gear pump 6 is driven to provide pressure oil for a lower cavity of the steering gear 4, and hydraulic oil in an upper cavity of the steering gear 4 returns to an oil inlet 61 of the bidirectional gear pump 6 through a pipeline to form a closed system; under the action of steering torque and hydraulic boosting force of the steering wheel 1, the ball nut in the steering gear 4 is driven to move upwards, and the vertical arm rotates anticlockwise.
The relation among the steering wheel rotating torque, the output torque of the servo motor and the load moment is as follows:
in the formula
Respectively the steering wheel rotation torque and the output torque and the load torque of the servo motor; a is the area of the piston of the steering gear cylinder; v is the discharge capacity of the bidirectional gear pump;
is the steering gear angular transmission ratio;
the total efficiency of the steering gear and the mechanical efficiency of the bidirectional gear pump are respectively;
the radius of the pitch circle of the rocker shaft gear sector in the steering gear is the pitch circle radius.
The oil drain port 63 of the bidirectional gear pump 6 is communicated with the closed oil tank 7, and when the bidirectional gear pump 6 works, a small amount of pressure oil continuously flows into the closed oil tank 7 from the oil drain port 63 in the bidirectional gear pump 6, so that the hydraulic oil in the closed oil way is continuously reduced; the pressure oil supplied by the oil outlet 62 of the bidirectional gear pump 6 is communicated with the control cavity of the second hydraulic control one-way valve 82, so that the second hydraulic control one-way valve 82 is reversely opened, and the oil inlet 61 of the bidirectional gear pump 6 is communicated with the closed oil tank 7, so that the oil is more smoothly supplemented to the oil circuit system by the closed oil tank 7. Wherein the first overflow valve 91 defines the maximum operating pressure of the system to prevent the bidirectional gear pump 6 from being damaged by pressure overrun when the load is overloaded or suddenly changed.
When the steering wheel 1 is turned, the controller 12 controls the output torque of the servo motor 5 and the opening degree of the electromagnetic proportional valve 10 according to the received torque signal; the servo motor 5 sets the lowest working rotating speed (500 r/min), when the steering speed is very low, and the power-assisted pressure oil flow required by the steering driven by the steering device 4 is smaller than the pressure oil flow provided by the lowest working rotating speed of the bidirectional gear pump 6, the controller 12 controls the electromagnetic proportional valve 10 to open a certain opening according to the torque signal, so that the redundant pressure oil flow flows back to the oil inlet 61 of the bidirectional gear pump 6 through the electromagnetic proportional valve 10, and the problem of poor low-speed characteristic of the bidirectional gear pump 6 is solved; when the steering wheel 1 is rotated at a middle and fast speed, the controller 12 controls the working rotating speed of the servo motor 5 to be greater than 500r/min according to the torque signal and controls the electromagnetic proportional valve 10 to be closed, and the servo motor 5 drives the bidirectional gear pump 6 to provide pressure oil for the system to be used for driving the steering gear 4 to steer.
The relation between the servo motor n2 and the rotating speed n1 of the steering wheel is as follows:
in the formula
Respectively the rotating speed of a steering wheel and the rotating speed of a servo motor;
as the speed ratio coefficient,
p is the screw pitch of the ball screw nut,
is a bidirectional gear pump volumetric efficiency.
The relationship between the control flow of the electromagnetic proportional valve and the rotating speed of the steering wheel is as follows:
wherein Q is the control flow of the electromagnetic proportional valve;
the total flow of the bidirectional gear pump at the rotating speed of 500 r/min;
the boosting flow provided by the bidirectional gear pump to the steering gear;
wherein the relational expression of the control flow of the electromagnetic proportional valve and the opening of the control valve port is
Wherein C is a throttling coefficient,
is the opening area of the valve port,
is the pressure difference between the front and the back of the valve port,
and m is an index determined by the valve port structure.
When the servo motor 5 or the bidirectional gear pump 6 and other elements are damaged and fail, the controller 12 controls the electromagnetic proportional valve 10 to be completely opened, so that the upper cavity and the lower cavity of the steering gear 4 are communicated, the steering gear 4 can be driven to steer by rotating the steering wheel 1, and the safety under the emergency working condition is improved.
The preferred scheme in the invention is as follows: the maximum output torque of the steering gear 4 is more than or equal to 8000Nm, the diameter of a cylinder piston in the steering gear 4 is 120mm, and the maximum working pressure is 17 MPa.
The bidirectional gear pump 6 has the following working parameters:
| serial number | Parameter name | Parameter value |
| 1 | Maximum working pressure/MPa | 17 |
| 2 | Relief valve set safety pressure/MPa | 18 |
| 3 | Rotation speed range/r/min | 500~2500 |
The servo motor 5 has the following working parameters:
| serial number | Parameter name | Parameter value |
| 1 | Rated power/W | 3000 |
| 2 | Rated torque/Nm | 27.2 |
| 3 | Rated speed/r/min | 1050 |
The product prototype test shows that the performance index can meet the requirement, and the maximum output torque is actually measured to be 8250 Nm; when the vehicle runs at a low speed, the steering hand force is light; when the vehicle runs at a high speed, the vehicle has good holding torque and road feel; in the angle control mode, the driving assist function can be realized.
In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and the preferred embodiments of the present invention are described in the above embodiments and the description, and are not intended to limit the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (6)
1. An electro-hydraulic steering system and a control method are characterized in that: the steering mechanism comprises a steering wheel (1), a steering shaft (2), a torsion angle sensor (3) and a steering gear (4) which are sequentially connected, and the hydraulic power-assisted mechanism comprises a controller (12), a servo motor (5), a bidirectional gear pump (6), a valve block (11) and a closed oil tank (7) which are sequentially connected.
2. The electro-hydraulic steering system and the control method according to claim 1, characterized in that: the steering gear (4) adopts a circulating ball type structure.
3. The electro-hydraulic steering system and the control method according to claim 1, characterized in that: the servo motor (5), the bidirectional gear pump (6), the valve block (11) and the sealed oil tank (7) are connected sequentially through a connecting piece (13), and the connecting piece (13) comprises a first bolt (131) and a second bolt (132).
4. The electro-hydraulic steering system and the control method according to claim 1, characterized in that: the valve block (11) comprises a first control valve (8), a second control valve (9) and an electromagnetic proportional valve (10), the first control valve (8) is composed of a first hydraulic control one-way valve (81) and a second hydraulic control one-way valve (82), and the second control valve (9) is composed of a first overflow valve (91) and a second overflow valve (92).
5. The electro-hydraulic steering system and the control method according to claim 4, wherein: the first hydraulic control one-way valve (81), the second hydraulic control one-way valve (82), the first overflow valve (91), the second overflow valve (92) and the electromagnetic proportional valve (10) are all of plug-in mounting type structures.
6. The electro-hydraulic steering system and the control method according to claim 1, characterized in that: an oil inlet (61), an oil outlet (62) and an oil drainage port (63) are arranged on the bidirectional gear pump (6).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210012388.1A CN114261443A (en) | 2022-01-07 | 2022-01-07 | Electro-hydraulic steering system and control method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202210012388.1A CN114261443A (en) | 2022-01-07 | 2022-01-07 | Electro-hydraulic steering system and control method |
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| CN202210012388.1A Pending CN114261443A (en) | 2022-01-07 | 2022-01-07 | Electro-hydraulic steering system and control method |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080243340A1 (en) * | 2007-03-29 | 2008-10-02 | Hung Stephen T | Power assist steering system |
| CN102372025A (en) * | 2010-08-26 | 2012-03-14 | 长沙中联重工科技发展股份有限公司 | Electric control closed type hydraulic steering system, control method and vehicle having system |
| CN108791478A (en) * | 2018-05-29 | 2018-11-13 | 王岚 | A kind of direct drive type electrohydraulic power steering stgear |
| CN109131547A (en) * | 2018-10-29 | 2019-01-04 | 北京航天发射技术研究所 | Moving cell and control method are made in a kind of steering of integrated electrical liquid |
| CN110949496A (en) * | 2019-11-15 | 2020-04-03 | 江苏大学 | Double-oil-pump type hybrid electric control steering system and control method thereof |
| CN111824251A (en) * | 2020-07-30 | 2020-10-27 | 清华大学 | Energy-saving intelligent electro-hydraulic steering system and control method |
-
2022
- 2022-01-07 CN CN202210012388.1A patent/CN114261443A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080243340A1 (en) * | 2007-03-29 | 2008-10-02 | Hung Stephen T | Power assist steering system |
| CN102372025A (en) * | 2010-08-26 | 2012-03-14 | 长沙中联重工科技发展股份有限公司 | Electric control closed type hydraulic steering system, control method and vehicle having system |
| CN108791478A (en) * | 2018-05-29 | 2018-11-13 | 王岚 | A kind of direct drive type electrohydraulic power steering stgear |
| CN109131547A (en) * | 2018-10-29 | 2019-01-04 | 北京航天发射技术研究所 | Moving cell and control method are made in a kind of steering of integrated electrical liquid |
| CN110949496A (en) * | 2019-11-15 | 2020-04-03 | 江苏大学 | Double-oil-pump type hybrid electric control steering system and control method thereof |
| CN111824251A (en) * | 2020-07-30 | 2020-10-27 | 清华大学 | Energy-saving intelligent electro-hydraulic steering system and control method |
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Application publication date: 20220401 |
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