An autonomous vehicle braking system

Abstract

The application discloses an unmanned vehicle braking system, comprising: a first hydraulic control circuit connected with a caliper; a second hydraulic control circuit connected with the first hydraulic control circuit; the first hydraulic control circuit is not configured with a brake pedal device; the first hydraulic control circuit is built pressure after being powered on, and it is determined to brake through the first hydraulic control circuit or to brake through the first hydraulic control circuit and the second hydraulic control circuit; the brake pedal device is reduced in the first hydraulic control circuit, the cost is lower, pressure control can be separately performed through the first hydraulic control circuit and the second hydraulic control circuit, front and rear axle braking force distribution is quickly realized, higher braking deceleration is realized, and the braking distance is effectively shortened.

Description

Technical Field

[0001] This invention relates to the field of automotive braking control, and more particularly to a braking system for autonomous vehicles. Background Technology

[0002] Because existing autonomous vehicles lack a driver, they lack a driver's brakes as an emergency backup in the event of a braking system failure, necessitating redundant braking as an emergency backup. In existing braking schemes, the oil suction circuit of the redundant braking unit passes through the TSV safety valve of the main braking circuit and the master cylinder of the brake pedal device. This leads to inconsistent pressure build-up rates between the two circuits and a decrease in the deceleration rate of both circuits, resulting in a longer braking distance and reduced stability during automatic emergency braking (AEB) operations. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by proposing a braking system for autonomous vehicles.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a braking system for an unmanned vehicle, comprising: The first hydraulic control circuit is connected to the caliper. The second hydraulic control circuit is connected to the first hydraulic control circuit; The first hydraulic control circuit is not equipped with a brake pedal device; After the first hydraulic control circuit is powered on, pressure is built up to determine whether braking is to be performed through the first hydraulic control circuit, or Braking is determined to be performed through the first hydraulic control circuit and the second hydraulic control circuit.

[0005] As a further description of the above technical solution: the pressure build-up process of the first hydraulic control circuit after power-on includes: The pressure-building cylinder is controlled to push the piston to move a preset distance to build up pressure, and the pressure-building pressure is determined. Based on the comparison between the pressure build-up pressure and the pressure threshold, if it is less than the pressure threshold, it is determined that braking will be performed through the first hydraulic control circuit and the second hydraulic control circuit. If the pressure exceeds the pressure threshold, braking is initiated through the first hydraulic control circuit.

[0006] As a further description of the above technical solution: the first hydraulic control circuit includes an oil reservoir, which is connected to a pressure-building circuit, and the pressure-building circuit is connected to the caliper.

[0007] As a further description of the above technical solution: the pressure building circuit includes the pressure building cylinder, and the output end of the pressure building cylinder is connected in parallel to the first pressure boosting chamber isolation valve and the second pressure boosting chamber isolation valve.

[0008] As a further description of the above technical solution: the first pressure chamber isolation valve is connected in parallel to the first liquid inlet valve and the second liquid inlet valve, and the second pressure chamber isolation valve is connected in parallel to the third liquid inlet valve and the fourth liquid inlet valve.

[0009] As a further description of the above technical solution: the first liquid inlet valve, the second liquid inlet valve, the third liquid inlet valve and the fourth liquid inlet valve are respectively connected to the corresponding calipers.

[0010] As a further description of the above technical solution: the caliper is connected to a liquid outlet valve, and the output end of the liquid outlet valve is connected to the oil reservoir and the pressure-building cylinder.

[0011] As a further description of the above technical solution: the first pressure chamber isolation valve and the second pressure chamber isolation valve are respectively connected to the first circuit isolation valve and the second circuit isolation valve, and the pipeline connecting the first circuit isolation valve and the second circuit isolation valve to the second hydraulic control circuit is detachably provided with a plug.

[0012] As a further description of the above technical solution: the second hydraulic control circuit includes a first plunger pump and a second plunger pump, the first plunger pump is connected in parallel to a first pressure regulating valve and a first suction valve, and the second plunger pump is connected in parallel to a second pressure regulating valve and a second suction valve.

[0013] As a further description of the above technical solution: the first circuit isolation valve and the second circuit isolation valve are respectively connected to the first pressure regulating valve and the second pressure regulating valve through plugs; The first pressure regulating valve, the first liquid suction valve, the second pressure regulating valve, and the second liquid suction valve are connected to the oil reservoir through the plug.

[0014] The above technical solution has the following advantages or beneficial effects: This application reduces the brake pedal device in the first hydraulic control circuit, resulting in lower cost. The pressure can be controlled independently through the first and second hydraulic control circuits, quickly achieving front and rear axle braking force distribution, achieving higher braking deceleration, and effectively shortening the braking distance. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the braking system proposed in this invention. Figure 2 This is a schematic diagram of the structure of the first hydraulic control circuit in this invention; Figure 3 This is a schematic diagram of the second hydraulic control circuit in this invention.

[0017] Legend: 1. First hydraulic control circuit; 11. Pressure building cylinder; 12. Oil reservoir; 13. First pressure boosting chamber isolation valve; 14. Second pressure boosting chamber isolation valve; 15. First inlet valve; 16. Second inlet valve; 17. Outlet valve; 18. Third inlet valve; 19. Fourth inlet valve; 2. Caliper; 3. Second hydraulic control circuit; 31. First plunger pump; 32. Second plunger pump; 33. First pressure regulating valve; 34. First suction valve; 35. Second pressure regulating valve; 36. Second suction valve; 4. Plug; 5. First circuit isolation valve; 6. Second circuit isolation valve. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Reference Figures 1-3 An embodiment of the present invention provides an unmanned vehicle braking system, comprising: a first hydraulic control circuit 1 connected to a caliper 2; a second hydraulic control circuit 3 connected to the first hydraulic control circuit 1; the first hydraulic control circuit 1 is not equipped with a brake pedal device; after the first hydraulic control circuit 1 is powered on, it builds up pressure and determines whether to brake through the first hydraulic control circuit 1 or to brake through the first hydraulic control circuit 1 and the second hydraulic control circuit 3.

[0020] In this embodiment, the first hydraulic control circuit 1 and the second hydraulic control circuit 3 are hydraulic control units (HCUs), which are respectively configured in two electronic control units (ECUs) for control. The two ECUs are independently powered and transmit braking control signals through a CAN network to achieve redundant braking control. The first hydraulic control circuit 1 is connected to the caliper 2 through a pressure-building circuit for pressure-building braking. The second hydraulic control circuit 3 is connected to the first hydraulic control circuit 1. When the first hydraulic control circuit fails or locks up, redundant braking control is performed. The brake pedal device, including the master cylinder, pedal simulator, and master cylinder pressure sensor, is reduced in the first hydraulic control circuit, resulting in lower cost. Pressure control can be performed independently through the first and second hydraulic control circuits, quickly achieving front and rear axle braking force distribution, achieving higher braking deceleration, and effectively shortening the braking distance.

[0021] It should be noted that during vehicle braking, the vehicle load will shift, causing the locking pressure of the front and rear wheels to change. It is impossible to guarantee that the locking pressure of the front and rear axles will always be the same. In order to prevent the wheels from locking, if one wheel locks, the pressure of the other three wheels will not increase. This will result in a very low deceleration of the entire vehicle. For example, the deceleration of a certain model is calculated to be 0.46g. The second hydraulic control circuit 3 in this embodiment can regulate the pressure of the front and rear axle calipers 2. When one wheel locks, only the pressure of the other wheel on the same axle will be restricted. This can also ensure wheel stability, but the pressure of the wheel on the other axle can continue to increase until the wheel on the other axle reaches the locking pressure, and the deceleration can reach 0.9g.

[0022] After the first hydraulic control circuit 1 is powered on, the pressure build-up process includes: The pressure-building cylinder 11 is controlled to push the piston to move a preset distance to build up pressure, and the pressure-building pressure is determined. Based on the comparison between the pressure build-up pressure and the pressure threshold, if it is less than the pressure threshold, braking is determined to be performed through the first hydraulic control circuit 1 and the second hydraulic control circuit 3. If the pressure exceeds the pressure threshold, braking is initiated via the first hydraulic control circuit 1.

[0023] In this embodiment, the presence of the plug 4 determines whether braking is performed through the first hydraulic control circuit 1 or redundant braking is performed through the first hydraulic control circuit 1 and the second hydraulic control circuit 3. Each time the vehicle is powered on, the first hydraulic control circuit 1 closes all inlet valves, opens the pressure chamber isolation valve and the circuit isolation valve, and controls the pressure-building cylinder 11 to push the piston a preset distance to build pressure. The preset distance can be selected as 5mm. The pressure of the piston at this preset distance is determined as the pressure-building pressure. The pressure-building pressure is compared with a pressure threshold, which can be selected as 2 bar. If it is less than the pressure threshold, it is determined that the plug 4 between the first hydraulic control circuit 1 and the second hydraulic control circuit 3 has been removed, and braking is performed through the first hydraulic control circuit 1 and the second hydraulic control circuit 3. If it is greater than the pressure threshold, it is determined that the plug 4 is installed between the first hydraulic control circuit 1 and the second hydraulic control circuit 3, and the two circuit oil lines are isolated, and braking is performed through the first hydraulic control circuit 1. No manual inspection of the plug's installation / removal status is required; the operating condition determination is automatically completed upon power-up. Furthermore, it is determined that when braking is performed through the first hydraulic control circuit 1, the circuit isolation valve does not need to be energized and closed, which can save power consumption during the braking process. It is determined that when braking is performed through the first hydraulic control circuit 1 and the second hydraulic control circuit 3, the circuit isolation valve needs to be energized and closed.

[0024] The first hydraulic control circuit 1 includes an oil reservoir 12, which is connected to a pressure-building circuit, which in turn is connected to a caliper 2. The pressure-building circuit includes a pressure-building cylinder 11, the output of which is connected in parallel to a first pressure-boosting chamber isolation valve 13 and a second pressure-boosting chamber isolation valve 14. The first pressure-boosting chamber isolation valve 13 is connected in parallel to a first inlet valve 15 and a second inlet valve 16, and the second pressure-boosting chamber isolation valve 14 is connected in parallel to a third inlet valve 18 and a fourth inlet valve 19. The first inlet valve 15, the second inlet valve 16, the third inlet valve 18, and the fourth inlet valve 19 are respectively connected to their corresponding calipers 2.

[0025] In this embodiment, the oil reservoir 12 stores hydraulic oil. A motor is connected to one side of the pressure-building cylinder 11, and a motor position sensor (MPS) is installed. Based on the received braking control signal, pressure is built up to achieve braking control. The output end of the pressure-building cylinder 11 is connected in parallel to a first pressure-boosting chamber isolation valve 13 and a second pressure-boosting chamber isolation valve 14, and is equipped with a pressure-boosting chamber pressure sensor (Ps_SP) to ensure that the hydraulic oil pressure output by the pressure-building cylinder 11 reaches the pressure required for pressure-building braking. The first pressure-boosting chamber isolation valve 13 and the second pressure-boosting chamber isolation valve 14 are respectively connected in parallel to a first inlet valve 15, a second inlet valve 16, a third inlet valve 18, and a fourth inlet valve 19, which deliver high-pressure hydraulic oil to the calipers 2 to achieve wheel braking clamping and realize axle-specific hydraulic pressure regulation. Even if the caliper 2 on either axle locks up, the braking pressure of the caliper 2 on the other axle is not limited.

[0026] The caliper 2 is connected to the liquid outlet valve 17, and the output end of the liquid outlet valve 17 is connected to the oil reservoir 12 and the pressure building cylinder 11.

[0027] In this embodiment, the high-pressure brake fluid inside the caliper can be returned through the outlet valve 17; one path returns to the reservoir 12 to ensure that there is hydraulic fluid in the reservoir 12 for braking when braking is performed, and the other path returns to the pressure building cylinder 11 for hydraulic fluid circulation.

[0028] The first pressurized chamber isolation valve 13 and the second pressurized chamber isolation valve 14 are respectively connected to the first circuit isolation valve 5 and the second circuit isolation valve 6. The pipeline connecting the first circuit isolation valve 5 and the second circuit isolation valve 6 to the second hydraulic control circuit 3 is detachably equipped with a plug 4.

[0029] In this embodiment, the first hydraulic control circuit 1 is independently controlled by installing the plug 4, and the first hydraulic control circuit 1 and the second hydraulic control circuit 3 are connected by removing the plug 4, thereby achieving redundant braking.

[0030] Furthermore, the valve cores of the first circuit isolation valve 5 and the second circuit isolation valve 6 face the second hydraulic control circuit 3. When the first hydraulic control circuit 1 is normally building pressure and braking, the valve cores are pressed against the valve seats, which is beneficial for sealing. If the first hydraulic control circuit 1 fails, resulting in the inability to build pressure, the second hydraulic control circuit 3 can build pressure to open the first circuit isolation valve 5 and the second circuit isolation valve 6, thus supplementing pressure to the caliper 2. The second hydraulic control circuit 3 includes a first plunger pump 31 and a second plunger pump 32. The first plunger pump 31 is connected in parallel to the first pressure regulating valve 33 and the first suction valve 34. The second plunger pump 32 is connected in parallel to the second pressure regulating valve 35 and the second suction valve 36. The first circuit isolation valve 5 and the second circuit isolation valve 6 are connected to the first pressure regulating valve 33 and the second pressure regulating valve 35 respectively through plugs 4. The first pressure regulating valve 33, the first suction valve 34, the second pressure regulating valve 35 and the second suction valve 36 are connected to the oil reservoir 12 through plugs 4.

[0031] In this embodiment, the first plunger pump 31 is a booster power source for redundant braking of the front axle, and is connected in parallel with the first pressure regulating valve 33 and the first suction valve 34. The second plunger pump 32 is a booster power source for redundant braking of the rear axle, and is connected in parallel with the second pressure regulating valve 35 and the second suction valve 36. The pressure regulating valve is used to adjust the pressure of the hydraulic oil of the corresponding axle, and the suction valve is used to absorb the hydraulic oil in the oil reservoir 12 during redundancy.

[0032] In one specific embodiment When the first hydraulic control circuit 1 brakes, hydraulic oil enters the pressure-building cylinder 11 from the oil reservoir 12, and after being pressurized by the first pressure-boosting chamber isolation valve 13 and the second pressure-boosting chamber isolation valve 14, it enters the caliper 2 through the first inlet valve 15, the second inlet valve 16, the third inlet valve 18 and the fourth inlet valve 19 respectively for braking.

[0033] When the first hydraulic control circuit 1 fails and the second hydraulic control circuit 3 performs redundant braking, hydraulic oil enters the first suction valve 34 and the second suction valve 36 from the oil reservoir 12, enters the first circuit isolation valve 5 and the second circuit isolation valve 6 through the first plunger pump 31 and the second plunger pump 32, and enters the caliper 2 for braking through the first inlet valve 15, the second inlet valve 16, the third inlet valve 18 and the fourth inlet valve 19 respectively.

[0034] When the first hydraulic control circuit 1 and the second hydraulic control circuit 3 brake together, the pressure on the front and rear axles increases and decreases synchronously before the wheels lock up. The hydraulic oil enters the first circuit isolation valve 5, the second circuit isolation valve 6, the first inlet valve 15, the second inlet valve 16, the third inlet valve 18, and the fourth inlet valve 19 through the first pressure chamber isolation valve 13 and the second pressure chamber isolation valve 14 respectively for braking. The first plunger pump 31 and the second plunger pump 32 simultaneously maintain the same pressure through the first pressure regulating valve 33 and the second pressure regulating valve 35 and are delivered back to the oil reservoir 12.

[0035] When the first hydraulic control circuit 1 locks up, such as when the caliper 2 of the right rear wheel of the RR locks up, the corresponding second pressure regulating valve 35 and second suction valve 36 are de-energized and closed, and the pressure will no longer increase. However, the pressure on the other shaft can continue to increase through the operation of the first plunger pump 31 and the first pressure regulating valve 33, thereby achieving a higher braking deceleration and effectively shortening the braking distance.

[0036] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0037] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A braking system for an unmanned vehicle, characterized in that, include: The first hydraulic control circuit (1) is connected to the caliper (2); The second hydraulic control circuit (3) is connected to the first hydraulic control circuit (1); The first hydraulic control circuit (1) is not equipped with a brake pedal device; After the first hydraulic control circuit (1) is powered on, it builds up pressure to determine whether braking is performed through the first hydraulic control circuit (1), or Braking is determined to be performed through the first hydraulic control circuit (1) and the second hydraulic control circuit (3).

2. The braking system according to claim 1, characterized in that: The first hydraulic control circuit (1) performs pressure build-up after being powered on, including: The pressure-building cylinder (11) is controlled to push the piston to move a preset distance to build up pressure, and the pressure-building pressure is determined. Based on the comparison between the pressure build-up pressure and the pressure threshold, if it is less than the pressure threshold, it is determined that braking will be performed through the first hydraulic control circuit (1) and the second hydraulic control circuit (3); If the pressure exceeds the pressure threshold, braking is determined to be performed through the first hydraulic control circuit (1).

3. The braking system according to claim 2, characterized in that: The first hydraulic control circuit (1) includes an oil reservoir (12), which is connected to a pressure building circuit, and the pressure building circuit is connected to the caliper (2).

4. The braking system according to claim 3, characterized in that: The pressure building circuit includes the pressure building cylinder (11), and the output end of the pressure building cylinder (11) is connected in parallel to the first pressure chamber isolation valve (13) and the second pressure chamber isolation valve (14).

5. The braking system according to claim 4, characterized in that: The first pressure chamber isolation valve (13) is connected in parallel to the first liquid inlet valve (15) and the second liquid inlet valve (16), and the second pressure chamber isolation valve (14) is connected in parallel to the third liquid inlet valve (18) and the fourth liquid inlet valve (19).

6. The braking system according to claim 5, characterized in that: The first inlet valve (15), the second inlet valve (16), the third inlet valve (18) and the fourth inlet valve (19) are respectively connected to the corresponding calipers (2).

7. The braking system according to claim 3, characterized in that: The caliper (2) is connected to a liquid outlet valve (17), and the output end of the liquid outlet valve (17) is connected to the oil reservoir (12) and the pressure-building cylinder (11).

8. The braking system according to claim 4, characterized in that: The first pressure chamber isolation valve (13) and the second pressure chamber isolation valve (14) are respectively connected to the first circuit isolation valve (5) and the second circuit isolation valve (6). The pipeline connecting the first circuit isolation valve (5) and the second circuit isolation valve (6) to the second hydraulic control circuit (3) is detachably equipped with a plug (4).

9. The braking system according to claim 8, characterized in that: The second hydraulic control circuit (3) includes a first plunger pump (31) and a second plunger pump (32). The first plunger pump (31) is connected in parallel to a first pressure regulating valve (33) and a first suction valve (34). The second plunger pump (32) is connected in parallel to a second pressure regulating valve (35) and a second suction valve (36).

10. The braking system according to claim 9, characterized in that: The first circuit isolation valve (5) and the second circuit isolation valve (6) are connected to the first pressure regulating valve (33) and the second pressure regulating valve (35) respectively through plugs (4); The first pressure regulating valve (33), the first liquid suction valve (34), the second pressure regulating valve (35) and the second liquid suction valve (36) are connected to the oil reservoir (12) through the plug (4).

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