Method for testing driving safety on waterlogged road surface

Abstract

The invention discloses a waterlogged road surface driving safety test method which comprises the following steps: A, mounting a loading device on a counter-force frame, mounting a tire restraint mechanism on the loading device, and mounting a tire on the tire restraint mechanism; the method comprises the following steps that B, water flow is sprayed out through a nozzle, and the water spraying thickness FT is controlled by replacing nozzles with different water outlet heights in a matched mode; c, adjusting the load P applied to the tire by the loading device until the tire is separated from the road surface and begins to rotate or the load P is zero; or the following steps are applied: B1, the loading device applies a constant load P to the tire, and the water flow with the specific water spraying thickness FT is sprayed; and C1, the flow velocity VV of the jet water flow is adjusted till the tires break away from the road surface and start to rotate or the flow velocity VV exceeds a reasonable value. According to the technical scheme, the ground pressure of various tires, road surface types and water accumulation conditions under the high-speed driving condition of the vehicle can be actually measured, the driving safety under different combinations is evaluated, and the whole testing process is safe and convenient.

Description

Technical Field

[0001] The invention relates to the technical field of driving safety testing, and in particular to a driving safety testing method for a flooded road surface. Background Art

[0002] The safety of driving on a road is related to factors such as the surface condition of the road, the structure of the interconnected voids within the road, rainfall, catchment area, driving speed, tire load, and pattern type.

[0003] my country's road facilities standards only have one technical requirement, the friction coefficient, which is the result of the contact between the tire and the road surface in a wet state. In fact, a large proportion of vehicle traffic accidents, especially major traffic accidents, occur during heavy rainfall. When a high-speed vehicle encounters waterlogging, the tires will instantly fall off the road surface, which is an important mode of accident occurrence.

[0004] Until now, due to the lack of safety testing methods at the critical point of hydroplaning, it has been impossible to quantitatively evaluate the relationship between the thickness of accumulated water and the safe vehicle speed. Currently, in related research, the test is usually carried out by paving a physical test section, controlling the thickness of the accumulated water film, and conducting a real vehicle test. The test target is set to the dynamic water pressure at the moment the vehicle passes by, so as to obtain the effective ground contact pressure of the tire.

[0005] Such a test has the following problems:

[0006] 1. Vehicle accidents usually involve high speeds. To achieve the corresponding speed requires a large site and good driving conditions. Similar tests in related studies are difficult to achieve the speed of expressways due to limited sites and difficulty in aligning the test positions.

[0007] 2. When a vehicle hits water head-on while driving fast, it may drift, and there is a great safety risk in the testing process.

[0008] 3. Installing the pressure sensor at the test location requires partial destruction of the road surface, which may cause surface changes and affect the test results.

[0009] Therefore, current research on the interaction and safety of tires, road surfaces and water films at high speeds is mainly based on simulation and calculation methods. There are few reports on actual measurements and the data is unstable. Summary of the invention

[0010] In view of the defects in the prior art, the present invention provides a method for testing driving safety on flooded roads. This technical solution can measure the ground pressure of various types of roads when vehicles are driving at high speed, evaluate the driving safety of different roads, and the entire testing process is safe and convenient.

[0011] 1. A method for testing driving safety on a flooded road, comprising the following steps:

[0012] A. Install a loading device on the reaction frame, install a tire restraint mechanism on the loading device, install the axle tire on the tire restraint mechanism, the tire restraint mechanism allows the tire to only maintain up and down freedom, the loading device can apply load to the tire, place the tire on the road, and the tire can rotate and move up and down freely;

[0013] Based on step A, apply the following steps:

[0014] B. Use a high-pressure, high-flow water pump to spray water with a specific thickness and flow rate VV through a nozzle, and make the water flow vertically impact the contact line between the tire and the road surface;

[0015] C. Adjust the load P applied by the loading device to the tire until the tire breaks contact with the road surface and starts to rotate, or the load P is zero. The test is terminated and the load P at this time is recorded as the water support force Pd;

[0016] Or based on step A, apply the following steps:

[0017] B1. The loading device applies a constant load P to the tire, so that the high-pressure and high-flow water pump sprays a water flow of a specific thickness and makes the water flow vertically impact the contact line between the tire and the road surface;

[0018] C1. Adjust the flow rate VV of the high-pressure, high-flow water pump and control the water spray thickness FT by replacing the nozzles with different water outlet heights until the tire breaks contact with the road and starts to rotate, or the flow rate VV and the water spray thickness FT exceed the target driving speed and water accumulation thickness. The test is terminated and the vehicle speed VV at this time is recorded as the safe vehicle speed VVS.

[0019] Preferably, a slide bar is fixedly mounted on the reaction frame, and the slide bar movably passes through the tire restraint mechanism.

[0020] Preferably, the loading device is a pneumatic cylinder or a hydraulic cylinder.

[0021] Preferably, the nozzle is connected to the water outlet of a large-flow high-pressure water pump, and the water inlet of the large-flow high-pressure water pump is connected to a water tank.

[0022] Preferably, the water outlet of the nozzle is in the shape of an elongated strip, and the width of the water outlet is greater than the tread width of the tire, and the height is the set water accumulation thickness.

[0023] Preferably, the tire is detachably connected to the tire restraint mechanism.

[0024] Preferably, a bearing is installed on the tire restraint mechanism, the tire is installed on a rotating shaft, and the rotating shaft is detachably connected to the bearing.

[0025] Preferably, the nozzle is detachably connected to the water outlet end of a large-flow high-pressure water pump.

[0026] The beneficial effects of the present invention are as follows: In the present technical solution, water flows at different speeds to impact the bottom of the tire, causing the tire to rotate, and the load that can be supported by different water pressures can be tested, which is directly used to judge safety. The load Pd that is separated from the water film under the conditions of specific driving speed and water accumulation thickness is obtained, which is used to evaluate the safety performance of specific tires and specific road surfaces. The safe driving speed VVS and water accumulation thickness FT under specific load P and road conditions are obtained, which are used to set road speed limit warnings that follow the rainfall. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0028] Figure 1 It is a front view of the bracket in the present invention;

[0029] Figure 2 It is a right side view of the high pressure water pump, nozzle and water tank in the present invention.

[0030] In the attached drawings, 1-road surface, 2-tire restraint mechanism, 3-tire, 4-large flow water pump, 5-nozzle, 6-reaction frame, 7-water tank, 8-loading device, 9-slide rod. DETAILED DESCRIPTION

[0031] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0032] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0033] Example 1

[0034] like Figure 1-2 As shown, this embodiment provides a method for testing driving safety on a flooded road, comprising the following steps:

[0035] A. Install a loading device 8 on the reaction frame 6, install a tire constraint mechanism 2 on the loading device 8, install the axle tire 3 on the tire constraint mechanism 2, the tire constraint mechanism 2 allows the tire 3 to only maintain up and down freedom, the loading device 8 can apply a load to the tire 3, place the tire 3 on the road surface 1, and the tire 3 can rotate freely and move up and down;

[0036] Based on step A, apply the following steps:

[0037] B. Use a high-pressure and high-flow water pump 4 to spray a water flow with a specific thickness and flow rate VV through a nozzle 5, and make the water flow vertically impact the contact line between the tire 3 and the road surface 1;

[0038] C. Adjust the load P applied by the loading device 8 to the tire 3 until the tire 3 breaks away from the contact with the road surface 1 and starts to rotate, or the load P is zero, and the test is terminated. The load P at this time is recorded as the water lift force Pd;

[0039] Or based on step A, apply the following steps:

[0040] B1, the loading device 8 applies a constant load P to the tire, so that the high-pressure and high-flow water pump 4 sprays a water flow of a specific thickness, and the water flow vertically impacts the contact line between the tire 3 and the road surface 1;

[0041] C1. Adjust the flow rate VV of the water jetted by the high-pressure and high-flow water pump 4, and control the water spray thickness FT by replacing the nozzles 5 with different water outlet heights, until the tire 3 breaks away from the contact with the road surface 1 and starts to rotate, or the flow rate VV and the water spray thickness FT exceed the target driving speed and water accumulation thickness. The test is terminated and the vehicle speed VV at this time is recorded as the safe vehicle speed VVS.

[0042] After the test is completed, the data is reported and a safety evaluation is conducted.

[0043] In this embodiment, the water spraying thickness FT is the simulated road surface water thickness FT.

[0044] The load Pd obtained in step C is the load that breaks away from the water film under the conditions of specific driving speed and water accumulation thickness, and is used to evaluate the safety performance of the tire 3 and the road surface 1.

[0045] The water flow velocity VVS obtained in step C1 is the safe driving speed under the condition of water accumulation of a specific thickness and road surface 1. The water spraying thickness FT is the simulated road surface water thickness, which is used to set the speed limit warning of the road under rainfall conditions.

[0046] The test principle is as follows:

[0047] When the vehicle is actually driving, the contact point between the tire 3 and the road surface 1 remains relatively stationary with the rotation axis of the tire 3. The speed of the rotation axis relative to the road surface 1 is the driving speed V. Therefore, the speed of the contact point relative to the road surface 1 is also the driving speed V. The water film is attached to the surface of the road surface 1. In an ideal state, it can be assumed that the water film is stationary relative to the road surface. The contact point of the tire 3 rushes towards the water film in a manner that compresses the space to zero in a short time at the driving speed V, instantly generating a huge water pressure, thereby reducing the contact pressure between the tire 3 and the road surface 1. When the ground pressure of the tire 3 is reduced to a certain level, drift and accidents occur.

[0048] In this technical solution, the tire 3 is placed on the road surface 1, and the bottom of the tire 3 contacts the road surface 1, so that the tire 3 can rotate and move up and down, and the tire 3 cannot move forward and backward. The nozzle 5 is used to impact the contact point between the bottom of the tire 3 and the road surface 1 with a certain thickness of water flow and a higher driving speed V. The interaction between the bottom of the tire 3 and the water flow is consistent with the interaction between the tire 3 and the water film during the actual driving process. When the water flow thickness and the driving speed V reach a certain level, the ground pressure of the tire 3 drops to zero, and the tire 3 starts to rotate. At this time, the driving speed V is the drift critical speed.

[0049] In this technical solution, water flows at different speeds to impact the bottom of the tire, causing the tire to rotate, and the load that can be supported by different water pressures can be tested, which is directly used to judge safety. The load Pd that breaks away from the water film under specific driving speed and water thickness conditions is obtained to evaluate the safety performance of specific tires and specific road surfaces. The safe driving speed VVS and water thickness FT under specific load P and road conditions are obtained to set road speed limit warnings that follow the rainfall.

[0050] This technical solution can measure the ground contact pressure of various types of road surfaces 1 when the vehicle is driving at high speed, and evaluate the driving safety of different road surfaces. This technical solution does not require a wide site, nor does it require the vehicle to drive quickly. The test process is convenient, the vehicle does not need to be driven, and the test safety is high. At the same time, it does not need to damage the road surface to install the pressure sensor, which will not cause surface changes and will not affect the test results.

[0051] In this embodiment, a slide bar 9 is fixedly mounted on the reaction frame 6, and the slide bar 9 movably penetrates the tire constraint mechanism 2. In this embodiment, the slide bar 9 movably penetrates the tire constraint mechanism 2, limiting the tire constraint mechanism 2 to only be able to move up and down.

[0052] In this embodiment, the loading device 8 is a pneumatic cylinder or a hydraulic cylinder, which can apply a corresponding load to the tire 3 and simulate possible load conditions in actual driving.

[0053] In this embodiment, the tire 3 is detachably connected to the tire restraint mechanism 2 .

[0054] In this embodiment, the tire restraint mechanism 2 is provided with a bearing, and the tire 3 is provided on a rotating shaft, and the rotating shaft is detachably connected to the bearing. In this embodiment, the rotating shaft and the bearing are detachably connected, so as to facilitate the replacement of different types of tires 3 for testing.

[0055] In this embodiment, the nozzle 5 is connected to the water outlet of the large-flow high-pressure water pump 4, and the water inlet of the large-flow high-pressure water pump 4 is connected to the water tank 7. In the embodiment, the water flow is driven by the large-flow high-pressure water pump 4, and the water tank 7 supplies water. The water tank 7 can be fixed or mobile, and the capacity should meet the needs of one test.

[0056] In this embodiment, the outlet of the nozzle 5 is in a long strip shape, and the width of the outlet is greater than the tread width of the tire 3, and the height is the set water accumulation thickness. In this embodiment, the width of the outlet of the nozzle 5 is greater than the tread width of the tire 3, and the tread width of the tire 3 can be fully covered.

[0057] In this embodiment, the nozzle 5 is detachably connected to the water outlet end of the large-flow high-pressure water pump 4 .

[0058] In this embodiment, the nozzle 5 is detachably connected to the water outlet of the high-pressure water pump 4. In this embodiment, the nozzle 5 is detachably connected, and the water outlet heights of different nozzles 5 are different (the height is the preset water accumulation thickness, usually 1-10mm). When it is necessary to spray water flows of different thicknesses, different nozzles 5 can be replaced for adjustment. The water outlet heights of different nozzles 5 should cover the possible range of the water film of the accumulated water as much as possible.

[0059] By spraying water streams of different thicknesses through different nozzles 5 , the ground contact pressure of the tire 3 at different water stream thicknesses and driving speeds V can be tested.

[0060] This technical solution can measure the ground contact pressure of various types of road surfaces 1 when the vehicle is driving at high speed, and evaluate the driving safety of different road surfaces. This technical solution does not require a wide site, nor does it require the vehicle to drive quickly. The test process is convenient, the vehicle does not need to be driven, and the test safety is high. At the same time, it does not need to damage the road surface to install the pressure sensor, which will not cause surface changes and will not affect the test results.

[0061] In this embodiment, the test object is various asphalt pavements for vehicles to travel on, which can be dense-graded pavements, intermittent-graded pavements, open-graded pavements or ultra-thin pavements, etc. A plate-shaped test piece of 30cm*30cm or larger size can be formed by an indoor test machine. It must be absolutely fixed during installation without shaking. The reaction frame 6 can also be installed on a physical road for testing.

[0062] The tire 3 is a car tire or a truck tire, or other tires that are driven on roads and need safety testing.

[0063] The tire 3 is mounted on the tire restraint mechanism 2 via a freely rotatable rotation axis. The tire restraint mechanism 2 can freely move up and down along the two slide bars 9 as a whole, but cannot move forward, backward, left, or right.

[0064] The loading capacity applied by the loading device 8 needs to reach more than 50% of the actual tire load, and the reaction frame 6 needs to withstand all possible loading forces.

[0065] The capacity of the water tank 7 needs to meet the test requirements, generally 1-10 cubic meters.

[0066] The high-pressure and high-flow water pump 4 must meet the test requirements.

[0067] A plurality of nozzles 5 are prepared, and the water outlets of the plurality of nozzles 5 are 1-20 mm.

[0068] In this embodiment, the nozzle 5 is a specific flat nozzle.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for testing driving safety on a flooded road, characterized in that: The steps include: A. A loading device (8) is installed on a reaction frame (6), a tire restraining mechanism (2) is installed on the loading device (8), and an axle tire (3) is installed on the tire restraining mechanism (2). The tire restraining mechanism (2) allows the tire (3) to maintain only up and down degrees of freedom. The loading device (8) can apply a load to the tire (3). The tire (3) is placed on a road surface (1), and the tire (3) can freely rotate and move up and down. Based on step A, apply the following steps: B. using a high-pressure, high-flow water pump (4) to spray a water flow with a specific thickness and flow rate VV through a nozzle (5), and making the water flow vertically impact the contact line between the tire (3) and the road surface (1); C. adjusting the load P applied by the loading device (8) to the tire (3) until the tire (3) breaks away from the contact with the road surface (1) and starts to rotate, or the load P is zero, and the test is terminated. The load P at this time is recorded as the water lift force Pd; Or based on step A, apply the following steps: B1, causing the loading device (8) to apply a constant load P to the tire, causing the high-pressure and high-flow water pump (4) to spray a water flow of a specific thickness, and causing the water flow to vertically impact the contact line between the tire (3) and the road surface (1); C1. Regulate the flow rate VV of the water jetted by the high-pressure and high-flow water pump (4), and control the water spray thickness FT by replacing the nozzles (5) with different water outlet heights, until the tire (3) breaks away from the contact with the road surface (1) and starts to rotate, or the flow rate VV and the water spray thickness FT exceed the target driving speed and water accumulation thickness, the test is terminated, and the vehicle speed VV at this time is recorded as the safe vehicle speed VVS.

2. A method for testing driving safety on a flooded road according to claim 1, characterized in that: A slide bar (9) is fixedly mounted on the reaction force frame (6), and the slide bar (9) movably penetrates the tire restraint mechanism (2).

3. A method for testing driving safety on a flooded road according to claim 1, characterized in that: The loading device (8) is a pneumatic cylinder or a hydraulic cylinder.

4. A method for testing driving safety on a flooded road according to claim 1, characterized in that: The nozzle (5) is connected to the water outlet of a large-flow high-pressure water pump (4), and the water inlet of the large-flow high-pressure water pump (4) is connected to a water tank (7).

5. A method for testing driving safety on a flooded road according to claim 1, characterized in that: The water outlet of the nozzle (5) is in the shape of an elongated strip, and the width of the water outlet is greater than the tread width of the tire (3), and the height is the set water accumulation thickness.

6. A method for testing driving safety on a flooded road according to claim 2, characterized in that: The tire (3) is detachably connected to the tire restraint mechanism (2).

7. A method for testing driving safety on a flooded road according to claim 6, characterized in that: A bearing is installed on the tire restraint mechanism (2), and the tire (3) is installed on the rotating shaft. The rotating shaft and the bearing are detachably connected.

8. A method for testing driving safety on a flooded road according to claim 4, characterized in that: The spray head (5) is detachably connected to the water outlet end of the large-flow high-pressure water pump (4).

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