CN108344683B

CN108344683B - Road surface friction coefficient detection device

Info

Publication number: CN108344683B
Application number: CN201810168863.8A
Authority: CN
Inventors: 刘剑
Original assignee: Bao Jufang
Current assignee: BEIJING JINGU MEASURING & CONTROL TECHNOLOGY INSTITUTE
Priority date: 2018-02-28
Filing date: 2018-02-28
Publication date: 2020-04-24
Anticipated expiration: 2038-02-28
Also published as: CN108344683A

Abstract

The invention relates to a pavement friction coefficient detection device, which effectively solves the problems of low detection reliability and incomplete detection at present; the technical scheme includes that the air pump comprises a box body, a cavity is formed in the box body, a sliding block is installed in the cavity, a friction plate is fixed below the sliding block, a piston is installed in the hollow part of the sliding block, a liquid outlet hole is formed in the right end face of the sliding block, a first air inlet hole is formed in the left end face of the sliding block, a plunger is installed in the first air inlet hole, a first air inlet pipe communicated with the first air inlet hole is installed outside the sliding block, a plurality of second air inlet holes communicated with the first air inlet holes are formed in the circumference of the first air inlet hole, an impeller and a winding shaft coaxial with the impeller are installed in the first air inlet pipe, a pull rope is connected between the winding shaft and the left end of the plunger, a circuit switch is installed on the left end face; the invention has the advantages of real and reliable detection result, complete detection and strong anti-interference capability.

Description

Road surface friction coefficient detection device

Technical Field

The invention relates to the field of road detection, in particular to a road surface friction coefficient detection device.

Background

The friction coefficient of the road surface is an extremely important index related to driving safety, the friction coefficient of the road surface is too small, so that the vehicle does not have enough adhesive force and driving force when driving on the road surface, the vehicle is easy to sideslip or brake, the vehicle is easy to have danger, and particularly, under the condition that the road surface is wet and slippery due to water accumulation after rain, the friction coefficient of the road surface is smaller, the accident is easy to occur, and therefore, the detection of the friction coefficient when the road surface is wet and slippery is extremely important. At present, the traditional pendulum type instrument method is generally adopted for detecting the friction coefficient of the road surface, the method is manual measurement, the pendulum type instrument is required to be moved, arranged and adjusted frequently, the method has high labor intensity, low speed and low work efficiency, in addition, the theoretical calculation value of the friction coefficient of the road surface is obtained by detecting various physical quantities such as resistance, temperature, humidity and the like and then calculating through a relation curve and a theory, however, the relation curve of the friction coefficient of the road surface and the various physical quantities is often very complicated and mostly neglects the theoretical relation of other variables, the correctness and the accuracy of the theoretical relation are both considerable, moreover, the friction coefficient of the road surface is often influenced by various road surface states and environments, and the result obtained by theoretical calculation through a plurality of physical quantities is quite possibly far away from the actual situation; in addition, the above methods are sampling detection, and the detection is not comprehensive.

Therefore, designing a detection device for detecting a wet and slippery road surface with high detection reliability and comprehensive detection is a problem which needs to be solved urgently.

Disclosure of Invention

Aiming at the situation, in order to overcome the defects of the prior art, the invention provides the pavement friction coefficient detection device, which effectively solves the problems of low detection reliability and incomplete detection at present.

The technical scheme for solving the problem is that the pavement friction coefficient detection device comprises a box body, wherein a cavity which is arranged along the left-right direction is formed in the box body, a slide block which can slide left and right is installed in the cavity, a friction plate which is arranged outside the box body and synchronously slides along with the slide block is fixedly connected below the slide block, the lower surface of the friction plate is horizontal, and a pressure spring is connected between the right end surface of the slide block and the right end surface of the cavity; the slide block is hollow, a piston capable of sliding left and right in the slide block is installed in the slide block, a liquid outlet hole communicated with the interior of the slide block is formed in the right end face of the slide block, a first pressure valve is arranged at the liquid outlet hole, a first air inlet hole and a first air exhaust hole are formed in the left end face of the slide block, a plunger in sliding fit with the first air inlet hole is installed in the first air inlet hole, a tension spring is connected between the left end of the plunger and the left end of the slide block, a sealing plug matched with the first air exhaust hole is fixedly installed in a cavity, the first air exhaust hole can be sealed by the sealing plug after the slide block moves left, a first air inlet pipe communicated with the first air inlet hole is installed outside the slide block, a plurality of second air inlet holes are formed in the circumference of the first air inlet hole, one port of each second air inlet hole is located; an impeller and a winding shaft which is coaxially and fixedly arranged with the impeller are arranged in the first air inlet pipe, a pull rope is connected between the winding shaft and the left end of the plunger, and a pressure relief hole is formed in the first air inlet pipe on the right side of the impeller; the circuit switch is installed to the cavity left end face, and the circuit switch is connected with the air pump, and the air pump starts when the circuit switch pushes down left, and the air pump stops when the circuit switch pops up right, and the gas outlet of air pump is through second intake pipe and first intake pipe intercommunication.

The invention has the advantages of real and reliable detection result, complete detection and strong anti-interference capability.

Drawings

FIG. 1 is a front cross-sectional view of the present invention.

Fig. 2 is an enlarged view of a portion a in fig. 1.

FIG. 3 is a front cross-sectional view of the position of the case after the slider has been moved to the left.

Fig. 4 is an enlarged view of a portion B of fig. 3.

Fig. 5 is a left side view of the impeller and the spool.

Fig. 6 is a front sectional view of the waste water collecting device.

Fig. 7 is a right sectional view of the case.

Detailed Description

The following description of the embodiments of the present invention will be made in detail with reference to the accompanying drawings.

As shown in fig. 1 to 7, the invention comprises a box body 1, a cavity 2 arranged along the left-right direction is arranged in the box body 1, a slide block 3 capable of sliding left and right is arranged in the cavity 2, a friction plate 4 which is arranged outside the box body 1 and slides synchronously with the slide block 3 is fixedly connected below the slide block 3, the lower surface of the friction plate 4 is horizontal, and a pressure spring 5 is connected between the right end surface of the slide block 3 and the right end surface of the cavity 2; the slide block 3 is hollow, a piston 6 capable of sliding left and right in the slide block 3 is installed in the slide block 3, a liquid outlet 7 communicated with the interior of the slide block 3 is formed in the right end face of the slide block 3, a first pressure valve 8 is arranged at the position of the liquid outlet 7, a first air inlet 9 and a first air outlet 10 are formed in the left end face of the slide block 3, a plunger 11 in sliding fit with the first air inlet 9 is installed in the first air inlet 9, a tension spring 12 is connected between the left end of the plunger 11 and the left end of the slide block 3, a sealing plug 13 matched with the first air outlet 10 is fixedly installed in the cavity 2, the first air outlet 10 can be sealed by the sealing plug 13 after the slide block 3 is moved left, a first air inlet pipe 14 communicated with the first air inlet 9 is installed outside the slide block 3, a plurality of second air inlets 15 are formed in the circumference of the first air inlet 9, one port of the second air inlets 15 is located on the left end face of the slide block 3 and is communicated with the; an impeller 16 and a winding shaft 17 which is coaxially and fixedly installed with the impeller 16 are installed in the first air inlet pipe 14, a pull rope 18 is connected between the winding shaft 17 and the left end of the plunger 11, and a pressure relief hole 19 is formed in the first air inlet pipe 14 on the right side of the impeller 16; the circuit switch 20 is installed on the left end face of the cavity 2, the circuit switch 20 is connected with the air pump 21, the air pump 21 is started when the circuit switch 20 is pressed down leftwards, the air pump 21 is stopped when the circuit switch 20 is popped up rightwards, and an air outlet of the air pump 21 is communicated with the first air inlet pipe 14 through the second air inlet pipe 22.

For collecting the surface gathered water, 1 right side of box be equipped with waste water collection device, waste water collection device includes the cylinder 23 of placing along the fore-and-aft direction level, a plurality of axial recesses 24 of circumference equipartition on the cylinder 23 lateral wall, install a sponge roller 25 in every recess 24, the recess 24 is exposed outside sponge roller 25 outside, be equipped with a plurality of collecting chambers 26 with recess 24 one-to-one in the cylinder 23, every recess 24 bottom all is equipped with and corresponds the communicating wash port 27 of collecting chamber 26, every collecting chamber 26 all is connected with return water pipeline 28, install water pump 29 on the return water pipeline 28, cylinder 23 top is installed and is not followed cylinder 23 pivoted clamp plate 30, clamp plate 30 highly is less than the height in the sponge roller 25 outside.

In order to conveniently determine the position of the unqualified road surface, the device is provided with a reading device 31, the reading device 31 can read and record the value of the automobile odometer, a control switch 32 is arranged on the left end face of the cavity 2, and the reading device 31 is connected with the control switch 32.

Rock when avoiding slider 3 horizontal slip in cavity 2, the outer wall of slider 3 and the inner wall of cavity 2 slide and laminate.

The bottom of the box body 1 is provided with a through groove 33 communicated with the cavity 2 along the left-right direction, the sliding block 3 is fixedly connected with the friction plate 4 through a connecting block 34, and the connecting block 34 is arranged in the through groove 33 and can slide left and right.

And a second exhaust hole 35 is formed on the side wall of the cavity 2 on the left side of the sliding block 3.

In order to adjust the pressure of the friction plate 4 to the ground, a vertical rod 36 is arranged above the box body 1, and a balancing weight 37 is detachably penetrated on the vertical rod 36.

The pressure relief opening 19 is connected to a second pressure valve 38, and the opening threshold of the second pressure valve 38 is greater than the opening threshold of the first pressure valve 8.

In order not to affect the left and right movement of the sliding block 3, the second air inlet pipe 22 is a hose.

The left end surface of the sliding block 3 is provided with a horizontal pressing rod 39, and after the sliding block 3 is moved to the left, the pressing rod 39 can contact and press the circuit switch 20 and the control switch 32.

When the device is used specifically, the left end of the box body 1 is hung behind a tractor, the friction plate 4 is pressed on a road surface to be detected, the tractor can pull the device to move on the road surface, the tractor is provided with a water sprinkling tank, the water sprinkling tank can sprinkle water to the road surface on the left side of the box body 1 to simulate the wet and slippery state of the road surface, a water outlet of the water return pipeline 28 is connected with the water sprinkling tank, certainly, a water sprinkling truck can be arranged in front of the tractor to sprinkle water to the road surface, and when the water sprinkling truck is arranged, the tractor is provided with a wastewater collecting box connected with the water return pipeline 28 to; the right side of a piston 6 in the sliding block 3 is provided with liquid paint, and a liquid outlet 7 is connected with a spray head which is positioned outside the box body 1 and on the right side of the waste water collecting device through a hose.

When the road surface is detected, the tractor and the water pump 29 are started, the numerical value of the odometer of the tractor at the moment is recorded, then the road surface is sprayed with water to simulate the wet and slippery state of the road surface, and the wet and slippery condition of the road surface under different water accumulation amounts can be simulated by adjusting the water spraying amount to the road surface; then, a tractor is started to start to pull the device to walk on the road surface to be detected after water is sprayed, the friction plate 4 is pressed on a wet and slippery road surface, the box body 1 moves leftwards along with the tractor, under the action of road surface friction force, the friction plate 4 is initially static relative to the road surface, namely the friction plate 4 moves rightwards relative to the box body 1, the friction plate 4 drives the sliding block 3 to move rightwards relative to the box body 1 through the connecting block 34 to compress the pressure spring 5, along with the compression of the pressure spring 5, the elastic force of the pressure spring 5 on the sliding block 3 is gradually increased, until the elastic force of the pressure spring 5 on the sliding block 3 is equal to the friction force of the road surface on the friction plate 4, the friction plate 4 and the sliding block 3 start to move leftwards along with the box body.

The cylinder 23 of the wastewater collection device on the right side of the box body 1 rolls on the road surface under the pulling of the box body 1, a plurality of sponge rollers 25 on the side wall of the cylinder 23 alternately contact with the road surface, the sponge rollers 25 contacting with the road surface absorb accumulated water sprayed on the road surface by a sprinkler pipe, along with the rotation of the cylinder 23, the sponge rollers 25 absorbing the water rotate to the lower part of the pressing plate 30, the pressing plate 30 compresses the sponge rollers 25 to extrude the water in the sponge, the extruded water enters the water collection chamber 26 below through the drain holes 27 at the bottom of the groove 24, the filtered water in the water collection chamber 26 is pumped back to the water spraying tank or the wastewater collection box through the water return pipeline 28 by the water pump 29, on the one hand, the water accumulation on the other.

If the friction coefficient of the road surface reaches the standard, the friction plate 4 and the slide block 3 can stably move leftwards along with the box body 1 and cannot greatly shake leftwards and rightwards in the box body 1; when the friction coefficient of the road surface is lower than the lowest standard, under the condition that the pressure of the friction plate 4 to the road surface is not changed, the friction force of the road surface to the friction plate 4 is reduced to be lower than the lowest standard value, the friction plate 4 and the slide block 3 are unbalanced in stress, the slide block 3 is pushed by the pressure spring 5 to move leftwards relative to the box body 1 under the action of the elastic force of the pressure spring 5, the sealing plug 13 is inserted into the first exhaust hole 10 to close the first exhaust hole 10, the slide block 3 moves leftwards, the pressure rod 39 contacts and presses the circuit switch 20 and the control switch 32, the control switch 32 controls the reading device 31 to read and record the value of the odometer of the tractor at the moment, the circuit switch 20 switches on the power source of the air pump 21, the air pump 21 is started to inflate the first air inlet pipe 14 through the second air inlet pipe 22, and the right openings of the first air inlet hole 9 and the, but is discharged from the pressure relief hole 19 by opening the second pressure valve 38 and is discharged out of the tank body 1 through the second vent hole 35; the air pumped into the first air inlet pipe 14 by the air pump 21 forms air flow in the first air inlet pipe 14, the air flow blows and also rotates the impeller 16, the impeller 16 rotates to drive the winding shaft 17 to rotate, the winding shaft 17 winds the pull rope 18 on the winding shaft 17 so as to pull the plunger 11 to slide leftwards in the first air inlet hole 9, after a period of time, the impeller 16 rotates for multiple circles, the plunger 11 is pulled to the leftmost position, the plunger 11 can not slide any more, the impeller 16 and the winding shaft 17 stop rotating, at the moment, the right end of the plunger 11 passes through the second air inlet hole 15 on the inner wall of the first air inlet hole 9 leftwards and is positioned at the left side of the hole, the second air inlet hole 15 is communicated with the first air inlet hole 9 to form a channel for air to enter the slide block 3 from the first air inlet pipe 14, the air pumped into the first air inlet pipe 14 by the air pump 21 enters the slide block 3 through, the left side of a piston 6 in a sliding block 3 is inflated to enable the air pressure on the left side of the piston 6 to be increased, the piston 6 applies pressure to the liquid paint on the right side, so that a first pressure valve 8 on a liquid outlet pipe is opened, the liquid paint in the sliding block 3 is sprayed to the road surface through the liquid outlet pipe and a spray head to mark the road surface under the action of the pressure of the piston 6, and the spray head is positioned on the right side of a roller 23, so that accumulated water at the sprayed road surface position is absorbed by a sponge roller 25, and the paint can be effectively sprayed and adhered to the road surface; when the air pump 21 pumps air to the left side of the piston 6, the air pressure on the left side of the piston 6 gradually rises to be larger than the opening threshold of the second pressure valve 38 again, the second pressure valve 38 is opened, and the air on the left side of the piston 6 is exhausted through the pressure relief hole 19 and the second exhaust hole 35, so that the air pressure on the left side of the piston 6 cannot rise continuously, the air pressure on the left side of the piston 6 is stabilized at the opening threshold of the second pressure valve 38, the pressure of the piston 6 on the right side of the paint is kept stable, and the stable and uniform spraying is ensured.

After the friction coefficient of the road surface reaches the standard value again, the right friction force borne by the friction plate 4 is increased to the standard value again, the friction plate 4 drives the sliding block 3 to compress the compression spring 5 to move rightwards, so that the circuit switch 20 and the control switch 32 are loosened, the air pump 21 stops working and does not blow air to the left side of the piston 6 any more, the sliding block 3 moves rightwards, the sealing plug 13 is pulled out of the first exhaust hole 10, the first exhaust hole 10 is opened, high-pressure air on the left side of the piston 6 is exhausted through the first exhaust hole 10 and the second exhaust hole 35, high pressure does not exist on the left side of the piston 6, the piston 6 does not extrude paint on the right side of the piston any more. Under the action of the tension spring 12, the plunger 11 moves rightwards to return to the original position and simultaneously pulls the winding shaft 17 and the impeller 16 to rotate reversely, and the plunger 11 closes the first air inlet hole 9 and the second air inlet hole 15 again.

In the sliding process of the friction plate 4, if stones are on the road surface or the road surface fluctuates to cause the friction plate 4 to jump slightly, or the friction force does not reach the standard and does not affect normal running, at the moment, the friction force of the friction plate 4 is temporarily reduced to enable the sliding block 3 to have a temporary forward rush leftwards, so that the compression rod 39 can temporarily press down the circuit switch 20 and the control switch 32, the air pump 21 starts to charge the air impeller 16 into the first air inlet pipe 14 to rotate, but the plunger 11 is pulled to the leftmost side after rotating for a plurality of circles, the second air inlet hole 15 and the first air inlet hole 9 are switched on, and in the short starting time of the air pump 21, the piston 6 cannot be pulled to the leftmost side, and air pumped by the air pump 21 cannot enter the sliding block 3, so that the device cannot spray mark on the road surface; the air can enter the sliding block 3 after the impeller 16 rotates for a plurality of circles, so that the piston 6 acts in a delayed manner, the influence of impurities such as uneven road surfaces or stones on a detection result is eliminated, the wire take-up speed and the movement speed of the plunger 11 can be adjusted by adjusting the shaft diameter of the wire winding shaft 17 to adjust the time delay, and the detection precision of the invention is adjusted; of course, if higher detection precision is required, the sweeper can be used to clean the impurities such as stones on the road surface to be detected so as to reduce the interference.

In the process, the sliding block 3 cannot press the second exhaust hole 35 to seal the second exhaust hole 35 in the stroke.

After the tractor runs through the road section detected at this time, the tractor stops and cuts off the power source of the air pump 21, then the numerical values recorded by the reading device 31 in the detection process are read, each numerical value corresponds to a section of road section with unqualified friction coefficient, the numerical value of the tractor odometer recorded when the tractor is not started is subtracted from each numerical value, namely the distance between each road section with unqualified friction coefficient and the initial detection point, after the approximate position of each road section is calculated, construction maintenance personnel are arranged to go to the position, the specific position of the spraying mark is found, and the construction maintenance can be carried out on the marked road surface.

The detection precision can be adjusted by adjusting the running speed of the tractor or changing the shaft diameter of the winding shaft 17, the slower the speed of the tractor is, the shorter the running distance of the tractor in the delay time, the shorter the reaction distance of the spraying mark is, and the higher the detection precision is, or the larger the shaft diameter of the winding shaft 17 is, the shorter the delay time is, the shorter the reaction distance of the spraying is, and the higher the detection precision is. The invention can also be suitable for road surface detection with different friction coefficient standards by additionally arranging the balancing weight 37 on the box body 1.

The invention has the following remarkable advantages: firstly, the method simulates the wet and slippery state of the road surface by sprinkling water to the road surface, directly detects the friction coefficient of the road surface by the friction force between the friction plate 4 and the road surface without conversion calculation and theoretical calculation of any intermediate variables such as temperature, humidity, resistance and the like, and ensures that the detection result is more accurate and real and has high reliability as the detection result is a direct measurement result of the actual friction coefficient of the road surface after the comprehensive action of all influence factors rather than a result of theoretical calculation; secondly, the method is comprehensive detection, the traction vehicle finishes the whole process of the road section to be detected, namely the detection of the full-length road section is finished, the sampling detection is not carried out, and the detection result is comprehensive and complete; in addition, the invention can carry out spraying marking on all unqualified road surfaces influencing driving, the quantity and the distribution position of all unqualified road sections can be obtained through the numerical value recorded by the reading device 31, and then the accurate position of the unqualified road sections is accurately determined through the spraying marking so as to arrange personnel for repairing, and in addition, through the matching of the movement of the winding wheel and the plunger 11, the air passage entering the sliding block 3 is opened in a delayed mode so as to realize the delayed right movement of the piston 6, so that the spraying is delayed, the mark error caused by the misoperation of the air pump 21 due to sundries or fluctuation on the road surface is filtered, and the anti-jamming capability of the invention is.

In conclusion, the invention has the advantages of real and reliable detection result, comprehensive and complete detection and strong anti-interference capability.

Claims

1. A pavement friction coefficient detection device comprises a box body (1), and is characterized in that a cavity (2) which is arranged along the left-right direction is arranged in the box body (1), a slide block (3) which can slide left and right is arranged in the cavity (2), a friction plate (4) which is arranged outside the box body (1) and synchronously slides along with the slide block (3) is fixedly connected below the slide block (3), the lower surface of the friction plate (4) is horizontal, and a pressure spring (5) is connected between the right end surface of the slide block (3) and the right end surface of the cavity (2); the inner part of the sliding block (3) is hollow, a piston (6) capable of sliding left and right in the sliding block (3) is installed in the sliding block (3), a liquid outlet hole (7) communicated with the inner part of the sliding block (3) is formed in the right end face of the sliding block (3), a first pressure valve (8) is arranged at the position of the liquid outlet hole (7), a first air inlet hole (9) and a first exhaust hole (10) are formed in the left end face of the sliding block (3), a plunger (11) in sliding fit with the first air inlet hole (9) is installed in the first air inlet hole (9), a tension spring (12) is connected between the left end of the plunger (11) and the left end of the sliding block (3), a sealing plug (13) matched with the first exhaust hole (10) is fixedly installed in the cavity (2), the sliding block (3) can seal the first exhaust hole (10) after moving left, a first air inlet pipe (14) communicated with the first air inlet hole (9) is installed outside the, one port of the second air inlet hole (15) is positioned on the left end surface of the sliding block (3) and communicated with the first air inlet pipe (14), and the other port is positioned on the inner wall of the first air inlet hole (9) and communicated with the first air inlet hole (9); an impeller (16) and a winding shaft (17) which is coaxially and fixedly installed with the impeller (16) are installed in the first air inlet pipe (14), a pull rope (18) is connected between the winding shaft (17) and the left end of the plunger (11), and a pressure relief hole (19) is formed in the first air inlet pipe (14) on the right side of the impeller (16); a circuit switch (20) is installed on the left end face of the cavity (2), the circuit switch (20) is connected with an air pump (21), the air pump (21) is started when the circuit switch (20) is pressed down leftwards, the air pump (21) is stopped when the circuit switch (20) is popped up rightwards, and an air outlet of the air pump (21) is communicated with the first air inlet pipe (14) through a second air inlet pipe (22).

2. The road surface friction coefficient detection device according to claim 1, characterized in that the right side of the box body (1) is equipped with a wastewater collection device, the wastewater collection device comprises a roller (23) horizontally placed along the front-back direction, a plurality of axial grooves (24) are uniformly distributed on the circumference of the side wall of the roller (23), a sponge roller (25) is installed in each groove (24), the outer side of the sponge roller (25) is exposed out of the groove (24), a plurality of water collection chambers (26) corresponding to the grooves (24) one by one are arranged in the roller (23), a drain hole (27) communicated with the corresponding water collection chamber (26) is arranged at the bottom of each groove (24), each water collection chamber (26) is connected with a water return pipeline (28), a water pump (29) is installed on the water return pipeline (28), a pressing plate (30) which does not rotate along with the roller (23) is installed above the roller (23, the height of the pressure plate (30) is lower than that of the outer side of the sponge roller (25).

3. The road surface friction coefficient detection device according to claim 1, characterized in that the device is provided with a reading device (31), the reading device (31) can read and record the value of the automobile odometer, a control switch (32) is arranged on the left end face of the cavity (2), and the reading device (31) is connected with the control switch (32).

4. The road surface friction coefficient detection device according to claim 1, characterized in that the outer wall of the slider (3) is in sliding fit with the inner wall of the cavity (2).

5. The road surface friction coefficient detection device according to claim 1, characterized in that the bottom of the box body (1) is provided with a through groove (33) communicated with the cavity (2) along the left-right direction, the sliding block (3) is fixedly connected with the friction plate (4) through a connecting block (34), and the connecting block (34) is arranged in the through groove (33) and can slide left and right.

6. The device for detecting the friction coefficient of a road surface according to claim 1, wherein a second exhaust hole (35) is formed in the side wall of the cavity (2) on the left side of the slider (3).

7. The pavement friction coefficient detection device according to claim 1, characterized in that a vertical rod (36) is installed above the box body (1), and a balancing weight (37) is detachably penetrated on the vertical rod (36).

8. A road surface friction coefficient detecting device according to claim 1, characterized in that a second pressure valve (38) is connected to the pressure relief hole (19), and the opening threshold of the second pressure valve (38) is larger than the opening threshold of the first pressure valve (8).

9. The device for detecting the road surface friction coefficient according to claim 1, characterized in that the second air inlet pipe (22) is a hose.

10. The road surface friction coefficient detection device according to claim 1, characterized in that a horizontal pressure rod (39) is installed on the left end surface of the sliding block (3), and after the sliding block (3) is moved to the left, the pressure rod (39) can contact and press the circuit switch (20) and the control switch (32).