JP2006105737A - Device for measuring of vehicular speed - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for measuring vehicular speed capable of accurately measuring the traveling speed on a wetting road surface, without regard to a general road and a test course. <P>SOLUTION: An optical noncontact speedometer 6 is installed in the vehicle 1 so that the measurement part faces the road surface 4. A cylindrical cover 9 for surrounding the periphery and extending to the road surface side, is installed in its measuring part 7. A water film removing means 10 for removing a water film 5 of the road surface 4, is arranged in front in the vehicle advancing direction of the cylindrical cover 9. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle speed measuring device, and more particularly to a vehicle speed measuring device that can accurately measure the traveling speed on a wet road surface regardless of whether it is a public road or a private test course.

  Commercial vehicles such as passenger cars and trucks are equipped with speedometers, but these speedometers do not necessarily represent true travel speeds, and have a simple structure that can provide approximate speeds. Therefore, it cannot be used as a speedometer for obtaining a traveling speed required for a test for examining fuel consumption characteristics, vibration characteristics, etc. in the development of a new tire.

  Conventionally, as a speed measuring device for measuring a true traveling speed for a test, a special fifth wheel for measurement is attached to a vehicle, and the true speed is measured based on the rotation speed of the fifth wheel, the tire outer diameter, and the like. It was common to obtain the traveling speed (for example, Patent Document 1). However, there is a restriction that a vehicle equipped with a special fifth wheel may not be able to travel on public roads due to laws and regulations, and can only be tested on a private test course.

  Optical non-contact speedometers have been proposed as means for eliminating such restrictions and making it possible to measure the true traveling speed even on ordinary roads (for example, Non-Patent Document 1). This optical non-contact speedometer measures the travel distance by projecting light onto the road surface and converting the amount of reflected light received into a pulse to calculate the speed from the relationship between the travel distance and time. Like to do.

However, it is based on the principle that light is projected in this way and the reflected light is incident. Therefore, when the road surface is wet due to rain or the like, the light is irregularly reflected by scattered water splashes, or the surface of the water film An error occurs due to the influence of a mixture of the light reflected on the road and the light transmitted through the water film and reflected on the road surface, and there is an obstacle that an accurate traveling speed cannot be measured. Therefore, the optical non-contact speedometer can be tested on a general road, but there is a restriction that speed data on a dry road surface cannot be obtained.
JP 50-149001 A Ono Sokki catalog “Non-contact speedometer LC series”, catalog no. 414-12

  An object of the present invention is to provide a vehicle speed measuring device that can accurately measure the traveling speed on a wet road surface regardless of whether it is a general road or a test course.

  A vehicle speed measuring device of the present invention that achieves the above object is a cylinder that is mounted on a vehicle with an optical non-contact speedometer so that the measuring section faces the road surface, and surrounds the measuring section and extends to the road surface side. A road surface water film removing means is provided in front of the cylindrical cover in the vehicle traveling direction.

  According to the present invention, the cylindrical cover surrounding the circumference of the optical non-contact velocimeter mounted on the vehicle is attached so as to extend to the road surface side, and the water film is removed in front of the cylindrical cover. In order to prevent the water film removing means from removing the water film on the road surface when traveling on wet roads and to prevent the cylindrical cover from splashing the splashed water and entering the measurement area of the measuring section. Accurate traveling speed can be measured without receiving disturbance caused by a film or the like. In addition, since the fifth wheel is not used, measurement can be performed regardless of whether it is a general road or a test course.

  The optical non-contact speedometer used for the speed measuring device of the present invention is a device that measures the traveling speed based on projecting light on the road surface and receiving the reflected light in a vehicle-mounted state. Any known optical non-contact velocimeter can be used.

  In the present invention, the optical non-contact velocimeter is attached so that the measurement unit faces the road surface when mounted on a vehicle. A cylindrical cover is attached to the measurement part of the optical non-contact speedometer attached in this way so as to surround the measurement part, and a water film removing means is attached to the front side of the cylindrical cover in the vehicle traveling direction. .

  The water film removing means is not particularly limited as long as it has a function of removing the water film on the road surface, but preferably a gas injection nozzle for injecting a high-pressure gas such as compressed air toward the road surface, or rubber A wiper made of a blade made of steel can be used. In particular, the gas injection nozzle is preferable and has a function of removing the water film in a non-contact manner with respect to the road surface. Therefore, smooth water film removal can be performed even during high-speed traveling.

  The water film removing means desirably removes the water film over the entire width in front of the measurement area of the measurement unit. Therefore, the water film removing means is preferably arranged so as to cross the vehicle traveling direction. In particular, an arrangement that crosses the vehicle traveling direction obliquely is preferable, and the water film can be smoothly removed in the left-right width direction while traveling by this oblique arrangement. The direction of inclination of the water film removing means may be a single flow on one side or may be a mountain shape and flow on the left and right sides.

  The width that the water film removing means occupies in the direction perpendicular to the vehicle traveling direction (projected length in the direction perpendicular to the vehicle traveling direction) is the same as, preferably, the lateral width that the cylindrical cover occupies in the same orthogonal direction. It is better to make it longer.

  The cylindrical cover surrounding the measurement part of the optical non-contact velocimeter is a means for preventing water splashed from the road surface from entering the inside of the cylindrical cover. That is, it is a means for preventing water splash from entering the measurement area of the measurement unit and preventing the diffuse reflection of the projection light and the reflected light due to the water splash. The cylindrical cover preferably has its lower end on the opening side as close to the road surface as possible within a range that does not hinder the traveling of the vehicle. A preferable distance between the lower end portion to be approached and the road surface is about 5 to 50 mm.

  The cylindrical cover may be further provided with a second gas injection nozzle, and the internal pressure may be maintained higher than the external air pressure by injecting a gas such as compressed air into the cylindrical cover. When the internal pressure of the cylindrical cover is higher than the external pressure, water droplets are less likely to enter the cylindrical cover, and the measurement accuracy can be improved.

  Furthermore, it is good to provide the 3rd gas injection nozzle which injects gas to the road surface side so that the circumference | surroundings of an opening part may be enclosed in the lower end part of a cylindrical cover. The third gas injection nozzle completely removes the remaining water film that could not be removed by the first gas injection nozzle in front of the cylindrical cover, and further prevents water droplets from entering the cylindrical cover. In the case where both the second gas injection nozzle and the third gas injection nozzle are provided at the same time on the cylindrical cover, the pressure applied by the second gas injection nozzle is set to be higher than the pressure applied by the third gas injection nozzle. It is good to make it high. By setting such a pressure, entry of water droplets into the cylindrical cover is surely prevented.

  In the present invention, the cylindrical cover may have a single structure, but preferably has a double structure of an inner cover and an outer cover. In the case of a double structure, the second gas injection nozzle and / or the third gas injection nozzle may be provided on the inner cover. Moreover, it is good to coat | cover a water absorption layer at least with the outer peripheral surface of an outer side cover. This water absorption layer is preferably provided on both the outer peripheral surface and the inner peripheral surface of the outer cover. By covering the water-absorbing layer, water droplets are efficiently adsorbed on the surface of the cylindrical cover and rebound is prevented, so that the effect of preventing the water droplets from entering the cylindrical cover can be improved. The water-absorbing layer is not particularly limited as long as it has a good absorption capacity. For example, a porous structure such as a foamed resin, a nonwoven fabric, a woven fabric, and a knitted fabric can be used.

  Hereinafter, the present invention will be specifically described with reference to embodiments shown in the drawings.

  FIG. 1 is a schematic view of a vehicle equipped with a speed measuring device of the present invention, and FIG. 2 is a bottom view as viewed in the direction of arrows X-X ′ in FIG. 1.

  Reference numeral 1 denotes a vehicle having a front wheel 2 and a rear wheel 3, and an arrow F direction is a forward direction. The vehicle 1 may be either a truck or a passenger car, and a commercially available vehicle can be used. Reference numeral 4 denotes a wet road surface, the surface of which is covered with a water film 5.

  An optical non-contact speedometer 6 is attached to the vehicle 1 so that the measuring unit 5 faces the road surface 4. The measuring unit 5 projects light on a road surface 4 from a built-in projector (not shown), receives the reflected light, and inputs the light to the speed measurement device 8 in the driver's seat. The speed measuring device 8 converts the input fluctuation of the reflected light amount into a pulse to obtain a travel distance, and calculates the speed from the relation with the travel time.

  The measurement unit 7 of the optical non-contact velocimeter 6 is covered with a cylindrical cover 9 having a double structure of an inner cover 9a and an outer cover 9b. The cylindrical cover 9 extends downward, and the opening at the lower end thereof faces the road surface 4 through a small gap. A gas injection nozzle 10 having a large number of injection holes 10n is provided in front of the cylindrical cover 9.

  As shown in FIG. 2, the gas injection nozzle 10 obliquely crosses the traveling direction of the vehicle as a water film removing means, and injects compressed air from a large number of injection holes 10n toward the road surface 4 to cause the water film 5 to be obliquely lateral. To eliminate. The gas injection nozzle 10 is preferably set to have a width equal to or greater than the lateral width of the cylindrical cover 9 as a width in a direction orthogonal to the traveling direction.

  In the cylindrical cover 9 having a double structure, a second gas injection nozzle 11 is provided inside the inner cover 9a, and a third gas injection nozzle 12 is provided in an annular shape at the lower end so as to surround the opening. It has been. The second gas injection nozzle 11 makes the pressure in the inner cover 9a higher than the external air pressure by injecting compressed air to prevent the intrusion of water droplets.

  The third gas injection nozzle 12 injects compressed air having a pressure lower than that of the second gas injection nozzle 11 toward the road surface, and completely removes the water film that could not be removed by the first gas injection nozzle 10. It removes and prevents the splash of water from entering the inner cover 9a. The density of the injection holes 12n provided in the third gas injection nozzle 12 is not particularly limited, but preferably, the front side area in the traveling direction is larger than the rear side area as shown in FIG.

  The first gas injection nozzle 10 and the third gas injection nozzle 12 are connected to a compressor 16 via a pressure adjustment valve 14, and the second gas injection nozzle 11 is connected to a compressor 16 via a pressure adjustment valve 15. It is connected to the. The pressure regulating valves 14 and 15 are configured so that the compressed air pressure of the second gas injection nozzle 11 is greater than the compressed air pressure of the first gas injection nozzle 10 and the third gas injection nozzle 12. Is set.

  Further, the outer cover 9b is provided with a water absorption layer 13 covering the outer peripheral surface and the inner peripheral surface thereof. The water absorption layer 13 adsorbs water droplets so that it does not enter the measurement area of the measurement unit 7 by rebounding. As the water absorption layer 13, a foamed resin, a nonwoven fabric, a woven fabric, a knitted fabric, or the like is preferably used.

  In the present invention, the gas injection nozzle 10 described above is preferably disposed obliquely with respect to the vehicle traveling direction. However, as an arrangement method thereof, as shown in the embodiment shown in FIGS. It may be. The gas injection nozzle 10 arranged in this mountain shape can exclude the water film on both the left and right sides with respect to the vehicle traveling direction.

  Further, the shape of the third gas injection nozzle 12 may be arbitrarily changed according to the shape of the cylindrical cover 9. In the embodiment of FIG. 4, the front side has a mountain shape.

It is the schematic of the vehicle carrying the speed measuring device of this invention. FIG. 2 is a bottom view as seen in the direction of arrows X-X ′ in FIG. 1. It is a bottom view corresponding to FIG. 2 of the speed measuring device which consists of other embodiment of this invention. It is a bottom view corresponding to FIG. 2 of the speed measuring device which consists of further another embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 4 Road surface 5 Water film 6 Optical non-contact speedometer 7 Measuring part 9 Cylindrical cover 9a Inner cover 9b Outer cover 10 Gas injection nozzle (water film removing means)
11 (second) gas injection nozzle 12 (third) gas injection nozzle 13 water absorption layer

Claims (6)

  An optical non-contact velocimeter is mounted on the vehicle so that the measuring unit faces the road surface, and a cylindrical cover is attached to the measuring unit so as to surround the periphery and extend toward the road surface. A vehicle speed measuring device provided with a water film removing means on a road surface.   The vehicle speed measuring device according to claim 1, wherein the water film removing means is constituted by a gas injection nozzle for injecting gas onto a road surface, and the gas injection nozzle is disposed so as to cross the vehicle traveling direction.   3. The vehicle speed measurement device according to claim 1, wherein a second gas injection nozzle is provided inside the cylindrical cover to make the internal pressure higher than the external air pressure. 4.   The vehicle speed measuring device according to claim 1, 2 or 3, wherein a third gas injection nozzle for injecting gas onto a road surface along an opening of the lower end portion is provided in front at a lower end portion of the cylindrical cover.   The vehicle according to claim 3 or 4, wherein the cylindrical cover has a double structure of an inner cover and an outer cover, and the second gas injection nozzle and / or the third gas injection nozzle is provided on the inner cover. Speed measuring device. The vehicle speed measuring device according to claim 5, wherein at least an outer peripheral surface of the outer cover is covered with a water absorbing layer.

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