JP4639739B2 - Vehicle speed measuring device - Google Patents

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 measurement 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. Generally, the traveling speed is obtained (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 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. 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.

In the vehicle speed measuring device of the present invention that achieves the above object, an optical non-contact speedometer (6) is mounted on the vehicle (1) so that the measuring section (7) faces the road surface (4), and the measurement is performed. The portion (7) has a double structure of an inner cover (9a) having an angled portion that is convex with respect to the vehicle traveling direction and an outer cover (9b), and surrounds the periphery of the measuring portion (7) A cylindrical cover (9) extending to the road surface (4) side is attached, and a gas injection nozzle (10) for injecting gas to the road surface (4) is provided in front of the cylindrical cover (9) in the vehicle traveling direction. In addition, the inner cover (9a) is provided with a second gas injection nozzle (11) that makes the internal pressure higher than the external air pressure. In front of the gas along the opening at the lower end of the inner cover (9a) Road third gas injection nozzle for injecting the (4) (12) is provided, it is characterized in that the coated water-absorbing layer (13) at least on the outer peripheral surface of the outer cover (9b).

  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 velocimeter attached in this way so as to surround the measurement part, and further , a gas injection nozzle which is a water film removing means on the front side in the vehicle traveling direction of the cylindrical cover To be installed.

Gas jet Nozzle for injecting toward the high-pressure gas such as compressed air to the road surface, because it has a function of removing water film without contact the road surface, it is possible to perform a smooth water film removal even at high speeds .

Gas injection nozzle Ru der those removing measurement zone in front of the full width or over water film measurement unit. Therefore, the gas injection nozzle is arranged so as to cross obliquely with respect to the traveling direction of the vehicle, and the water film can be smoothly removed in the left-right width direction while traveling by this oblique arrangement. Inclination direction of the gas jet nozzle is assumed to flow in both right and left sides in the mountain shape.

The width that the gas injection nozzle occupies in the orthogonal direction of the vehicle traveling direction (projected length in the direction orthogonal to the vehicle traveling direction) is the same as, or more preferably, the lateral width that the cylindrical cover occupies in the same orthogonal direction. It is better to make it long.

  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, double structure of the inner cover and the outer cover. On the inner side cover Ru provided with the second gas injection nozzle及Beauty third gas injection nozzle. Also, it covers the water-absorbing layer on at least the outer peripheral surface of the outer 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 measurement unit 7 faces the road surface 4. The measuring unit 7 projects light from a built-in projector (not shown) onto the road surface 4, 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 the reference example of FIG. 2, the gas injection nozzle 10 crosses the vehicle traveling direction obliquely as a water film removing means, and injects compressed air from a large number of injection holes 10 n toward the road surface 4, thereby forming the water film 5. Eliminate diagonally to the side. 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 annularly 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, and prevents 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 4 , and removes the water film that could not be removed by the first gas injection nozzle 10. It completely removes and prevents water droplets 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 its outer peripheral surface and inner peripheral surface. The water absorption layer 13 adsorbs water droplets and prevents it from entering the measurement area of the measurement unit 7 by rebounding. As the water absorption layer 13, foamed resin, nonwoven fabric, woven fabric, knitted fabric and the like are 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 in the reference example of FIG. 3 or the embodiment of the present invention illustrated in FIG. , the chevron inclined to the left and right sides. 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. It is the reference example of the bottom view seen by XX 'arrow in FIG. It is a bottom view corresponding to FIG. 2 of the speed measuring device which consists of other reference examples of this invention. Is a bottom view corresponding to FIG. 2 of the speed measurement device consisting of the implementation of the 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 (1)

Mount the optical non-contact velocimeter (6) on the vehicle (1) so that the measuring part (7) faces the road surface (4),
The measurement unit (7) has a double structure of an inner cover (9a) having a mountain-shaped portion that is convex with respect to the vehicle traveling direction and an outer cover (9b), and the periphery of the measurement unit (7) A cylindrical cover (9) that surrounds and extends toward the road surface (4) is attached,
A gas injection nozzle (10) for injecting gas onto the road surface (4) is made to flow in a mountain shape protruding in the vehicle traveling direction on both the left and right sides in front of the cylindrical cover (9) in the vehicle traveling direction. And place
The inner cover (9a) is provided with a second gas injection nozzle (11) whose internal pressure is higher than the external pressure, and gas is supplied to the lower end of the inner cover (9a) along the opening of the lower end. Providing a third gas injection nozzle (12) for injecting onto the road surface (4);
A vehicle speed measuring device in which at least an outer peripheral surface of the outer cover (9b) is covered with a water absorbing layer (13).

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