Device for measuring the temperature of water covering a road surface

Abstract

A device for measuring the temperature of water covering a road surface includes a member for measuring water temperature and channelling means for channelling the water covering the road surface. The channelling means includes a measuring chamber for measuring the temperature of the water covering the road surface. The measuring member includes a temperature measuring head situated in the measuring chamber. The device also includes driving means for driving the device over the road surface, the means being arranged in such a way that the temperature measuring head is situated at some distance from the road surface.

Claims

1. A temperature measurement device for measuring a temperature of water covering a road surface, comprising: a measurement member for measuring water temperature; a channelling structure, which directly channels water covering the road surface, the channelling structure including a support portion that forms part of: a measuring chamber, which is open to the road surface, for measuring a temperature of the channelled water, wherein the measurement member includes a temperature measuring head situated in the measuring chamber, and a collecting chamber, which is open to the road surface, the collecting chamber being situated upstream of the measuring chamber when considering a direction in which water flows with respect to the device; and a roller, which is supported by the support portion, and which causes the measurement member and the channelling structure to be driven over the road surface in such a way that: the collecting chamber and the measuring chamber form channels that are delimited by the road surface and the support portion, and the temperature measuring head is situated to face the road surface at a distance from the road surface.

2. The temperature measurement device according to claim 1, wherein the collecting chamber has a flared overall shape and includes a water channelling section that narrows when considering the direction in which water flows with respect to the device.

3. The temperature measurement device according to claim 1, wherein the measurement member is a thermocouple.

4. The temperature measurement device according to claim 3, wherein the collecting chamber has a flared overall shape and includes a water channelling section that narrows when considering the direction in which water flows with respect to the device.

5. A method for measuring a temperature of water covering a road surface, the method comprising: driving a test vehicle over the road surface; sprinkling on the road surface water from aboard the test vehicle, the water being sprinkled at least at first and second different temperatures in succession; and for each of the sprinkled water at the first temperature and the sprinkled water at the second temperature, measuring a temperature of the sprinkled water over which a tire of the test vehicle has driven, wherein the test vehicle includes: a sprinkler for performing the sprinkling, a temperature measurement device for performing the measuring, and the tire, which is positioned downstream from the sprinkler and upstream of the temperature measurement device when considering a direction of travel of the test vehicle, wherein, when the test vehicle is running, the tire drives over the sprinkled water, and the temperature measurement device measures the temperature of the sprinkled water over which the tire has driven, and wherein the temperature measurement device includes: a measurement member for measuring water temperature, a channelling structure, which directly channels water covering the road surface, the channelling structure including a support portion that forms part of: a measuring chamber, which is open to the road surface, for measuring a temperature of the channelled water, wherein the measurement member includes a temperature measuring head situated in the measuring chamber, and a collecting chamber, which is open to the road surface, the collecting chamber being situated upstream of the measuring chamber when considering a direction in which water flow with respect to the device, and a roller, which is supported by the support portion, and which causes the measurement member and the channelling structure to be driven over the road surface in such a way that: the collecting chamber and the measuring chamber form channels that are delimited by the road surface and the support portion, and the temperature measuring head is situated to face the road surface at a distance from the road surface.

6. The method according to claim 5, further comprising: driving the test vehicle over a second road surface; and sprinkling on the second road surface water from aboard the test vehicle, the water being sprinkled at least at the first and second different temperatures in succession; and for each of the sprinkled water at the first temperature and the sprinkled water at the second temperature, measuring a temperature of the sprinkled water over which the tire has driven on the second road surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Aspects of the invention will better understood from reading the following description, which is given solely by way of non limiting examples and made with reference to the accompanying drawings, in which:

(2) FIGS. 1 and 2 illustrate a vehicle according to an embodiment of the invention;

(3) FIGS. 3 to 7 illustrate a measuring device according to one or more embodiments of the invention; and

(4) FIG. 8 illustrates a method according to an embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(5) FIG. 1 depicts a vehicle according to an embodiment of the invention, denoted by the overall reference 10. The vehicle 10 includes a towing vehicle 12 and a trailer 14.

(6) The vehicle 10, in this instance the towing vehicle 12, includes water storage means 16. The vehicle 10 also includes channelling means 18 for channelling water from the storage means 16 to the trailer 14. The storage means 16 includes a source 20, known as a hot source, and a source 22, known as a cold source. Water from the source 22 is at a temperature lower than that of the source 20. The vehicle 10 also includes a controller 24 for controlling a flowrate from each source 20, 22. For example, the controller may include valves. Additionally, the vehicle 10 includes means 26 for measuring a temperature of the water from each source 20, 22.

(7) With reference to FIGS. 2 and 3, the vehicle 10, in this instance the trailer 14, includes mixer 28 for mixing the water from the hot source 20 and the cold 22 source. The trailer 14 further includes a sprinkler 30 for sprinkling a road surface T with water from the vehicle 10, in this particular instance with water from the storage means 16. The trailer 14 also includes means 32 for measuring a temperature of the road surface T situated upstream of the road surface T sprinkled by the sprinkler 30 when considering the direction of travel of the vehicle 10 when the vehicle is running, and means 34 for measuring a temperature of water from the sprinkler 30. The trailer 14 further includes a test wheel R fitted with a tyre P that is to be tested.

(8) In addition, the trailer 14 includes means 36 for measuring a temperature of the road surface T situated downstream of the road surface T over which the tyre P has driven when considering the direction of travel of the vehicle 10 when the vehicle 10 is running, and a device 37 for measuring a temperature of at least some of the water over which the tyre P has driven when the vehicle is running. The tyre P is situated downstream of the sprinkler 30 and upstream of the device 37 when considering the direction of travel of the vehicle 10 so that, when the vehicle 10 is running, the tyre P is driven over at least some of the water sprinkled by the sprinkler 30. The trailer 14 also includes suspension means 38 for suspending the device 37 with respect to the trailer 14. Finally, the vehicle 10 includes means 39 for measuring the coefficients of slip and of grip of the tyre P.

(9) As depicted in FIG. 2, the channelling means 18 includes pipes 40, 42 between the mixing means 28 and the hot source 20 and the cold source 22, respectively. The mixing means 28 includes a mixing chamber 44 into which each pipe 40, 42 opens and an outlet 46, in the form of an orifice, for the mixed water.

(10) With reference to FIGS. 3 to 7, the means 26 for measuring the water from each source 20, 22 includes two thermocouples (not depicted). The means 34 for measuring the sprinkled water also includes a thermocouple 50 having a measuring head 52 situated in the outlet 46 so that the measuring head 52 measures the temperature of the water sprinkled by the sprinkler 30. The means 32 and 36 includes infrared pyrometers 54, 56 situated respectively upstream and downstream of the tyre P when considering the direction of travel of the vehicle 10 when the vehicle is running.

(11) The device 37 includes driving means 58 for driving the device 37 over the road surface T, the driving means 58 including a wheel 60. The device 37 also includes a support 62 for the driving means 58.

(12) The device 37 further includes channelling means 64 for channelling at least some of the water over which the tyre P has driven and which is covering the road surface T upstream of the device 37 when considering the direction of travel of the vehicle 10 when the vehicle is running.

(13) The channelling means 64 includes a collecting chamber 66 for collecting the water over which the tyre P has driven and a measuring chamber 68 for measuring the temperature of the water covering the road surface T and which is taken from the collecting chamber 66. The collecting chamber 66 is situated upstream of the measuring chamber 68 when considering the direction in which the water flows with respect to the device 37. The device 37 further includes a member 70 for measuring the temperature of the water over which the tyre P has driven and covering the road surface T when the device 37 drives on this road surface T. The member 70 includes a measuring head 72 situated in the measuring chamber 68. In this particular embodiment, the member 70 is a thermocouple.

(14) The driving means 58 is arranged in such a way that the measuring head 72 is situated at some distance from the road surface T when the device 37 is running. In this particular embodiment, the support 62 is situated approximately 1 mm away from the road surface T when the device 37 is running.

(15) With reference to FIGS. 6 and 7, the collecting and measuring chambers 66, 68 form channels that channel the water and that are delimited, firstly, by the support 62 and, secondly, by the road surface T. Thus, each channel formed by the collecting and measuring chambers 66, 68 is open to the road surface T. The collecting chamber 66 has an inlet 74 of cross section SE and an outlet 76 opening into the measuring chamber 68 and of cross section SS. The collecting chamber 66 forms a channel with a flared overall shape that has a water passage section S that narrows when considering the direction in which the water flows with respect to the device 37. Thus, SS<SE. The measuring chamber 68 has an inlet 78 of cross section SS, the inlet 78 forming the outlet 76 and an outlet 80 opening to outside of the support 62. The measuring chamber 68 forms a channel of constant cross section SS.

(16) With reference to FIG. 4, the suspension means 38 includes a deformable parallelogram 82 and an elastically deformable member 84, in this particular instance a spring. The parallelogram 82 has two bar-like branches 86, 88 mounted such that they can rotate about parallel axes A1, A2 with respect to the support 62 and about parallel axes A3, A4 with respect to a chassis 90 of the vehicle 10, in this instance of the trailer 14. The deformable member 84 is situated between the branch 88 and the chassis 90 to both of which the deformable member 84 is fixed.

(17) FIG. 8 illustrates a chart representing a method of taking measurements on a wet road surface, and which method is implemented by means of the vehicle 10, In this particular embodiment, the method is for measuring a braking performance of the tyre P on a wet road surface. FIG. 8 shows variations, as a function of time, in the temperature of the mixed water (the curve in thick continuous line), the temperature of the sprinkled water (the curve in thick broken line) measured by the means 34, the temperature of the ground after sprinkling upstream of the tyre P (the curve in thin continuous line) measured by the means 32, the temperature of the ground after sprinkling downstream of the tyre P (the curve in thin broken line) measured by the means 36, the temperature of the water downstream of the tyre P (the curve drawn with crosses) measured by the device 37, the value of the coefficient of grip of the tyre P (the curve drawn with triangles), and the value of the coefficient of slip of the tyre P (the curve drawn with squares) measured by the means 39.

(18) The vehicle 10 fitted with the tyre P is driven over a first predetermined road surface T1.

(19) During a first cycle and from t=2.1 s onwards, the road surface T1 is sprinkled with water at T=41.5° C., taken from the vehicle 10. The various temperatures are then measured.

(20) At t=5 s, the braking of the tyre P begins and the coefficients of slip G and of grip μ of the tyre P are measured.

(21) At t=5.8 s, the sprinkling stops. Note that the variations in the temperatures measured using the infrared pyrometres 54, 56 (the curves in thin continuous line and in thin broken line) are not consistent with the variations in temperature measured using the thermocouples 50, 70 (the curve in thick broken line and the one drawn with crosses). This is because the ground temperatures measured downstream and upstream of the type P are decreasing whereas the temperatures of the sprinkled water as measured downstream and upstream of the tyre are increasing. Measuring ground temperature using infrared pyrometers does not therefore appear to be a method that is reliable in the case of a wet road surface.

(22) Next, during a second cycle, the temperature of the sprinkled water is changed and the road surface T1 is sprinkled with water at T=50° C. taken from the vehicle 10 (not depicted). The measurements taken in the first cycle are then taken again in the same way.

(23) As many measurement cycles at as many different temperatures as necessary can be run.

(24) The vehicle 10 is then driven over a second predetermined road surface T2 exhibiting different characteristics. These characteristics include, for example, the particle size. The various measurement cycles are then repeated on the second predetermined road surface T2 as many times as necessary.