JP2007153264A - Road condition detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a road condition detecting device for detecting the condition of a road on which a vehicle travels. <P>SOLUTION: In this road condition detecting device 100, an air temperature detecting section 10 detects the temperature of the air. A tire inside temperature detecting section 20 detects temperature inside a tire. A tire groove part temperature detecting section 30 detects the temperature of tire grooves. A determination section 40 determines a plurality of road condition on the basis of differences between the air temperature, the tire inside temperature and the tire groove temperature and a difference between the tire groove temperature and the air temperature detecting section. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a road surface state detection device that detects a road surface state in which a vehicle or the like travels.

  2. Description of the Related Art Conventionally, a technique for controlling a vehicle according to a situation when the vehicle is running or braking is known. Patent Document 1 discloses a vehicle information providing apparatus that determines whether or not a road surface condition is dry from each temperature detected by an outside air temperature meter and a tire surface temperature sensor, and regulates information provision to the passenger about the road surface condition. It is disclosed.

Further, Patent Document 2 discloses a predetermined low friction coefficient that includes a road surface on which an icy road is on the basis of a change in value based on an acquired wheel speed and an acquired outside air temperature. An anti-skid control device that determines whether or not a road surface is included is disclosed.
JP 2004-178195 A JP 2005-88771 A

  However, the vehicle information providing apparatus disclosed in Patent Document 1 can only determine that the road surface condition is dry when the difference between the tire surface temperature and the road surface temperature is equal to or greater than a predetermined value. Further, the anti-skid control device disclosed in Patent Document 2 cannot originally determine the road surface state in a state where the value based on the wheel speed does not change, that is, in a stable traveling state.

  This invention is made | formed in view of such a condition, The place made into the objective is to provide the road surface state detection apparatus which detects the road surface state on which a vehicle etc. drive | work.

  In order to solve the above-described problems, a road surface state detection device according to an aspect of the present invention includes an outside air temperature detecting unit that detects the temperature of outside air, a tire inside temperature detecting unit that detects the temperature inside the tire, and the temperature of the tire groove portion. A plurality of tire groove temperature detectors, a temperature of the outside air, a difference between the temperature in the tire and the temperature of the tire groove, and a difference between the temperature of the tire groove and the temperature of the outside air. And a determination unit that determines the road surface state of the vehicle.

  According to this aspect, not only the road surface condition such as snow and freezing can be detected from the temperature of the outside air detected by the outside air temperature detector, but also about other road surface conditions such as wet road surface conditions and dry road surface conditions. Can also be detected.

  The determination unit has a temperature of the outside air that is equal to or higher than a first predetermined value, and a difference between the temperature in the tire and the temperature of the tire groove is equal to or higher than a second predetermined value, and the tire groove It may be determined that the road surface condition is wet when the difference between the temperature of the air and the temperature of the outside air is less than a third predetermined value.

  According to this aspect, it is possible to detect that the road surface is wet by a plurality of temperature detection units without using a humidity sensor or the like.

  The tire groove temperature detector may be provided at the bottom of the tire groove.

  According to this aspect, the temperature of the tire groove portion can be detected over a long period of time even if the tire is consumed due to running, and the road surface condition can be detected with high accuracy.

  According to the present invention, it is possible to detect a road surface state where a vehicle or the like travels.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

(Vehicle state detection device)
FIG. 1 is a block diagram illustrating a configuration of a vehicle state detection device according to the present embodiment. FIG. 2 is a schematic diagram of a vehicle provided with an outside air temperature detection unit and a tire internal temperature detection unit of the vehicle state detection device according to the present embodiment. FIG. 3 is a schematic cross-sectional view of a tire provided with a tire groove temperature detector of the vehicle state detection device according to the present embodiment.

  A road surface state detection device 100 shown in FIG. 1 includes an outside air temperature detection unit 10 that detects the temperature of outside air, a tire inside temperature detection unit 20 that detects the temperature inside the tire, and a tire groove part temperature detection that detects the temperature of the tire groove part. And a determination unit 40 that determines a road surface state based on the temperature of the outside air detected by each detection unit, the temperature in the tire, and the temperature of the tire groove.

  The outside air temperature detection unit 10 is mounted on a vehicle 300 such as an automobile as shown in FIG. The mounting position is not particularly limited as long as the outside air temperature can be detected. However, in order to detect the temperature with higher accuracy, the front portion of the vehicle is considered in consideration of the effect of heat generated by the vehicle 300 itself. Is preferred.

  The tire internal temperature detection unit 20 is provided inside the tire 50, and may be provided, for example, in a device that monitors the air pressure of the tire provided near the valve of the rim 60. In addition, information on the tire internal temperature detected by the tire internal temperature detection unit 20 is sent to the determination unit 40 by radio. Note that the method of sending the tire temperature information to the determination unit 40 is not limited to wireless communication. For example, when a conductor fixed on the vehicle side contacts a predetermined conductor provided on the rotating tire 50. Alternatively, the tire temperature information may be sent to the determination unit 40.

  The tire groove temperature detector 30 is provided in the groove 52 a of the tread 52 of the tire 50. In consideration of the fact that the depth of the groove 52a is reduced by the wear of the tread 52, the groove 52a may be provided at the bottom of the groove 52a. Further, the tire groove temperature detector 30 may be entirely embedded in the tire 50 as necessary, or may be arranged so that a part thereof is exposed to the groove 52a. Further, the tire groove temperature information detected by the tire groove temperature detector 30 is sent to the determination unit 40 by radio. Note that the method of sending the tire groove temperature information to the determination unit 40 is not limited to wireless communication. For example, when a conductor fixed on the vehicle side contacts a predetermined conductor provided on the rotating tire 50. Alternatively, the tire temperature information may be sent to the determination unit 40.

  The determination unit 40 includes a calculation unit 42 that compares temperature information input from each detection unit with a predetermined value, and a storage unit 44 that stores a predetermined value used in the calculation unit 42. The determination unit 40 may serve as a control unit such as an ECU provided in the vehicle 300, or may be configured by combining an independent CPU, RAM, ROM, and the like. The determination unit 40 transmits information on the detected road surface state to the vehicle control device 200 such as a drive control device, a brake control device, or a steering control device.

(Road condition judgment method)
Next, a road surface state determination method by the road surface state detection device 100 according to the present embodiment will be described with reference to FIGS.

  FIG. 4 is a flowchart when the road surface state is detected by the road surface state detection device 100 according to the present embodiment. FIG. 5 to FIG. 7 are graphs showing changes in the detected temperature in each detection unit in order to explain the determination in the steps of the flowchart shown in FIG.

  The road surface state detection device 100 starts detecting the road surface state continuously or every predetermined time. When the detection is started, the outside air temperature detecting unit 10 detects the outside air temperature t1, the tire inside temperature detecting unit 20 detects the tire inside temperature t2, and the tire groove part temperature detecting unit 30 detects the tire groove part temperature t3 (S10). , S12, S14).

  Next, the outside air temperature t1 is compared with the predetermined value α (S18). The predetermined value α is a value determined to determine whether or not the road surface condition is snow or frozen (hereinafter referred to as Snow / Ice condition), and is typically 0 ° C. (see FIG. 5). . However, the predetermined value α may be a value other than 0 ° C. in consideration of a measurement error of the outside air temperature detection unit 10 and a freezing point depression due to a snow melting agent or the like.

  Here, if t1 <α (No in S18), that is, if the outside air temperature t1 is lower than the predetermined value α (see FIG. 5), the road surface state is determined as the Snow / Ice state (S20). In this case, the information on the detected road surface state is determined by the various vehicle control devices 200 provided in the vehicle 300 so as to change the vehicle control according to the Snow / Ice state from a plurality of vehicle control modes. It is good to transmit from 40 (S22). On the other hand, when t1 ≧ α (Yes in S18), it is determined that the road surface state is not the Snow / Ice state, and the process proceeds to the next step.

  Next, the difference between the tire internal temperature t2 and the tire groove temperature t3 is compared with the predetermined value β (S24). As shown in FIG. 6, the tire internal temperature t2 and the tire groove temperature t3 gradually increase after the vehicle 300 starts running, and then become stable. In this case, a difference occurs between the tire internal temperature t2 and the tire groove temperature t3. In general, tires store heat when traveling, but they are particularly easy to store because there is no air circulation and no contact with outside air. On the other hand, although the surface portion of the tire stores heat to some extent, the temperature is lower than in the tire because it touches the outside air and the road surface.

  Further, the difference between the tire groove temperature t3 and the tire internal temperature t2 varies depending on the outside air and the road surface state. In particular, when the road surface is in a dry state (hereinafter referred to as a “Dry state”), the temperature is unlikely to decrease because air with low thermal conductivity is interposed when the road surface takes heat from the tire surface. Conversely, when the road surface is wet (hereinafter referred to as a wet state), the temperature tends to decrease because water having higher heat conductivity than air is present when the road surface takes heat from the tire surface.

  Therefore, the road surface state detection device 100 according to the present embodiment uses the above-described phenomenon to detect the road surface state other than the Snow / Ice state, and stores the tire internal temperature t2 and the tire groove temperature t3 in the storage unit 44. A predetermined value β for comparison with the difference is stored. By comparing with this predetermined value β, a new road surface condition can be detected.

  Here, when t2−t3 <β (No in S24), that is, when the difference between the tire internal temperature t2 and the tire groove temperature t3 is smaller than a predetermined value β (see FIG. 6), the tire is compared with the tire internal temperature t2. Since the groove part temperature t3 has not decreased so much, it is determined that the road surface state is the dry state (S26). In this case, the information on the detected road surface state is determined from the determination unit 40 so that various vehicle control devices 200 provided in the vehicle 300 are changed to vehicle control corresponding to the dry state from among a plurality of vehicle control modes. It is good to transmit (S28). On the other hand, when t2−t3 ≧ β (Yes in S24), it is determined that the road surface state is not the Dry state, and the process proceeds to the next step.

  Next, the difference between the tire groove temperature t3 and the outside air temperature t1 is compared with a predetermined value γ (S30). As shown in FIG. 7, the outside air temperature t1 is irrelevant to the traveling of the vehicle 300, whereas the tire groove temperature t3 gradually increases after the vehicle 300 starts traveling and then becomes stable. In that case, a difference occurs between the tire groove temperature t3 and the outside air temperature t1. Generally, when the vehicle travels, the tire stores heat, so that the temperature of the tire groove becomes higher than the outside air temperature.

  Further, the difference between the tire groove temperature t3 and the outside air temperature t1 varies depending on the outside air and the road surface state. In particular, when the road surface is in a dry state (hereinafter referred to as a “Dry state”), the temperature is unlikely to decrease because air with low thermal conductivity is interposed when the road surface takes heat from the tire surface. Conversely, when the road surface is wet (hereinafter referred to as a wet state), the temperature tends to decrease because water having higher heat conductivity than air is present when the road surface takes heat from the tire surface.

  Therefore, the road surface state detection device 100 according to the present embodiment uses the above-described phenomenon to detect the road surface state other than the Snow / Ice state and the Dry state in the storage unit 44 in the tire groove temperature t3 and the outside air temperature. A predetermined value γ for comparison with the difference from t1 is stored. By comparing with this predetermined value γ, a new road surface condition can be detected.

  Here, when t3−t1 <γ (No in S30), that is, when the difference between the tire groove temperature t3 and the outside air temperature t1 is smaller than the predetermined value γ (see FIG. 7), the tire groove portion reaches a temperature close to the outside air temperature t1. Since the temperature t3 has decreased, it is determined that the road surface state is the wet state (S32). In this case, the information of the detected road surface state is determined from the determination unit 40 so that various vehicle control devices 200 provided in the vehicle 300 are changed from the plurality of vehicle control modes to vehicle control according to the wet state. It is good to transmit (S34). On the other hand, if t3−t1 ≧ γ (Yes in S30), it is determined that the road surface state is neither the Dry state nor the Wet state, and the vehicle control up to that point is maintained (S36).

  Note that the predetermined values α, β, and γ in the present embodiment may be stored in the storage unit 44 as fixed values, or may be stored in the storage unit 44 as a function of the detected temperature in each detection unit. Good. Alternatively, a table showing the relationship between the predetermined value and the detected temperature may be stored in the storage unit 44 and referred to.

  As described above, according to the road surface state detection device according to the present embodiment, a plurality of road surface states more than the number of the temperature detection units can be easily detected in advance by comparing the detected temperatures from the plurality of temperature detection units. Can do. As a result, vehicle control such as drive control, brake control, and steering control can be optimized in advance based on the road surface state information, and safer vehicle operation is possible.

It is a block diagram which shows the structure of the vehicle state detection apparatus which concerns on this embodiment. It is a schematic diagram of a vehicle provided with an outside air temperature detection unit and a tire internal temperature detection unit of the vehicle state detection device according to the present embodiment. It is a cross-sectional schematic diagram of a tire provided with a tire groove temperature detection unit of the vehicle state detection device according to the present embodiment. It is a flowchart at the time of detecting the road surface state by the road surface state detection apparatus which concerns on this embodiment. FIG. 5 is a graph showing changes in detected temperature in each detection unit in order to explain the determination in S18 of the flowchart shown in FIG. FIG. 5 is a graph showing changes in detected temperature in each detection unit in order to explain the determination in S24 of the flowchart shown in FIG. 4. FIG. 5 is a graph showing changes in detected temperature in each detection unit in order to explain the determination in S30 of the flowchart shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Outside air temperature detection part, 20 Tire inside temperature detection part, 30 Tire groove part temperature detection part, 40 Judgment part, 42 Calculation part, 44 Memory | storage part, 50 Tire, 52 tread, 52a Groove part, 60 rim | limb, 100 Road surface state detection apparatus, 200 vehicle control device, 300 vehicle.

Claims (3)

An outside temperature detector for detecting the temperature of the outside air;
A tire temperature detector that detects the temperature inside the tire;
A tire groove temperature detector for detecting the temperature of the tire groove,
A determination unit that determines a plurality of road surface conditions by using the temperature of the outside air, the difference between the temperature in the tire and the temperature of the tire groove, and the difference between the temperature of the tire groove and the temperature of the outside air;
A road surface state detection device comprising:   The determination unit has a temperature of the outside air that is equal to or higher than a first predetermined value, and a difference between the temperature in the tire and the temperature of the tire groove is equal to or higher than a second predetermined value, and the tire groove The road surface state detection device according to claim 1, wherein the road surface state is determined to be wet when a difference between the temperature of the outside air and the temperature of the outside air is less than a third predetermined value.   The road surface condition detection device according to claim 1, wherein the tire groove temperature detection unit is provided at a bottom of the tire groove.

Images