JP2019099058A - μ GRADIENT DETECTION DEVICE, INSTALLATION TIRE DETERMINATION DEVICE, ROAD SURFACE STATE DETERMINATION DEVICE, INSTALLATION TIRE AND ROAD SURFACE STATE DETERMINATION DEVICE - Google Patents

Abstract

To determine a road surface state, particularly, the occurrence of hydro-planing, and to determine a classification of an installation tire, without installing an acceleration sensor on a tire.SOLUTION: A μ gradient detection device 30 comprises a detection part 32 for detecting vibration of a vehicle, a storage part 34 for storing a vehicle vibration characteristic with a μ gradient as a parameter and a μ gradient detection part 36 for detecting reduction in the μ gradient by collating the detected vibration and the vehicle vibration characteristic. An installation tire determination part 40 determines that a studless tire is installed when detecting reduction in the μ gradient when a vehicle speed detected by a vehicle speed detection part 38 is less than a hydro-planing occurrence vehicle speed. When a vehicle speed detected by the vehicle speed detection part 38 is the hydro-planing occurrence vehicle speed or more, a determination is made that hydro-planing is caused when detecting reduction in the μ gradient in a studless tire uninstallation.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a μ gradient detection device, a mounted tire determination device, a road surface state determination device, a mounted tire, and a road surface state determination device.

  Conventionally, techniques for estimating road surface conditions such as hydroplaning have been proposed.

  Patent Document 1 measures road surface temperature T during traveling, tire vibration, tire generated sound, and wheel speed V, and outputs acceleration sensor output and data on wheel speed V, which are data of tire vibration. From this, the vibration level ratio R, which is the ratio of the magnitude GL of the vibration component in the 1 to 2 kHz band and the magnitude GH of the vibration component in the 3 to 5 kHz band, is calculated from The sound pressure signal which is the output is analyzed by 1 / N octave, and the sound pressure level ratio Q which is the ratio of the band power value PA of 500 Hz to the band power value PB of 8000 Hz is calculated from the octave distribution waveform. It is described that the road surface state is estimated using data, data of vibration level ratio R, data of sound pressure level ratio Q, and data of wheel speed V.

  In Patent Document 2, as a technique related to estimation of road surface condition, acceleration / deceleration speed of a vehicle body and rotational speed of wheels are detected, and a tire model and a suspension front / rear spring element are considered before and after vehicle acceleration / deceleration. Based on the wheel speed difference of the wheels, the distribution ratio of the braking force and the driving force to the front and rear wheels, and the distribution ratio of each wheel load corrected according to the detected acceleration / deceleration are known values, and the tire radius of each wheel It is described that at least one of a road surface μ gradient and a spring constant of a synthetic spring combining the above-mentioned spring elements is estimated, and a tire type is estimated based on the estimated road surface μ gradient and the spring constant.

JP, 2011-46256, A Japanese Patent Application Publication No. 2003-306093

  In Patent Document 1, it is difficult to capture a signal into the vehicle cabin, since the acceleration sensor is mounted on a tire that is a rotating body. In addition, although it is conceivable to mount a pressure sensor or a strain gauge in the tire, it is similarly difficult to capture a signal into the vehicle cabin. Furthermore, when using an acceleration sensor, vibration levels in high frequency bands of 1 to 2 kHz, 3 to 5 kHz, and 8 kHz are targeted, sampling of at least 16 kHz is required, and there is also a problem of large measurement load.

  In Patent Document 2, the vehicle longitudinal velocity (sprung longitudinal acceleration) is affected by the road surface inclination, and thus there is a possibility of erroneous determination. In addition, although the installation of a studless tire is estimated as a tire type, a reduction in road surface μ gradient occurs even when hydroplaning occurs, so it is difficult to distinguish between the two.

  An object of the present invention is to provide a technology for determining a road surface state, particularly, the occurrence of hydroplaning, and determining the type of a mounted tire without mounting an acceleration sensor or the like on the tire.

  According to the present invention, the vibration detection unit for detecting the vibration of a predetermined portion of the vehicle, the storage unit for storing the vehicle vibration characteristics using the μ gradient as a parameter, the detected vibration and the vehicle vibration characteristics are compared. A μ gradient detection device comprising a μ gradient detection unit that detects a decrease in gradient.

  In one embodiment of the present invention, the vibration detection unit detects vibration of at least one of an engine and a motor, and the μ gradient detection unit collates with the vehicle vibration characteristic when different drive torques are applied. When the resonant vibration of at least one of the engine and the motor is detected, the decrease of the μ gradient is detected.

  In another embodiment of the present invention, the vibration detection unit detects vibration of a drive shaft, and the μ gradient detection unit collates the vibration characteristic of the drive shaft by applying different drive torques. A decrease in the μ slope is detected when a damping of the resonant vibration is detected.

  In still another embodiment of the present invention, the vibration detection unit detects a vibration of at least one of an engine and a motor and a vibration of a drive shaft, and the μ gradient detection unit detects the vibration of different drive torques. When the resonance vibration of at least one of the engine and the motor is detected and the attenuation of the resonance vibration of the drive shaft is detected by comparing with the vehicle vibration characteristic, the decrease of the μ gradient is detected.

  Further, the present invention provides a mounted tire of a vehicle based on the μ gradient detection device, the vehicle speed detection unit, the decrease of the μ gradient detected by the μ gradient detection device, and the vehicle speed detected by the vehicle speed detection unit. It is a mounting | wearing tire determination apparatus provided with the determination part which determines.

  In one embodiment of the present invention, a threshold vehicle speed storage unit for storing a threshold vehicle speed of hydroplaning occurrence is provided, and the determination unit determines the μ gradient when the vehicle speed detected by the vehicle speed detection unit is less than the threshold vehicle speed. It is determined that a tire with a small driving stiffness, such as a studless tire, is mounted when a drop in the tire is detected.

  Further, according to the present invention, the road surface state is determined based on the μ gradient detection device, the vehicle speed detection unit, the decrease of the μ gradient detected by the μ gradient detection device, and the vehicle speed detected by the vehicle speed detection unit. It is a road surface state determination apparatus provided with a determination part.

  In one embodiment of the present invention, the determination unit determines hydroplaning when a decrease in the μ gradient is detected by the μ gradient detection device with the increase in the vehicle speed.

  In another embodiment of the present invention, a threshold vehicle speed storage unit for storing a threshold vehicle speed for hydroplaning occurrence is provided, and the determination unit is configured to determine the μ gradient when the vehicle speed detected by the vehicle speed detection unit is equal to or higher than the threshold vehicle speed. It is determined that hydroplaning has occurred when a drop in is detected.

  Further, the present invention provides a mounted tire of a vehicle based on a μ gradient detection device, a vehicle speed detection unit, a decrease of the μ gradient detected by the μ gradient detection device, and a vehicle speed detected by the vehicle speed detection unit. It is a mounting | wearing tire provided with the determination part which determines a road surface state, and a road surface state determination apparatus.

  In one embodiment of the present invention, a threshold vehicle speed storage unit for storing a threshold vehicle speed of hydroplaning occurrence is provided, and the determination unit determines the μ gradient when the vehicle speed detected by the vehicle speed detection unit is less than the threshold vehicle speed. When it is detected that the tire has a low driving stiffness including a studless tire, a decrease in the μ gradient is detected when the vehicle speed detected by the vehicle speed detection unit is equal to or higher than the threshold vehicle speed. If it is not determined that the driving stiffness including the studless tire is small, it is determined that hydroplaning occurs.

  According to the present invention, it is possible to detect a decrease in the μ gradient without attaching an acceleration sensor or the like to the tire. Further, according to the present invention, it is possible to determine the road surface condition, particularly the occurrence of hydroplaning, based on the decrease of the detected μ gradient. Further, according to the present invention, the mounted tire can be determined based on the decrease of the detected μ slope. Further, according to the present invention, it is possible to discriminate and determine the mounted tire and the road surface state based on the detected decrease of the μ slope and the vehicle speed.

It is principle model explanatory view showing the connection relation of each part of vehicles. It is a road surface friction characteristic figure. FIG. 5 is an explanatory view of the μ gradient at each operation point of FIG. 2; It is a transfer characteristic view from the drive torque by the difference of (mu) gradient to sprung front-and-back acceleration. FIG. 2 is a configuration block diagram of the μ gradient detection device of the first embodiment. FIG. 1 is a configuration block diagram of a mounted tire determination device of a first embodiment. FIG. 2 is a detailed block diagram of a mounted tire determination device according to a first embodiment. It is a figure which shows the real vehicle measurement result of a road surface friction characteristic. FIG. 7 is an explanatory view of a μ gradient with respect to a vehicle speed. It is a figure (the 1) showing a measurement result of vehicles vibration. It is a figure (the 2) showing a measurement result of vehicles vibration. It is a figure (the 3) which shows the measurement result of vehicle vibration. FIG. 7 is a block diagram of a road surface state determination device according to a second embodiment. FIG. 7 is a block diagram of a detailed configuration of a road surface state determination device of a second embodiment. 5 is a processing flowchart of the first and second embodiments. It is a road surface mu characteristic view in each road surface and various tires.

  Hereinafter, embodiments of the present invention will be described based on the drawings.

<Basic principle>
First, the basic principle of the present embodiment will be described.

Hydroplaning (hereinafter abbreviated as “hypre” as appropriate) occurs when the dynamic pressure of water exceeds the tire contact pressure Pc. That is, assuming that 密度 is the density of water and Vv is the vehicle speed, the dynamic pressure of water is expressed by 1/2 · ρ · Vv ² , so this magnitude relationship is
1/2 · ρ · Vv ² > Pc (1)
It is.

Also, when k is tread stiffness, w is tire contact width, and l is tire contact length, μ slope α is
α = 1/2 · k · w · l ² (2)
It is expressed by

  According to the equation (1), the dynamic pressure of water increases as the vehicle speed increases, and the tire surpasses the tire contact pressure to rise, so the contact area w · l with the road surface of the equation (2) decreases. As a result, according to the equation (2), the μ gradient α is lowered at the time of occurrence of the hypre.

  In addition, since the tread stiffness k of the equation (2) decreases when the tire is mounted with a small driving stiffness including a studless tire, the μ gradient α also decreases according to the equation (2) when a tire including a studless tire has a small driving stiffness. It will be. FIG. 16 is a road surface μ characteristic for each road surface and various tires described in Methods and Instruments for On-Board Measurement of Tire / Road Friction, Bert Breuer, Thomas Bechmann etc, Technishe Hochshule Darmstadt, SAE Paper No. 942470. Show. The horizontal axis indicates the tire slip ratio, and the vertical axis indicates the tire driving force / wheel load. In the studless tire, the μ slope decreases from the tire slip rate origin.

  As described above, although the μ slope α is lowered both at the time of occurrence of high advance and at the time of wearing of the tire having a small driving stiffness including the studless tire, the occurrence of highpre occurs at high vehicle speed conditions. If α decreases, it can be determined that a tire with a small driving stiffness including a studless tire is mounted, and if a tire with a small driving stiffness including a studless tire has no determination of a tire mounting, a high vehicle speed may be determined as highpresence. . Hereinafter, a studless tire will be described as a typical example of a tire having a small driving stiffness.

The high-prey generated vehicle speed Vh can be defined by the following equation based on the equation (1).
Vh V (2 · Pc / ρ) ^0.5 (3)

Therefore, studless tire attachment and determination of occurrence of hype can be made in the next two steps.
Step 1: Judgment as studless tire attachment when μ gradient drop is detected in the state of vehicle speed Vv <Vh Second step: μ gradient drop is detected in the state of vehicle speed Vv ≧ Vh, and studless in the first step Determined as occurrence of high wear when tire mounting judgment is not made

  Then, the vehicle vibration characteristics, specifically the vibration characteristics of the engine and the drive shaft, change according to the size of the μ gradient, so the relationship between the two is stored in advance. The magnitude of the μ gradient, that is, the decrease of the μ gradient can be detected by comparing the characteristics of the vibration measurement value at the time of acceleration of the vehicle to which the driving torque is applied with the vehicle vibration characteristics stored in advance.

  However, when a driving torque that reaches the tire driving force limit is applied, the μ gradient can be reduced even when the studless tire is fitted or highs are not generated. Therefore, the slip rates at at least two points before the tire slip rate becoming the tire driving force limit. If the μ gradient is detected and both of the μ gradients decrease, it is desirable to determine that the studless tire is fitted or that the tire is high-prevented. The tire driving force limit is set to be at the time of occurrence of a tire tire having a smaller tire driving force limit between the attachment of studless tire and the generation of the tire.

  In this embodiment, the vibration detection sensor is attached to the engine, the drive shaft or the like so as to obtain a measurement value of the vibration characteristic, so that there is an advantage that the attachment is easy compared to the case of attaching the sensor in the tire.

  Further, the vehicle vibration associated with the μ gradient decrease is a relatively low frequency of 20 Hz or less, so it can be handled with a low sampling period, and the measurement load can be suppressed without requiring a high sampling period as in the prior art.

  In addition, since it is determined that the studless tire is attached in a state of less than the high-prey generated vehicle speed, it is possible to clearly separate whether the μ gradient drop is due to the studless tire or the highpre generation in the relevant vehicle speed range, ensuring running safety. It is also possible to determine whether or not it is necessary.

  Furthermore, in the present embodiment, attention is paid to the frequency of vibration, so that there is also an advantage that it is possible to determine the occurrence of studless tires and occurrence of hypre without being influenced by the vehicle operating conditions such as road surface gradient and driving torque. .

  The embodiments will be specifically described below.

First Embodiment
In this embodiment, the detection of the decrease of the μ gradient and the determination of the studless tire mounting will be described.

  As an example of the vehicle vibration change at the time of the μ gradient decrease, actualization of vibration of engine longitudinal resonance and damping of vibration of drive shaft resonance are used.

  FIG. 1 shows a principle block diagram. As shown in FIG. 1A, the engine 10, the transmission 12, the drive shaft 14, the tire 16, the unsprung 18, the sprung 20, and the engine block 22 are connected to one another. The engine block 22 has six degrees of freedom including rotation in the front and rear, left and right, up and down, and around each axis, but as shown in FIG. .

  FIG. 2 shows road surface friction characteristics showing the relationship between the slip ratio and the tire driving force / wheel load. In FIG. 2, two cases are shown, where the μ gradient near the origin of the slip ratio is small (characteristic indicated by reference numeral 100) and when it is large (characteristic indicated by reference numeral 200). In the characteristic 100, the μ slope decreases at two points at different slip rates, but in the characteristic 200, the slip rate decreases at the tire driving force limit, and the μ slope does not decrease when the slip rate is less than the limit.

  FIG. 3 shows a comparison of the μ slopes at the a, b operating points of FIG. The horizontal axis represents tire driving force / wheel load, and the vertical axis represents μ gradient. In the characteristic 100, the μ gradient decreases at any of the a and b operating points, and on the other hand, in the characteristic 200, the μ gradient does not decrease at the a operating point although the μ gradient decreases at the b operating point.

  FIG. 4 shows the transfer characteristics from drive torque to sprung, using the μ slope values and vehicle specifications shown in FIG. The horizontal axis represents frequency, and the vertical axis represents sprung longitudinal acceleration / drive torque. In the figure, the transfer characteristic of the a operating point of the characteristic 100 is 100a, the transfer characteristic of the b operating point of the characteristic 100 is 100b, the transfer characteristic of the a operating point of the characteristic 200 is 200a, and the transfer characteristic of the b operating point of the characteristic 200 is 200b. As shown.

  In the case of the characteristic 200 where the μ gradient near the origin of the slip ratio is large, both peaks of the drive shaft resonance and the longitudinal resonance of the engine appear prominently at the a operating point. Also, at the b operating point where the μ slope decreases, only the engine front-rear resonance peak appears notably, and the drive shaft resonance peak decreases.

  On the other hand, in the case of the characteristic 100 in which the μ gradient decreases from the vicinity of the origin of the slip ratio, only the front and rear resonance peaks of the engine significantly appear at both the a operating point and the b operating point.

  From this, for example, driving torque is applied at each of the a operating point and b operating point in a state where the traveling vehicle speed is smaller than the vehicle speed Vh shown in equation (3), and vibration of engine longitudinal resonance at different driving torque application By detecting or detecting the vibration damping of the drive shaft resonance, the μ gradient is continuously reduced from near the origin of the slip ratio, and in this case, it can be determined that the studless tire is mounted.

  When the μ gradient value is detected as a numerical value, frequency characteristics, drive shaft resonance, vibration peak values of engine longitudinal resonance, etc. as shown in FIG. It may be calculated from the comparison of the sprung longitudinal acceleration / drive torque with the frequency analysis value.

  FIG. 5 shows a configuration block diagram of the μ gradient detection device 30 in the present embodiment.

  The μ gradient detection device 30 includes a vehicle vibration characteristic detection unit 32, a μ gradient-vehicle vibration characteristic relationship storage unit 34, and a μ gradient detection unit 36.

  The vehicle vibration characteristic detection unit 32 detects a frequency analysis value of sprung longitudinal acceleration / drive torque as a vehicle vibration characteristic.

  The μ gradient-vehicle vibration characteristic relationship storage unit 34 previously stores, as a table, frequency characteristics, drive shaft resonance, vibration peak values of engine longitudinal resonance, etc., using transmission gear and μ gradient as parameters.

  The μ gradient detection unit 36 detects a decrease in the μ gradient by comparing the vibration characteristic detected by the vehicle vibration characteristic detection unit 32 with the frequency characteristic stored in the μ gradient-vehicle vibration characteristic relationship storage unit 34. Output.

  FIG. 6 shows a configuration block diagram of the mounted tire determination device in the present embodiment.

  The mounted tire determination device includes a μ gradient detection device 30, a vehicle speed detection unit 38, and a mounted tire determination unit 40.

  The μ gradient detection device 30 includes the constituent blocks shown in FIG. 5, detects a decrease in the μ gradient, and outputs the detection result to the mounted tire determination unit 40.

  The vehicle speed detection unit 38 detects the vehicle speed and outputs the detected vehicle speed to the mounted tire determination unit 40.

  The mounted tire determination unit 40 determines the mounting of a mounted tire, specifically, a studless tire, based on the vehicle speed and the detection signal of the μ slope decrease, and outputs the determination result. That is, the mounted tire determination unit 40 determines that the studless tire is mounted when a decrease in the μ gradient is detected in the state of the vehicle speed Vv <Vh.

  FIG. 7 shows a detailed block diagram of the mounted tire determination device.

  Engine (E / G) 6 degrees of freedom vibration detection unit 50, sprung back and forth vibration detection unit 52, drive shaft vibration detection unit 56, engine rotational speed vibration detection unit 58, gear stage detection unit 62 respectively engine vibration and sprung back and forth Vibration, drive shaft vibration, engine rotational speed vibration, gear stages are detected, and frequency components of drive shaft resonance to engine longitudinal resonance region are passed by the band pass filter units 64 to 70, and the engine six degrees of freedom resonance collating unit 72 and The data is output to the drive shaft resonance check unit 74.

  Further, the engine 6 degrees of freedom resonance storage unit 54 outputs the resonance frequency of the engine 6 degrees of freedom to the engine 6 degrees of freedom resonance check unit 72, and the drive shaft resonance storage unit 60 is the drive shaft resonance check unit 74 Output to

  On the other hand, the vehicle speed detection unit 38 detects the vehicle speed and outputs it to the drive torque limit value storage unit 42.

  Drive torque limit value storage unit 42 outputs a drive torque limit value to drive torque command value determination unit 44 based on the detected vehicle speed.

  Drive torque command value determination unit 44 determines the drive torque command value within the drive torque limit value and outputs the drive torque command value to acceleration start determination unit 48, as well as outputting the drive torque command value to drive torque generation unit 46.

  The acceleration start determination unit 48 outputs to the engine six degrees of freedom resonance check unit 72 whether or not the acceleration is started, that is, whether or not the drive torque is applied.

  Based on the signal from acceleration start determination unit 48, engine 6-degree-of-freedom resonance check unit 72 generates vibration of engine longitudinal resonance that matches the resonance frequency stored in E / G 6 degrees of freedom resonance storage unit 54 when applying drive torque. It is determined whether or not there is any, and when a vibration in the longitudinal resonance of the engine is detected at the time of application of the drive torque, a detection signal is output to the .mu.

  Similarly, drive shaft resonance verification unit 74 performs drive shaft resonance at a resonance frequency corresponding to the transmission gear stored in drive shaft resonance storage unit 60 when applying drive torque based on the signal from acceleration start determination unit 48. It is determined whether or not there is vibration damping, and when vibration damping of drive shaft resonance is detected at the time of applying drive torque, in other words, resonance according to the transmission gear stored in drive shaft resonance storage unit 60 If the frequency does not match the detected drive shaft resonance frequency, the detection signal is output to the μ gradient detection unit 36.

  The μ gradient detection unit 36 detects the decrease in μ gradient based on the detection signals of the engine 6 degrees of freedom resonance collating unit 72 and the drive shaft resonance collating unit 74 and the gear stage signal from the gear stage detection unit 62 to determine the mounted tire Output to section 40. Further, the μ gradient detection unit 36 outputs a torque application command to the drive torque limit value storage unit 42. Thus, the drive torque limit value storage unit 42 applies two different drive torques, and the μ gradient detection unit 36 detects a decrease in the μ gradient at the time of two different drive torque applications.

  The mounted tire determination unit 40 mounts the studless tire when a decrease in the μ gradient is detected in the state of the vehicle velocity Vv <Vh based on the vehicle speed from the vehicle speed detection unit 38 and the detection signal from the μ gradient detection unit 36. It judges as and outputs a judgment result.

  The drive torque command value determination unit 44, the acceleration start determination unit 48, the engine 6 degrees of freedom resonance verification unit 72, the drive shaft resonance verification unit 74, the μ gradient detection unit 36, and the mounted tire determination unit 40 in FIG. Can be realized by a processor of The processor implements each of these configuration blocks by reading and executing a processing program stored in a non-volatile memory such as an EEPROM. Note that at least one of these configuration blocks may be realized by a hardware circuit, and the hardware processing may use a circuit such as an ASIC or an FPGA (field programmable gate array).

  In the figure, the drive torque limit value storage unit 42, the E / G 6 degrees of freedom resonance storage unit 54, and the drive shaft resonance storage unit 60 are configured as separate storage units, but these are configured by a single memory. May be

Second Embodiment
In the present embodiment, determination of occurrence of hi-pre will be described.

  FIG. 8 shows the results of comparing the road surface friction characteristics in the non-hypre and hipre states with reference to the high μ road (dry road). The horizontal axis represents the slip ratio, and the vertical axis represents the tire driving force / wheel load. FIG. 8 (a) shows a non-hyper state at medium vehicle speed, and FIG. 8 (b) shows a high vehicle speed, that is, a hyper state at vehicle speed defined by equation (3). Based on this result, the tire driving force / wheel load characteristics with respect to the slip ratio are linearly approximated to calculate the μ slope.

  FIG. 9 shows the result of calculating the μ gradient in FIG. The horizontal axis represents the vehicle speed, and the vertical axis represents the μ gradient. Since the μ gradient decreases in the high-presence state of the high vehicle speed, it is possible to determine the occurrence of the high pre by detecting the μ gradient decrease.

  FIG. 10 shows measured waveforms of a high μ road (dry road) and a low μ road (hypre state) at the time of driving torque application (b operating point) not reaching the tire driving force limit in the high pre state. FIG. 10 (a) is a waveform of a high μ path (drying path), and FIG. 10 (b) is a waveform of a low μ path (hypre state). The horizontal axis represents time, and the vertical axis represents drive shaft torque, engine longitudinal acceleration, and drive wheel speed. The vehicle speed and the transmission gear are under the same conditions. The engine longitudinal acceleration is subjected to band pass filter processing for passing frequency components in the drive shaft resonance to engine longitudinal resonance regions. From these figures, it can be seen that vibration in the longitudinal resonance of the engine is remarkable and the drive shaft resonance is attenuated in the hyperplane state in which the μ gradient decreases as compared with the high μ road.

  FIG. 11 shows measured waveforms of the high μ road (dry path) and the low μ road (hypre state) when the drive torque is applied (a operating point) smaller than that of FIG. FIG. 11 (a) is a waveform of a high μ road (drying road), and FIG. 11 (b) is a waveform of a low μ road (hypre). The horizontal axis represents time, and the vertical axis represents drive shaft torque, engine longitudinal acceleration, and drive wheel speed. The vehicle speed and the transmission gear are under the same conditions. The engine longitudinal acceleration is subjected to band pass filter processing for passing frequency components in the drive shaft resonance to engine longitudinal resonance regions. It can be seen that, even in the case of different driving torques, vibration in the longitudinal resonance of the engine is remarkable and the drive shaft resonance is attenuated in the hyperplane state in which the μ gradient decreases as compared with the high μ road.

  FIG. 12 shows the results of driving torque application in comparison with and without reaching the tire driving force limit at low μ road and medium vehicle speeds. FIG. 12 (a) shows the case where the tire driving force limit is reached, and FIG. 12 (b) shows the case where the tire driving force limit is not reached. The horizontal axis represents time, and the vertical axis represents drive shaft torque, engine longitudinal acceleration, and drive wheel speed. The vehicle speed and the transmission gear are under the same conditions. The engine longitudinal acceleration is subjected to band pass filter processing for passing frequency components in the drive shaft resonance to engine longitudinal resonance regions. When driving torque is applied to reach the tire driving force limit, oscillations in the longitudinal resonance of the engine are remarkable, and when driving torque is not reached to reach the tire driving force limit, vibration of drive shaft torque resonance is remarkable. Therefore, it is possible to determine the occurrence of the generation of highs in the cases of FIG. 10 and FIG.

  FIG. 13 shows a configuration block diagram of the road surface state determination device in the present embodiment. Although substantially the same as the mounted tire determination device shown in FIG. 6, a road surface state determination unit 41 is provided instead of the mounted tire determination unit 40.

  The road surface state determination unit 41 determines whether or not the occurrence of the hypre has occurred based on the detection signal from the μ slope detection device 30 and the vehicle speed from the vehicle speed detection unit 38, and outputs the determination result. That is, when the μ gradient decrease is detected in the state of the vehicle speed Vv ≧ Vh, it is determined that the generation is high. As described above, the road surface state determination unit 41 may determine that the tire is high when the studless tire is not mounted.

  FIG. 14 shows a detailed block diagram of the road surface condition judging device. Although substantially the same as the mounted tire determination device shown in FIG. 7, a road surface state determination unit 41 is provided instead of the mounted tire determination unit 40.

  Engine (E / G) 6 degrees of freedom vibration detection unit 50, sprung back and forth vibration detection unit 52, drive shaft vibration detection unit 56, engine rotational speed vibration detection unit 58, gear stage detection unit 62 respectively engine vibration and sprung back and forth Vibration, drive shaft vibration, engine rotational speed vibration, gear stages are detected, and frequency components of drive shaft resonance to engine longitudinal resonance region are passed by the band pass filter units 64 to 70, and the engine six degrees of freedom resonance collating unit 72 and The data is output to the drive shaft resonance check unit 74.

  Further, the engine 6 degrees of freedom resonance storage unit 54 outputs the resonance frequency of the engine 6 degrees of freedom to the engine 6 degrees of freedom resonance check unit 72, and the drive shaft resonance storage unit 60 is the drive shaft resonance check unit 74 Output to

  On the other hand, the vehicle speed detection unit 38 detects the vehicle speed and outputs it to the drive torque limit value storage unit 42.

  Drive torque limit value storage unit 42 outputs a drive torque limit value to drive torque command value determination unit 44 based on the detected vehicle speed.

  Drive torque command value determination unit 44 determines the drive torque command value within the drive torque limit value and outputs the drive torque command value to acceleration start determination unit 48, as well as outputting the drive torque command value to drive torque generation unit 46.

  The acceleration start determination unit 48 outputs to the engine six degrees of freedom resonance check unit 72 whether or not the acceleration is started, that is, whether or not the drive torque is applied.

  Engine 6-degree-of-freedom resonance collating section 72 has vibration of engine longitudinal resonance at the resonance frequency stored in E / G 6-degree-of-freedom resonance storage section 54 when applying drive torque based on the signal from acceleration start determination section 48 It is determined whether or not the engine front-rear resonance vibration is detected when the drive torque is applied, and a detection signal is output to the μ gradient detection unit 36.

  Similarly, whether drive shaft resonance collating unit 74 has vibration damping of drive shaft resonance at the resonance frequency stored in drive shaft resonance storage unit 60 when applying drive torque based on the signal from acceleration start determination unit 48 It is determined whether or not vibration damping of drive shaft resonance is detected at the time of application of drive torque, that is, a resonance frequency corresponding to the transmission gear stored in drive shaft resonance storage unit 60, and the detected drive shaft If the resonance frequency does not match, the detection signal is output to the μ slope detection unit 36.

  The μ gradient detection unit 36 detects the decrease in μ gradient based on the detection signals of the engine 6 degrees of freedom resonance collating unit 72 and the drive shaft resonance collating unit 74 and the gear signal from the gear detection unit 62 to determine the road surface state Output to the part 41. Further, the μ gradient detection unit 36 outputs a torque application command to the drive torque limit value storage unit 42. Thus, the drive torque limit value storage unit 42 applies two different drive torques, and the μ gradient detection unit 36 detects a decrease in the μ gradient at the time of two different drive torque applications.

  The road surface state determination unit 41 detects that the studless tire is not in the case where the μ gradient reduction is detected in the state of the vehicle speed Vv ≧ Vh based on the vehicle speed from the vehicle speed detection unit 38 and the detection signal from the μ gradient detection unit 36. Under the condition of attachment, it is determined that the occurrence of hi-pre has occurred, and the determination result is output.

Embodiment 3
In the first embodiment, the attachment of the studless tire is determined, and in the second embodiment, the occurrence of the generation of highs is determined. However, the presence or absence of the attachment of the studless tires and the presence or absence of the generation of highs may be determined.

  The configuration block diagram of the mounted tire and the road surface state determination device in the present embodiment is substantially the same as the configuration shown in FIGS. 13 and 14, but in the road surface state determination portion 41 the mounted tire determination portion 40 shown in FIGS. Similarly, the studless tire attachment is determined, and the occurrence of high rise is also determined. Specifically, attachment of the studless tire is determined when the vehicle speed is less than the highpre generation vehicle speed, and it is determined that highpre occurrence is generated when the vehicle speed is higher than the highpre occurrence vehicle speed and the studless tire is not attached. In the configuration of the present embodiment, the road surface state determining unit 41 in FIGS. 13 and 14 may be read as a mounted tire and a road surface state determining unit.

  FIG. 15 shows a processing flowchart of this embodiment.

  First, a detection reference value for the high preliminary vehicle speed Vh and the μ gradient decrease is set and stored in the memory (S101). Further, the initial value of the mounted tire is assumed to be a summer tire, and the determination flag is reset to zero.

  Next, the transmission gear and the vehicle speed Vv are read (S102).

  Next, a drive torque is applied (S103), and a sensor signal related to vehicle vibration is read (S104). Specifically, sensor signals for detecting each vibration of E / G 6 degrees of freedom vibration, sprung back and forth vibration, drive shaft vibration, and engine rotational speed vibration are read.

  Next, feature quantities of vibration related to the μ gradient are extracted (S105). Specifically, the engine front and rear resonance frequency signal and the drive shaft resonance frequency signal are extracted.

  Next, the decrease of the μ gradient is detected by comparing the feature quantity of the vibration and the reference value (S106). Specifically, the decrease in the μ gradient is detected depending on whether the engine front-rear resonance frequency signal is remarkable above the reference value and the drive shaft resonance frequency signal is attenuated below the reference value.

  Next, it is determined whether or not different driving torque application is performed twice or more (S107). If the application of the different drive torque is less than two times, the processing after S103 is repeated (NO in S107).

  If the different application of the drive torque reaches twice (YES in S107), it is next determined whether or not the [mu] slope is all lowered at the time of two or more application of the drive torque (S108).

  If the μ gradient is lowered at two or more different driving torque application times (YES in S108), it is determined whether the vehicle speed Vv is smaller than the highpre vehicle speed Vh (S109). If Vv <Vh, it is determined that the studless tire is mounted, and the flag is set to 1 (S110). On the other hand, if Vv ≧ Vh, it is determined whether or not the flag is set to 1 (S111), and if the flag is not set to 1, it is determined that generation is high (S112). If the μ gradient has not decreased twice or more (NO in S108), or if the flag is already set to 1 even in VvVVh (NO in S111), no determination is made.

  In addition, the process of S101-S110 can be said to be a process of Embodiment 1 which determines a mounting | wearing tire.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation is possible.

  For example, in the case of a hybrid vehicle traveling by an engine and a motor, it may be applied as an engine and a motor instead of the engine 10, and in the case of an electric vehicle traveling by a motor, it may be replaced by a motor. In short, the longitudinal resonance vibration of at least one of the engine and the motor may be used.

  Although the μ gradient is shown in FIG. 2 and the like as the relationship between the tire driving force and the wheel load with respect to the slip ratio, the tire driving force may be replaced with the tire driving force and the wheel load.

  Further, in the first embodiment, as shown in FIG. 7, the engine 6 degrees of freedom resonance collating unit 72 and the drive shaft resonance collating unit 74 are provided, and both occurrence of engine longitudinal resonance and attenuation of drive shaft resonance are detected. A decrease in the gradient is detected, but at least one of the engine 6 degrees of freedom resonance check unit 72 and the drive shaft resonance check unit 74 is provided to detect at least one of the appearance of engine longitudinal resonance and the damping of drive shaft resonance. Therefore, the decrease of the μ gradient may be detected. The same applies to FIG. 14 of the second embodiment.

  Furthermore, although the engine longitudinal resonance frequency and the drive shaft resonant frequency are used in the embodiment, it goes without saying that the engine (or motor) longitudinal resonance cycle and the drive shaft resonant cycle may be used.

Reference Signs List 10 engine, 12 transmission, 14 drive shaft, 16 tires, 18 springs, 20 springs, 22 engine blocks, 30 μ gradient detection device, 38 vehicle speed detection unit, 40 mounted tire determination unit, 41 road surface condition determination unit.

Claims (11)

A vibration detection unit that detects vibration of a predetermined portion of the vehicle;
a storage unit that stores vehicle vibration characteristics using a μ gradient as a parameter;
A μ gradient detection unit that detects a decrease in μ gradient by comparing the detected vibration with the vehicle vibration characteristic;
Μ gradient detection device comprising: The vibration detection unit detects vibration of at least one of an engine and a motor,
The μ gradient detection unit detects a decrease in the μ gradient when at least one of the engine vibration and the motor resonance vibration is detected by collating with the vehicle vibration characteristic when different drive torques are applied. The μ gradient detection device according to 1. The vibration detection unit detects the vibration of the drive shaft,
The μ gradient detection unit detects the decrease of the μ gradient when the attenuation of the resonance vibration of the drive shaft is detected by collating with the vehicle vibration characteristic at the time of applying different driving torques. Mu-gradient detection device as described. The vibration detection unit detects vibration of at least one of an engine and a motor and vibration of a drive shaft,
At the time of different driving torque application, the μ gradient detection unit collates with the vehicle vibration characteristic to detect resonant vibration of at least one of the engine and the motor and detect attenuation of resonant vibration of the drive shaft. The μ gradient detection device according to claim 1, wherein the decrease of the μ gradient is detected. The μ gradient detection device according to any one of claims 1 to 4.
A vehicle speed detection unit,
A determination unit that determines a mounted tire of a vehicle based on the decrease of the μ gradient detected by the μ gradient detection device and the vehicle speed detected by the vehicle speed detection unit;
A mounted tire determination device comprising: The mounted tire determination device according to claim 5, wherein the determination unit determines hydroplaning when a decrease in the μ gradient is detected by the μ gradient detection device as the vehicle speed increases. A threshold vehicle speed storage unit for storing a threshold vehicle speed of hydroplaning occurrence;
The determination unit determines that a tire having a small driving stiffness including a studless tire is mounted when a decrease in the μ gradient is detected when the vehicle speed detected by the vehicle speed detection unit is less than the threshold vehicle speed. The mounted tire determination device according to claim 1. The μ gradient detection device according to any one of claims 1 to 4.
A vehicle speed detection unit,
A determination unit that determines a road surface state based on the decrease of the μ gradient detected by the μ gradient detection device and the vehicle speed detected by the vehicle speed detection unit;
Road surface state determination device provided with A threshold vehicle speed storage unit for storing a threshold vehicle speed of hydroplaning occurrence;
The road surface state determination device according to claim 8, wherein the determination unit determines that hydroplaning has occurred when a decrease in the μ gradient is detected when the vehicle speed detected by the vehicle speed detection unit is equal to or higher than the threshold vehicle speed. The μ gradient detection device according to any one of claims 1 to 4.
A vehicle speed detection unit,
A determination unit that determines a mounted tire of a vehicle and a road surface state based on the decrease of the μ gradient detected by the μ gradient detection device and the vehicle speed detected by the vehicle speed detection unit;
A tire equipped with a tire and a road surface condition judging device. A threshold vehicle speed storage unit for storing a threshold vehicle speed of hydroplaning occurrence;
The determination unit determines that a tire having a small driving stiffness including a studless tire is mounted when a decrease in the μ gradient is detected when the vehicle speed detected by the vehicle speed detection unit is less than the threshold vehicle speed, and the vehicle speed When the vehicle speed detected by the detection unit is equal to or higher than the threshold vehicle speed, a decrease in the μ slope is detected, and when it is not determined that the tire has low driving stiffness including the studless tire, hydroplaning is determined to occur. The mounted tire and the road surface state determination device according to claim 10.