JP7006210B2 - μ Gradient detection device, mounted tire judgment device, road surface condition judgment device, mounted tire and road surface condition judgment device - Google Patents

Description

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

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

Patent Document 1 measures the road surface temperature T during traveling, the vibration of the tire, the sound generated by the tire, and the wheel speed V, as well as the output of the acceleration sensor and the data of the wheel speed V, which are the vibration data of the tire. Therefore, the vibration level ratio R, which is the ratio between 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 of the frequency spectrum of the vibration in the pre-stepping region, is calculated, and the vibration level ratio R of the microphone is calculated. The sound pressure signal that is the output is analyzed by 1 / N octave, and the sound pressure level ratio Q, which is the ratio between the band power value PA of 500 Hz and the band power value PB of 8000 Hz, is calculated from the octave distribution waveform, and the road surface temperature T is calculated. It is described that the road surface condition is estimated by using the data, the data of the vibration level ratio R, the data of the sound pressure level ratio Q, and the data of the wheel speed V.

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

Japanese Unexamined Patent Publication No. 2011-46256 Japanese Patent Application Laid-Open No. 2003-306093

In Patent Document 1, since the acceleration sensor is attached to the tire which is a rotating body, it is difficult to capture the signal into the vehicle interior. It is also conceivable to install a pressure sensor or strain gauge inside the tire, but it is also difficult to capture the signal into the vehicle interior. Further, when an accelerometer is used, the vibration level in the high frequency band of 1 to 2 kHz, 3 to 5 kHz, and 8 kHz is targeted, sampling of at least 16 kHz is required, and there is a problem that the measurement load is large.

In Patent Document 2, the vehicle body front-rear speed (spring front-rear acceleration) is affected by the road surface inclination, so that there is a possibility of erroneous determination. In addition, although it is estimated that studless tires will be installed as the tire type, it is difficult to distinguish between the two because the road surface μ gradient decreases even when hydroplaning occurs.

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

The present invention is a vibration detection unit that detects vibration of a predetermined portion of a vehicle, a storage unit that stores vehicle vibration characteristics using a μ gradient as a parameter, and μ by collating the detected vibration with the vehicle vibration characteristics. It is a μ gradient detection device including 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 the engine and the motor, and the μ gradient detection unit collates with the vehicle vibration characteristics when different drive torques are applied. When at least one of the resonance vibrations of the engine and the motor is detected, the decrease in the μ gradient is detected.

In another embodiment of the present invention, the vibration detection unit detects the vibration of the drive shaft, and the μ gradient detection unit collates with the vehicle vibration characteristics when a different drive torque is applied to the drive shaft. When the attenuation of the resonance vibration is detected, the decrease of the μ gradient is detected.

In still another embodiment of the present invention, the vibration detection unit detects at least one vibration of the engine and the motor and vibration of the drive shaft, and the μ gradient detection unit detects the vibration of the drive shaft when different drive torques are applied. When at least one of the resonance vibrations of the engine and the motor is detected by collating with the vehicle vibration characteristics and the attenuation of the resonance vibration of the drive shaft is detected, the decrease in the μ gradient is detected.

Further, in the present invention, the mounted tire of the vehicle is determined based on the μ gradient detection device, the vehicle speed detection unit, the decrease in the μ gradient detected by the μ gradient detection device, and the vehicle speed detected by the vehicle speed detection unit. It is a mounted tire determination device including a determination unit for determination.

In one embodiment of the present invention, a threshold vehicle speed storage unit that stores the threshold vehicle speed at which hydroplaning occurs is provided, and the determination unit has the μ gradient when the vehicle speed detected by the vehicle speed detection unit is less than the threshold vehicle speed. When a decrease in the tire is detected, it is determined that a tire having a small driving stiffness such as a studless tire is installed.

Further, the present invention determines the road surface condition based on the μ gradient detection device, the vehicle speed detection unit, the decrease in 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 condition determination device including a determination unit.

In one embodiment of the present invention, the determination unit determines hydroplaning when the μ gradient detection device detects a decrease in the μ gradient as the vehicle speed increases.

In another embodiment of the present invention, a threshold vehicle speed storage unit that stores the threshold vehicle speed at which hydroplaning occurs is provided, and the determination unit has the μ gradient when the vehicle speed detected by the vehicle speed detection unit is equal to or higher than the threshold vehicle speed. When a decrease in is detected, it is determined that hydroplaning has occurred.

Further, the present invention relates to a vehicle-mounted tire and a vehicle based on a μ-gradient detection device, a vehicle speed detection unit, a decrease in the μ-gradient detected by the μ-gradient detection device, and a vehicle speed detected by the vehicle speed detection unit. It is a mounted tire and a road surface condition determination device including a determination unit for determining a road surface condition.

In one embodiment of the present invention, a threshold vehicle speed storage unit that stores the threshold vehicle speed at which hydroplaning occurs is provided, and the determination unit has the μ gradient when the vehicle speed detected by the vehicle speed detection unit is less than the threshold vehicle speed. When a decrease in the tire is detected, it is determined that a tire having a small driving stiffness including a studless tire is mounted, and when the vehicle speed detected by the vehicle speed detection unit is equal to or higher than the threshold vehicle speed, the decrease in the μ gradient is detected and When it is not determined that the tire having a small driving stiffness including the studless tire is mounted, it is determined that hydroplaning has occurred.

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 occurrence of the road surface condition, particularly hydroplaning, based on the detected decrease in the μ gradient. Further, according to the present invention, the mounted tire can be determined based on the detected decrease in the μ gradient. Further, according to the present invention, it is possible to discriminate and determine the mounted tire and the road surface condition based on the detected decrease in the μ gradient and the vehicle speed.

It is a principle model explanatory drawing which shows the connection relation of each part of a vehicle. It is a road surface friction characteristic diagram. It is a μ gradient explanatory diagram at each operating point of FIG. It is a transmission characteristic diagram from the drive torque to the forward / backward acceleration on the spring due to the difference in μ gradient. It is a block diagram of the structure of the μ gradient detection apparatus of Embodiment 1. FIG. It is a block diagram of the structure of the mounted tire determination device of Embodiment 1. FIG. It is a detailed block diagram of the mounted tire determination device of Embodiment 1. FIG. It is a figure which shows the actual vehicle measurement result of the road surface friction characteristic. It is a μ gradient explanatory diagram with respect to a vehicle speed. It is a figure (the 1) which shows the measurement result of the vehicle vibration. It is a figure (2) which shows the measurement result of the vehicle vibration. It is a figure (3) which shows the measurement result of the vehicle vibration. It is a block diagram of the road surface condition determination apparatus of Embodiment 2. It is a detailed block diagram of the road surface condition determination apparatus of Embodiment 2. FIG. It is a processing flowchart of Embodiments 1 and 2. It is a road surface μ characteristic diagram of each road surface and various tires.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

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

Hydroplaning (hereinafter, appropriately abbreviated as "high pre") occurs when the dynamic pressure of water exceeds the tire contact pressure Pc. That is, if ρ is the density of water and Vv is the vehicle speed, the dynamic pressure of water is expressed by 1/2, ρ, and Vv ² , so this magnitude relationship is
1/2 ・ ρ ・ Vv ² > Pc ・ ・ ・ (1)
Is.

If k is the tread rigidity, w is the tire contact width, and l is the tire contact length, the μ gradient α is
α = 1/2 ・ k ・ w ・ l ² ... (2)
It is expressed by.

From the formula (1), the higher the vehicle speed, the higher the dynamic pressure of the water and the tire floats above the tire contact pressure, so that the contact area w · l with the road surface of the formula (2) decreases. As a result, the μ gradient α decreases when the high pre occurs according to the equation (2).

Further, when a tire having a small driving stiffness including a studless tire is mounted, the tread rigidity k of the formula (2) decreases. Therefore, according to the formula (2), the μ gradient α also decreases when a tire having a small driving stiffness including a studless tire is mounted. It will be. FIG. 16 shows the road surface μ characteristics of each road surface and various tires described in Methods and Instruments for On-Board Measurement of Tyre / Road Friction, Bert Breuer, Thomas Bechmann etc, Technishe Hochshule Darmstadt, SAE Paper No. 942470. show. The horizontal axis shows the tire slip ratio, and the vertical axis shows the tire driving force / wheel load. In studless tires, the μ gradient decreases from the origin of the tire slip ratio.

In this way, the μ gradient α will decrease both when high pres occur and when tires with small driving stiffness including studless tires are installed, but since high pres occur under high vehicle speed conditions, μ gradients occur at low vehicle speeds. If α decreases, it can be determined that tires with low driving stiffness including studless tires are installed, and if there is no judgment that tires with small driving stiffness including studless tires are installed and the μ gradient α decreases at high vehicle speed, it can be determined that high pre-occurrence has occurred. .. In the following, a studless tire will be described as a typical example of a tire having a small driving stiffness.

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

Therefore, it is possible to determine the occurrence of studless tires and high pres by the following two steps.
1st step: Judgment that studless tires are installed when μ gradient decrease is detected when vehicle speed Vv <Vh 2nd step: μ gradient decrease is detected when vehicle speed Vv ≧ Vh, and studless tires are detected in the 1st step Judgment that high pre-occurrence occurs when tire mounting judgment is not made

Then, since the vehicle vibration characteristics, specifically the vibration characteristics of the engine and the drive shaft, change depending on the magnitude of the μ gradient, the relationship between the two is stored in advance, in other words, the vehicle vibration characteristics are set in advance using the μ gradient as a parameter. By storing and collating the characteristics of the vibration measurement value at the time of vehicle acceleration to which the drive torque is applied with the vehicle vibration characteristics stored in advance, the magnitude of the μ gradient, that is, the decrease in the μ gradient can be detected.

However, when a driving torque that reaches the tire driving force limit is applied, the μ gradient can decrease even when studless tires are not installed or high pres are generated. If the μ gradient is detected and the μ gradient is lowered at both points, it is desirable to determine that studless tires are installed or that high pres have occurred. The tire driving force limit is the time when the tire driving force limit is small among the studless tire mounting and the high pre-occurrence.

In the present embodiment, since the vibration detection sensor is attached to the engine, the drive shaft, or the like in order to obtain the measured value of the vibration characteristic, there is an advantage that the attachment is easier than the case where the sensor is attached in the tire.

Further, since the vehicle vibration related to the decrease in the μ gradient has a relatively low frequency of 20 Hz or less, it can be dealt with with a low sampling cycle, does not require a high sampling cycle as in the conventional case, and the measurement load is suppressed.

In addition, since it is determined that studless tires are installed when the vehicle speed is lower than the vehicle speed at which high pres occur, it is possible to clearly distinguish whether the μ gradient decrease is due to studless tires or high pres in the vehicle speed range, ensuring driving safety. It is also possible to determine whether or not it is necessary.

Further, in the present embodiment, since the frequency of vibration is focused on, there is an advantage that it is possible to determine the mounting of studless tires and the occurrence of high pres without being affected by the vehicle operating conditions such as the road surface gradient, the magnitude of the driving torque, and the loading condition. ..

Hereinafter, embodiments will be specifically described.

<Embodiment 1>
In this embodiment, the detection of the decrease in the μ gradient and the determination of the mounting of the studless tire will be described.

As an example of the change in vehicle vibration when the μ gradient is lowered, the actual vibration of the front-rear resonance of the engine and the damping of the vibration of the drive shaft resonance are used.

FIG. 1 shows a principle configuration diagram. As shown in FIG. 1A, this is a model in which 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 each other. The engine block 22 has 6 degrees of freedom including rotation in front / back, left / right, up / down, and around each axis, and is simply expressed by 2 degrees of freedom behavior in front / back and pitch as shown in FIG. 1 (b). ..

FIG. 2 shows the road surface friction characteristic showing the relationship between the slip ratio and the tire driving force / wheel load. FIG. 2 shows two cases, one is a case where the μ gradient near the origin of the slip ratio is small (characteristic indicated by reference numeral 100) and the other is a case where the μ gradient is large (characteristic indicated by reference numeral 200). In the characteristic 100, the μ gradient decreases at both points at different slip rates, but in the characteristic 200, the μ gradient decreases at the tire driving force limit, and there is no decrease in the μ gradient when the slip ratio is less than the limit.

FIG. 3 shows a comparison of the μ gradients at the operating points a and b in FIG. The horizontal axis shows the tire driving force / wheel load, and the vertical axis shows the μ gradient. In the characteristic 100, the μ gradient decreases at both the a and b operating points, while in the characteristic 200, the μ gradient decreases at the b operating point, but the μ gradient does not decrease at the a operating point.

FIG. 4 shows the transmission characteristics from the drive torque to the spring using the μ gradient value and vehicle specifications shown in FIG. The horizontal axis shows frequency, and the vertical axis shows forward / backward acceleration / drive torque on the spring. In the figure, the transmission characteristic of the a operating point of the characteristic 100 is 100a, the transmission characteristic of the b operating point of the characteristic 100 is 100b, the transmission characteristic of the a operating point of the characteristic 200 is 200a, and the transmission characteristic of the b operating point of the characteristic 200 is 200b. Shown as.

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

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

From this, when the traveling vehicle speed is smaller than the high pre-generated vehicle speed Vh shown in Eq. (3), for example, the drive torque is applied at each of the a operating point and the b operating point, and the vibration of the engine front-rear resonance occurs when different drive torques are applied. By detecting or detecting the vibration damping of the drive shaft resonance, the μ gradient is continuously lowered from the vicinity of the slip ratio origin, 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, the transmission gear stage, the frequency characteristics as shown in FIG. 4 with the μ gradient as parameters, the vibration peak value of the drive shaft resonance, the front-rear resonance of the engine, etc. are stored in the memory as a table. It may be calculated by comparing with the frequency analysis value of the spring front-rear acceleration / drive torque.

FIG. 5 shows a block diagram of the μ gradient detection device 30 according to 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 the frequency analysis value of the spring front-rear acceleration / drive torque as the vehicle vibration characteristic.

The μ gradient-vehicle vibration characteristic relationship storage unit 34 stores in advance the frequency characteristics, the drive shaft resonance, the vibration peak value of the engine front-rear resonance, etc. as a table with the transmission gear stage and the μ gradient as parameters.

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

FIG. 6 shows a block diagram of the mounted tire determination device according to 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 configuration block shown in FIG. 5, detects a decrease in the μ gradient, and outputs the output to the mounted tire determination unit 40.

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

The mounted tire determination unit 40 determines the mounting of the mounted tire, specifically, the studless tire, based on the vehicle speed and the detection signal of the μ gradient decrease, and outputs the determination result. That is, the mounted tire determination unit 40 determines that the studless tire is mounted when the μ gradient decrease 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 degree of freedom vibration detection unit 50, spring front and rear vibration detection unit 52, drive shaft vibration detection unit 56, engine rotation speed vibration detection unit 58, gear stage detection unit 62 engine vibration, spring front and rear vibration detection unit, respectively. Vibration, drive shaft vibration, engine rotation speed vibration, and gear stage are detected, and the frequency components in the drive shaft resonance-engine front-rear resonance region are passed by the bandpass filter units 64 to 70, and the engine 6 degree of freedom resonance matching unit 72 and It is output to the drive shaft resonance matching unit 74.

Further, the engine 6-degree-of-freedom resonance storage unit 54 outputs the resonance frequency of the engine 6-degree-of-degree degree to the engine 6-degree-of-degree resonance matching unit 72, and the drive shaft resonance storage unit 60 outputs the resonance frequency of the drive shaft to the drive shaft resonance matching 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.

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

The 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 the drive torque generation unit 46, and outputs the drive torque command value to the acceleration start determination unit 48.

The acceleration start determination unit 48 outputs to the engine 6 degree of freedom resonance matching unit 72 whether or not acceleration has been started, that is, whether or not a drive torque has been applied.

The engine 6-degree-of-freedom resonance collating unit 72 vibrates the front-rear resonance of the engine that matches the resonance frequency stored in the E / G6-degree-of-freedom resonance storage unit 54 when the drive torque is applied based on the signal from the acceleration start determination unit 48. When the vibration of the front-rear resonance of the engine is detected when the drive torque is applied, the detection signal is output to the μ gradient detection unit 36.

Similarly, the drive shaft resonance collating unit 74 resonates with the drive shaft at a resonance frequency corresponding to the transmission gear stage stored in the drive shaft resonance storage unit 60 when the drive torque is applied based on the signal from the acceleration start determination unit 48. If the vibration attenuation of the drive shaft resonance is detected when the drive torque is applied, in other words, the resonance corresponding to the transmission gear stage stored in the drive shaft resonance storage unit 60 is determined. When the frequency and the detected drive shaft resonance frequency do not match, the detection signal is output to the μ gradient detection unit 36.

The μ gradient detection unit 36 detects the decrease in the μ gradient based on the detection signals of the engine 6 degree of freedom resonance matching unit 72 and the drive shaft resonance matching unit 74 and the gear stage signal from the gear stage detection unit 62, and determines the mounted tire. Output to unit 40. Further, the μ gradient detection unit 36 outputs a torque application command to the drive torque limit value storage unit 42. As a result, 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 when two different drive torques are applied.

The mounted tire determination unit 40 mounts the studless tire when the μ gradient decrease 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. And output the judgment result.

One or more of the drive torque command value determination unit 44, the acceleration start determination unit 48, the engine 6 degree of freedom resonance matching unit 72, the drive shaft resonance matching unit 74, the μ gradient detection unit 36, and the mounted tire determination unit 40 in FIG. It can be realized with the processor of. The processor realizes each of these constituent blocks by reading and executing a processing program stored in a non-volatile memory such as EEPROM. At least one of these constituent blocks may be realized by a hardware circuit, and the hardware processing may be performed by using a circuit such as an ASIC or FPGA (field programmable gate array).

Further, in the figure, the drive torque limit value storage unit 42, the E / G6 degree of freedom resonance storage unit 54, and the drive shaft resonance storage unit 60 are configured as separate storage units, but these are configured as a single memory. You may.

<Embodiment 2>
In this embodiment, the determination of the occurrence of high pres will be described.

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

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

FIG. 10 shows the measurement waveforms of the high μ road (dry road) and the low μ road (high pre state) when the drive torque is applied to the extent that the tire driving force limit is not reached in the high pre state (b operating point). FIG. 10A is a waveform of a high μ path (dry path), and FIG. 10B is a waveform of a low μ path (high pre-state). The horizontal axis shows time, and the vertical axis shows drive shaft torque, engine front-rear acceleration, and drive wheel speed. The vehicle speed and transmission gear are under the same conditions. The engine front-rear acceleration is subjected to bandpass filter processing that allows frequency components in the drive shaft resonance to engine front-rear resonance range to pass through. From these figures, it can be seen that the vibration of the front-rear resonance of the engine is remarkable and the drive shaft resonance is attenuated in the high pre-state where the μ gradient is lower than that of the high μ path.

FIG. 11 shows measurement waveforms of a high μ path (dry path) and a low μ path (high pre-state) when a drive torque smaller than that of FIG. 10 is applied (a operating point). FIG. 11A is a waveform of a high μ path (dry path), and FIG. 11B is a waveform of a low μ path (high pre-state). The horizontal axis shows time, and the vertical axis shows drive shaft torque, engine front-rear acceleration, and drive wheel speed. The vehicle speed and transmission gear are under the same conditions. The engine front-rear acceleration is subjected to bandpass filter processing that allows frequency components in the drive shaft resonance to engine front-rear resonance range to pass through. It can be seen that even when different drive torques are applied, the vibration of the front-rear resonance of the engine is remarkable in the high-pre state where the μ gradient is lower than that of the high μ path, and the drive shaft resonance is attenuated.

FIG. 12 shows a comparison of the results of driving torque application when the tire driving force limit is reached and when the tire driving force limit is not reached on a low μ road and a medium vehicle speed. FIG. 12A is a case where the tire driving force limit is reached, and FIG. 12B is a case where the tire driving force limit is not reached. The horizontal axis shows time, and the vertical axis shows drive shaft torque, engine front-rear acceleration, and drive wheel speed. The vehicle speed and transmission gear are under the same conditions. The engine front-rear acceleration is subjected to bandpass filter processing that allows frequency components in the drive shaft resonance to engine front-rear resonance range to pass through. When the drive torque that reaches the tire driving force limit is applied, the vibration of the engine front-rear resonance is remarkable, and when the driving torque that does not reach the tire driving force limit is applied, the vibration of the drive shaft torque resonance is remarkable. Therefore, it is possible to determine the occurrence of high pres in the cases of FIGS. 10 and 11 in which the vibration of the front-rear resonance of the engine becomes remarkable when different drive torques are applied.

FIG. 13 shows a block diagram of the road surface condition determination device according to the present embodiment. It is almost the same as the mounted tire determination device shown in FIG. 6, but includes a road surface condition determination unit 41 instead of the mounted tire determination unit 40.

The road surface condition determination unit 41 determines whether or not high pre-generation has occurred based on the detection signal from the μ gradient detection device 30 and the vehicle speed from the vehicle speed detection unit 38, and outputs a 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 high pre-occurrence has occurred. As described above, the road surface condition determination unit 41 may determine that high pre-generation has occurred when the studless tire is not mounted.

FIG. 14 shows a detailed block diagram of the road surface condition determination device. It is almost the same as the mounted tire determination device shown in FIG. 7, but includes a road surface condition determination unit 41 instead of the mounted tire determination unit 40.

Engine (E / G) 6 degree of freedom vibration detection unit 50, spring front / rear vibration detection unit 52, drive shaft vibration detection unit 56, engine rotation speed vibration detection unit 58, gear stage detection unit 62 engine vibration, spring front / rear vibration detection unit, respectively. Vibration, drive shaft vibration, engine rotation speed vibration, and gear stage are detected, and the frequency components in the drive shaft resonance-engine front-rear resonance region are passed by the bandpass filter units 64 to 70, and the engine 6 degree of freedom resonance matching unit 72 and It is output to the drive shaft resonance matching unit 74.

Further, the engine 6-degree-of-freedom resonance storage unit 54 outputs the resonance frequency of the engine 6-degree-of-degree degree to the engine 6-degree-of-degree resonance matching unit 72, and the drive shaft resonance storage unit 60 outputs the resonance frequency of the drive shaft to the drive shaft resonance matching 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.

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

The 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 the drive torque generation unit 46, and outputs the drive torque command value to the acceleration start determination unit 48.

The acceleration start determination unit 48 outputs to the engine 6 degree of freedom resonance matching unit 72 whether or not acceleration has been started, that is, whether or not a drive torque has been applied.

The engine 6-degree-of-freedom resonance collating unit 72 has vibration of front-rear resonance of the engine at the resonance frequency stored in the E / G6-degree-of-freedom resonance storage unit 54 when the drive torque is applied based on the signal from the acceleration start determination unit 48. It is determined whether or not, and when the vibration of the front-rear resonance of the engine is detected when the drive torque is applied, the detection signal is output to the μ gradient detection unit 36.

Similarly, does the drive shaft resonance collating unit 74 have vibration attenuation of the drive shaft resonance at the resonance frequency stored in the drive shaft resonance storage unit 60 when the drive torque is applied based on the signal from the acceleration start determination unit 48? When it is determined whether or not the drive torque is applied and the vibration attenuation of the drive shaft resonance is detected, that is, the resonance frequency corresponding to the transmission gear stage stored in the drive shaft resonance storage unit 60 and the detected drive shaft. When the resonance frequency does not match, the detection signal is output to the μ gradient detection unit 36.

The μ gradient detection unit 36 detects the μ gradient drop based on the detection signals of the engine 6 degree of freedom resonance matching unit 72 and the drive shaft resonance matching unit 74 and the gear stage signal from the gear stage detection unit 62, and determines the road surface condition. Output to unit 41. Further, the μ gradient detection unit 36 outputs a torque application command to the drive torque limit value storage unit 42. As a result, 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 when two different drive torques are applied.

The road surface condition determination unit 41 is not a studless tire when the μ gradient decrease 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 mounting conditions, it is determined that high pres have occurred and the determination result is output.

<Embodiment 3>
In the first embodiment, the mounting of the studless tire is determined, and in the second embodiment, the occurrence of the high pre is determined. However, the presence or absence of the studless tire and the presence or absence of the high pre may be determined together.

The block diagram of the mounted tire and the road surface condition determination device in the present embodiment is almost the same as the configuration shown in FIGS. 13 and 14, but the road surface condition determination unit 41 is the same as the mounted tire determination unit 40 shown in FIGS. 6 and 7. Similarly, it is determined that the studless tire is installed and that the high pre-occurrence is also determined. Specifically, it is determined that the studless tire is installed when the vehicle speed is less than the vehicle speed at which the high pre-occurrence occurs, and it is determined that the studless tire is installed when the vehicle speed is equal to or higher than the vehicle speed at which the high pre-occurrence occurs and the studless tire is not installed. In the configuration of the present embodiment, the road surface condition determination unit 41 in FIGS. 13 and 14 may be read as the mounted tire and the road surface condition determination unit.

FIG. 15 shows a processing flowchart of the present embodiment.

First, the high pre-vehicle speed Vh and the detection reference value of the μ gradient decrease are set and stored in the memory (S101). Further, the initial value of the mounted tire is set to the summer tire, and the determination flag is reset to 0.

Next, the transmission gear stage 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, the sensor signals for detecting each vibration of E / G6 degree of freedom vibration, spring front-rear vibration, drive shaft vibration, and engine rotation speed vibration are read.

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

Next, a decrease in the μ gradient is detected by comparing the vibration feature amount with the reference value (S106). Specifically, the front-rear resonance frequency signal of the engine is remarkable when it is above the reference value, and the decrease in the μ gradient is detected depending on whether or not the drive shaft resonance frequency signal is attenuated below the reference value.

Next, it is determined whether or not different drive torques are applied twice or more (S107). If different drive torques are applied less than twice, the processing after S103 is repeated (NO in S107).

If different drive torques are applied twice (YES in S107), then it is determined whether or not the μ gradient is reduced when two or more drive torques are applied (S108).

If the μ gradient is reduced when different drive torques are applied two or more times (YES in S108), it is determined whether or not the vehicle speed Vv is smaller than the high pre-vehicle speed Vh (S109). If Vv <Vh, it is determined that the studless tire is installed, 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 high pre-generation occurs (S112). If the μ gradient has not decreased more than once (NO in S108), or if the flag is already set to 1 even if Vv ≧ Vh (NO in S111), neither determination is performed.

The processing of S101 to S110 can be said to be the processing of the first embodiment for determining the mounted tire.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments and can be modified in various ways.

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, a motor may be used instead of the engine 10. In short, at least one of the front-rear resonance vibrations of the engine and the motor may be used.

Further, although the μ gradient is shown as the relationship between the tire driving force / wheel load with respect to the slip ratio in FIG. 2 and the like, the tire driving force may be used instead of the tire driving force / wheel load.

Further, in the first embodiment, as shown in FIG. 7, the engine 6-degree-of-freedom resonance matching unit 72 and the drive shaft resonance matching unit 74 are provided, and the appearance of the front-rear resonance of the engine and the attenuation of the drive shaft resonance are both detected to be μ. Although the decrease in the gradient is detected, at least one of the engine 6-degree-of-freedom resonance matching unit 72 and the drive shaft resonance matching unit 74 is provided, and at least one of the appearance of the engine front-rear resonance and the attenuation of the drive shaft resonance is detected. Therefore, a decrease in the μ gradient may be detected. The same applies to FIG. 14 of the second embodiment.

Further, in the embodiment, the front-rear resonance frequency of the engine and the resonance frequency of the drive shaft are used, but it goes without saying that the front-rear resonance cycle of the engine (or the motor) and the resonance cycle of the drive shaft may be used.

10 engine, 12 transmission, 14 drive shaft, 16 tires, 18 unsprung, 20 sprung, 22 engine block, 30 μ gradient detection device, 38 vehicle speed detection unit, 40 mounted tire determination unit, 41 road surface condition determination unit.

Claims (10)

A vibration detection unit that detects vibrations in a predetermined part of the vehicle,
A storage unit that stores vehicle vibration characteristics with the μ gradient as a parameter,
A μ-gradient detection unit that detects a decrease in the μ-gradient by collating the detected vibration with the vehicle vibration characteristics.
Equipped with
The vibration detection unit detects vibration of at least one of the engine and the motor, and detects the vibration of at least one of the engine and the motor.
The μ gradient detection unit detects a decrease in the μ gradient when at least one of the resonance vibrations of the engine and the motor is detected by collating with the vehicle vibration characteristics when different drive torques are applied.
μ gradient detector. A vibration detection unit that detects vibrations in a predetermined part of the vehicle,
A storage unit that stores vehicle vibration characteristics with the μ gradient as a parameter,
A μ-gradient detection unit that detects a decrease in the μ-gradient by collating the detected vibration with the vehicle vibration characteristics.
Equipped with
The vibration detection unit detects the vibration of the drive shaft and detects the vibration of the drive shaft.
The μ gradient detection unit detects a decrease in the μ gradient when the attenuation of the resonance vibration of the drive shaft is detected by collating with the vehicle vibration characteristics when different drive torques are applied.
μ gradient detector. A vibration detection unit that detects vibrations in a predetermined part of the vehicle,
A storage unit that stores vehicle vibration characteristics using the μ gradient as a parameter,
A μ-gradient detection unit that detects a decrease in the μ-gradient by collating the detected vibration with the vehicle vibration characteristics.
Equipped with
The vibration detection unit detects the vibration of at least one of the engine and the motor and the vibration of the drive shaft, and detects the vibration.
When different drive torques are applied, the μ gradient detection unit detects the resonance vibration of at least one of the engine and the motor by collating with the vehicle vibration characteristics, and detects the attenuation of the resonance vibration of the drive shaft. In some cases, the decrease in the μ gradient is detected.
μ gradient detector. The μ gradient detection device according to any one of claims 1 to 3 ,
Vehicle speed detector and
A determination unit that determines the mounted tire of the vehicle based on the decrease in 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. The mounted tire determination device according to claim 4 , wherein the determination unit determines hydroplaning when the μ gradient detection device detects a decrease in the μ gradient as the vehicle speed increases. Equipped with a threshold vehicle speed storage unit that stores the threshold vehicle speed at which hydroplaning occurs.
4. 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 described in 1. The μ gradient detection device according to any one of claims 1 to 3 ,
Vehicle speed detector and
A determination unit that determines the road surface condition based on the decrease in the μ gradient detected by the μ gradient detection device and the vehicle speed detected by the vehicle speed detection unit.
A road surface condition determination device comprising. Equipped with a threshold vehicle speed storage unit that stores the threshold vehicle speed at which hydroplaning occurs.
The road surface condition determination device according to claim 7 , 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 3 ,
Vehicle speed detector and
A determination unit that determines the tires mounted on the vehicle and the road surface condition based on the decrease in the μ gradient detected by the μ gradient detection device and the vehicle speed detected by the vehicle speed detection unit.
A mounted tire and a road surface condition determination device. Equipped with a threshold vehicle speed storage unit that stores the threshold vehicle speed at which hydroplaning occurs.
When the vehicle speed detected by the vehicle speed detection unit is less than the threshold vehicle speed and the decrease in the μ gradient is detected, the determination unit determines that a tire having a small driving stiffness including a studless tire is mounted, and the vehicle speed When the vehicle speed detected by the detection unit is equal to or higher than the threshold vehicle speed, the decrease in the μ gradient is detected, and when it is not determined that the tire having a small driving stiffness including the studless tire is mounted, it is determined that hydroplaning has occurred. The mounted tire and road surface condition determination device according to claim 9 .

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