JP4898867B2 - Load distribution judgment method - Google Patents

Description

  The present invention relates to a method and apparatus for determining load distribution for each wheel of a vehicle or load distribution for each axle, and a vehicle load distribution determination program.

  When the air pressure of the tires mounted on the vehicle decreases, the fuel consumption deteriorates and there is a risk of bursting at high speeds. Conventionally, when a tire is depressurized, a decrease in air pressure is detected by utilizing changes in tire characteristics such as a decrease in the dynamic load radius of the tire and a change in resonance frequency.

For example, a conventional tire pressure drop detection device reduces the outer diameter (tire dynamic load radius) of a tire with normal internal pressure when a specific tire of a vehicle is depressurized, so the rotational angular velocity increases compared to other normal tires. The principle of doing is used. For example, in a method of detecting a decrease in internal pressure from a relative difference in tire rotation angular velocity,
DEL = {(F1 + F4) / 2- (F2 + F3) / 2} / {(F1 + F2
+ F3 + F4) / 4} × 100 (%)
(Patent Document 1). Here, F1 to F4 are rotational angular velocities of the front left tire, the front right tire, the rear left tire, and the rear right tire, respectively.

  However, since the tire characteristics also change due to changes in the load, such as the number of passengers and the weight of the load, if it is impossible to distinguish between changes in the load and tire pressure, Therefore, it is impossible to accurately determine a decrease in tire air pressure.

  The determination value DEL becomes zero when all the four wheels have normal air pressure. However, when pressure reduction occurs in one wheel, the determination value changes depending on the degree of change in the dynamic load radius. Assuming that the drop in air pressure to alert the driver is 30% of the normal pressure, the judgment value at 30% decompression is set as a threshold value, and an alarm is issued when the judgment value exceeds the threshold value. You just have to leave. However, the larger the load is, the smaller the amount of decrease in the dynamic load radius at the time of decompression is. Therefore, for the same 30% decompression, the judgment value at the time of 30% decompression in the case of one person riding is the same as in the case of five people riding Greater than the judgment value at 30% decompression.

  For example, it is assumed that the determination value at 30% decompression is 0.3 for a single passenger and 0.25 for a five passenger ride. In the case of this example, if an alarm is to be issued with 30% pressure reduction even when five people are on board, the threshold must be 0.25. However, at a threshold value of 0.25, a warning is given at 25% pressure reduction when one person gets on (30 × 0.25 ÷ 0.3 = 25).

  As an apparatus for determining load distribution, there are inventions described in Patent Documents 2 to 4. In Patent Document 2, a means for detecting a resonance level is required, in Patent Document 3, a means for detecting a braking force and a road surface μ gradient calculating means are required, and in Patent Document 4, an acceleration / deceleration detecting means is required. .

  In addition, Patent Documents 5 and 6 disclose that load distribution information is used to detect a decrease in tire air pressure. However, Patent Document 5 detects a load using a suspension stroke sensor. A change in the resonance frequency before and after the door, trunk, or filler opening is opened or closed is determined as a load change, or a load is detected using a suspension stroke sensor.

  In Patent Document 7, it is described that the ratio of the rotational speed of the front wheel and the rotational speed of the rear wheel changes between braking and non-braking, but the rotational speed of the front wheel and the rear wheel during braking are described. The relationship between the rotation speed ratio and the vehicle load is not described.

JP 63-305011 A Japanese Patent Laid-Open No. 11-23425 JP-A-11-189136 JP 2003-306093 A Japanese Patent Laid-Open No. 9-196791 JP-A-10-115578 Japanese Patent Laid-Open No. 9-2222

  As described above, since the characteristic for determining tire air pressure also changes depending on the load, measures such as changing the determination threshold corresponding to the change in load are required to accurately determine a decrease in tire air pressure. Conventionally, a special suspension stroke sensor has been required to measure the load. However, it is not common to equip a suspension stroke sensor.

  An object of the present invention is to provide a method for determining a load distribution of a vehicle without providing a special load sensor in the vehicle.

  It is another object of the present invention to provide a method for detecting a decrease in tire air pressure, in which a threshold value is provided for each load, and an accurate pressure reduction alarm corresponding to the load can be issued using the load distribution determination value.

  The vehicle load distribution determination method according to the present invention uses the rotation speed of a wheel mounted on the vehicle and a determination flag for determining whether the vehicle is being braked or not. By comparing the result of comparing the rotational speeds of the two wheels with the result of comparing the rotational speeds of the two wheels at a predetermined load, the load distribution for each wheel of the vehicle or the load distribution for each axle is determined. It is characterized by that.

  In the present invention, “the rotational speed of two wheels” means (1) the rotational speed of each of two wheels of a vehicle, and (2) the rotational speed of each of at least two wheels of all the wheels. The average value and the average value of the rotation speed of each of the remaining at least two wheels, or (3) the average value of the rotation speed of one of the wheels and the rotation speed of each of the remaining at least two wheels. Say.

  The vehicle load distribution determination device according to the present invention includes a means for detecting the rotational speed of the wheel mounted on the vehicle, a means for detecting whether or not the vehicle is being braked, and a case where the vehicle is being braked. And calculating means for comparing the rotational speeds of the two wheels of the wheels, and means for storing the rotational speeds of the two wheels at a predetermined load, the comparison result of the calculating means and the stored predetermined The load distribution for each wheel of the vehicle or the load distribution for each axle is determined by comparing the rotational speeds of the two wheels in the load.

  Further, the vehicle load distribution determination program according to the present invention detects a vehicle for determining the load distribution of the vehicle, means for detecting the rotational speed of the wheel mounted on the vehicle, and whether the vehicle is being braked. Means for comparing the rotational speeds of two of the wheels when the vehicle is braking, and means for storing the rotational speeds of the two wheels at a predetermined load or a comparison result thereof. The means for determining the load distribution for each wheel of the vehicle or the load distribution for each axle by comparing the comparison result of the calculation means with the rotational speed or comparison result of the two wheels at the stored predetermined load. It is made to function.

  As the rotation speed of two of the wheels, the rotation speed of the two wheels is the average of the rotation speed of the two front wheels of the vehicle and the average of the wheel rotation speed of the two rear wheels of the two wheels on the left side of the vehicle. Average of wheel rotation speed and average of wheel rotation speed of right two wheels, rotation speed of front wheel and rear wheel of left two wheels of vehicle, rotation speed of front wheel and rear wheel of right two wheels of vehicle Speed, the average of the rotation speed of the front wheels and the rotation speed of the two rear wheels when the vehicle is a three-wheel vehicle with one front wheel, the rotation of the rear wheels when the vehicle is a three-wheel vehicle with one rear wheel The average of the speed and the rotational speed of the two front wheels can be used.

  In the case where the vehicle is a six-wheel vehicle, the rotational speeds of the two wheels are the average of the rotational speeds of the front two wheels and the average of the rotational speeds of the rear four wheels, and the average of the rotational speeds of the last two wheels and the front side 4. The average of the rotation speed of the wheels, the average of the rotation speed of the left three wheels and the average of the rotation speed of the right three wheels, the average of the rotation speed of the two front wheels and the average of the rotation speed of the last two wheels, the rotation speed of the two front wheels The average and the average of the rotational speeds of the two central drive shafts, or the average of the rotational speeds of the last two wheels and the average of the rotational speeds of the two central drive shafts can be used.

  In the present invention, the rotational speed of the wheel is the product of the rotational angular speed of the wheel and a given tire radius. In addition, vehicle load distribution refers to the magnitude relationship of loads applied to any two sets of wheels that do not include a common wheel in a certain vehicle, for example, the magnitude relationship of loads applied to each vehicle wheel, or for each axle. It refers to the magnitude relationship of such loads.

  In the vehicle load distribution determination method according to the present invention, the rotation speed comparison between the two wheels may be performed by a value obtained by dividing a difference between the left front wheel rotation speed and the left rear wheel rotation speed by the left rear wheel rotation speed. it can.

  Further, the rotation speeds of the two wheels may be compared by a value obtained by dividing a difference between the right front wheel rotation speed and the right rear wheel rotation speed by the right rear wheel rotation speed.

  Furthermore, the comparison of the rotational speeds of the two wheels may be made by a value obtained by dividing the difference between the front two-wheel rotational speed and the rear two-wheel rotational speed by the rear two-wheel rotational speed.

  The tire pressure drop detection method according to the present invention is characterized in that a threshold value for detecting a tire pressure drop is changed according to a load distribution determination result using the vehicle load distribution determination method. As a vehicle load distribution determination method for changing a threshold value for detecting a decrease in tire air pressure, a determination flag for determining the rotational speed of wheels mounted on the vehicle and whether or not the vehicle is being braked is used. When the vehicle is being braked, the vehicle is compared by comparing the result of comparing the rotational speeds of the two wheels of the wheels with the result of comparing the rotational speeds of the two wheels at a predetermined load. The load distribution for each wheel or the load distribution for each axle can be determined.

  The tire pressure drop detecting device according to the present invention is characterized in that a threshold value for detecting a tire pressure drop is changed according to a load distribution determination result using the vehicle load distribution determining method. As a vehicle load distribution determination method for changing a threshold value for detecting a decrease in tire air pressure, a determination flag for determining the rotational speed of wheels mounted on the vehicle and whether or not the vehicle is being braked is used. When the vehicle is being braked, the vehicle is compared by comparing the result of comparing the rotational speeds of the two wheels of the wheels with the result of comparing the rotational speeds of the two wheels at a predetermined load. The load distribution for each wheel or the load distribution for each axle can be determined.

  The vehicle load distribution determination method according to the present invention detects that the vehicle is being braked. When the vehicle is being braked, two of the four wheels mounted on the vehicle (for example, the front wheel of the four wheels). The wheel rotation speed (for example, the average rotation speed of the two front wheels and the average rotation speed of the two rear wheels) is compared (for example, the average rotation speed of the two front wheels / two rear wheels). Rotational speed average of -1), the comparison value and the same wheel combination (two front wheels and two rear wheels) measured at a predetermined load (for example, the load of one and five passengers in the vehicle) The load distribution of the vehicle is determined by comparing with the comparison value of the calculated values at. For example, a load distribution determination value during traveling is obtained by the interpolation method from the comparison value during traveling based on the comparison value for one passenger and the comparison value for five passengers. In the example shown in the first embodiment described later, the average of the front left wheel rotational speed / the rear left wheel rotational speed-1, the front right wheel rotational speed / the rear right wheel rotational speed-1, and the rotational speed of the front two wheels / Using a comparison value of average -1 for the rotational speed of the rear two wheels, a small passenger car (Toyota Corolla) is loaded with luggage (weight 60kg) on the right side of the driver, the rear seat, and the right side of the trunk in the case of five passengers In this case, the front and rear load distribution ratios are the same, but it can be determined that the left and right load distributions are different.

  The load distribution that can be determined includes, for example, the load distribution between the two front wheels and the two rear wheels, the load distribution between the two left wheels and the two right wheels, the load distribution between the two front wheels and the rear wheels, and the right two front wheels. There are rear wheel load distribution, front wheel left wheel and right wheel load distribution, or rear wheel left wheel and right wheel load distribution.

  In order to detect that braking is in progress, it is only necessary to detect whether the brake is being operated. For example, since a brake light (so-called brake lamp) is linked to the operation of the brake, it is possible to detect whether the brake is operated simply by branching and inputting the on / off signal of the brake light It is.

  Further, by changing the tire pressure drop detection threshold according to the determined load distribution, it is possible to accurately detect the tire pressure drop even when the loaded load changes. In the example shown in the second embodiment to be described later, a tire decompression threshold (one person) corresponding to the load distribution determination value is obtained using the result of determining the load distribution based on the rotation speed ratio of the front and rear wheels during braking. By setting a threshold value of 0.3 for passengers and a threshold value of 0.25 for passengers, in a normal passenger car (Nissan Cedric), when one wheel is depressurized by 25%, one passenger and five passengers In any case of boarding, it is not determined that the pressure is reduced, and in a state where one wheel is decompressed by 30%, it can be determined that the pressure is reduced in both cases of one person riding and five people riding. As a result, it is possible to notify the driver of the risk of tire decompression without error under the same decompression determination conditions even in different load distribution states.

  According to the present invention, the load distribution information determined as described above is used in an ABS (anti-lock brake system) device, a TRC (traction control) device, or the like, thereby performing optimal control according to the load distribution. Can do.

  For example, in the ABS device, the load distribution can be input from the load distribution determination device of the present invention, and the distribution of the brake operation force of each wheel can be set according to the load distribution. The ABS device detects slipping (tire lock) every moment and adjusts the brake operation force in real time, but by setting the brake operation force for each wheel according to the load distribution, It becomes possible to obtain the maximum braking force immediately before each wheel is locked, and safer and more reliable braking can be realized. As a result, even if the load distribution is different, the braking operation can be performed in a state in which the driver can control the direction without tilting the vehicle body with respect to the traveling direction during braking.

  In the TRC device, the load distribution is input from the load distribution determination device of the present invention, and for example, the driving force distribution of the left and right wheels is adjusted, or the upper limit of the driving force according to the load distribution is set to start / accelerate Slip can be eliminated and more effective vehicle drive control can be realized.

  According to the load distribution determination method of the present invention, even if a special suspension stroke sensor is not used, only the brake on / off information is added to the minimum wheel speed information required for the tire pressure drop alarm device. Load distribution can be determined.

  Further, even if the load changes, a tire pressure drop alarm can be issued with a certain target pressure reduction amount.

It is a flowchart which shows an example of the load distribution determination method concerning Embodiment 1 of this invention. It is a graph showing the change of the calculation value for load distribution determination in the case of 2 passengers and 5 passengers + luggage concerning Embodiment 1 of the present invention. It is a graph showing the relationship between the calculated value for load distribution determination when the load changes, and the load distribution ratio between the front shaft and the rear shaft according to the first embodiment of the present invention. It is a graph showing the relationship between the calculation value for three load distribution determinations, and the front-back G, when 5 people board in connection with Embodiment 1 of this invention. 6 is a graph showing the relationship between three calculated values for load distribution determination and front and rear G when the load is biased to the right side of the vehicle according to the first embodiment of the present invention. It is a block diagram which shows an example of the tire air pressure fall detection apparatus in connection with Embodiment 2 of this invention. It is a flowchart which shows another example of the load distribution determination method concerning this invention.

  Compare the speed of two wheels out of the wheels mounted on the vehicle (in the case of a four-wheeled vehicle, two of the four wheels may be used, or two average values of two of the four wheels may be compared. Good).

  For a given vehicle, consider two states that differ only in the loading state.

The magnitude relationship between the two corresponding wheel speeds during braking in the state A is expressed by F1 = F2 ^* 1.0020, and the magnitude relationship between the two corresponding wheel speeds during braking in the state B is F1 = F2. ^* Assuming that it is expressed by 1.0025 (F1 means the rotation speed of wheel 1 and F2 means the rotation speed of wheel 2), wheel 1 is compared to wheel 2 in state A compared to wheel 2 in state B. Then it is getting faster.

  At this time, it is determined that the load on the wheel 1 has increased or the load on the wheel 2 has decreased in the state B than in the state A.

  Further, in state C, if the magnitude relationship between the two corresponding wheel speeds during braking is expressed by F1 = F2 * 1.0050, state C has a higher load on wheel 1 than state A. It is determined that the change from the state A to the state B has become twice as large, or the load on the wheel 2 has become twice the change from the state A to the state B.

  As calculated values of the rotational speeds of the two predetermined wheel combinations, the average of the rotational speeds of the two front wheels and the average of the rotational speeds of the two rear wheels, the average of the rotational speeds of the two left wheels and the right side 2 The average wheel rotation speed of the wheels, the rotation speed of the front wheels and rear wheels of the left two wheels, the rotation speed of the front wheels and rear wheels of the right two wheels, the left wheel rotation speed and the right wheel rotation speed of the two front wheels Alternatively, the left wheel rotation speed and the right wheel rotation speed of the two rear wheels can be set.

  Also, in the case of a three-wheel vehicle (for example, one front wheel), the average value of the rotation speed of the front wheels and the rotation speed of the two rear wheels is calculated as the calculated value of the rotation speed of the wheels in the predetermined two combinations of wheels. The left wheel rotation speed and the right wheel rotation speed of the two wheels can be set.

  If the relative change in the loading state of the vehicle can be determined and a certain specific state (eg, single rider) is stored, the change in the loading state from that condition can be detected (eg: the wheel rotation speed of the left and right two wheels) In this comparison, if the right and left equal loading states are stored, it is possible to detect the left and right uneven loading).

  The load distribution that can be determined includes, for example, the load distribution between the two front wheels and the two rear wheels, the load distribution between the two left wheels and the two right wheels, the load distribution between the two front wheels and the rear wheels, and the right two front wheels. There are rear wheel load distribution, front wheel left wheel and right wheel load distribution, or rear wheel left wheel and right wheel load distribution.

  The present invention utilizes the fact that, for example, the front and rear wheel ratios during braking differ between when one person is on board and when five persons are on board, and the degree of difference varies depending on the total load such as the number of passengers.

In the following description, the rotational speed of the wheel is expressed as follows.
W _** : Wheel rotation speed,
** indicates wheel position (FL: front left, FR: front right, RL: rear left, RR: rear right)
For example, the front left wheel rotation speed is _WFL .

Embodiment 1
Next, an example in which the method of the present invention is applied to a Toyota Corolla (FF vehicle: 5 passengers) and actually compared will be described. For the two wheel speeds to be compared, the average wheel speed of the front two wheels and the average wheel speed of the rear two wheels were used.

FIG. 2 shows the value of ((W _FL + W _FR ) / 2) / ((W _RL + W _RR ) / 2) −1, that is, the value of “front two-wheel average rotational speed / rear two-wheel average rotational speed−1” It is the graph plotted with respect to the longitudinal acceleration (the gravitational acceleration is a unit; hereinafter referred to as the longitudinal G). The data were measured in a state where two people (driver and assistant) got on the front seat while braking, and a state in which 60 kg of weight was loaded in the cargo compartment in addition to the capacity boarding. The route that measured the data is a route of less than 30 km that goes back and forth between Rokko Island and Naruhama via the Hanshin Expressway Wangan Line. The travel time was approximately 40 minutes.

  The comparison value used (average of front two wheels / average of rear two wheels −1) takes a positive value when front wheel rotational speed> rear wheel rotational speed, and becomes negative when front wheel speed <rear wheel speed. . The magnitude of the absolute value is proportional to the degree to which the faster wheel speed is faster than the other speed. In the case of this comparative example, during braking, the front wheel, which is a driving wheel, has a greater braking force and slightly slips in the reverse direction of rotation, so the rear two wheels rotate faster than the front two wheels. Compared to the two-passenger state, the difference between the five-passenger + baggage state is larger.

  The magnitude of the absolute value of the comparison value used (average of the front two wheels / average of the rear two wheels-1) is proportional to the extent that the faster wheel speed is faster than the other speed. In the case of this comparative example, the difference is larger in the state of 5 passengers + luggage than in the case of 2 passengers.

Next,
(1) Driver only
(2) Passengers in the driver's seat and passenger seat (2 people in total)
(3) Driver, passenger seat, and rear passenger seat on the right (3 people in total)
(4) Driver, passenger seat, rear seat right and rear seat left (4 people in total)
(5) Driver and passengers on the right and left of the backseat (3 people in total)
(6) Passengers in the driver, front passenger seat, rear right seat, left rear seat, and rear seat center (a total of five passengers)
(7) Driver, passenger seat, rear right seat, left rear seat, left seat center and passengers (total of 5 passengers) and trunk center (weight 60kg) (equivalent to the maximum load of the vehicle (Toyota Corolla))
(8) Driver, right rear seat, right trunk (weight 60kg)
The same measurement was carried out at a total of 8 levels (2 times at each level, 2 × 8 = 16 sets).

  Table 1 shows the weight per wheel (wheel weight) and the weight per axle (axle weight) at each level. FIG. 3 is a graph showing the relationship between the comparative value during braking (average of front two wheels / average of rear two wheels −1) and front and rear load distribution (front axle weight / rear axle weight) at each level. This graph means that if the comparison value during braking changes, it can be seen that the load distribution before and after has changed. If the relationship is known), the load distribution can be determined by the regression line relationship or the interpolation method from the running comparison value. Further, the wheel rotation speed during braking can be measured and the comparison value can be calculated and set using the 8 levels (or some of them) as a predetermined load condition.

  Of the eight levels, (6) and (8) have a front / rear load distribution ratio of 1.28. Table 2 shows the left / right load distribution.

4 and 5 plot the comparison values of wheel rotational speeds for the combinations of three patterns of wheels against the front and rear G in the load distribution of (6) (FIG. 4) and (8) (FIG. 5). It is a graph. 4 and 5, LF / R-1 represents left front wheel rotational speed / left rear wheel rotational speed -1 (that is, W _FL / W _RL -1), and RF / R-1 represents right front wheel rotational speed / right rear wheel. Rotational speed-1 (ie, W _FR / W _RR -1), and F / R-1 is the average of the rotational speeds of the front two wheels / the average of the rotational speeds of the rear two wheels -1 (ie, ((W _FL + W _FR ) / 2) / ((W _RL + W _RR ) / 2) -1).

4 and 5, the difference between “W _FL / W _RL −1” and “W _FR / W _RR −1” in the load distribution of (6) (the difference between the average values) is 0.004458. is there. On the other hand, the difference (average difference) between “W _FL / W _RL −1” and “W _FR / W _RR −1” in the load distribution of (8) is −0.0009. Thus, by comparing the difference between “W _FL / W _RL −1” and “W _FR / W _RR −1”, it can be determined that the left and right load distribution has changed. If the difference between the comparison values for two conditions with different left and right distributions is known (when the regression line or a corresponding relationship is known), the right and left distribution can be specified from the difference between the comparison values.

  FIG. 1 is a flowchart illustrating an example of a method for determining a load distribution state. A method for determining the load distribution state will be described with reference to FIG.

  Normally, the load state does not change unless the vehicle stops. Passengers get on and off and load and unload only when the vehicle stops. Also, when the fuel tank is filled from the empty state, the load state changes, but the vehicle is also stopped when fuel is supplied. Therefore, although not described in the flowchart of FIG. 1, it is detected whether the vehicle has stopped for a certain period of time or not, and it is determined whether the load state has changed before or after that time. Conversely, while the vehicle is not stopped, it is assumed that the load state has not changed, and the calculated value of the wheel rotation speed during that time can be averaged or linearly approximated.

  In order to detect that the vehicle has stopped, it may be detected that the wheel rotation speed is 0 for a certain time, or that the ignition switch is turned off or the automatic transmission is in the P range for a certain time. Can also be detected.

  In the first embodiment, while the vehicle has not stopped for a certain time (for example, 3 minutes), the calculated value of the wheel rotational speed during which the vehicle is braking is sampled for an average value for a predetermined time (for example, 30 minutes). Is calculated. Moreover, the load distribution state assumes 6 patterns. For example, in the vehicle (Toyota Corolla), 6 patterns of 1 to 5 passengers and 5 passengers + 60 kg of luggage can be assumed.

It is determined that the vehicle is braking (step S10), and when the vehicle is braking, the rotational speed ratio of the front and rear wheels ((W _FL + W _FR ) / 2) / ((W _RL + W _RR ) / 2) − 1 (hereinafter referred to as the front-to-back ratio) is sampled (step S11). Sampling is performed for a certain time (assuming that the vehicle is not stopped), and an average value A is calculated (step S13). In the present embodiment, the sampling is performed for a certain time (step S12), but the sampling may be performed until a certain number of samples is obtained.

  In order to detect that braking is in progress, it is detected whether the brake is being operated. Since a brake light (so-called brake lamp) is interlocked with the operation of the brake, in order to detect whether the brake is operated, an on / off signal of the brake light is branched and inputted.

  The calculated average value A is compared with the previously stored front-to-back ratio average value M (n) to determine load distribution. The longitudinal ratio average value M (n) at a predetermined load is measured in advance and stored. In this embodiment, the front-to-rear ratio average value M (1) in the case of a single passenger who is the minimum load and the front-to-back ratio average value M (6) in the case of the maximum load of 5 persons and 60 kg are measured in advance. Thus, M (2) to M (5) are equally divided values. δ is a value obtained by dividing the difference between M (6) and M (1) into 10 equal parts.

  The comparison between the front-to-rear ratio average value A and M (n) during traveling is made based on whether or not it is within a certain width range centering on M (n). For example, in this embodiment, since there are six patterns, if the value obtained by dividing the difference between M (1) and M (6) into 10 equal parts is δ and A is in the range of M (n) ± δ (step S15). , A is determined to have the same load distribution as M (n) (step S19).

  Or you may set the front-back ratio average value measured beforehand in all 6 patterns as M (n). In this case, whether or not the average value A before and after the running is within the range of (M (n-1) + M (n)) / 2 to (M (n) + M (n + 1)) / 2 is determined. judge. The value corresponding to δ of M (1) -δ or M (6) + δ uses (M (2) -M (1)) / 2 or (M (6) -M (5)) / 2 To do.

  If the running front / rear ratio average value A does not fall within the range of any of the front / rear ratio average values M (n) (branch from step S17 to N), abnormality processing is performed (step S18). As the abnormal processing, for example, it is assumed that an alarm is given for simultaneous depressurization of two front wheels or two rear wheels, or simultaneous depressurization of four wheels.

  FIG. 7 is a flowchart showing another example of the load distribution determination method of the present invention. In the method of FIG. 7, the load distribution state of 6 patterns is assumed similarly to the method of FIG. In the flowchart of FIG. 7, the determination that the front-rear ratio average value A during braking and the stored front-rear ratio average value M (n) are greater or smaller is the same as in FIG. Is determined in the range of (M (n-1) + M (n)) / 2 to (M (n) + M (n + 1)) / 2, which is omitted in FIG. FIG. 7 shows a method of setting the reference front-rear ratio average value M (n) while the vehicle is traveling. That is, if the longitudinal ratio average value A during braking is larger than the maximum M (6), M (6) is replaced with A, and if A is smaller than the minimum M (1), M (1) is replaced with A. Thus, the average value before and after the maximum load distribution and the minimum load distribution of the vehicle is set as the vehicle is repeatedly traveled.

  Thus, the load distribution at that time can be determined by comparing the front-rear ratio average value during braking with the stored front-rear ratio average value. In the example of FIG. 1 or FIG. 7, it can be determined which of six patterns the load state is.

  In the first embodiment, the load distribution state is six patterns. However, the number of patterns is not limited to six, and any number may be set in consideration of the number of data samplings and the detection accuracy. . If the number of data sampling is increased to increase the accuracy, the pattern can be divided finely. Further, if it is sufficient to roughly determine the load distribution state, it is possible to quickly determine the load distribution state with fewer patterns.

Embodiment 2
FIG. 6 is a block diagram of a tire pressure drop detecting device according to the embodiment of the present invention. The tire pressure drop detection device 10 inputs whether the vehicle is braking from the brake detection device 1 via the input device 3 and stores it in the memory 5. Further, wheel rotational speed information is inputted from the wheel speed detecting device 2 and stored in the memory 5. The wheel rotation speed information from the wheel speed detection device 2 may be a pulse generated by the rotation of the wheel. In that case, the wheel rotation speed can be calculated from the period of the input pulses or the number of pulses at a certain time interval. The CPU 4 executes a program stored in the memory 5. In this embodiment, only one memory 5 is described. However, the program may be stored in a ROM (read only memory) and the operation data may be stored in a RAM (random access memory). Further, a decompression alarm display device 7 that displays the determined tire pressure decompression alarm and a vehicle drive control device 8 that uses load distribution information and tire air pressure reduction information are connected.

  In the brake detection, the on / off signal of the brake light is branched and inputted as in the first embodiment.

  The load is determined by the load distribution determination method described in the first embodiment, and a tire air pressure decrease determination threshold value corresponding to the load is set. Based on the wheel rotation speed information input from the wheel speed detection device 2, a tire air pressure decrease determination value is calculated, and the determination value is compared with a threshold value to determine whether the tire is depressurizing beyond a specified range. judge. When it is determined that the determination value is equal to or greater than the threshold value and the pressure is reduced, an alarm is displayed by, for example, lamp lighting or a buzzer sounding (pressure reduction alarm display device 7).

  Further, the load distribution information can be output to the vehicle control device 8 (for example, an ABS device or a TRC device) and used for vehicle drive control. In this case, the tire pressure drop detection device 10 is also a load distribution determination device.

  For example, in the ABS device, the load distribution can be input from the load distribution determination device of the present invention, and the distribution of the brake operation force of each wheel can be set according to the load distribution. The ABS device detects slipping (tire lock) every moment and adjusts the brake operation force in real time, but by setting the brake operation force for each wheel according to the load distribution, It becomes possible to obtain the maximum braking force immediately before each wheel is locked, and safer and more reliable braking can be realized. As a result, even if the load distribution is different, the braking operation can be performed in a state in which the driver can control the direction without tilting the vehicle body with respect to the traveling direction during braking.

  In the TRC device, the load distribution is input from the load distribution determination device of the present invention, and for example, the driving force distribution of the left and right wheels is adjusted, or the upper limit of the driving force according to the load distribution is set to start / accelerate Slip can be eliminated and more effective vehicle drive control can be realized.

  Next, a method for accurately performing the pressure reduction determination by changing the threshold value of the tire pressure reduction determination according to the load distribution using the load distribution determination value will be described according to an embodiment.

Vehicle used in the example: Nissan Cedric (June 2000 model GH-HY34)
Used tires: Dunlop b> LM702 215 / 45ZR17
Tire pressure drop judgment value:
(((W _FL + W _RR ) / 2− (W _FR + W _RL ) / 2) / (W _FL + W _FR + W _RL + W _RR ) / 4) × 100
Where W _** : wheel rotation speed,
** represents the wheel position (FL: front left, FR: front right, RL: rear left, RR: rear right).
The weight of the driver was 72 kg, and the other passengers were substituted with a weight of 60 kg per person.

  For a combination of a vehicle and a tire, the judgment value is 0 at normal internal pressure, but the judgment value at 30% decompression is 0.3 for one passenger and 0.25 for five passengers. The threshold value for depressurization judgment value was set to 0.3 for depressurization determination in the load distribution for one passenger, and 0.25 for depressurization determination for the load distribution for five passengers.

The load distribution state is determined by using the rotational speed ratio of the front and rear wheels ((W _FL + W _FR ) / 2) / ((W _RL + W _RR ) / 2) -1 when braking. The method similar to the example 1 and the flowchart of FIG. 1 was applied after matching the maximum load of the vehicle (Nissan Cedric) of this example.

  With that setting, a driving test was performed with 25% pressure reduction for one wheel, and a threshold value corresponding to the load was selected based on the load determination, and an alarm was issued in both cases of one person and five persons It never happened.

  When the driving test was performed with 30% decompression of one wheel under the same setting, a threshold value corresponding to the load was selected based on the load judgment, and a warning was issued for both one and five passengers. It was.

  Thus, by setting the depressurization determination threshold value according to the load distribution, the tire pressure drop can be accurately detected according to the load. In the example of the second embodiment, in a normal passenger car (Nissan Cedric), when one wheel is depressurized by 25%, it is not determined that the pressure is depressurized in either case of one passenger or five passengers. In a state where the pressure is reduced by 30%, it can be determined that the pressure is reduced in both cases of one passenger and five passengers. Therefore, by using the result of the load distribution determination method of the present invention and setting the tire pressure reduction determination threshold value according to the load distribution state, the driver can use the same pressure reduction determination condition even in different load distribution states. It is possible to notify the danger of tire decompression without error.

  In the first and second embodiments, a small passenger car (Toyota Corolla) and an ordinary passenger car (Nissan Cedric) have been described as examples. However, the load distribution determination method of the present invention is limited to a small passenger car or an ordinary passenger car. It can be applied to vehicles equipped with hollow tires such as mini vehicles, three-wheeled vehicles, minivans, wagons, trucks, and buses.

  Further, in the present embodiment, as the rotation speed of the two wheels, the average rotation speed of the two front wheels and the average rotation speed of the two rear wheels of the four-wheel vehicle, the rotation speed of the left two front wheels, and the rotation of the rear wheels. The load distribution determination has been described with reference to the speed, the rotation speed of the front wheels of the right two wheels, and the rotation speed of the rear wheels. However, the load distribution of the target two wheels can be determined by comparing the rotation speeds of any other two wheels. Can be determined. For example, the load distribution on the left and right of the vehicle can be determined by comparing the average of the rotational speeds of the left two wheels and the average of the rotational speeds of the right two wheels. Also, in a three-wheeled vehicle with one front wheel (rear wheel), the load distribution between the front and rear of the vehicle is compared by comparing the average of the rotational speed of the front wheel (rear wheel) and the rotational speed of the two rear wheels (front wheels). Can be determined.

  Furthermore, in a six-wheel vehicle with four rear wheels, the rotation speed of the two wheels is the average of the rotation speed of the two front wheels and the average of the rotation speed of the four rear wheels, or the average of the rotation speed of the three left wheels. The average of the rotation speeds of the right three wheels can be set, and the load distribution before and after the vehicle or the load distribution on the left and right of the vehicle can be determined. Furthermore, in the case of a six-wheeled vehicle using a combination of a semi-trailer tractor and a semi-trailer, the two-wheel rotation speed is the average of the four-wheel rotation speed of the semi-trailer tractor and the average of the rotation speed of the two semi-trailer wheels. The average of the rotation speed of the front two wheels of the tractor and the average of the rotation speed of the two rear wheels, the average of the rotation speed of the two front wheels of the semi-trailer tractor and the average of the rotation speed of the two semi-trailer wheels, or after the semi-trailer tractor The average of the rotational speeds of the two wheels and the average of the rotational speeds of the two semi-trailer wheels can be determined, and the load distribution applied to the two wheels of the semi-trailer tractor and the semi-trailer or the load distribution for each axle can be determined.

  In this specification, not all combinations can be exhausted as the rotational speed of the two wheels, but by setting the combination of the rotational speeds of the two wheels and applying the method of the present invention according to the above example, The load distribution of the combination of the two wheels can be determined.

DESCRIPTION OF SYMBOLS 1 Braking detection apparatus 2 Wheel speed detection apparatus 3 Input device 4 CPU
5 Memory 6 Output Device 7 Depressurization Alarm Display Device 8 Vehicle Drive Control Device 10 Tire Pressure Drop Detection Device

Claims (5)

A method of determining load distribution of a vehicle based on a rotational speed of a wheel mounted on the vehicle, the step of detecting the rotational speed of the wheel, a step of determining whether the vehicle is being braked, and When the braking speed is being compared, the rotation speed comparison value of the two wheels among the wheels is compared with the rotation speed comparison value of the two wheels at a predetermined load, and the rotation speed ratio of the two wheels being braked is determined as the load distribution. A vehicle load distribution determination method comprising a step of determining load distribution of a vehicle by an interpolation method using the correlation. A load distribution determination device for determining load distribution of a vehicle based on a rotation speed of a wheel mounted on the vehicle, the means for detecting the rotation speed of the wheel, and a means for determining whether or not the vehicle is being braked When the vehicle is being braked, the rotation speed comparison value of the two wheels out of the wheels is compared with the rotation speed comparison value of the two wheels at a predetermined load. Means for determining vehicle load distribution by an interpolation method utilizing the fact that is correlated with load distribution. A computer for determining the load distribution of the vehicle; means for detecting the rotational speed of wheels mounted on the vehicle; means for detecting whether the vehicle is braking; and when the vehicle is braking Compare the rotation speed comparison value of two of the wheels with the rotation speed comparison value of the two wheels at a predetermined load, and use the fact that the rotation speed ratio of the two wheels being braked is correlated with the load distribution A vehicle load distribution determination program that functions as means for determining vehicle load distribution by an interpolation method . A tire pressure drop detection method using a threshold value for detecting tire pressure drop, comprising:
A tire pressure drop detection method for changing a threshold value for detecting a tire pressure drop according to a load distribution judgment result using the vehicle load distribution judgment method according to claim 1. A tire pressure drop detecting device using a threshold value for detecting a tire pressure drop,
A tire air pressure drop detection device that changes a threshold value for detecting a tire air pressure drop according to a load distribution judgment result using the vehicle load distribution judgment method according to claim 1.

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