Different-diameter tire determination system

Abstract

To provide a different-diameter tire determination system that enables the presence / absence of different-diameter tires to be more accurately determined than conventional technology.SOLUTION: A different-diameter tire presence / absence determination unit 33 determines that different-diameter tires are present when the difference between a calculation result of a calculation unit 32 obtained while the vehicle is running and a calculation result of the calculation unit 32 obtained before the running or a predetermined value is greater than a threshold value. Therefore, unlike the conventional technology, the presence / absence of different-diameter tires can be determined while the vehicle is running regardless of whether the vehicle has been stopped for a predetermined period of time or more. Therefore, the presence / absence of different-diameter tires can be determined more accurately than in the conventional technology. As a result, erroneous determinations in brake control can be suppressed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a different diameter tire determination system that determines whether or not there is a different diameter tire. [Background technology]

[0002] When a tire gets punctured, it is replaced with a different-diameter tire (an emergency tire, also called a reserve tire or a small-diameter tire; the same applies below). In brake controls such as ABS (anti-skid control, anti-lock control) and TRC (traction control), replacing the tires with different-diameter tires may cause malfunctions. In more detail, for example, if three wheels have normal tires and one wheel has a different-diameter tire that is smaller than the normal tire, (i) when the vehicle speed is generated from the normal tire, the different-diameter tire is in the same state as if it were slipping due to driving force, which may cause a TRC malfunction, and (ii) when the vehicle speed is generated from the different-diameter tire, the normal tire is in the same state as if it were slipping due to braking, which may cause an ABS malfunction. Therefore, tire diameter determination (assuming that there are wheels equipped with small diameter tires such as Tempa) is performed.

[0003] Conventionally, there is a brake control device that performs the following (A). (A) "Tire diameter determination is performed only when the following conditions are met: the vehicle has been driven for a specified time, brake control has not been performed, and the vehicle acceleration is within a specified range. Once a determination is made, no further determination is made during that IG trip (ignition trip). However, if it is determined that the vehicle has been stopped for a specified time or longer, a re-determination is made as there is a possibility that the tires have been changed."

[0004] Also, a control technique similar to this control technique (A) is disclosed in JP-A-07-232633. In the control technique disclosed in this publication, after a puncture is detected, it is determined whether or not the vehicle has stopped for a predetermined time or more (a time long enough to change to tires with a different diameter), and if it is determined that the vehicle has stopped for the predetermined time or more, it is determined whether or not to change to tires with a different diameter.

[0005] However, the above control technique (A) and the control technique disclosed in the above publication have the following problems. Whether or not different-diameter tires have been replaced is determined by stopping the vehicle for a specified period of time or longer. However, when tires with different diameters are replaced in a relatively short period of time (within the specified time), such as when an experienced worker performs the work, the system may not be able to determine whether or not different-diameter tires have been replaced, and it may not be possible to correctly determine whether or not different-diameter tires have been replaced. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 07-232633 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide an different diameter tire determination system that can determine the presence or absence of different diameter tires more accurately than conventional systems. [Means for solving the problem]

[0008] The present invention which achieves the above object is as follows. (1) Having a control device that calculates the wheel speed of each tire; The control device includes: a calculation unit that calculates a wheel speed to dynamic load radius ratio of each of the tires and / or a spring constant of each of the tires based on the wheel speeds; a different diameter tire presence / absence determination unit that determines the presence or absence of different diameter tires based on the calculation result of the calculation unit; It has The different diameter tire presence / absence determination unit determines that different diameter tires are present when the difference between the calculation result of the calculation unit while the vehicle is running and the calculation result of the calculation unit before the running or the difference between the calculation result and a predetermined value is greater than a threshold value. Effect of the Invention

[0009] According to the different diameter tire determination system described above in (1), the following effects can be obtained. The different-diameter tire presence / absence determination unit determines that different-diameter tires are present when the difference between the calculation result of the calculation unit while the vehicle is running and the calculation result of the calculation unit before the running or the difference between the calculation result and a predetermined value is greater than a threshold value, so that unlike conventional methods, it is possible to determine the presence or absence of different-diameter tires while the vehicle is running regardless of whether the vehicle has been stopped for a predetermined period of time or more. Therefore, it is possible to more accurately determine the presence or absence of different-diameter tires than conventional methods. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram of an odd-diameter tire determination system according to a first embodiment of the present invention, although this diagram is also applicable to a second embodiment of the present invention. [Diagram 2] 4 is a control flowchart of a control device in the first embodiment of the present invention (wherein a calculation unit calculates a dynamic load radius ratio based on a wheel speed). [Diagram 3] 10 is a control flowchart of a control device in a second embodiment of the present invention (wherein a calculation unit calculates a spring constant of each tire). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A different diameter tire determination system 10 according to an embodiment of the present invention will be described below with reference to the drawings.

[0012] Although not shown, a vehicle equipped with the different diameter tire determination system 10 has four wheels, a right front tire, a left front tire, a right rear tire, and a left rear tire. To detect the wheel speed of each of the four wheels, a wheel speed sensor 20FR for the right front tire, a wheel speed sensor 20FL for the left front tire, a wheel speed sensor 20RR for the right rear tire, and a wheel speed sensor 20RL for the left rear tire are disposed on the corresponding wheels, as shown in Fig. 1. The wheel speed sensors 20FR, 20FL, 20RR, and 20RL are components of the different diameter tire determination system 10.

[0013] The different diameter tire determination system 10 has a control device 30. The control device 30 is made up of an ECU (Electric Control Unit) capable of at least brake control.

[0014] The control device 30 is (a) a wheel speed calculation unit 31 that calculates the wheel speed of each tire from the output signals of the wheel speed sensors 20FR, 20FL, 20RR, and 20RL; (b) a calculation unit 32 that calculates a wheel speed to dynamic load radius ratio of each tire and / or a spring constant of each tire based on the wheel speed calculated by the wheel speed calculation unit 31; (c) a different-diameter tire presence / absence determination unit 33 that determines the presence or absence of different-diameter tires based on the calculation result of the calculation unit 32; and has.

[0015] Regarding (b) above (b1) When the calculation unit 32 calculates the dynamic load radius ratio of the wheel speed of each tire, the dynamic load radius ratio α is calculated using the following formula (A). α=(VwFR / VwFL)-(VwRR / VwRL) (A) In addition, VwFR: Wheel speed calculated based on the signal from the wheel speed sensor of the right front tire VwFL: Wheel speed calculated based on the left front tire wheel speed sensor signal VwRR: Wheel speed calculated based on the wheel speed sensor signal of the right rear tire VwRL: Wheel speed calculated based on the left rear tire wheel speed sensor signal It is.

[0016] Incidentally, the technology for calculating the dynamic load radius ratio of the wheel speed of each tire is used in a technology for determining whether there is a wheel with low tire pressure from the amount of change in the dynamic load radius ratio of the wheel speed of each tire (comparison of the wheel speeds of each wheel) (for example, Patent No. 3695884), and is publicly known.

[0017] (b2) When the calculation unit 32 calculates the spring constant of each tire, the calculation unit 32 may calculate the resonant frequency of each tire, which has a certain relationship with the spring constant, together with the spring constant or instead of the spring constant.

[0018] Incidentally, the technology for calculating the spring constant (resonance frequency) of each tire based on the wheel speed of each tire is well known and is used in a technology (e.g., Patent No. 3300572) that calculates the amount of change in the spring constant (resonance frequency) of each tire based on the wheel speed and determines that the tire air pressure has decreased if the change exceeds a predetermined range.

[0019] Regarding (c) above The different diameter tire presence / absence determination unit 33 determines that different diameter tires are present (that tires have been replaced with different diameter tires) when the difference between the calculation result of the calculation unit 32 during the current driving of the vehicle and the calculation result of the calculation unit 32 before the driving or the difference between the calculation result and a predetermined value is greater than a threshold value.

[0020] Example 1 Fig. 2 is a flowchart showing an example of a control routine of the control device 30 when the calculation unit 32 calculates the dynamic load radius ratio and the different diameter tire presence / absence determination unit 33 determines the presence / absence of different diameter tires based on the calculation result (dynamic load radius ratio) calculated by the calculation unit 32. The routine of Fig. 2 is repeatedly executed at predetermined time intervals.

[0021] First, in step S101, when the ignition is turned from OFF to ON (IG-OFF to IG-ON), the process proceeds to step S102, where the stored value (α_Mem) of the dynamic load radius ratio at the previous IG-OFF is set as the dynamic load radius ratio α_Last in the previous run, and the process proceeds to step S103. Then, in step S103, the wheel speed calculation unit 31 reads the output signals of each wheel speed sensor 20FR, 20FL, 20RR, 20RL to calculate the wheel speed of each tire, and the process proceeds to step S104.

[0022] In step S104, it is determined whether or not the vehicle is running based on the wheel speed of each tire calculated by the wheel speed calculation unit 31. If it is determined in step S104 that the vehicle is running, the process proceeds to step S105, where the calculation unit 32 calculates the dynamic load radius ratio α_Now in the current run. Then, in step S106, the different diameter tire presence / absence determination unit 33 determines whether or not the absolute value of the difference (amount of change) between the dynamic load radius ratio α_Now in the current run and the dynamic load radius ratio α_Last in the previous run is greater than a threshold value K_α_Th for determining whether or not the tires have been replaced with different diameter tires. If it is determined that the absolute value is greater, the process proceeds to step S107, where it is presumed (determined) that the tires have been replaced with different diameter tires, and the process proceeds to step S109. On the other hand, if it is determined that the absolute value is not greater in step S106, the process proceeds to step S108, where it is presumed (determined) that the tires have not been replaced with different diameter tires, and the process proceeds to step S109.

[0023] In step S109, it is determined whether the ignition has changed from ON to OFF (IG-ON to IG-OFF). If it is determined in step S109 that the IG-ON remains on and has not changed to IG-OFF, the process returns to step S103. On the other hand, if it is determined in step S109 that the IG-OFF has been changed, the process proceeds to step S112, where the dynamic load radius ratio α_Now calculated in the current traveling is set as a new stored value (α_Mem), and the process proceeds to the end step.

[0024] On the other hand, if it is determined in step S104 that the vehicle is not running, the process proceeds to step S110, where it is determined whether or not the dynamic load radius ratio α_Now has been calculated since IG-ON in S101. If it is determined in step S110 that the dynamic load radius ratio α_Now has been calculated, the process proceeds to step S111, where the calculated dynamic load radius ratio α_Now is set as the dynamic load radius ratio α_Last in the previous run, and the process proceeds to step S109. On the other hand, if it is determined in step S110 that the dynamic load radius ratio α_Now has not been calculated, the process returns to step S103.

[0025] In the above control routine shown in FIG. 2, the difference (difference amount) in the dynamic load radius ratio before and after the run is used for judgment, but the judgment may also be made based on the difference (threshold, amount of change) between the calculated dynamic load radius ratio α_Now in the current run and a predetermined value (constant).

[0026] Example 2 Fig. 3 is a flowchart showing an example of a control routine of the control device 30 when the calculation unit 32 calculates the spring constant of each tire, and the different diameter tire presence / absence determination unit 33 determines the presence / absence of different diameter tires based on the calculation results calculated by the calculation unit 32. The routine in Fig. 3 is repeatedly executed at predetermined time intervals. In Fig. 3, ** indicates the right front, left front, right rear, or left rear. The calculation in Fig. 3 is performed for each of the four wheels.

[0027] First, in step S201, when the ignition is turned from OFF to ON (IG-OFF to IG-ON), the process proceeds to step S202, where the stored tire spring constant (TK_Mem_**) at the previous IG-OFF is set as the tire spring constant TK_Last_** during the previous run, and the process proceeds to step S203. Then, in step S203, the wheel speed calculation unit 31 reads the output signals of each wheel speed sensor 20FR, 20FL, 20RR, 20RL, calculates the wheel speed of each tire, and the process proceeds to step S204.

[0028] In step S204, it is determined whether or not the vehicle is running based on the wheel speed of each tire calculated by the wheel speed calculation unit 31. If it is determined in step S204 that the vehicle is running, the process proceeds to step S205, where the calculation unit 32 calculates the tire spring constant TK_Now_** in the current run by frequency analysis of the wheel speed calculated by the wheel speed calculation unit 31. Then, the process proceeds to step S206, where the different diameter tire presence / absence determination unit 33 determines whether or not the difference (amount of change) between the tire spring constant TK_Now_** in the current run and the tire spring constant TK_Last_** in the previous run is greater than a threshold value K_TK_Th for determining whether or not the tires have been replaced with different diameter tires. If it is determined that the difference (amount of change) is greater, the process proceeds to step S207, where it is presumed (determined) that the tires have been replaced with different diameter tires, and the process proceeds to step S209. On the other hand, if it is determined that the difference (amount of change) is not greater in step S206, the process proceeds to step S208, where it is presumed (determined) that the tires have not been replaced with different diameter tires, and the process proceeds to step S209.

[0029] In step S209, it is determined whether the ignition has changed from ON to OFF (IG-ON to IG-OFF). If it is determined in step S209 that the IG-ON remains on and has not changed to IG-OFF, the process returns to step S203. On the other hand, if it is determined in step S209 that the IG-OFF has occurred, the process proceeds to step S212, where the tire spring constant TK_Now_** calculated during the current run is set as a new stored value (TK_Mem_**), and the process proceeds to the end step.

[0030] On the other hand, if it is determined in step S204 that the vehicle is not running, the process proceeds to step S210, where it is determined whether or not the tire spring constant TK_Now_** has been calculated since IG-ON in S201. If it is determined in step S210 that the tire spring constant TK_Now_** has been calculated, the process proceeds to step S211, where the calculated tire spring constant TK_Now_** is set as the tire spring constant TK_Last_** in the previous run, and the process proceeds to step S209. On the other hand, if it is determined in step S210 that the tire spring constant TK_Now_** has not been calculated, the process returns to step S203.

[0031] In the control routine shown in Fig. 3, the difference (difference amount) in the tire spring constant before and after the running is used for the judgment, but the judgment may be made based on the difference (threshold, difference amount) between the calculated tire spring constant TK_Now_** in the current running and a predetermined value (constant). Also, in the control routine shown in Fig. 3, the spring constant may be replaced with a resonance frequency having a certain relationship with the spring constant.

[0032] Next, the operation and effects of the present invention will be described. When the difference between the calculation result of the calculation unit 32 while the vehicle is running and the calculation result of the calculation unit 32 before the running or the difference between the difference and a predetermined value is greater than a threshold value, the different diameter tire presence / absence determination unit 33 determines that different diameter tires are present, so that, unlike the conventional technology, the presence / absence of different diameter tires can be determined while the vehicle is running regardless of whether the vehicle has been stopped for a predetermined period of time or more. Therefore, the presence / absence of different diameter tires can be determined more accurately than the conventional technology. As a result, erroneous determinations in brake control can be suppressed.

[0033] Although specific embodiments (embodiment 1 and embodiment 2) of the present invention have been described above, the present invention is not limited to the above embodiments. For example, embodiment 1 and embodiment 2 may be used together as another embodiment. In addition, by using the existing technology (A) in the conventional brake control device, embodiment 1, and embodiment 2 together, the total accuracy of tire diameter determination may be improved and the time required for determination may be shortened.

[0034] In addition, in the case where Example 1 and Example 2 are used together, the operating ranges of Example 1 and Example 2 may be divided according to the vehicle speed range depending on the requirements to obtain advantages. For example, Example 2 may be used from 0 to 80 [km / h] to take advantage of the advantage of being able to identify tires that have been replaced with tires of different diameters, and Example 1 may be used from 75 to MAX [km / h] because Example 1, which performs the calculations for all four wheels together, can reduce the calculation load on the microcomputer, unlike Example 2, which performs the calculations for each of the four wheels. [Explanation of symbols]

[0035] 10 Different diameter tire identification system 20FR Wheel speed sensor for right front tire 20FL Wheel speed sensor for left front tire 20RR Wheel speed sensor for right rear tire 20RL Wheel speed sensor for left rear tire 30 Control device 31 Wheel speed calculation section 32 Calculation section 33 Different diameter tire presence / absence detection section

Claims

[Claim 1] A control device is provided for calculating the wheel speed of each tire. The control device includes: a calculation unit that calculates a wheel speed to dynamic load radius ratio of each of the tires and / or a spring constant of each of the tires based on the wheel speeds; a different diameter tire presence / absence determination unit that determines the presence or absence of different diameter tires based on the calculation result of the calculation unit; It has The different diameter tire presence / absence determination unit determines that different diameter tires are present when the difference between the calculation result of the calculation unit while the vehicle is running and the calculation result of the calculation unit before the running or the difference between the calculation result and a predetermined value is greater than a threshold value.

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