JP4165320B2 - Tire condition detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tire condition detection device, and more particularly to a tire condition detection device suitable for detecting the condition of a tire.
[0002]
[Prior art]
Conventionally, a tire state detection device in which a strain sensor is provided on an inner surface of a rubber tire is known (see, for example, Patent Document 1). In this tire condition detection device, the strain sensor outputs a signal corresponding to the tire strain. The tire condition detection device detects the degree of tire distortion based on the output of the distortion sensor, and displays the result so as to be visible to the driver. Therefore, the driver can know the degree of tire distortion by viewing the display.
[0003]
[Patent Document 1]
JP 2002-211119 A
[0004]
[Problems to be solved by the invention]
However, it is possible to accurately determine whether or not a tire has a phenomenon such as low internal pressure, abnormal deformation, or abnormal torsion during turning by simply detecting the tire distortion and showing the distortion itself to the driver. Cannot be shown to the driver of the occurrence of the abnormal phenomenon.
[0005]
The present invention has been made in view of the above-described points, and an object of the present invention is to provide a tire condition detection device capable of accurately detecting the condition of a tire.
[0006]
[Means for Solving the Problems]
The above purpose is , Ta A first strain gauge disposed on the side wall of the ear and outputting a signal corresponding to a strain in a radial direction of the tire;
A second strain gauge disposed on the tire sidewall and outputting a signal corresponding to the strain in the circumferential direction of the tire;
Tire condition determining means for determining the condition of the tire based on the time change of the output signal of the first strain gauge and the time change of the output signal of the second strain gauge;
This is achieved by a tire condition detection device comprising:
[0007]
In the present invention, the strain in the radial direction of the tire is measured by a first strain gauge. Further, the strain in the tire circumferential direction is measured by a second strain gauge. When a road surface disturbance is input to the tire during traveling of the vehicle and when the tire is in a low internal pressure state, the tire is distorted in the radial direction. On the other hand, radial distortion due to road disturbance is temporary, whereas radial distortion due to low internal pressure is persistent. Therefore, if the temporal change of the output signal of the first strain gauge is measured, it can be distinguished whether the radial strain is due to road disturbance or low internal pressure. Further, when the tire reaches a low internal pressure state, abnormal deformation due to standing waves tends to occur in the tire. When the standing wave is generated, the tire is distorted in the circumferential direction. The tire location where such distortion occurs is kept substantially constant with respect to the portion that actually contacts the ground. That is, when viewed from one point of the tire, distortion occurs periodically during one rotation of the tire. Therefore, if the temporal change in the output signal of the second strain gauge disposed at a specific location of the tire is measured, it is possible to determine whether or not a standing wave has occurred.
[0008]
in this case ,in front The tire condition determining means may determine that a single road disturbance has been input to the tire when the output of the first strain gauge for every predetermined period shows a fluctuation exceeding a predetermined value. .
[0009]
Also, When a plurality of the first strain cages are arranged at predetermined intervals in the circumferential direction on the sidewall of the tire, The tire condition determining means includes plural The output of the first strain gauge every predetermined period is In a predetermined order Showing the prescribed distortion Each other When there is almost no fluctuation, it may be determined that the tire is in a low internal pressure state.
[0010]
Also ,in front The tire state determination means determines that a standing wave is generated in the tire when the output from the second strain gauge rises to a state showing a predetermined strain at a predetermined cycle according to the rotation speed of the tire. You can do that.
[0011]
More ,in front A plurality of second strain gauges are arranged on the sidewalls of the tire at predetermined intervals in the circumferential direction, and the tire condition determining means is configured such that the outputs from the second strain gauges have a predetermined phase shift from each other. When standing up to a state exhibiting a predetermined distortion at a predetermined cycle according to the rotational speed of the tire, it may be determined that a standing wave is generated in the tire.
[0012]
Also, the above purpose is , Ta A first strain gauge disposed on the sidewall of the ear so as to extend in an angular direction of approximately 45 ° with respect to the radial direction and outputting a signal corresponding to tire strain;
A second strain that is disposed on the sidewall of the tire in an angle direction of about 45 ° with respect to the radial direction and extends in a direction substantially perpendicular to the first strain gauge, and outputs a signal corresponding to the strain of the tire. Gauge,
Tire condition determining means for determining a tire condition based on an output signal of the first strain gauge and an output signal of the second strain gauge;
This is achieved by a tire condition detection device comprising:
[0013]
In the present invention, tire strain is measured by a first strain gauge and a second strain gauge. When the vehicle turns, an inertial force that tends to move forward and a lateral force that tends to be steered act on the tire, causing the tire to twist about the vertical axis. In this case, a tire inner diameter side portion that approaches a tire inner diameter side portion that moves away from one point on the tire outer diameter side appears on the sidewall in the vicinity of the tire ground contact portion. That is, one of the sidewalls in the vicinity of the tire ground contact portion extending in an angle direction of approximately 45 ° with respect to the radial direction and in a direction substantially orthogonal to each other expands, and the other contracts. Therefore, when the output signals of the first and second strain gauges extending in an angle direction of approximately 45 ° with respect to the radial direction and in a direction orthogonal to each other exhibit a strain satisfying a predetermined expansion / contraction relationship, the vehicle runs on the tire. It can be determined that there is a twist with great danger.
[0014]
in this case ,in front The tire condition determining means, when the output by one of the first and second strain gauges indicates a predetermined strain in the gauge extension direction and the output by the other indicates a predetermined strain in the gauge contraction direction, What is necessary is just to determine with the twist about the vertical axis which arises in a tire having a danger on driving | running | working.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a system configuration diagram of a tire condition detection apparatus 10 according to a first embodiment of the present invention. FIG. 2 shows a tire side view showing the types and arrangement of strain gauges provided in the tire condition detection device 10 of the present embodiment. FIG. 3 is a perspective view of the inside of the tire in which the strain gauge of this embodiment is arranged. FIG. 4 is a diagram schematically showing signal exchange between the strain gauge and the electronic control unit of the present embodiment.
[0016]
The tire state detection device 10 of the present embodiment is mounted on a vehicle. The vehicle has wheels on the front left FL, right front FR, left rear RL, and right rear RR. The wheel is constituted by a cylindrical wheel 12 and a tire 14 integrated with the wheel 12. The tire 14 is an annular member made of a flexible material such as rubber, and is attached around the wheel 12. The tire 14 is formed in a U-shaped cross section by a ground surface 16 that can be grounded to a road surface and a sidewall 18 that extends perpendicularly to the ground surface 16. An air layer is formed between the tire 14 and the wheel 12. The above-described tire condition detection device 10 detects the condition of each tire 14 included in the vehicle.
[0017]
Each tire 14 is provided with a radial strain gauge 20 and a circumferential strain gauge 22 attached to the outside or inside of the inner surface of the sidewall 18. Four radial strain gauges 20 are provided on the inner surface of the sidewall 18 of the tire 14, and are arranged 90 ° apart from each other at intervals in the circumferential direction. The radial strain gauge 20 is disposed such that its longitudinal direction extends in the radial direction of the tire 14. Hereinafter, the four radial strain gauges 20 are appropriately referred to as first, second, third, and fourth radial strain gauges 20 in the order of going in the direction opposite to the rotation direction of the tire 14.
[0018]
Further, four circumferential strain gauges 22 are provided on the inner surface of the sidewall 18 of the tire 14, and the circumferential strain gauges 22 are sandwiched between the two radial strain gauges 20 at intervals of 90 ° in the circumferential direction. Arranged almost in the middle. The circumferential strain gauge 22 is disposed such that its longitudinal direction extends in the circumferential direction of the tire 14. Hereinafter, the four circumferential strain gauges 22 are appropriately referred to as first, second, third, and fourth circumferential strain gauges 22 in the order of going in the direction opposite to the rotation direction of the tire 14.
[0019]
A battery 26 and a transmitter 28 are electrically connected to the radial strain gauge 20 and the circumferential strain gauge 22 via a signal line 30 for each tire 14. Both the battery 26 and the transmitter 28 are attached to the inner surface of the sidewall 18 of the tire 14. Each radial strain gauge 20 receives power supply from the battery 26 and outputs a signal corresponding to the strain in the radial direction generated in the sidewall 18 of the tire 14, that is, in the expansion / contraction direction of the tire diameter. Each of the circumferential strain gauges 22 receives power from the battery 26 and outputs a signal corresponding to the strain in the circumferential direction generated in the sidewall 18 of the tire 14, that is, in the expansion and contraction direction around the tire. . Both the output signal from the radial strain gauge 20 and the output signal from the circumferential strain gauge 22 are transmitted from the transmitter 28 to the outside of the tire.
[0020]
The tire condition detection device 10 includes an electronic control unit (hereinafter referred to as ECU) 24. The ECU 24 is connected to a receiver 32 disposed on the vehicle body in the vicinity of each tire 14. Each receiver 32 receives a signal transmitted from the transmitter 28 incorporated in the corresponding tire 14 and supplies the signal to the ECU 24. Both the output signal of the radial strain gauge 20 and the output signal of the circumferential strain gauge 22 are supplied to the ECU 24 for each tire 14. The ECU 24 detects the state of each tire 14 as described below based on the output signal of the radial strain gauge 20 and the output signal of the circumferential strain gauge 22 transmitted for each tire 14.
[0021]
A warning lamp 34 and an alarm speaker 36 are also connected to the ECU 24. The warning lamp 34 is an indicator lamp that is disposed in a vehicle cabin that can be visually recognized by the vehicle driver, and that visually alerts the vehicle driver. The alarm speaker 36 is a device that emits a sound or a buzzer toward the passenger compartment and alerts the vehicle driver by hearing. The ECU 24 turns on the warning lamp 34 or outputs sound or the like from the alarm speaker 36 according to the state of the tire 14.
[0022]
By the way, the state of the tire 14 includes a low internal pressure state in which the air layer is not maintained at an appropriate air pressure. When the tire 14 is in a low internal pressure state, the tire 14 is likely to be abnormally deformed (standing wave) in which the outer peripheral surface is deformed into a standing wave shape while the vehicle is running. Such a standing wave causes the temperature of the tire 14 to rise significantly because the energy is almost converted into heat energy, and as a result, the function of the tire 14 cannot be secured. Therefore, in order to ensure safe driving of the vehicle, it is necessary to accurately detect the state of the tire 14 before the function of the tire 14 is lost.
[0023]
Hereinafter, a method of detecting the state of the tire 14 by the tire state detection device 10 of the present embodiment will be described.
[0024]
FIG. 5 is a tire cross-sectional view for comparing the case where the internal pressure in the air layer of the tire 14 is normal (FIG. (A)) and the case where the internal pressure is low (FIG. (B)). When the internal pressure of the tire 14 is normal, as shown in FIG. 5A, there is no significant distortion near the ground contact portion of the tire 14, and the side of the tire 14 is upward when viewed from the front of the tire. The bulge from the ground to the ground becomes smaller. On the other hand, when the internal pressure of the tire 14 is a low internal pressure, as shown in FIG. 5B, the diameter of the tire 14 on the ground contact side is shortened due to the vehicle weight, and the tire 14 is greatly deformed near the ground contact. Such deformation is a large swell in the tire axial direction from the upper side to the ground contact portion when the side surface of the tire 14 is viewed from the front of the tire. Accompanied by.
[0025]
The distortion in the radial direction of the sidewall 14 of the tire 14 is not limited to the case where the tire 14 is in a low internal pressure state, but also occurs when a road surface disturbance due to a step or a stone is input to the tire 14. For this reason, the low internal pressure state of the tire 14 cannot be accurately detected simply by determining whether or not a large radial distortion has occurred in the sidewall 18 of the tire 14.
[0026]
FIG. 6 shows the time change of the output of the radial strain gauge 20 when a single road disturbance is input to the tire 14 in this embodiment. Moreover, FIG. 7 shows the time change of the output of the radial strain gauge 20 when the tire 14 is in a low internal pressure state in the present embodiment. The road surface disturbance to the tire 14 described above occurs randomly or only once. On the other hand, the low internal pressure of the tire 14 continues the state where the ground contact portion is distorted.
[0027]
In this regard, when the tire 14 is in the low internal pressure state, as shown in FIG. _-1 When the ground contact portion in the vicinity of the arrangement position of the wire is distorted, first, the first radial strain gauge 20 _-1 Outputs a signal indicating a large strain corresponding to the tire internal pressure. And if the tire 14 rotates 90 degrees after that, the 2nd radial direction strain gauge 20 _-2 The ground contact portion in the vicinity of the arrangement position of the strain is distorted, and the second radial strain gauge 20 _-2 Outputs a signal indicating distortion according to the tire internal pressure. Thereafter, similarly, the third and fourth radial strain gauges 20 _-3 And 20 _-Four Also outputs a signal indicating a strain corresponding to the tire internal pressure, and when the tire 14 makes one revolution, the first radial strain gauge 20 _-1 Outputs a signal indicating a large distortion similar to the previous time. That is, when the internal pressure is low, the first to fourth radial strain gauges 20 regularly output a signal indicating a large strain in that order every time the tire 14 rotates 90 °, and the output Show approximately the same degree of distortion.
[0028]
On the other hand, if a single road disturbance is input, as shown in FIG. 6, for example, the first radial strain gauge 20 _-1 If the grounding portion near the position where the first radial strain is distorted, the first radial strain gauge 20 _-1 Outputs a signal indicating a large strain, but even if the tire 14 rotates 90 ° after that, the second radial strain gauge 20 _-2 The ground contact portion in the vicinity of the arrangement position of the second radial strain gauge 20 is not distorted. _-2 Does not output a signal showing large distortion. Similarly, the third and fourth radial strain gauges 20 _-3 , 20 _-Four Does not output a signal indicating a large strain, and the first radial strain gauge 20 when the tire 14 makes one revolution. _-1 Does not output a signal indicating a large distortion as in the previous case.
[0029]
That is, when a road surface disturbance is input, one of the first to fourth four radial strain gauges 20 once outputs a signal indicating a large strain, but thereafter, unlike a low internal pressure, the radial strain The output of the gauge 20 does not show a large strain like the output of the one cage 20 described above. In this case, after one gauge 20 outputs a signal indicating a large strain, the output and the outputs of the radial strain gauges 20 adjacent to each other in the first to fourth order when the tire 14 rotates 90 ° are mutually connected. While showing a big fluctuation | variation, the output and the output of the same radial direction strain gauge 20 when the tire 14 makes one rotation show a big fluctuation | variation mutually.
[0030]
Therefore, in the tire state detection device 10 of the present embodiment, the ECU 24 determines whether or not the output of the radial strain gauge 20 indicates a strain that causes the tire internal pressure to reach a predetermined low internal pressure, and the positive determination is made. In the case where it is made, the output and the forward feed output of the first to fourth radial strain gauges 20 provided for every 90 ° of the tire angle every 90 ° of rotation show large fluctuations. It is determined whether or not. As a result, after the output of one radial strain gauge 20 shows a strain to such a degree as to reach a predetermined low internal pressure, the same strain is the same as the output of another radial strain gauge 20 or the same after one rotation of the tire. If it does not appear in the output of the radial strain gauge 20 and it is determined that the peak values of the outputs of the four radial strain gauges 20 show large fluctuations with each other, the tire is isolated when the large strain described above occurs. It is determined that a rough road surface disturbance has been input.
[0031]
Further, the ECU 24 outputs a large strain of a predetermined low internal pressure in the order of the first to fourth radial strain gauges 20 every time the tire 14 rotates 90 °, and the output values hardly fluctuate with each other. It is determined whether it is a thing. As a result, when it is determined that the output indicating the strain of the predetermined low internal pressure continues in the order of the first to fourth radial strain gauges 20 and the output value is determined to hardly fluctuate, the tire 14 is low. Determined to be in the internal pressure state.
[0032]
In such processing, not only is it determined whether or not radial distortion has occurred in the sidewall 18 of the tire 14, but temporal changes in the radial distortion are observed. While radial distortion due to road disturbance is temporary, radial distortion due to low internal pressure is regular and continuous. Therefore, according to the tire condition detection device 10 of the present embodiment, it is possible to distinguish whether the radial distortion generated in the sidewall 18 is due to road surface disturbance or low internal pressure, and the accurate condition of the tire 14 is determined. Detection can be performed.
[0033]
In the tire state detection device 10 of the present embodiment, when it is determined that the tire 14 is in the low internal pressure state, the warning lamp 34 is turned on to notify the vehicle driver that the tire 14 is in the low internal pressure state, A sound or the like is output from the alarm speaker 36. The low internal pressure of the tire 14 facilitates the generation of standing waves. Therefore, in this embodiment, the vehicle driver is warned of the low internal pressure state, which is one of the main causes of the standing wave of the tire 14. For this reason, the vehicle driver can recognize that a standing wave is likely to occur in the tire 14.
[0034]
FIG. 8 shows a view when the tire 14 in which a standing wave is generated is viewed from the rear. The standing wave-like standing wave generated in the tire 14 during traveling of the vehicle is such that the ground contact surface 16 which is the outer peripheral surface repeats unevenness in the radial direction every predetermined angle over the circumferential direction. At this time, convex portions extending radially from the center on the side surface of the tire 14 are formed at predetermined angles, and unevenness in the tire axial direction is repeated at predetermined angles over the circumferential direction as shown in FIG. That is, the abnormal deformation due to the standing wave is accompanied by distortion in the circumferential direction on the sidewall 18 on the side surface of the tire.
[0035]
FIG. 9 shows an example of a temporal change in the output of the circumferential strain gauge 22 when a standing wave is generated in the tire 14 in this embodiment. The standing wave generated in the tire 14 is a standing wave that repeats irregularities at every predetermined angle in the circumferential direction. In this regard, when a standing wave is generated in the tire 14, focusing on one of the four circumferential strain gauges 22, the gauge 22 has a relatively large strain at a period corresponding to the rotational speed of the tire 14. The output of the signal indicating is repeated. When attention is paid to the relationship between the outputs of the gauges 22, the outputs of the gauges 22 cause a phase shift corresponding to the rotation speed of the tire 14 with respect to the outputs of the adjacent gauges 22.
[0036]
Therefore, in the tire state detection device 10 of the present embodiment, the ECU 24 determines whether or not the output of the circumferential strain gauge 22 shows a large strain to some extent, and also shows a large strain in the output of the circumferential strain gauge 22. It is determined whether or not the rising to the position occurs at a cycle according to the rotational speed of the tire 14. Further, the ECU 24 determines whether or not the outputs of the first to fourth circumferential strain gauges 22 are out of phase in that order.
[0037]
As a result of the determination, the ECU 24 indicates that the output of the circumferential strain gauge 22 exhibits a large strain, and thereafter, the output of the same circumferential strain gauge 22 periodically rises to a state indicating the strain, and the cycle. If a natural rise occurs while causing a phase shift in the order of the first to fourth circumferential strain gauges 22, it is determined that a standing wave is generated in the tire 14.
[0038]
In such a process, it is determined whether or not a circumferential distortion has occurred in the sidewall 18 of the tire 14, and a temporal change in the circumferential distortion is observed. Therefore, according to the tire state detection device 10 of the present embodiment, it is possible to accurately determine whether or not a standing wave is generated in the sidewall 18.
[0039]
In the tire condition detection device 10 of this embodiment, when it is determined that a standing wave is generated in the tire 14, a warning lamp 34 is lit to notify the vehicle driver of the occurrence of the standing wave phenomenon, and an alarm speaker is provided. A sound or the like is output from 36. For this reason, the vehicle driver can recognize that a standing wave has actually occurred in the tire 14.
[0040]
As described above, in the tire condition detection device 10 of the present embodiment, both the low internal pressure state of the tire 14 and the standing wave that is likely to occur at the low internal pressure are accurately detected, and the detection result is notified to the vehicle driver. it can. In this regard, it is possible to detect the signs correctly at an early stage before the function of the tire 14 is not ensured due to the standing wave, and to ensure safe driving of the vehicle.
[0041]
In the first embodiment, the radial strain gauge 20 is the “first strain gauge” described in claims 1 to 5, and the circumferential strain gauge 22 is the “first strain gauge” described in claims 1 to 5. 2, the ECU 24 determines the low internal pressure state of the tire 14 and the road surface disturbance input based on the time change of the output signal of the radial strain gauge 20, and the circumferential direction. The “tire condition determining means” described in claims 1 to 5 is realized by determining the standing wave phenomenon of the tire 14 based on the time change of the output signal of the strain gauge 22.
[0042]
Incidentally, in the first embodiment, four radial strain gauges 20 and four circumferential strain gauges 22 are arranged on the inner surface of the sidewall 18 of the tire 14 in the circumferential direction. , 22 may be set to a number corresponding to the diameter of the tire 14, the cross-sectional height of the sidewall 18, etc., and at least one of them may be arranged.
[0043]
Further, in the first embodiment, the radial strain gauge 20 and the circumferential strain gauge 22 are arranged separately and independently, specifically, with an interval of 45 °. As shown, the gauges 20 and 22 may be arranged at the same location. In this case, the radial strain gauges 20 and the circumferential strain gauges 22 have longitudinal directions orthogonal to each other.
[0044]
Next, a second embodiment of the present invention will be described.
[0045]
FIG. 11 is a diagram for explaining a strain gauge provided in the tire condition detection device 100 of the present embodiment. In the present embodiment, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof is omitted.
[0046]
In the present embodiment, each tire 14 is provided with a strain gauge 102 attached to the outside or the inside of the inner surface of the sidewall 18. Four strain gauges 102 are provided on the inner surface of the sidewall 18 of the tire 14 and are arranged at intervals of 90 ° in the circumferential direction. The strain gauge 102 includes an α-cross strain gauge 104 and a β-cross strain gauge 106 that are arranged so that their longitudinal directions extend in a direction substantially 45 ° with respect to the radial direction of the tire 14. The pair of cross strain gauges 104 and 106 are disposed at the same location on the sidewall 18 of the tire 14 and extend in directions orthogonal to each other. Hereinafter, the four strain gauges 102 are appropriately referred to as first, second, third, and fourth strain gauges 102 in the order of going in the direction opposite to the rotation direction of the tire 14, respectively.
[0047]
A battery 26 and a transmitter 28 are electrically connected to the α cross strain gauge 104 and the β cross strain gauge 106 for each tire 14. Each α-cross strain gauge 104 receives power supply from the battery 26 and outputs a signal corresponding to strain caused by expansion and contraction in the 45 ° direction with respect to the radial direction generated in the sidewall 18 of the tire 14. Each β-cross strain gauge 106 is supplied with power from the battery 26 and has a direction of 45 ° with respect to the radial direction generated on the sidewall 18 of the tire 14 and a direction orthogonal to the expansion / contraction direction of the α-cross strain gauge 104. Outputs a signal according to the distortion caused by expansion and contraction. Both the output signal of the α cross strain gauge 104 and the output signal of the β cross strain gauge 106 are transmitted from the transmitter 28 to the receiver 32 outside the tire and supplied to the ECU 24. The ECU 24 detects the state of each tire 14 based on the output signal of the α cross strain gauge 104 and the output signal of the β cross strain gauge 106 transmitted for each tire 14 as described later.
[0048]
By the way, when the vehicle turns, an inertial force that tends to move forward and a lateral force that tends to be steered act on the tire 14. For this reason, the tire 14 is twisted around the vertical axis when the vehicle turns. If this twist is permitted when the vehicle travels, no inconvenience occurs. However, if the twist exceeds the allowable value, the vehicle body becomes unstable and the vehicle falls into a dangerous state. Therefore, in order to ensure safe driving of the vehicle, it is necessary to determine whether or not the twist of the tire 14 around the vertical axis is within an allowable range.
[0049]
FIG. 12 is a diagram for explaining a twisting phenomenon around the vertical axis that occurs in the tire 14. For example, in the situation where the vehicle moves forward from the left side to the right side as shown in FIG. 12, when the twist of the tire 14 occurs in the ω1 direction shown in FIG. It is twisted against the outer diameter side part. At this time, a portion extending in an angular direction of approximately 45 ° from the ground contact point to the front side in the radial direction from the ground contact point extends, and an angular direction of approximately 45 ° from the ground contact point in the radial direction to the rear side. The portion that extends to shrinks. Further, when the twist of the tire 14 occurs in the ω2 direction shown in FIG. 12, a portion extending in an angular direction of approximately 45 ° from the ground contact point to the front side in the radial direction is contracted and contacted therewith. A portion extending in an angular direction of approximately 45 ° extends rearward from the point in the radial direction.
[0050]
FIG. 13 shows an example of a change over time in the output of the strain gauge 102 when a large twist about the vertical axis occurs in the tire 14 in this embodiment. Since the torsion of the tire 14 during the turning of the vehicle occurs in the vicinity of the ground contact portion, when the torsion of the tire 14 occurs, the distortion due to the torsion in the order of the first to fourth strain gauges 102 is output to the output of the strain gauge 102. Appears. That is, the output of each strain gauge 102 causes a phase shift corresponding to the rotational speed of the tire 14 with respect to the output of the adjacent gauge 102. When the tire 14 is twisted, the output of the α cross strain gauge 104 of the strain gauge 102 and the output of the β cross strain gauge 106 are opposite in phase.
[0051]
Therefore, in the tire condition display device 100 of the present embodiment, the ECU 24 causes the outputs of the α cross strain gauge 104 and the β cross strain gauge 106 of the strain gauge 102 to be larger than a predetermined allowable value on the expansion side or the contraction side, respectively. Whether or not is indicated. When one of the gauges 104 and 106 exhibits a large strain on the expansion side, the other exhibits a large strain on the contraction side, and when one exhibits a large strain on the contraction side, the other expands. It is determined whether a large distortion is shown on the side.
[0052]
As a result of the determination, the ECU 24 indicates that the output of the α cross strain gauge 104 shows a large strain on the expansion side and at the same time the output of the β cross strain gauge 106 paired with the gauge 104 shows a large strain on the contraction side, or When the output of the α cross strain gauge 104 shows a large strain on the contraction side and at the same time the output of the β cross strain gauge 106 paired with the gauge 104 shows a large strain on the expansion side, an allowable value is given to the tire 14. It is determined that a large twist that exceeds the maximum is occurring.
[0053]
In such processing, the twist phenomenon of the tire 14 is observed using two orthogonal strain gauges 104 and 106. Therefore, according to the tire state detection device 100 of the present embodiment, it is possible to accurately determine that the tire 14 is twisted around the vertical axis that is dangerous during vehicle travel.
[0054]
In the tire condition detection apparatus 100 according to the present embodiment, when it is determined that the tire 14 has a large torsion exceeding an allowable value, the vehicle driver is notified of the occurrence of the torsion phenomenon so as to promote a decrease in the vehicle speed. The warning lamp 34 is turned on, and sound or the like is output from the alarm speaker 36. For this reason, the vehicle driver can recognize that the tire 14 has a torsion exceeding an allowable value, and can reduce the speed of the vehicle. When the vehicle speed is reduced, the twist of the tire 14 is alleviated, so that safe driving of the vehicle is ensured.
[0055]
In the second embodiment, the α cross strain gauge 102 and the β cross strain gauge 104 of the strain gauge 102 are the “first strain gauge” and the “second strain gauge” described in claims 6 and 7. The ECU 24 determines whether the tire 14 is twisted about the vertical axis based on the relationship between the output signal of the α cross strain gauge 102 and the output signal of the β cross strain gauge 104. The “tire condition determining means” described in claims 6 and 7 is realized.
[0056]
By the way, in the second embodiment, four strain gauges 102 are arranged on the inner surface of the sidewall 18 of the tire 14 in the circumferential direction. The number may be set according to the height of the cross section, etc., and it is sufficient that at least one is arranged.
[0057]
In the second embodiment, the α cross strain gauge 104 and the β cross strain gauge 106 are disposed so as to extend in a direction substantially 45 ° with respect to the tire radial direction. What is necessary is just to make it extend in the optimal direction according to the twist phenomenon of the tire 14 according to a kind etc.
[0058]
Further, in the second embodiment, when it is determined that the tire 14 has a large torsion exceeding the allowable value, a warning lamp 34 displays and a sound speaker 36 outputs a sound to the vehicle driver. However, the vehicle may be automatically decelerated by wheel braking, engine braking, fuel supply suppression, shift down, or the like. In this case, the vehicle speed is immediately reduced regardless of the operation of the vehicle driver, so that dangerous traveling is avoided and safe traveling is reliably ensured.
[0059]
In the first and second embodiments, the strain gauges 20, 22, and 102 are arranged outside or inside the inner surface of the sidewall 18 of the tire 14, but as shown in FIG. It is good also as arrange | positioning so that both the outer side and inner side of the inner surface of 18 may be opposed. According to such a configuration, the state of the tire 14 can be determined in detail, and the above-described low internal pressure state, road disturbance input, standing wave, and torsion phenomena can be accurately determined.
[0060]
Further, in the first embodiment, the tire 14 is checked for the low internal pressure state, road disturbance input, and standing wave phenomenon. In the second embodiment, the tire 14 is twisted. However, the radial strain gauge 20, the circumferential strain gauge 22, and the strain gauge 102 may be arranged on the sidewall 18 of the tire 14 at intervals in the circumferential direction so as to determine all the phenomena. .
[0061]
【The invention's effect】
As described above, according to the first aspect of the invention, the tire Precise detection of single road disturbance input can do.
[0063]
Claim 2 According to the described invention, it is possible to accurately detect that the tire is in a low internal pressure state.
[0064]
Claim 3 as well as 4 According to the described invention, it is possible to accurately detect that a standing wave phenomenon occurs in the tire.
[0065]
Claims 5 According to the described invention, it is possible to accurately detect that a torsion accompanied by a great danger in traveling occurs in the tire.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a tire condition detection apparatus according to a first embodiment of the present invention.
FIG. 2 is a tire side view showing the types and arrangement of strain gauges provided in the tire condition detection device of the present embodiment.
FIG. 3 is a perspective view of the inside of a tire in which a strain gauge according to this embodiment is disposed.
FIG. 4 is a diagram schematically showing signal exchange between the strain gauge and the electronic control unit according to the present embodiment.
FIG. 5 is a tire cross-sectional view for comparing the case where the tire internal pressure is normal (FIG. 5A) and the case where the tire internal pressure is low (FIG. 5B).
FIG. 6 is a diagram showing a time change of strain gauge output when a single road surface disturbance is input to a tire in this example.
FIG. 7 is a diagram showing a time change of strain gauge output when the tire is in a low internal pressure state in the present example.
FIG. 8 is a view of a tire in which a standing wave is generated when viewed from the rear.
FIG. 9 is a diagram showing a time change of strain gauge output when a standing wave is generated in the tire in this example.
FIG. 10 is a view for explaining a strain gauge provided in a tire condition detection device which is a modification of the present invention.
FIG. 11 is a diagram for explaining a strain gauge included in a tire condition detection device according to a second embodiment of the present invention.
FIG. 12 is a diagram for explaining a twisting phenomenon around a vertical axis that occurs in a tire.
FIG. 13 is a diagram showing a time change of strain gauge output when a large twist about a vertical axis occurs in a tire in this example.
FIG. 14 is a view for explaining a strain gauge provided in a tire condition detection device which is a modified example of the present invention.
[Explanation of symbols]
10,100 Tire condition detection device
14 tires
18 sidewall
20 radial strain gauge
22 Circumferential strain gauge
24 Electronic control unit (ECU)
102 strain gauge
104 α cross strain gauge
106 β cross strain gauge

Claims (5)

A first strain gauge disposed on the tire sidewall and outputting a signal corresponding to the radial strain of the tire;
A second strain gauge disposed on the tire sidewall and outputting a signal corresponding to the strain in the circumferential direction of the tire;
Tire condition determining means for determining the condition of the tire based on the time change of the output signal of the first strain gauge and the time change of the output signal of the second strain gauge;
Equipped with a,
The tire condition determining means, when the output for each predetermined period of the first strain gauge showed variation exceeding a predetermined value, and characterized that you determined sporadic road surface disturbance is input to the tire Tire condition detection device. A first strain gauge disposed on the tire sidewall and outputting a signal corresponding to the radial strain of the tire;
A second strain gauge disposed on the tire sidewall and outputting a signal corresponding to the strain in the circumferential direction of the tire;
Tire condition determining means for determining the condition of the tire based on the time change of the output signal of the first strain gauge and the time change of the output signal of the second strain gauge;
With
A plurality of the first strain cages are arranged at predetermined intervals in the circumferential direction on the sidewall of the tire,
The tire state determination means determines that the tire is in a low internal pressure state when outputs of the plurality of first strain gauges for a predetermined period show a predetermined strain in a predetermined order and hardly vary from each other. features and to filter bad state detecting device to be. A first strain gauge disposed on the tire sidewall and outputting a signal corresponding to the radial strain of the tire;
A second strain gauge disposed on the tire sidewall and outputting a signal corresponding to the strain in the circumferential direction of the tire;
Tire condition determining means for determining the condition of the tire based on the time change of the output signal of the first strain gauge and the time change of the output signal of the second strain gauge;
With
The tire state determination means determines that a standing wave is generated in the tire when the output from the second strain gauge rises to a state showing a predetermined strain at a predetermined period corresponding to the rotation speed of the tire. features and to filter bad state detecting device that. A first strain gauge disposed on the tire sidewall and outputting a signal corresponding to the radial strain of the tire;
A second strain gauge disposed on the tire sidewall and outputting a signal corresponding to the strain in the circumferential direction of the tire;
Tire condition determining means for determining the condition of the tire based on the time change of the output signal of the first strain gauge and the time change of the output signal of the second strain gauge;
With
A plurality of the second strain gauges are arranged at predetermined intervals in the circumferential direction on the sidewall of the tire,
The tire condition determining means is configured to apply a standing wave to the tire when the outputs from the second strain gauges rise to a condition indicating a predetermined distortion at a predetermined period corresponding to the rotation speed of the tire while causing a predetermined phase shift from each other. There occurring characterized and to filter bad state detecting device to be determined. A first strain gauge disposed on the sidewall of the tire so as to extend in an angular direction of approximately 45 ° with respect to the radial direction and outputting a signal corresponding to the tire strain;
A second strain that is disposed on the sidewall of the tire in an angle direction of about 45 ° with respect to the radial direction and extends in a direction substantially perpendicular to the first strain gauge, and outputs a signal corresponding to the strain of the tire. Gauge,
Tire condition determining means for determining a tire condition based on an output signal of the first strain gauge and an output signal of the second strain gauge;
Equipped with a,
When the output from one of the first and second strain gauges indicates a predetermined strain in the gauge extension direction and the output from the other indicates a predetermined strain in the gauge contraction direction, the tire condition determination means tire condition detecting device characterized that you determined that torsion of the vertical axis generated in the tire becomes as dangerous on the running.

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