JP2005140503A - Wheel for vehicle and load monitor for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel having a load sensor, and a load monitor for a vehicle capable of giving a warning to overloading or an overload. <P>SOLUTION: A monitor body 9 comprises: an input interface 91 connected with a vehicle body side antenna 6; a total weight estimation part 92 estimating total weight on the basis of an input signal from the input interface 91; a weight excess decision part 93 deciding weight excess on the basis of the total weight estimated by the total weight estimation part 92; a warning signal generation part 94 outputting a warning instruction on the basis of a decision result of the weight excess decision part 93; and an output interface 95 connected with warning equipment 8 (a warning light 81 and a warning buzzer 82). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle wheel used for overloading and overload monitoring and a vehicle load monitoring device.

  The steering stability of an automobile greatly depends on the internal pressure (tire pressure) of a tire air chamber, which is a contact point with a road surface, in addition to the structure of a suspension device and a steering device. For example, in a tire whose tire air pressure has decreased, a decrease in rigidity, an increase in contact area, and an increase in contact length are unavoidable, so that the ability to follow steering is significantly reduced. In addition, a decrease in tire air pressure can cause tire temperature rise and standing wave during high-speed driving, as well as deterioration of driving fuel consumption, so it must be strictly prevented from the viewpoint of stability and economy. is there. Conventionally, automobile drivers and operation managers often check and manage tire pressures using an air charger (air gauge) such as a gas station.

  By the way, a decrease in tire air pressure also occurs when a tread is perforated by stepping on a nail or a glass piece while the tire is running, but in a tubeless tire in recent years, between a tire bead and a wheel rim. There is a large proportion of slow leaks where air gradually leaks. In the slow leak, the deterioration of the steering stability progresses very slowly, so that it is difficult for the driver to notice the decrease in the tire air pressure early while driving.

  Therefore, in order to monitor the decrease in tire pressure during driving, a pneumatic sensor consisting of a strain gauge, transmitter, battery, etc. is attached to each wheel, and the radio signal output from this pneumatic sensor is received by the receiving antenna on the vehicle side. A tire pressure monitoring device (TPMS: Tire Pressure Monitoring System) that detects tire pressure and air temperature has been proposed (for example, see Patent Document 1). Also, using the detected value of the wheel speed sensor provided for ABS (anti-lock brake system) etc., the tire vibration frequency with respect to the value at normal air pressure stored in ROM etc. according to the vehicle speed range There has been proposed a tire pressure monitoring device that determines a decrease in tire pressure when the peak value of the spectrum decreases or shifts (moves on the frequency axis) (see, for example, Patent Document 2). Further, in order to reduce product cost and improve performance, the method of Patent Document 1 (hereinafter referred to as a sensor method) and the method of Patent Document 2 (hereinafter referred to as an ABS method) are combined, for example, an air pressure sensor. There has also been proposed a hybrid type tire pressure monitoring apparatus that includes only one or two wheels.

On the other hand, in large trucks and the like, overloading of cargo exceeding a specified amount is normally performed on the loading platform, and road damage and rear-end collisions resulting from this are problematic. As a device for preventing and controlling overloading, there is known a shaft weight measuring device that measures each axle weight of a vehicle with a loading plate and a load cell, and calculates the total weight by adding the measured axle weights. (For example, see Patent Document 3).
Japanese Patent Laid-Open No. 2003-291615 (paragraphs 0011 to 0014, FIG. 1) Japanese Patent No. 2836652 (Claim 1, FIG. 4) Japanese Patent Laying-Open No. 2002-90214 (paragraph 0019, FIG. 1)

However, since the tire pressure monitoring device warns the driver based only on the tire pressure (tire pressure and air temperature in Patent Document 1), the tire load factor can be accurately determined. There wasn't.
As is well known, the weight of a vehicle body, an occupant, and a load acts on a tire of an automobile as a load, and as the load increases, the amount of deformation and heat generation of the tire during high-speed traveling and the like increase. The maximum load (limit load) that can suppress the deformation and heat generation of the tire within an allowable range varies depending on the value of the tire air pressure, and the deformation of the sidewall and the tread is reduced. The load factor is a value obtained by dividing an actual load by a limit load, and is usually set to about 70 to 80% in an automobile in consideration of handling stability, ride comfort, and the like. However, in the conventional tire pressure monitoring device, the load acting on the tire is not detected, so a warning of a decrease in tire air pressure must be given on the assumption that a large load acts, and a light load that reduces the load factor There was a problem that sometimes unnecessary warnings were made. When the load factor exceeds 100% due to overloading, there may be a problem due to tire deformation or heat generation even if the amount of decrease in tire air pressure is outside the warning range.

  Of the tire pressure monitoring devices described above, in the case of the sensor type, if the air pressure sensor falls off in the wheel due to excessive impact or the like, the inner surface of the tire may be damaged by the air pressure sensor that moves around in the tire. In the ABS system, the tire pressure is not directly detected, so that it is more difficult to give a warning according to the tire load. In the hybrid system, the same problem as in the ABS system occurs when the number of pneumatic sensors is reduced.

  On the other hand, the axle load measuring device has a loading plate that is larger than the vehicle width of a large truck as a constituent member, so it is large and heavy, requiring many days and costs for manufacturing, and can be installed. The facility was also limited. Also, with this axle load measuring device, it was not possible to measure the weight when loading earth and sand into a dump truck at the construction site.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a wheel provided with a load sensor and a vehicle load monitoring device capable of warning for overloading and overloading. .

A vehicle wheel according to the invention of claim 1 is provided with a wheel disc attached to a hub of a vehicle, a rim that is provided on an outer peripheral side of the wheel disc, a tire is mounted, and an air chamber is formed with the tire, A load sensor that is attached to a mounting portion of the tire in the rim and detects a load applied to the tire from the rim is provided.
In the vehicle wheel according to the first aspect, for example, the tire load of each wheel of a four-wheeled vehicle is detected by each load sensor.

A vehicle wheel according to a second aspect of the present invention is the vehicle wheel according to the first aspect, wherein an air pressure sensor attached to the rim for detecting an internal pressure of the air chamber and transmitting a detection result to the outside is provided. Further, the detection result of the load sensor is transmitted to the outside by the air pressure sensor.
In the vehicle wheel according to the second aspect, the detection result of the load sensor and the detection result of the air pressure sensor are transmitted from the transmitting means of the air pressure sensor and received by the antenna on the vehicle body side.

According to a third aspect of the present invention, in the vehicle wheel according to the first or second aspect, the load sensor is a pressure-sensitive conductive elastomer sensor.
In the vehicle wheel according to the second aspect, when a load is applied from the rim to the tire, the pressure-sensitive conductive elastomer sensor bends according to the load and changes its electric resistance and impedance.

A vehicle wheel according to a fourth aspect of the present invention is the vehicle wheel according to any one of the first to third aspects, wherein the load sensor has an annular shape.
In the vehicle wheel according to the fourth aspect, a part of the load sensor bends regardless of the rotation position of the tire.

A vehicle wheel according to a fifth aspect of the present invention is the vehicle wheel according to any one of the first to fourth aspects, wherein the load sensor is mechanically coupled to the air pressure sensor. It is characterized by.
In the vehicle wheel according to the fifth aspect, the air pressure sensor is held not only by the wheel but also by a load sensor.

A load monitoring device for a vehicle according to a sixth aspect of the invention is a load detection unit that is mounted on each wheel of the vehicle, detects a load applied to the tire, and transmits the detection result to the outside.
A receiving means provided on a body of the vehicle for receiving a detection result of the load detecting means;
Warning means for warning the driver based on the detection result of the load detection means is provided.

  In the vehicle load monitoring apparatus according to claim 6, for example, when the receiving means receives the tire load of each wheel detected by each load detecting means, and the sum of these tire loads exceeds a predetermined value, the vehicle is overweight. The determination means determines that the total vehicle load is excessive, and the warning means that receives the determination result issues a visual warning or an audible warning to the driver.

A vehicle load monitoring apparatus according to a seventh aspect of the invention is the vehicle load monitoring apparatus according to the sixth aspect, wherein the vehicle load monitoring apparatus detects an air pressure of a tire provided on each wheel of the vehicle and attached to the wheel, An air pressure sensor for transmitting the detection result to the outside is further provided, and the detection result of the load detecting means is transmitted to the outside by the air pressure sensor.
In the vehicle load monitoring apparatus according to the seventh aspect, the detection result of the load detection means and the detection result of the air pressure sensor are transmitted from the transmission means of the air pressure sensor and received by the antenna on the vehicle body side.

  A load monitoring device for a vehicle according to an invention of claim 8 is provided on each wheel of the vehicle, detects the air pressure of a tire mounted on the wheel, and transmits the detection result to the outside, A receiving means provided on a vehicle body for receiving a detection result of the air pressure sensor; a load detecting means for detecting a load applied to the tire; a detection result of the air pressure sensor; and a detection result of the load detecting means; The load factor estimating means for estimating the load factor of the tire, and the load factor of the tire is excessive when the load factor estimated by the load factor estimating means is equal to or greater than a predetermined overload determination threshold. An overload determining unit for determining and a warning unit for performing a warning based on a determination result of the overload determining unit are provided.

  In the vehicle load monitoring apparatus according to claim 8, for example, the receiving means receives the tire air pressure and the tire internal temperature detected by the air pressure sensor and the tire load detected by the load detecting means, and these tire air pressure, tire internal temperature and The load factor estimating means estimates the tire load factor from the tire load, and when this load factor exceeds a predetermined value, the overload determining means determines that the tire load factor is excessive, and the determination result is The received warning means issues a visual warning or an audible warning to the driver or the like.

A vehicle load monitoring apparatus according to a ninth aspect of the present invention is the vehicle load monitoring apparatus according to any one of the sixth to eighth aspects, wherein the load detecting means includes the wheel and the tire. It is a pressure-sensitive conductive elastomer sensor interposed therebetween.
In the vehicle load monitoring device according to claim 9, when a load is applied from the rim to the tire, the pressure-sensitive conductive elastomer sensor bends in accordance with the load, so that the electric resistance and impedance of the pressure-sensitive conductive elastomer sensor are reduced. Change.

  According to the vehicle wheel of the first aspect, for example, since the tire load can be detected by the single wheel, the total weight of the vehicle can be confirmed at any time even at a construction site or the like. Further, according to the vehicle wheel of the second aspect, it is not necessary to provide an independent transmission means for the load sensor, and the configuration can be simplified and the manufacturing cost can be reduced. According to the vehicle wheel of the third aspect, since the shape of the load sensor and the degree of freedom of installation are high, it is easy to use existing wheels and tires. According to the vehicle wheel of the fourth aspect, the load is detected regardless of the rotational position of the tire. In addition, according to the vehicle wheel of the fifth aspect, it is difficult for the air pressure sensor to drop off from the wheel. According to the vehicle load monitoring apparatus of the sixth aspect, for example, the driver can recognize that the total vehicle weight set for the vehicle has been exceeded, thereby ensuring the safety of the operation. According to the vehicle load monitoring apparatus of the seventh aspect, it is not necessary to provide an independent transmission means for the load sensor, and the configuration can be simplified and the manufacturing cost can be reduced. Further, according to the vehicle load monitoring apparatus of the eighth aspect, since the warning means gives a warning according to the tire load factor, an excessive warning is given at a light load or a warning is given at an overload. There is nothing missing. According to the vehicle load monitoring apparatus of the ninth aspect, the shape and the degree of freedom of installation of the load sensor are high, and it becomes easy to use existing wheels and tires.

  Hereinafter, two embodiments of a vehicle load monitoring apparatus according to the present invention will be described. Both the vehicle load monitoring devices of both embodiments are provided with a tire pressure sensor (hereinafter referred to as a pneumatic sensor unit) and a load sensor (hereinafter referred to as a load sensor unit) attached to each wheel of a four-wheeled vehicle. The tire pressure is detected by the load sensor unit while the tire load is detected by the load sensor unit. And the thing of 1st Embodiment estimates a vehicle gross weight from the detection result etc. of each load sensor unit, and warns a driver | operator when this vehicle gross weight exceeds the overweight determination threshold value. In the second embodiment, the limit load is estimated from the detection result of the air pressure sensor unit, and the estimated load obtained from the detection result of the load sensor unit is divided by the limit load to estimate the load factor. A warning is given to the driver when the load factor is equal to or greater than the overload determination threshold.

<< First Embodiment >>
FIG. 1 is a plan view showing the configuration of a vehicle according to the first embodiment, FIG. 2 is a block diagram showing the configuration of the monitoring device main body according to the first embodiment, and FIG. 3 is related to the first embodiment. FIG. 4 is a perspective view showing a wheel, and FIG. 4 is an enlarged sectional view of a part A in FIG.

<Vehicle device configuration>
First, with reference to FIG. 1, the apparatus structure of the vehicle which concerns on 1st Embodiment is demonstrated. In the description, the four wheels and the members arranged corresponding thereto, that is, the tire, the air pressure sensor unit, the load sensor unit, and the antenna are collectively referred to by numerals, and the individual members are arranged. According to the installation position, identification is performed by using subscripts of fl (front left), fr (front right), rl (back left) rr (back right). Moreover, when naming generically, it describes as "wheel 3", for example, and when describing each member, it describes as "wheel 3fr", for example.

  As shown in FIG. 1, a vehicle (passenger car in this embodiment) 1 includes four wheels 3 on which tires 2 are mounted, and each wheel 3 is a pneumatic sensor unit that measures tire air pressure and tire internal temperature. 4 and a load sensor unit (load detection means) 5 for detecting a tire load are mounted. The air pressure sensor unit 4 and the load sensor unit 5 are electrically and mechanically connected, and the tire pressure and tire temperature detection signals and the tire load detection signals are output from the air pressure sensor unit 4 as radio signals. .

  In the vehicle 1, four vehicle body side antennas (receiving means) 6 are installed in the vicinity of each wheel 3, and an in-vehicle ECU (Electronic Control Unit) 7 and a warning device 8 (a warning light 81 and a warning buzzer 82) are installed in the vehicle interior. (Warning means) is installed. The in-vehicle ECU 7 includes a microcomputer, a ROM, a RAM, a peripheral circuit, an input / output interface, various drivers, and the like, and the vehicle-side antenna 6 and the like are connected via a communication line (CAN (Controller Area Network) in this embodiment). A warning device 8 is connected. In the case of the first embodiment, the warning device 8 is shared by a warning when the tire air pressure decreases and a warning when overloading or overloading. The warning lamp 81 has a total of four lamps on the front, rear, left and right sides thereof, and can indicate the position of the tire 2 where the tire air pressure has decreased.

<Configuration of monitoring device body>
Next, with reference to FIG. 2, the structure of the monitoring apparatus main body which concerns on 1st Embodiment incorporated in vehicle-mounted ECU7 is demonstrated.
The monitoring apparatus body 9 of the first embodiment includes an input interface 91 to which the vehicle body side antenna 6 is connected, a total weight estimation unit 92 that estimates a total weight based on an input signal from the input interface 91, and a total weight estimation unit 92. An overweight determination unit 93 that performs an overweight determination based on the estimated total weight, a warning signal generation unit 94 that outputs a warning command based on the determination result of the overweight determination unit 93, and a warning device 8 (a warning light 81 and a warning buzzer) 82) is connected to the output interface 95 to be connected.

<Configuration of wheel>
Next, the configuration of the wheel will be described with reference to FIGS. The wheel 3 is a die-cast molded product (so-called aluminum wheel) made of an aluminum alloy, and as shown in FIG. 3, a wheel disk 31 attached to a hub (not shown) of the vehicle, The rim 32 is formed on the outer peripheral side. In addition to the tire 2, a pneumatic sensor unit 4 and a load sensor unit 5 are attached to the rim 32 of the present embodiment.

  As shown in FIG. 4 (enlarged cross-sectional view of part A in FIG. 3), the rim 32 is formed with an annular wall 33 that forms the air chamber 21 together with the tire 2 on the outer periphery, while facing the wheel disc 31 side. Thus, a valve hole 34 is formed. A tire valve 41 integrated with the air pressure sensor unit 4 is fitted into the valve hole 34, and the tire valve 41 is fastened to the rim 32 by a nut 49. Reference numeral 22 in FIG. 4 indicates a bead of the tire 2 that is fitted to the rim 32.

  As shown in FIG. 5, the air pressure sensor unit 4 corresponds to a CPU (Central Processing Unit) 42, a pressure sensor 43 that generates an output corresponding to the tire air pressure, and a tire internal temperature (temperature in the air chamber 21). And a temperature sensor 44 for generating an output. Outputs from the pressure sensor 43 and the temperature sensor 44 are converted into digital values via an A / D (Analog / Digital) conversion circuit (not shown) and input to the CPU 42.

  The air pressure sensor unit 4 includes a power source (lithium battery or the like) 45, and this power source 45 functions as an operating source for the CPU 42 and the like. The air pressure sensor unit 4 includes a sensor-side antenna 46 having a transmission / reception function, and receives an activation signal and a control signal transmitted from the in-vehicle ECU 7 (see FIG. 1) via the sensor-side antenna 46, The detection signals of the pressure sensor 43 and the temperature sensor 44 are transmitted to the in-vehicle ECU 7 (see FIG. 1) via the vehicle body side antenna 6 (see FIG. 1). In FIG. 5, a member denoted by reference numeral 48 is a connector attached to the air pressure sensor unit 4, and a CPU 42 (signal SIG), a power supply 45 (Vcc), and a ground (GND) are connected to the connector 48.

  For example, a 315 MHz PCM (Pulse Code Modulation) digital radio wave signal is transmitted from the sensor-side antenna 46 of the air pressure sensor unit 4. Although not shown, a voltage sensor is provided in the power supply circuit between the power supply 45 and the CPU 42 and outputs a signal corresponding to the output voltage of the power supply 45. The output of the voltage sensor is also A / D converted and input to the CPU 42.

  On the other hand, the load sensor unit 5 shown in FIGS. 3 and 4 is a pressure-sensitive conductive elastomer sensor in which conductive particles are blended with an elastic body (in this embodiment, rubber), and the rubber is deformed by the load. Thus, a path of conductive particles is generated inside, and the volume resistance is thereby changed. The load sensor unit 5 is formed in an annular shape as shown in FIG. 6 and is externally fitted and fastened to the rim 32 by its elasticity as shown in FIGS. You may make it fix firmly. The load sensor unit 5 is formed with a connector 51 on the inner side (left side in FIG. 6), and this connector 51 is coupled to the connector 48 formed on the air pressure sensor unit 4.

  As shown in FIG. 7, the connector 51 is formed with terminals for the power supply voltage Vcc, the ground GND, and the signal SIG, and is coupled to the connector 48 of the air pressure sensor unit 4 so that the air pressure sensor unit 4 and the load sensor unit are connected. While power is supplied to 5, a tire load detection signal is sent from the load sensor unit 5 to the air pressure sensor unit 4. The connectors 51 and 48 may be connected by insertion, but may be fastened by fastening means such as a screw in order to achieve a strong connection.

<Operation of First Embodiment>
When the driver turns on the ignition key of the vehicle 1, the pressure sensor 43 detects the tire air pressure P and the temperature sensor 44 detects the tire temperature T in the air pressure sensor unit 4 at a predetermined detection interval. To do. Further, as shown in FIG. 8, the load sensor unit 5 generates a load detection voltage (hereinafter referred to as detection voltage) VF corresponding to the actual load Fwr applied from the wheel 3 to the tire 2, and this detection voltage VF Is transmitted to the air pressure sensor unit 4. The tire pressure P, the tire internal temperature T, and the detection voltage VF are transmitted at a predetermined transmission interval from the sensor side antenna 46 (see FIG. 5) of the air pressure sensor unit 4, and the vehicle body side antenna 6 (see FIGS. 1 and 2). And input to a RAM (not shown) in the monitoring apparatus main body 9 (see FIG. 2).

  In the case of the present embodiment, the in-vehicle ECU 7 performs air drop determination based on the tire air pressure P and the tire internal temperature T detected by the air pressure sensor unit 4. FIG. 9 is a graph showing the relationship between the tire air pressure P and the tire internal temperature T. As the tire internal temperature T increases and decreases as shown in the figure, the tire air pressure P also increases and decreases linearly. The tire air pressure P at the reference temperature To is obtained by multiplying the corresponding coefficient (performing temperature correction). The vehicle-mounted ECU 7 turns on a warning lamp 81 provided on an instrument panel or the like and sounds a warning buzzer 82 when there is a tire 2 in which the tire air pressure P is lower than the air pressure reduction determination threshold (see FIG. 2). .

  On the other hand, the monitoring device main body 9 executes the total weight monitoring control shown in the flowchart of FIG. 10 at a predetermined control interval (for example, 10 milliseconds).

  When the gross weight monitoring control is started, the monitoring device main body 9 determines whether or not the vehicle 1 is stopped in step S1 of FIG. 10, and if this determination is No, after jumping to RETURN, the monitoring device 9 Return and repeat control. This is because when the vehicle 1 is running, the detection voltage VF of the load sensor unit 5 increases or decreases each time the tire 2 steps over the road surface unevenness and the like, and accurate total weight monitoring control cannot be performed. Here, the determination in step S1 may be performed based on the detection result of a vehicle speed sensor (not shown). If the detection voltage VF is corrected according to the traveling speed or acceleration / deceleration, the total weight monitoring control is performed on the condition that the vehicle 1 is traveling at a constant speed, traveling straight, and on a flat road. It is possible.

  If the vehicle 1 is in a stopped state and the determination in step S1 is Yes, the monitoring apparatus main body 9 has received a detection voltage VF (VFfl, VFfr, VFrl, VFrr) of each wheel after stopping in step S2. It is determined whether or not, and if this determination is No, after jumping to RETURN, returning to START, the control is repeated.

When determination of step S2 becomes Yes, the monitoring apparatus main body 9 estimates the tire load Fw of each wheel from the detection voltage VF input into RAM at step S3.
<Estimation of tire load>
Hereinafter, an estimation procedure of the tire load Fw will be described.
As shown in FIG. 8, an actual load Fwr is applied to the load sensor unit 5 from the wheel 3, while a tire air pressure P is applied from the tire 2 in a direction opposite to the actual load Fwr. Therefore, the pressure applied to the load sensor unit 5 is a value obtained by subtracting the tire air pressure P from the actual load Fwr. In the case of this embodiment, the tire pressure P and the tire load Fw are variously tested, and a detection voltage VF-tire load Fw map shown as an example in FIG. 11 is created and stored in the ROM in advance. deep.

  When the tire pressure P and the tire internal temperature T are input, the monitoring device main body 9 performs the above-described temperature correction on the tire pressure P, and from the detected voltage VF and the temperature corrected tire pressure P, 11, the tire load Fw is estimated based on the detected voltage VF-tire load Fw map.

  When the estimation of the tire load Fw of each wheel is completed, the monitoring device body 9 adds the tire load Fw of each wheel and estimates the total weight Wg of the vehicle 1 in step S4. Thereafter, in step S5, the monitoring apparatus main body 9 determines whether or not the estimated total weight Wg is equal to or greater than the excess weight determination threshold value Wgth. If this determination is No, after jumping to RETURN, the monitoring apparatus 9 enters START. Return and repeat control.

  When the total weight Wg reaches the excess weight determination threshold Wgth and the determination in step S5 is Yes, the monitoring device main body 9 generates a warning signal and outputs it to the warning device 8 in step S6. In the case of the present embodiment, the warning device 8 that has received the warning command issues a warning to the driver that the total weight has been exceeded. For example, all four lamps of the warning lamp 81 are turned on, while the warning buzzer 82 sounds.

  As a result, the driver can quickly recognize overloading and cancel overloading by lowering a part of the load. In order to prevent overloading in advance, the monitoring device main body 9 blinks the warning lamp 81 when the total weight Wg does not reach overloading (for example, when it reaches 90% of the overweight determination threshold Wgth). The warning buzzer 82 may be intermittently sounded intermittently.

<< Second Embodiment >>
The vehicle load monitoring apparatus according to the second embodiment will be described below.
FIG. 12 is a block diagram illustrating a configuration of a monitoring apparatus main body according to the second embodiment. In the second embodiment, the device configuration of the vehicle, the configuration of the wheel, and the like are the same as those of the first embodiment, but only the configuration of the monitoring device main body built in the in-vehicle ECU is different.

<Configuration of monitoring device body>
First, with reference to FIG. 12, the structure of the monitoring apparatus main body which concerns on 2nd Embodiment is demonstrated.
The monitoring apparatus main body 100 according to the second embodiment includes an input interface 101 to which the vehicle body side antenna 6 is connected, a load factor estimation unit 102 that estimates a load factor based on an input signal from the input interface 101, and a load factor estimation unit 102. Overload determination unit 103 that performs overload determination based on the estimated load factor, warning signal generation unit 104 that outputs a warning command based on the determination result of overload determination unit 103, and warning device 8 (warning lamp 81 and warning buzzer) 82) is connected to the output interface 105 to be connected.

<Operation of Second Embodiment>
When the driver turns on the ignition key of the vehicle 1, the pressure sensor 43 detects the tire air pressure P and the temperature sensor 44 detects the tire temperature T in the air pressure sensor unit 4 at a predetermined detection interval. To do. Further, as shown in FIG. 8, the load sensor unit 5 generates a load detection voltage (hereinafter referred to as detection voltage) VF corresponding to the actual load Fwr applied from the wheel 3 to the tire 2, and this detection voltage VF Is transmitted to the air pressure sensor unit 4. The tire pressure P, the tire internal temperature T, and the detection voltage VF are transmitted at a predetermined transmission interval from the sensor side antenna 46 (see FIG. 5) of the air pressure sensor unit 4, and the vehicle body side antenna 6 (see FIGS. 1 and 2). And input to a RAM (not shown) in the monitoring apparatus main body 100 (see FIG. 2).

  In the case of the present embodiment, the in-vehicle ECU 7 performs the air drop determination similarly to the first embodiment based on the tire air pressure P and the tire internal temperature T detected by the air pressure sensor unit 4, and the tire air pressure P is determined from the air pressure drop determination threshold value. When there is a tire that has been lowered, the warning lamp 81 provided on the instrument panel or the like is turned on and the warning buzzer 82 is sounded.

  On the other hand, the monitoring apparatus main body 100 executes the overload monitoring control shown in the flowchart of FIG. 13 at a predetermined control interval (for example, 10 milliseconds).

  When the overload monitoring control is started, the monitoring apparatus main body 100 determines whether or not the vehicle 1 is stopped in step S11. If this determination is No, after jumping to RETURN, the control returns to START. repeat. This is because when the vehicle 1 is running, the detection voltage VF of the load sensor unit 5 increases or decreases each time the tire 2 steps over the road surface unevenness and the like, and accurate load factor monitoring control cannot be performed. Here, the determination in step S11 may be performed based on the detection result of a vehicle speed sensor (not shown). If the detection voltage VF is corrected according to the traveling speed or acceleration / deceleration, the total weight monitoring control is performed on the condition that the vehicle 1 is traveling at a constant speed, traveling straight, and on a flat road. It is possible.

  If the vehicle 1 is in a stopped state and the determination in step S11 is Yes, the monitoring apparatus main body 100 has input the detection voltage VF (VFfl, VFfr, VFrl, VFrr) of each wheel after stopping in step S12. It is determined whether or not, and if this determination is No, after jumping to RETURN, returning to START, the control is repeated.

When determination of step S12 becomes Yes, the monitoring apparatus main body 100 estimates the tire load Fw of each wheel from the detection voltage VF input into RAM at step S13.
<Estimation of tire load estimation>
Hereinafter, an estimation procedure of the tire load Fw will be described.
As shown in FIG. 8, an actual load Fwr is applied to the load sensor unit 5 from the wheel 3, while a tire air pressure P is applied from the tire 2 in a direction opposite to the actual load Fwr. Therefore, the pressure applied to the load sensor unit 5 is a value obtained by subtracting the tire air pressure P from the actual load Fwr. In the case of the present embodiment, the test is performed by variously changing the tire pressure P and the tire load Fw, and a detection voltage VF-tire load Fw map shown in FIG. 14 as an example is created and stored in the ROM in advance. deep.

  When the tire air pressure P and the tire internal temperature T are input, the monitoring apparatus main body 100 performs the above-described temperature correction on the tire air pressure P, and from the detected voltage VF and the temperature air pressure P after the temperature correction, 11, the tire load Fw is estimated based on the detected voltage VF-tire load Fw map.

  When the estimation of the tire load Fw of each wheel is completed, the monitoring apparatus main body 100 performs overload determination based on the overload determination map of FIG. 14 from the tire load Fw and the temperature-corrected tire pressure P in step S14. If this determination is No, after jumping to RETURN, returning to START, the control is repeated. The overload determination map of FIG. 14 obtains a limit load that does not cause damage to the tire by experiments or the like, and for example, an area exceeding 95% of this limit load (indicated by hatching in FIG. 14) is a warning zone. . As can be seen from FIG. 14, the tire load increases as the tire air pressure decreases and the tire load Fw increases.

  When the tire load Fw of a certain tire 2 is excessive or the tire air pressure P is excessive, and the determination in step S14 is Yes, the monitoring apparatus main body 100 generates a warning signal and outputs it to the warning device 8 in step S15. . In the case of this embodiment, the warning device 8 that has received the warning command issues a warning to the driver that the tire is overloaded. For example, in the warning lamp 81, a lamp corresponding to the tire 2 that is overloaded blinks, while other lamps are lit, and the warning buzzer 82 sounds intermittently.

  As a result, the driver can eliminate the overload by increasing the tire air pressure of the overloaded tire 2 or lowering a part of the load.

  This is the end of the description of specific embodiments. However, aspects of the present invention are not limited to these embodiments. For example, in the first embodiment, the total vehicle weight estimated from the tire load or the like is compared with an overweight determination threshold value to give a warning. For example, the tire load is digitally displayed for each wheel. You may do it. In the above embodiment, the annular pressure-sensitive conductive elastomer sensor is externally fitted to the rim of the wheel. However, in order to facilitate manufacturing, the plate-shaped pressure-sensitive conductive elastomer sensor is attached to the wheel. The rim may be wound in a C shape and then connected to the air pressure sensor unit. As the load sensor, a strain gauge or the like other than the pressure-sensitive conductive elastomer sensor may be used, or a load sensor interposed between the vehicle body and the suspension may be used. In the above embodiment, a warning light or a warning buzzer is used as a warning means. However, a voice warning device or the like may be used. In addition, the specific configuration of the vehicle and the load monitoring device, the specific procedure of the control, and the like can be changed as appropriate without departing from the spirit of the present invention.

It is a top view which shows the apparatus structure of the vehicle which concerns on 1st Embodiment. It is a block diagram which shows the structure of the monitoring apparatus main body which concerns on 1st Embodiment. It is a perspective view which shows the wheel which concerns on 1st, 2nd embodiment. FIG. 4 is an enlarged cross-sectional view of a part A in FIG. 3. It is a circuit block diagram of an air pressure sensor. It is a perspective view of a load sensor unit. It is a figure which shows the connection part of a load sensor unit and an air pressure sensor unit. It is explanatory drawing which shows the relationship etc. of a tire load and a tire air pressure. It is a graph which shows the relationship between tire air pressure and tire internal temperature. It is a flowchart which shows the procedure of the gross weight monitoring control which concerns on 1st Embodiment. It is a graph which shows the relationship between a detection voltage and a tire load. It is a block diagram which shows the structure of the monitoring apparatus main body which concerns on 2nd Embodiment. It is a flowchart which shows the procedure of the overload monitoring control which concerns on 2nd Embodiment. It is an overload determination map concerning a 2nd embodiment.

Explanation of symbols

1 Vehicle 2 Tire 3 Wheel 4 Air Pressure Sensor Unit (Pneumatic Sensor)
5 Load sensor unit (load sensor, load detection means)
6 Vehicle side antenna (receiving means)
7 In-vehicle ECU
8 Warning devices (Warning means)
9 Monitoring device body 21 Air chamber 31 Wheel disc 32 Rim 81 Warning light (warning means)
82 Warning buzzer (Warning means)
100 Monitoring device body

Claims (9)

A wheel disc attached to the hub of the vehicle;
A rim that is provided on the outer peripheral side of the wheel disc, is mounted with a tire, and forms an air chamber with the tire; and
A vehicle wheel comprising: a load sensor that is attached to a mounting portion of the tire in the rim and detects a load applied to the tire from the rim. An air pressure sensor attached to the rim, further detecting an internal pressure of the air chamber and transmitting a detection result to the outside;
The vehicle wheel according to claim 1, wherein a detection result of the load sensor is transmitted to the outside by the air pressure sensor.   The vehicle wheel according to claim 1, wherein the load sensor is a pressure-sensitive conductive elastomer sensor.   The vehicle wheel according to any one of claims 1 to 3, wherein the load sensor has an annular shape.   The vehicle wheel according to any one of claims 1 to 4, wherein the load sensor is mechanically coupled to the air pressure sensor. Load detecting means mounted on each wheel of the vehicle, detecting a load applied to the tire, and transmitting the detection result to the outside;
A receiving means provided on a body of the vehicle for receiving a detection result of the load detecting means;
A vehicle load monitoring apparatus, comprising: warning means for giving a warning to a driver based on a detection result of the load detection means. Provided in each wheel of the vehicle, further comprising an air pressure sensor for detecting the air pressure of a tire mounted on the wheel and transmitting the detection result to the outside,
The vehicle load monitoring apparatus according to claim 6, wherein a detection result of the load detection means is transmitted to the outside by the air pressure sensor. An air pressure sensor that is provided on each wheel of the vehicle, detects the air pressure of a tire mounted on the wheel, and transmits the detection result to the outside;
Receiving means provided on a body of the vehicle for receiving a detection result of the air pressure sensor;
Load detecting means for detecting a load applied to the tire;
Load factor estimation means for estimating the load factor of the tire based on the detection result of the air pressure sensor and the detection result of the load detection means;
An overload determination unit that determines that the load factor of the tire is excessive when the load factor estimated by the load factor estimation unit is equal to or greater than a predetermined overload determination threshold;
A vehicle load monitoring apparatus comprising: warning means for giving a warning to a driver based on the determination result of the overload determination means.   The vehicle load according to any one of claims 6 to 8, wherein the load detecting means is a pressure-sensitive conductive elastomer sensor interposed between the wheel and the tire. Monitoring device.

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