Patent Application
20240010199
The present disclosure relates to a vehicle speed control system.
There is known a vehicle behavior control device that detects a state of a tire and controls the traveling of a vehicle (see, for example, Japanese Patent No. 4466386).
In this vehicle behavior control device, control that reduces the speed of the vehicle is carried out in a case in which a run-flat tire enters into a run-flat state.
By the way, due to traveling, the rubber that structures a pneumatic tire deforms repeatedly and generates heat. The amount of heat that is generated also becomes great at a region where the deformation (strain, stress) of the rubber is great. If the temperature of the rubber becomes excessively high, there are cases in which the vicious cycle of the rubber softening, tire deformation increasing, and the tire temperature rising arises. Therefore, if traveling is continued in a state in which the temperature of the rubber has become high, the rubber will ultimately be destroyed, and traveling of the vehicle will become difficult, and there are cases in which the vehicle will not be able to travel to its destination.
In the prior art, although it is possible to reduce the speed of the vehicle at the time when a tire is punctured, consideration is not given to the generation of heat at the tire. Therefore, there is the possibility that traveling will be continued in a state in which the rubber of the tire has become an excessively high temperature, and ultimately, the tire breaking down can be imagined.
Further, in the prior art, there are cases in which the speed of the vehicle is reduced excessively in order to control the behavior of the vehicle, and there is also the possibility that the traveling time to the destination will be extended.
In order to suppress destruction of the rubber, the generation of heat of the rubber must be suppressed. Further, if the speed can be raised in a range in which the generation of heat at the rubber can be suppressed such that the aforementioned vicious cycle does not occur, it is possible to reach the destination without causing breakdown of the tire, and the traveling time to the destination can be shortened.
In consideration of the above-described circumstances, an object of the present disclosure is to provide a vehicle speed control system that takes tire temperature into consideration and can shorten the traveling time to a destination without causing the tire to break down.
A vehicle speed control system relating to a first aspect comprises: a thermometer measuring a temperature of a tire; and a control device controlling a speed of a vehicle based on a measured temperature of the tire obtained by the thermometer.
In the vehicle speed control system relating to the first aspect, the thermometer can measure the temperature of the tire.
The control device can control the speed of the vehicle based on the measured temperature of the tire obtained by the thermometer.
Due to traveling, the elastic body such as rubber or the like that structures the tire elastically deforms and generates heat, and the temperature thereof rises. If the temperature of the rubber rises excessively, the rubber softens. If the rubber softens, there are cases in which this results in the vicious cycle of tire deformation increasing and moreover the temperature of the rubber rising. Further, if the temperature of the rubber rises excessively, there are cases in which the rubber deteriorates or the rubber is destroyed, which leads to a deterioration in the durability of the tire.
In the vehicle speed control system relating to the first aspect, the control device controls the speed of the vehicle on the basis of the measured temperature of the tire and suppresses generation of heat of the rubber, so that the above-described vicious cycle does not arise. By suppressing generation of heat of the rubber in this way, the aforementioned vicious cycle is suppressed, the speed can be raised within a range in which the tire does not break down, and it is possible shorten the traveling time to the destination without causing the tire to break down.
As described above, in accordance with the vehicle speed control system of the present disclosure, the temperature of a tire is taken into consideration, and the traveling time to a destination can be shortened without the causing the tire to break down.
A vehicle 36, to which a vehicle speed control system 8 relating to a first embodiment of the present disclosure is applied, is described by using
As illustrated in
The pneumatic tire 14 of the present embodiment has a carcass 18 that spans in a toroidal form over a pair of bead portions 16. The carcass 18 of the present embodiment is structured from a single carcass ply 18P in which plural cords are lined-up parallel to one another and coated with rubber.
In the present embodiment, a belt 20, which is formed from two belt plies that are a first belt ply 20A and a second belt ply 20B, is disposed at the tire radial direction outer side of the carcass 18.
Note that the end portions of the belt 20 are covered by belt reinforcing layers 22.
A tread rubber layer 24 is disposed at the tire radial direction outer side of the belt 20. Further, side rubber layers 26 are disposed at the tire axial direction outer sides of the carcass 18.
The end portions of the carcass ply 18P are wound upwardly on bead cores 28 of the bead portions 16 toward the tire radial direction outer side.
Here, the portion, which extends from the one bead core 28 to the another bead core 28 of the carcass ply 18P, is main body portion 18A. The portions that are wound upward and extend from the bead cores 28 toward the tire radial direction outer side are upwardly-wound portions 18B. Bead fillers 30, which are formed from a rubber of a high hardness and which extend from the bead cores 28 toward the tire radial direction outer side, are disposed between the main body portion 18A and the upwardly-wound portions 18B of the carcass ply 18P.
A thermometer 32 and a transmitter 34 are mounted to the outer peripheral portion of the rim 12A. The thermometer 32 is, as an example, a non-contact-type infrared thermometer.
As illustrated in
A control device 40 that controls the output of an engine 36B is provided at the vehicle body 36A.
The schematic structure of the control device 40 that can be made to function as a vehicle speed control device as an example is illustrated in
The control device 40 is structured by a computer that includes a CPU 40A that is an example of a hardware processor, a RAM 40B, a ROM 40C, an I/O 40D and the like. The CPU 40A, the RAM 40B, the ROM 40C and the I/O 40D are connected to a bus 40E that can transmit and receive data and commands. Further, a computing program 40F is stored in the ROM 40C.
Further, the engine (fuel injection device) 36B, the receiver 38, a display device 42, a warning lamp 50, and the like are connected to an I/O 42D.
The measured temperature data that is transmitted by the transmitter 34 is sent to the control device 40 via the receiver 38. Note that the display device 42 is provided at the instrument panel of the vehicle 36, and various types of information relating to the vehicle 36 can be displayed on the display device 42.
Upper limit temperature T1 of the pneumatic tire 14, lower limit pressure P1 of the pneumatic tire 14, upper limit temperature T2 at the time of reduced internal pressure, and the like are stored in advance in the ROM 40C of the control device 40.
At the control device 40, the CPU 40A reads-out the computing program 40F stored in the ROM 40C, and expands the computing program 40F in the RAM 40B, and the expanded computing program 40F is executed.
(Operation, Effects)
Speed control at the vehicle speed control system 8 of the present embodiment is described next on the basis of the flowchart shown in
By executing speed limiting in this way, the bead portions 16 becoming high temperature, and the rubber of the bead fillers 30 softening and deteriorating, can be suppressed, and the durability of the bead portions 16 can be ensured.
Note that, in order to inform the driver that speed limiting is carried out, in step 104, a warning by characters or the like may be displayed on the display device 42, or the warning lamp 50 may be turned on.
In this way, by using the vehicle speed control system 8 of the present embodiment, at the time of traveling of the pneumatic tire 14, generation of heat of the bead portions 16 can be suppressed, the vehicle 36 can be made to travel fast within a range that does not cause breakdown of the bead portions 16, the traveling time to the destination can be shortened, and the vehicle 36 can go to the destination quickly.
Note that, in the present embodiment, the temperature of the bead portion 16 is measured, and speed limiting is executed in a case in which the temperature of the bead portion 16 exceeds the upper limit temperature T1 that is set in advance. However, speed limiting may be executed in a case in which the temperature of a region other than the bead portion 16 is measured, and the measured temperature of the region exceeds the upper limit temperature T1 that is set in advance.
In the present embodiment, the temperature of the bead portion 16 at the vehicle outer side is measured, but the temperature of the bead portion 16 at the vehicle inner side may be measured, or the temperatures of the bead portions 16 at both the vehicle outer side and the vehicle inner side may be measured.
A region where it is easy for the rubber to generate heat, or in other words, a region where the strain during traveling is large, for example, the cord end portions (vicinities of the belt ends), the tire maximum width portion, and the like are regions other than the bead portion 16.
For example, in vicinities of the cord end portions of the carcass or the belt, there are portions having and portions not having cords that have a higher Young's modulus than the rubber, and these are portions where the rigidity as a structural body varies sharply and regions where large stress and strain arise when traveling. It is easy for a rise in temperature to occur at such portions where there is large strain. Therefore, by measuring the temperature at such a portion and controlling the traveling speed by using this as a reference, the vicious cycle can be prevented more, and breakdown of the pneumatic tire 14 can be suppressed.
Further, in a case of traveling at high speed in a state in which excessive load is applied to the pneumatic tire 14, there are cases in which the tread rubber layer 24 generates heat excessively. In cases in which such a situation is envisaged, the temperature at the tread inner surface side may be measured.
Note that, in the vehicle speed control system 8 of the present embodiment, the place where the temperature of the pneumatic tire 14 is measured is not limited to one place, and may be plural places. Further, as needed, the upper limit temperature T1 can be made to differ per region of the pneumatic tire 14.
The vehicle speed control system 8 relating to a second embodiment of the present disclosure is described next in accordance with
As illustrated in
In addition to the thermometer 32, a pressure gauge 46 that measures the internal pressure of the tire is provided at the rim 12A. The measured pressure data that is measured by the pressure gauge 46 is transmitted from the transmitter 34 to the receiver 38. Note that the pressure gauge 46 may be mounted to the air valve of the rim 12A.
In the present embodiment, the control device 40 controls the speed of the vehicle 36 on the basis of measured temperature data and measured pressure data. A program
Speed control at the vehicle speed control system 8 of the present embodiment is described next on the basis of the flowchart illustrated in
Note that a case in which the internal pressure becomes less than the lower limit pressure P1 that is set in advance is, as an example, a case in which there is a puncture of the pneumatic tire 14.
By executing speed limiting at the time of run-flat traveling in this way, the side reinforcing rubbers 44 becoming high temperature, the rubbers thereof softening and deteriorating, the side reinforcing rubbers 44 no longer being able to exhibit their original functions, and traveling becoming impossible due to destruction of the rubbers can be suppressed. Due thereto, the traveling distance at the time of running on a flat can be extended.
Further, in order to inform the driver that speed limiting due to a decrease in internal pressure is carried out, in step 208, a warning by characters or the like may be displayed on the display device 42, or the warning lamp 50 may be turned on.
Note that, in order to inform the driver that speed limiting has been cancelled, in step 212, the fact that the speed limiting has been cancelled may be displayed by characters or the like on the display device 42. However, the warning that the internal pressure has decreased is continued.
In this way, by using the vehicle speed control system 8 of the present embodiment, at the time of run-flat traveling on the run-flat tire 15, generation of heat of the side reinforcing rubbers 44 is suppressed, the vehicle 36 can be made to travel fast within a range that does not cause breakdown of the run-flat tire 15, the traveling time to the destination can be shortened, and the vehicle 36 can go to the destination quickly.
Note that estimation of the run-flat traveling distance in accordance with an ISO run-flat test was carried out by assuming usage of a side-reinforced-type run-flat tire (tire size: 225/45RF17).
It is assumed that a temperature sensor is affixed to the tire innermost surface side of the portion that juts out furthest toward the outer side in the tire width direction, and that the measured temperature data is transmitted by using a wireless device mounted to the rim wheel, and that measurement can be carried out at an external device, and, under the premise of measuring the traveling distance on a drum tester, the traveling distance at a speed of 80 km/h until traveling becomes impossible is predicted.
Running is carried out for one hour at a speed of 80 km/h under ISO testing conditions (ISO 16992: 2018) that are the certification criterion for run-flat tires. Estimation of the extent to which the traveling distance is extended when speed limiting is carried out as in the present embodiment on the basis of these test standards, is described hereinafter.
Estimation is carried out under the assumption that, after running at 80 km/h, at the point in time when the results of temperature measurement become 140° C., the speed is lowered to and running is continued.
First, at the drum tester, the test tire is made to run at 80 km/h, and running is continued until the temperature becomes 140° C. In a case in which the running time at the time when the temperature reaches 140° C. is 0.5 h, the traveling distance is 80 km/h×0.5 h=km.
Thereafter, if running is carried out with the speed lowered to 40 km/h that is half of 80 km/h, the generation of heat is halved, and therefore, predicting of the traveling distance is carried out by estimating that the traveling distance is 2 times that.
Accordingly, assuming that, after running for 0.5 h at 80 km/h, traveling for 1 h at 40 km/h is possible, the traveling distance is 40 km+40 km/h×1 h=120 km, and it can easily be predicted that the traveling distance can be extended by carrying out speed limiting.
Although two embodiments of the present disclosure have been described above, the present disclosure is not limited to the above, and can, of course, be implemented by being modified in various ways other than the above, within a scope that does not depart from the gist thereof.
For example, at the run-flat tire 15, control that combines the control of the first embodiment and the control of the second embodiment may be carried out.
Further, the vehicle to which the present disclosure can be applied is not limited to a passenger vehicle, and may be a bus, a truck, construction equipment, a motorcycle, a vehicle of a new transportation system or the like, and can be applied to all vehicles that use pneumatic tires.
In the second embodiment, the pneumatic tire is the side-reinforced-type run-flat tire but the present disclosure can be applied also to a run-flat tire using a core. In a run-flat tire that uses a core, at the time of run-flat traveling, there are cases in which the outer peripheral surface of the core contacts the tire inner peripheral surface of the tire width direction central portion of the tread, and the tread generates heat. Therefore, the generation of heat at the region that contacts the core can be suppressed by measuring the temperature of the tread inner surface of that tire and carrying out speed control.
In the above-described embodiments, the non-contact-type thermometer 32 is mounted to the rim 12A, but the non-contact-type thermometer 32 may be mounted to the vehicle body 36A (the wheel house, the suspension or the like) and may measure the tire temperature from the tire outer side.
In the above-described embodiments, an infrared thermometer is used as the thermometer 32 in order to measure the temperature of the pneumatic tire 14 or the run-flat tire 15, without contact. However, a contact-type thermometer may be mounted to the tire inner surface and the tire temperature measured.
The vehicle speed control systems 8 of the above-described embodiments can also be applied to autonomous vehicles in which the vehicle 36 can be driven automatically. By incorporating the vehicle speed control system 8 into an autonomous vehicle, in a case in which the tire temperature or internal pressure or the like becomes abnormal, the traveling speed of the autonomous vehicle is lowered automatically, and the autonomous vehicle can be made to travel safely.
The vehicle speed control systems 8 of the present disclosure are not limited to vehicles that travel on public roads, and can also be applied to vehicles for racing or the like that make hard use of tires. Due thereto, for example, a tire breaking down and the vehicle becoming unable to travel in the middle of the course can be suppressed, and the vehicle can be made to travel to the pit.
Note that the above embodiments describe examples of suppressing breakdown of the pneumatic tire 14 and the run-flat tire 15 that use rubber as an elastic body, but the vehicle speed control systems 8 of the present embodiments can also suppress breakdown of pneumatic tires that use a thermoplastic elastomer as the elastic body.
In the above-described embodiments, a puncture (decrease in internal pressure) is sensed by directly measuring the internal pressure of the pneumatic tire 14 by the pressure gauge 46. However, the decrease in internal pressure of the pneumatic tire 14 is not limited to being measured directly by the pressure gauge 46, and can also be sensed indirectly by the change in the number of rotations of the pneumatic tire 14 (comparison with the other tires) or the like. The decrease in the internal pressure of the pneumatic tire 14 can be sensed by a known, indirect-type TPMS (tire pressure monitoring system).
The disclosure of Japanese Patent Application No. 2020-176887 filed on Oct. 21, 2020 is, in its entirety, incorporated by reference into the present specification.
All publications, patent applications, and technical standards mentioned in the present specification are incorporated by reference into the present specification to the same extent as if such individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-176887 | Oct 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/025027 | 7/1/2021 | WO |
