JPH0717131B2 - Device for displaying the condition of car tires - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a device for displaying the condition of a tire of a vehicle, more specifically, a rotation speed sensor arranged on a wheel and a signal from the rotation speed sensor. The present invention relates to a device for displaying the condition of a tire of a vehicle, which includes a reference speed generator that forms a reference speed and a comparator that compares a reference speed with a signal from a rotation speed sensor.

(B) Conventional technology Conventionally, a device for continuously monitoring the tire pressure of a vehicle has been known, and in this device, the rotation speed of a vehicle wheel is monitored and compared with a reference speed. In this case, when the tire pressure is rapidly reduced, it is recognized that there is a deviation in the number of revolutions, and the warning device is activated. Such a device is described, for example, in DE-A 2518816, in which the arithmetic mean of the wheel speeds is used as the reference speed.

However, although such a device can detect a sudden change in the tire condition, particularly the tire pressure, these changes are caused by long-term changes, for example, changes caused by increased abrasion of the tire. It has the disadvantage that it cannot be detected if it happens to each wheel as well.

Furthermore, DE 2813058 describes a method in which an anti-skidding device provided in a vehicle is used to detect a sudden pressure drop in a tire. For this reason, the mechanical tire pressure detector provided on the wheel magnetically short-circuits the troughs of the gear-type rotation speed sensor, resulting in a large delay that cannot be recognized by the anti-skidding device. To be done. A state that can be distinguished from this physically possible delayed value is detected and processed in the processing circuit.

Therefore, the conventional device has a drawback that it can detect only the pressure decrease occurring in each tire.

(C) Purpose Accordingly, the present invention eliminates such conventional drawbacks, and is a tire for a vehicle capable of inexpensively and reliably identifying a tire abnormality in which the pressure of each tire suddenly decreases. It is an object of the present invention to provide a device for displaying the state of.

According to the invention, in order to achieve this object, a rotation speed sensor arranged on each of the associated wheels for measuring the rotation speed of the wheel and associated with each wheel for comparing the signal of each rotation speed sensor with a reference speed In a device for displaying the state of a vehicle tire, which is provided with a comparator provided with, a signal from a brake switch, an accelerator pedal switch and a steering angle sensor is received, and the brake pedal and the accelerator pedal are not operated and the steering wheel is A logic circuit that generates a signal by identifying an uncut straight running state, and a reference speed generator that is driven in response to a signal from the logic circuit and forms an average value of the signals of the respective rotation speed sensors as a reference speed. And a memory for updating and storing the average value formed by the reference speed generator in response to the signal from the logic circuit. A configuration is adopted in which the signal of each rotation speed sensor and the average value stored in the memory are divided by the vehicle speed and compared in each of the comparators.

Further, in the present invention, instead of the above average value, the minimum value of the signal of each rotation speed sensor is used as the reference speed.

D) Embodiments The present invention will be described in detail below with reference to embodiments shown in the drawings.

In FIG. 1, the reference numeral 10.11 is the rear wheel of the automobile, and 12.13 is the non-driving front wheel. The rear wheels 10.11 are driven by an engine (not shown) via a differential gear. On the other hand, front wheel 12.13 is steering wheel 1.
Steered by 5. Brake device 1 for each wheel 10-13
6 to 19 are arranged and each braking device is actuated by a braking control device 20, which preferably comprises an anti-skidding device (anti-locking device). The brake control device 20 further receives a signal from the brake pedal 21. Furthermore, each wheel 10 to 13 has a rotation speed sensor that measures the rotation speed of the wheel.
22 to 25 are attached, and the signal from each rotation speed sensor is input to the electronic control unit 26. This electronic control unit 26
Is connected to the brake control device 20 via a data line 27. In the embodiment shown in FIG. 1, a signal from the brake pedal 21 is further input to the electronic control unit 26, and a signal obtained from the steering angle sensor 28 is also input.

In the embodiment shown in FIG. 1, the electronic control unit 26 controls the wheels 10 to 13 respectively.
Can identify the tire condition. That is, wheel 10 ~
The rotational speed of 13 is processed by the electronic control unit 26 via the sensors 22 to 25 and compared with the reference speed. The generation of the reference speed will be explained later with reference to FIG. In that case, the reference speed is measured when the traveling state reaches a predetermined state. The predetermined traveling state is a state in which the vehicle is running immediately, and the vehicle is traveling in a state where the propulsion is not received by the brake either. Therefore, various rotational speeds generated when traveling on a curve, wheel slips when the vehicle is accelerated, wheel slips when the brake is applied, etc. are excluded from the formation of the reference speed.

A reference speed generator 29 is shown in FIG. 2, the output signal of which is supplied to a memory 31.52 via a switch 30. The output of the memory 31.52 is input via the switching switch 51 to the input terminals of the comparators 32 to 35 which generate outputs to the displays 36 to 39. The reference speed former 29 is controlled by the output of an AND gate having 5 input terminals. A first input terminal of the AND gate is connected to an automatically or manually operated switch 41 and a memory 42, and a second input
The input terminals of are the brake switch 43 and the inverter 44.
The third input terminal has a steering angle sensor 28 and a zero detector 46 connected to the subsequent stage, and the fourth input terminal has an accelerator pedal sensor 47 and a zero detector connected to the subsequent stage.
48 and the fifth input terminal are connected to another device 46, respectively. As another input amount, the vehicle speed V _F is determined via the vehicle sensor 45, and the value is input to the memory 31.52 and one input terminal of each comparator 32 to 35. Further, the signals from the rotation speed sensors 22 to 25 are input to the reference speed forming unit 29 and also connected to the other input terminals of the comparators 32 to 35.

Next, the operation of the configuration shown in FIG. 2 will be described.

The running state of the vehicle is identified when the vehicle runs straight on without being subjected to propulsion or braking. Therefore, the brake pedal 21 is not operated via the brake switch 43 and the inverter 44, the steering wheel 15 is not operated via the steering angle sensor 28, and the zero detector 46, and the accelerator pedal is not operated. It is checked via switch 47 and the zero detector that the accelerator pedal is not actuated. Therefore, when the output of 44.46.48 gives a positive logic signal, various rotation speeds due to curve running, rotation when the output is too large and the wheel turns from the wheel or the wheel slips when the brake is applied. It can be seen that the vehicle is in a running state where the number does not occur. Also, via another device 49, it may be removed from the reference speed formation via the device 49 if the reference speed formation becomes inaccurate, for example when the vehicle load is uneven. can do.

When the driver wants to calibrate the reference speed generator 29, he operates the switch 41 to set the memory 42. Then, when the running state as described above occurs, the AND gate 40 is turned on, and the reference speed forming unit 29 forms the reference speed based on the value obtained in the running state. The switch 41 is then performed manually as indicated by the dotted arrow, but it is also possible to operate the switch 41 automatically. That is, the switch 41 may be automatically inserted at each predetermined time or each predetermined output interval at the start of each traveling or according to a predetermined standard. In any case, the calibration of the reference speed forming unit 29 is performed when the above-mentioned predetermined traveling state is brought about by setting the memory 42.

The reference speed forming unit 29 obtains the reference speed based on the signals from the rotation speed sensors 22 to 25. In that case, the average value of the signal from the rotation speed sensor is formed, but the value of the minimum rotation speed may be obtained as the value that most closely approximates the desired running state. It is also possible to set a reference speed for each wheel. If switch 30.51 is in the position shown in FIG. 2, the value in memory 31 is used. As described above, when the memory 42 is set and a predetermined traveling state appears, the AND gate 40 becomes conductive. In this case, various vehicle speeds can be considered, and it is necessary to normalize the rotation speed of the wheels in accordance with each vehicle speed. That is, the quotient of wheel rotation speed / vehicle speed must be obtained. Memory for this
The vehicle speed signal VF from the vehicle speed detector 45 is input to one input terminal of each of the comparators 31 and 52 and each of the comparators 32 to 35. By the lead wires from the vehicle speed detector 45 to the memories 31, 52, the reference speeds stored in the memories 31, 52 are normalized, that is, divided by the vehicle speed VF. By each lead wire to each comparator,
It is schematically shown that the wheel rotation speeds from the respective rotation speed sensors 22 to 25, which are input to the respective comparators, are divided by the vehicle speed VF (the division circuits are not shown). The reference speed thus normalized is input to one of the input terminals of the comparators 32 to 35, where it is compared with the similarly normalized rotation speed signal of each wheel. Since the wheel rotation speed is proportional to the vehicle speed and inversely proportional to the tire diameter, the reference speed and each wheel rotation speed signal are divided by the vehicle speed to remove the influence of the vehicle speed and to obtain a signal related to the tire diameter. Will be compared. If the tire condition changes in a short time, for example when the tire pressure suddenly decreases, the wheel speed changes rapidly, which drives the display device via the associated comparator. For example, if the reference speed is the average value of the signals from each wheel speed sensor, if the pressure in one tire suddenly decreases, the increase in the signal from the speed sensor associated with that tire will be:
Since it becomes larger than the increase of the average value, it is possible to identify the abnormality of the tire by setting the threshold value of the comparator to a predetermined value. Similarly, if the reference speed is set to the minimum value of the signal from each wheel speed sensor, when the pressure of one tire suddenly decreases, the signal from the speed sensor associated with that tire changes to the other speed. Since it is larger than the several sensor signals (ideally the values corresponding to the respective minimum values), it is possible to similarly identify the abnormality of the tire. On the other hand, at least another memory 52 is provided in order to be able to monitor the tire condition as it fluctuates over time. Since data can be stored in the memory 52 when, for example, a new tire is replaced, the rotation speed of the wheel can be compared with the value when the new tire is replaced by switching the switch 30.51. As a result, it is possible to monitor changes in tire abrasion and unevenness over a long period of time.

In a vehicle equipped with an anti-skidding device (anti-lock device), various elements used therein, such as a rotation speed sensor and a sensor for detecting operation of a brake pedal, can be used. When the anti-skidding device is a so-called three-channel anti-skidding device and commonly detects both wheels of the rear axle (when a sensor is provided in the differential gear), one wheel speed deviation is detected. A coefficient of 2 is used for weighting. This is because half of the wheel speed deviations act on the propeller shaft.

In this way, the latest value is always stored in the memory 31,
A "learning" system is provided so that different amounts of air can be added to the tires to compensate for non-uniformity, and memory 52
With the provision of, and, if necessary, further memory, it is possible to monitor the tire over a long period of time.

As described above, according to the present invention, since a learning system can be obtained, it is possible to detect a state change that suddenly occurs in each tire and also to generate a variation that appears evenly in each wheel over a long period of time. It can be reliably detected. Further, by such learning, it becomes possible to eliminate the non-uniformity caused by the non-uniform inflating method when inflating the tire at the time of detection.

Further, by controlling this learning system through a logic circuit, the traveling state when traveling straight without propelling or braking, that is, when traveling on a curve, when the wheel idles at the time of starting, or when slipping by braking is performed. It becomes possible to accurately detect a running state in which the tire does not fluctuate due to the running state.

By storing various reference speed values, it becomes possible to observe the condition of the tire at various times. For example, when a new tire is loaded, the reference value can be stored, so that the wear of the tire can be observed over a long period of time, and when the limit value is exceeded, it can be displayed. .

If the vehicle is equipped with an anti-skidding device, various elements used in this anti-skidding device can be used. If the anti-skidding device is of the so-called three-channel system, the rotational speeds of both wheels provided on the drive shaft are measured together and the signal is weighted correspondingly to compensate and process. You can

(E) Effect As described above, according to the present invention, the reference speed (the average value of the rotation speed sensor signals or the minimum value thereof) used for comparison of the respective rotation speed sensor signals of the wheels is the rotation speed sensor of each wheel. The reference speed is corrected every moment (so-called learning) because it is calculated and supplied to the memory and updated and stored there. Therefore, when the tire is replaced, the tire is re-inflated, or the temperature changes. Even if the diameters are different, the latest reference speed can be obtained without the need to input the tire diameter again, and the tire condition can be monitored more accurately.

Further, in the present invention, the signal of each rotation speed sensor and the reference speed stored in the memory are respectively divided by the vehicle speed and compared by the comparator, so that the tire condition can be monitored regardless of the vehicle speed.

Further, in the present invention, since the reference speed is formed only from each rotation speed sensor that is originally necessary, another sensor is not required to form the reference speed, and the entire configuration can be simplified. Various effects can be obtained.

[Brief description of drawings]

Each drawing shows an embodiment of the present invention. FIG. 1 is a block diagram for explaining the principle of the present invention, and FIG. 2 is a block diagram for explaining the signal processing system in more detail. 10.11 ... Rear wheel, 12.13 ... Front wheel 14 ... Differential gear 15 ... Steering wheel 16-19 ... Brake device, 20 ... Brake control device 21 ... Brake pedal, 22-25 ... Rotation speed sensor 26 ... Electronic control device, 28 … Steering angle sensor 29… Reference speed generator, 31, 52… Memories 36 to 39… Display

Claims (6)

[Claims] 1. A rotation speed sensor (22-25) for measuring the rotation speed of a wheel, which is arranged on each of the associated wheels (10-13),
A device for displaying the state of a tire of a vehicle, which is provided with a comparator (32 to 35) provided in association with each wheel for comparing the signal of each rotation speed sensor and a reference speed, including a brake switch, an accelerator pedal switch, and A logic circuit (40) for receiving a signal from the steering angle sensor to generate a signal by identifying a straight running state in which the brake pedal and the accelerator pedal are not operated and the steering wheel is not cut, and a signal from the logic circuit. A reference speed former (29) which is driven in response to a signal from each speed sensor to form an average value as a reference speed, and the average formed by the reference speed former in response to a signal from the logic circuit. Memory for updating and storing values (3
1) is provided, and the signal of each rotation speed sensor and the average value stored in the memory are respectively divided by the vehicle speed (VF) and compared in each of the comparators to display the tire condition of the vehicle. Device to do. 2. A vehicle is provided with an anti-skidding device, and the rotational speed sensor and the brake switch include a rotational speed sensor of the anti-skidding device and a sensor for detecting a brake pedal operation. A device for displaying the condition of the tire of the vehicle according to item 1. 3. The vehicle tire according to claim 1, wherein a vehicle speed sensor (45) for detecting a vehicle speed on the ground is used to detect the vehicle speed. A device that displays status. 4. A rotation speed sensor (22-25) arranged on each of the associated wheels (10-13) for measuring the rotation speed of the wheel,
A device for displaying the state of a tire of a vehicle, which is provided with a comparator (32 to 35) provided in association with each wheel for comparing the signal of each rotation speed sensor and a reference speed, including a brake switch, an accelerator pedal switch, and A logic circuit (40) for receiving a signal from the steering angle sensor to generate a signal by identifying a straight running state in which the brake pedal and the accelerator pedal are not operated and the steering wheel is not cut, and a signal from the logic circuit. A reference speed former (29) which is driven in response to a signal from each speed sensor to form a minimum value of the signal as a reference speed, and the minimum speed formed by the reference speed former in response to a signal from the logic circuit. Memory for updating and storing values (3
1) is provided, and the signal of each rotation speed sensor and the minimum value stored in the memory are respectively divided by the vehicle speed (VF) and compared in each comparator to display the tire condition of the vehicle. Device to do. 5. A vehicle is provided with an anti-skidding device, and a rotation speed sensor of the anti-skidding device and a sensor for detecting a brake pedal operation are used as the rotation speed sensor and the brake switch. A device for displaying the condition of the tire of the vehicle according to item 4. 6. A vehicle tire according to claim 4 or 5, wherein a vehicle speed sensor (45) for detecting a vehicle speed on the ground is used to detect the vehicle speed. A device that displays status.