JPH0472723B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a device for detecting a decrease in air pressure of a tire mounted on a vehicle such as a motorcycle.

BACKGROUND ART As an example of such a device, an automobile tire air pressure abnormality warning device disclosed in Japanese Patent Application Laid-Open No. 52-40383 is known. The device described in the publication includes a permanent magnet attached to a wheel, a coil attached to a supporting member such as a knuckle arm that supports the wheel, and a generator configured by the permanent magnet and coil, which is installed at each wheel of a vehicle. An alarm switch closes when there is an imbalance in the amount of power generated by the generators, and it detects that there is a tire with low air pressure due to the imbalance in the amount of power generated by each generator, and alerts the user. A warning will be sent to passengers.

However, with the above-mentioned conventional device, even if the tire air pressure has not decreased, the air pressure is adjusted when there is a difference in the rotational speed of each wheel due to the inner wheel difference that occurs between the front and rear wheels while the vehicle is turning. It may be mistakenly detected as having a tire with a low temperature.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, it is an object of the present invention to provide a tire air pressure drop detection device that can accurately detect a drop in tire air pressure while preventing erroneous detection.

In order to achieve the above-mentioned object, the tire air pressure drop detection device according to the present invention generates rotation speed data representing the constant speed straight-ahead state of the vehicle and the rotation speed of each wheel of the vehicle, and The present invention is characterized in that the rotational speed data is corrected and a tire air pressure drop signal is generated based on the corrected rotational speed data in a constant speed straight-ahead state.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a motorcycle equipped with a tire air pressure drop detection device according to the present invention. In this motorcycle, front suspension stroke sensors (hereinafter referred to as F suspension
It is abbreviated as stroke sensor. ) 3 and a rear suspension stroke sensor (hereinafter abbreviated as R suspension stroke sensor) 4.
These stroke sensors 3 and 4 are cylindrical members 3a attached to the bottom case 5 of the front fork or the swing arm 6 of the rear suspension.
and rod-like members 3b and 4b, which are attached to the fork pipe 7 of the front fork or the frame pipe 8 below the seat and inserted into the cylindrical members 3a and 4a, are provided with sliding resistance in the rod-shaped members 4a. It is constructed by providing a slider that slides while maintaining contact with the slider, and the resistance value of the sliding resistance is detected as the amount of buffer stroke of the suspension.

Furthermore, as shown in FIG. 2, a steering angle sensor 11 is disposed on a bottom bridge 10 that constitutes the steering system of the motorcycle. The steering angle sensor 11 is composed of a potentiometer housed in a cylindrical case 11a, and the cylindrical case 11a is located at the lower end of a pivot shaft 10a of a bottom bridge 10 rotatably supported on a head pipe 12 of the vehicle body frame. The cylindrical case 1 is tightly fitted into the fitting hole 13 provided in the cylindrical case 1.
The cylindrical case 11a rotates together with the bottom bridge 10 when the protrusion 11b formed on the bottom bridge 1a engages with the notch 13a of the fitting hole 13. On the other hand, a cylindrical case 11a carrying the slider of the potentiometer
The rotating shaft 11c, which is rotatable relative to the frame, has two planes parallel to each other at its tip, and is fitted into a long hole formed in a positioning plate 15 that is attached to the frame from below. 11c
Rotation relative to the frame is restricted. Therefore, when the bottom bridge 10 is rotated by operating the handle, a relative rotation occurs between the cylindrical case 11a and the rotating shaft 11c, and the amount of rotation is obtained as the resistance value of the potentiometer. .

The suspension stroke sensor 3 mentioned above,
4 and the steering angle sensor 11, the motorcycle also includes an engine speed sensor 16 that detects the speed of the vehicle engine, a gear position sensor 17 that detects the gear position of the transmission, and a clutch that detects the engagement/disengagement state of the clutch. Sensor 18, front wheel rotation speed sensor 19 that detects the rotation speed of the front wheels
is provided.

As shown in Figure 3, the output signals emitted by each of these sensors are
is supplied to a microcomputer consisting of: The microcomputer controls the ignition timing of the in-vehicle engine according to a pre-stored program described below based on the supplied sensor output signal, and also determines whether the tire pressures of the front wheels 1 and rear wheels 2 are decreasing. and generates a tire pressure drop signal. In response to this tire air pressure drop signal, current is supplied from the drive circuit 25 to display means such as an indicator lamp 26 disposed on the instrument panel along with instruments such as a vehicle speedometer, thereby displaying that the tire air pressure is dropping. It's becoming like that.

Next, the operation of the microcomputer will be explained according to the flowchart shown in FIG.
The program shown as a flowchart in FIG. 4 is executed in response to a clock pulse signal generated at predetermined intervals by a fixed-cycle clock source built into the CPU 21. In this program, first, the rotational speed N _F of the front wheel 1 is acquired from the front wheel rotational speed sensor 19 (step S ₁ ), and it is determined whether or not N _F =0 (step S ₂ ). Here, if N _F = 0, it is determined that the motorcycle is in a stopped state, and the buffer stroke amount S _R of the rear suspension is read from the R suspension and stroke sensor 4 (step S ₃ ).
It is determined whether _STR is greater than a predetermined value K _O (step S ₄ ). If S _R is larger than the predetermined value K _O , it is determined that two people are on board or luggage is loaded, and a flag indicating this is set to 1 (step
_S5 ). Conversely, if _STR is smaller than the predetermined value _KO , the flag is reset to 0 (step _S6 ).

In (step S ₂ ), if N _F =0, the disengaged state of the clutch is determined using the output signal from the clutch sensor 18 (step S 2 ).
_S7 ). If it is determined that the clutch is in the connected state, the gear position G _P of the transmission is read from the gear position sensor 17 (step S ₈ ), and the steering angle θ _ST is read from the steering angle sensor 11 (step S ₉ ). Next, it is determined whether or not the steering angle θ _ST is within a predetermined range (±ε).
_S10 ), determines whether the motorcycle is traveling straight or not. That is, when θ _ST is within a predetermined range, it is determined that the motorcycle is traveling straight, and conversely, when θ _ST is outside the predetermined range, it is determined that the motorcycle is not traveling straight. When θ _ST is within the specified range and it is determined that the vehicle is traveling straight,
Buffer stroke amount of rear suspension and front suspension from R suspension stroke sensor 4 and F suspension stroke sensor 3, respectively.
Import ST _R and _{ST F} (step S ₁₁ ), and
It is determined whether the difference from _STR is greater than a predetermined value _K1 (step _S12 ). By making this determination, it is possible to determine whether the motorcycle is running at a constant speed or not. That is, during sudden acceleration, the distributed load on the rear wheels increases and the distributed load on the front wheels decreases, so _STR increases and _STF decreases. Therefore, the difference between _STF and _STR increases and becomes larger than the predetermined value _K1 . Furthermore, during sudden deceleration, the front and rear wheel distribution loads are reversed, and in this case as well, the difference between _STF and _STR increases and becomes larger than the predetermined value _K1 . Therefore, in step _S12 , if |ST _F −ST _{R |} > K ₁ , it is determined that the vehicle is running at a constant speed, and if |ST _F −ST _R | It is determined that the vehicle is in a deceleration state. In addition, if flag F is set to 1, taking into account the sinking of the rear suspension when two people are riding or when loading luggage, the value of ST _R or ST _F taken in step _S11 is corrected. It is preferable to make the judgment in step _S12 by adding . Furthermore, it is also possible to provide an acceleration sensor in the motorcycle and determine whether or not the motorcycle is running at a constant speed based on the output signal of the acceleration sensor.

In step _S12 , if it is determined that the vehicle is running at a constant speed, the engine speed sensor 16
Get the engine speed Ne from (step _S13 ),
The rotational speed Ne of the rear wheels is calculated from this Ne and the gear position _GP taken in step _S8 (step _S14 ). Note that this rear wheel rotation speed N _R can also be obtained by searching a map according to Ne and _GP based on a map stored in advance.

Next, it is determined whether a flag F indicating that two people are on board or luggage is loaded is set to 1 (step _S15 ), and if F=1, the rear wheel rotation speed N _R is determined. Or, multiply the front wheel rotation speed N _F by the correction coefficient C _R or C _F to calculate the new rear wheel rotation speed.
Determine N _R or front wheel rotation speed N _F (step
_S16 ). By correcting N _R or N _F in this way, the effective tire radius (dynamic load radius) of the rear wheels decreases due to two people riding or loaded with luggage, and the rear wheel rotation speed increases compared to when one person rides. It is necessary to compensate for the amount that is lost.

Next, if F=1 in step _S15 , the corrected N _F and N _R are determined in step _S16 .
It is determined _{whether or not the ratio} of
If it is not 1, it is determined whether the ratio between _NF taken in step _S1 and _NR found in step _S14 is within a predetermined range (step _S17 ). Here, the ratio of N _F and N _R is N _F /N _R
If the value is not within the predetermined range, it is determined that the tire pressure of the front or rear wheels has decreased, and furthermore, whether the indicator lamp 26 indicating that the tire pressure has decreased is already lit or not. If the display lamp 26 is not lit yet, it outputs a tire pressure reduction signal to _the drive circuit 25, and the drive circuit 25
to turn on the indicator lamp 26 (step
_S19 ), and then drives the timer after resetting it (step _S20 ).

If the indicator lamp 26 is on in step _S18 , it is determined in step _S20 whether the elapsed time T after the timer is activated, which is indicated by the timer activated, exceeds a predetermined time _K4 . (Step _S21 ) If the predetermined time _K4 has elapsed, it is determined that the reduced tire pressure has continued for more than the predetermined time, and the microcomputer triggers the ignition system 30 based on another program. The ignition is cut off by preventing the generation of the ignition signal to be outputted for the purpose of the ignition (step _S22 ).

If N _F /N _R is within the predetermined range in step _S17 , it is determined that there is no decrease in tire pressure, and if the indicator lamp 26 is on, it is turned off (step _S23 ). The timer driven in step _S20 is stopped (step _S24 ).

Furthermore, if it is determined in step _S7 that the clutch is disengaged, if it is determined in step _S10 that the motorcycle is not in a straight-ahead state, or if it is determined in step _S12 that the motorcycle is not in a constant speed traveling state, In this case, steps _S13 to _S24 are not executed, and therefore, it is not determined whether the tire air pressure has decreased. This means that if the clutch is disengaged, it will not be possible to obtain the correct value for the rear wheel rotation speed N _R , and if the motorcycle is not traveling straight, the rotation speed of the front and rear wheels will vary due to the difference between the inner wheels. If the motorcycle is not running at a constant speed, the effective radius of the front and rear wheels will change due to changes in the distributed load on the front and rear wheels, and this will spread the change in the rotational speed of the front and rear wheels, causing a change in tire air pressure. This is because it is not possible to obtain the rotational speeds N _F and N _R of the front and rear wheels that are effective for accurately detecting a decrease.

In the above embodiment, it is determined whether or not the tire pressure has decreased depending on whether the ratio of rotational speeds of the front and rear wheels N _F /N _R is within a predetermined range. Buffer stroke amount of suspension and rear suspension ST _F , ST _R
and the rotational speed of the front and rear wheels _NF , _NR is ST _F ,
When _STR increases, the effective radius of the tires of the front and rear wheels decreases, and N _F and N _R increase in a proportional relationship, and the following equation (C is a proportionality constant) holds, so (N _F /N _R ) =C×(ST _F /ST _R ) Depending on whether or not the value obtained by multiplying N _F by ST _R and the value obtained by multiplying N _R by ST _F are within a predetermined range that includes the proportionality constant C, the tire air pressure is determined. It is also possible to judge whether or not it has decreased. In this case, it is possible to make a highly accurate determination that also takes into consideration the buffer stroke amount of the suspension.

In this embodiment, the case where the present invention is applied to a motorcycle has been described as an example, but the present invention can also be applied to a four-wheeled vehicle. When applied to a four-wheeled vehicle, by combining the comparison of the rotation speeds of the front and rear wheels and the left and right wheels, it becomes possible to specifically identify which tire's air pressure is decreasing.

Effects of the Invention As explained above, the tire air pressure drop detection device according to the present invention generates rotation speed data representing the constant speed straight-ahead state of the vehicle and the rotation speed of each wheel of the vehicle, and further generates rotation speed data representing the constant speed straight-ahead state of the vehicle and the number of revolutions of each wheel of the vehicle. The system corrects the rotational speed data accordingly and generates a tire pressure drop signal based on the corrected rotational speed data when the vehicle is running straight at a constant speed, so when the vehicle turns and an inner wheel difference occurs between the front and rear wheels. As a result, even if there is a difference in rotational speed between the two wheels, this will not be mistakenly detected as a decrease in tire air pressure, and a decrease in tire air pressure can be accurately detected regardless of riding or loading conditions.

[Brief explanation of the drawing]

Fig. 1 is a side view of a motorcycle to which the present invention is applied, Fig. 2 is a diagram showing a steering angle sensor attached to the motorcycle shown in Fig. 1, and Fig. 3 is a block diagram of an embodiment of the device of the present invention. FIG. 4 is a flowchart showing the operation of the apparatus according to the embodiment of the present invention. Explanation of symbols of main parts, 3...Front suspension stroke sensor, 4...Rear suspension stroke sensor, 11...Steering angle sensor, 16...Engine speed sensor, 17...Gear position sensor, 18... ...clutch sensor,
19...Front wheel rotation speed sensor, 21...CPU,
26...Display lamp, 30...Ignition system.

Claims (1)

[Claims] 1 Constant speed running state detection means for detecting that the vehicle is in a constant speed running state, straight running state detection means for detecting that the vehicle is in a straight running state, and riding state detection means for detecting the riding or loading state. a wheel rotation speed detection means for generating rotation speed data of each wheel of the vehicle; a correction means for correcting the rotation data according to a detection result by the riding state detection means; A tire air pressure drop detection device comprising a tire air pressure drop signal generating means for generating a tire air pressure drop signal based on the rotation speed and data passed through the correction means at a certain time.