JP2734682B2 - Tire pressure control method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a tire pressure control method for controlling the increase and decrease of tire air pressure while a vehicle is running.

(Prior art and its problems) Conventionally, a sensor for detecting the remaining fuel amount in a fuel tank is provided, and when the remaining fuel amount in the tank becomes equal to or less than a predetermined value, a warning light of a dash panel is turned on or an alarm sound is emitted. A system that warns the driver of running out of fuel by issuing a warning or the like is widely used in vehicles. However, the conventional out-of-fuel warning system only issues a warning to the driver and does not automatically control the driving state of the vehicle.

For example, when driving at midnight or driving on a highway,
Even if an out-of-fuel warning is issued, it is necessary to travel a long distance to the nearest gas station, and depending on the driver's driving technique, the vehicle runs out of fuel before reaching the nearest gas station and cannot run. May occur. In such a case, a driving technique that consumes as little fuel as possible until reaching the nearest gas station is required.

The present invention has been made in view of such a demand, and provides a tire pressure control method that can automatically run a long distance as much as possible with remaining fuel when the remaining fuel becomes small. It is.

(Means for Solving the Problems) According to the present invention, in order to achieve the above-described object, in a tire pressure control method for increasing or decreasing the tire air pressure during traveling, a fuel remaining amount in a fuel tank is detected. A tire pressure control method for increasing the tire pressure when the remaining fuel amount is equal to or less than a predetermined value.

Preferably, it is desirable to detect the vehicle speed and set the tire pressure in accordance with the vehicle speed, and it is desirable to issue an alarm that encourages economic driving when the vehicle speed exceeds a predetermined value.

(Operation) The present invention has been made by focusing on the relationship between the tire air pressure and the fuel efficiency, and FIG. 7 shows the relationship between the tire air pressure (tire pressure) and the rolling resistance of the tire. As the pressure increases, the rolling resistance decreases. When the rolling resistance is reduced, the fuel efficiency is improved. Therefore, when the tire pressure is increased, the fuel efficiency is improved (see FIG. 8). Further, FIG. 9 is shows the relationship between the vehicle speed and the rolling resistance and fuel consumption, rolling resistance and the vehicle speed from the figure is larger than the predetermined value V ₁ near increases suddenly,
The fuel efficiency also deteriorates as the vehicle speed V increases.

Therefore, by detecting the remaining amount of fuel in the fuel tank and increasing the tire pressure when the remaining amount of fuel is equal to or less than the predetermined value, economical driving is realized regardless of the driver's intention.

If the vehicle speed exceeds a predetermined value, an alarm is issued and the driver is encouraged to run economically.

Embodiment An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

First, the tire pressure control device for implementing the method of the present invention is
This will be described with reference to FIGS. The tire pressure control device 1 includes a supply system air passage 3 and a tire system air passage 4. One end 3a of the supply system air passage 3 is connected to a discharge port 5a of the compressor 5, and the other end 3b is connected to a reserve tank 6. Each is connected.

A pressure switch 11 for monitoring the air pressure in the reserve tank 6 is electrically connected to the compressor 5. When the air pressure in the reserve tank 6 becomes smaller than a predetermined lower limit, the pressure switch 11 is turned on to drive the compressor 5, The drive is turned off when the power becomes larger than the predetermined upper limit value. Therefore, high-pressure air in a predetermined value range is always stored in the reserve tank 6. The suction port 5b of the compressor 5 is connected to the discharge port 5a through a pipe 9, and the pipe 9 has an exhaust valve 8
Are arranged. The exhaust valve 8 is, for example, a normally closed electromagnetic on-off valve, and is electrically connected to a controller (ECU) 10 described later.

An air supply valve 12 is provided between the reserve tank 6 and the compressor 5 in the air supply passage 3 between the supply tank 12 and the compressor 5.
An air dryer 13 is connected between them. The air supply valve 12
For example, a normally closed electromagnetic on-off valve is electrically connected to the controller 10. Further, the compressor 5 side and the reserve tank 6 side of the air supply valve 12 are connected via a pipe 14, and a check valve 15 is provided in the pipe 14. The check valve 15 allows the air flow in the pipe 14 only to flow from the compressor 5 side to the reserve tank 6, and is provided with a coil spring 15a, and is opened when the air pressure on the compressor 5 side reaches a predetermined value. Give a valve.

The air dryer 13 dries the air fed from the compressor 5. The moistened air dryer 13 passes through the air dryer 13 from a tire air passage 4 described later,
It is dried by the air discharged to the atmosphere via the pipe 9 and the opened exhaust valve 8.

One end 4a of the tire air passage 4 is connected to a branch point between the air dryer 13 and the air supply valve 12 in the intake air passage 3, and the other end is branched in four directions to form branch passages 4b, 4c, 4d. , 4e are connected to the corresponding tires FR, FL, RR, RL, respectively.

Control valves 40, 41, 42, 43 are respectively connected to the branch paths 4b to 4e, and a pressure sensor 34 is provided between each control valve and the corresponding tire.
Are arranged. Each of the control valves 40 to 43 is, for example, a normally closed electromagnetic on-off valve, and is electrically connected to the controller 10. Further, each pressure sensor 34 is electrically connected to the controller 10, detects the air pressure in an air passage connected to each tire, and supplies a detection signal to the controller 10.

FIG. 3 shows a connection portion between the vehicle body side and the tire side of the tire system air passage 4 relating to the front tire FR (FL) which is a driving wheel, and the knuckle 20 on the vehicle body side is formed inside the axle hub 021 on the tire side. The end half is rotatably supported via a bearing 22. A joint shaft 25 is spline-coupled to the inner peripheral wall of the axle hub 21 and inserted therethrough.
An annular air chamber 23 is provided between the knuckle 20 and the outer peripheral wall of the hub 21 on the outer side of the bearing 22 to form seal members 24a and 24.
It is formed airtight by b.

A cap 30 is detachably and hermetically attached to the center of the outer wall surface of the axle hub 21, and an air chamber 31 is defined inside the cap 30. The air chamber 31 is connected to the tire FR via a port 30a and a pipe (not shown).
(FL).

The knuckle 20 has an air passage 4A formed therein.
One end of 4A is open to the air chamber 23, and the other end is connected to the above-described branch path 4b (4c). The above-described pressure sensor is provided on the connection between the branch passage and the air passage 4A, that is, on the vehicle body side.
34 is installed. Further, the air chamber 23 and the air chamber 31 are communicated with each other by a plurality of air passages 4B formed in the axle hub 21.

On the other hand, FIG. 4 shows a connection part between the vehicle body side and the tire side of the tire air passage 4 relating to the rear tire RR (RL) which is an idler wheel. Are rotatably supported via bearings 28 and 29. At the center of the outer wall surface of the axle hub 26, a cap 50 similar to the front side is detachably attached so as to cover the outer end surface of the knuckle spindle 27, and
An air chamber 52 is defined inside the cap 50 in an airtight manner. And this air chamber 52 is port 50a,
And it communicates with the inside of the rear tire RR (RL) via a pipe (not shown).

An air passage 4A 'is formed in the knuckle spindle 27. One end of the air passage 4A' is open to the air chamber 52, and the other end is connected to the branch passage 4d (4e). I have. The connection between this branch and the air passage 4A ', that is,
The pressure sensor 34 described above is attached to the vehicle body.

The controller 10 includes a central processing unit (CPU), storage devices such as a ROM and a RAM, an I / O interface (neither is shown), and the like. The input side of the controller 10 includes the above-described pressure sensors 34 and a vehicle speed sensor 4 for detecting a vehicle speed.
4, steering angle sensor 45 that detects the steering angle, and fuel switch 4
6 are electrically connected to each other, and a detection signal is supplied from each sensor. The fuel switch 46 detects the remaining amount of fuel in a fuel tank (not shown) and outputs an ON signal when the remaining amount of fuel is equal to or less than a predetermined value. On the other hand, the air supply valve 12, the exhaust valve 8, the control valves 40 to 43, and the like are connected to the output side of the controller 10, and a warning light 48, which is disposed on an instrument panel in front of the driver, 49 are electrically connected. The warning light 48 is a remaining amount warning light that is turned on when the fuel switch 46 detects that the remaining fuel amount is equal to or less than a predetermined value, as described later. This is a fuel economy warning light that lights when the vehicle speed is equal to or less than a predetermined value and the vehicle speed is equal to or more than a predetermined value.

The controller 10 controls the air supply valve 1 based on the detection signals supplied from the various sensors described above, as described in detail later.
2. The tire pressure is controlled to a required value by outputting an energizing signal covering or extinguishing signal to the exhaust valve 8 and the control valves 40 to 43 and opening and closing these valves. That is, when it is desired to increase the tire pressure, while the exhaust valve 8 is closed, the control valves (40 to 43) corresponding to the tire are opened, and the air supply valve 12 is opened, whereby the reserve tank 6 is opened.
Supplies high pressure air to the tire. On the other hand, when it is desired to bleed air from the tire and reduce the tire pressure, the air supply valve 12 is closed and the control valve (40
43) and opening the exhaust valve 8, a part of the air of the tire is released to the atmosphere.

Next, a procedure for controlling tire pressure by the controller 10 will be described with reference to FIG.

First, in step S10, the controller 10 sets an initial pressure _PIN of each tire. As the initial pressure _PIN , a value stored in advance in the storage device described above may be read, or a shared load of each tire may be detected and set according to the detected value.

Next, the process proceeds to step S12, where the fuel switch (SW) 46
It is determined whether or not is outputting an ON signal. That is, it is determined whether the remaining fuel amount in the fuel tank is equal to or less than a predetermined value.
If the fuel is sufficiently remaining in the tank (the determination result of step S12 is negative (No)), the process proceeds to step S14,
A correction value P ₀ according to the vehicle speed V is set from a normal table.

Figure 5 shows the vehicle speed V, and the relationship between the vehicle speed correction value P _0, which is set according to the vehicle speed. The curve shown as a normal table in the figure is applied when fuel is sufficiently stored in the fuel tank. As will be described later, the curve shown as a fuel efficiency table when the fuel remaining amount is equal to or less than a predetermined value. Is applied. Such a relationship table of the vehicle speed V and the vehicle speed correction value P _0, experimentally obtained in advance and stored in the storage apparatus described above.

On the other hand, if the fuel switch 46 is turned on and the remaining amount of fuel in the fuel tank is equal to or less than a predetermined value, that is, if the determination result of step S12 is affirmative (Yes), the process proceeds to step S16, and the remaining amount warning lamp 48 is turned on. After being turned on, it is determined whether or not the vehicle speed V detected by the vehicle speed sensor 44 is lower than a predetermined value V ₁ (for example, 70 km / h). If this traveling at a predetermined speed greater than V ₁ vehicle speed, rolling resistance is significantly increased, which is disadvantageous in economy running (see FIG. 9). Therefore, when the vehicle speed V exceeds a predetermined value V ₁ was, alerts the driver by lighting the fuel warning lamp 49, prompting the economic running (step S20).

Then, the process proceeds to step S22, the vehicle speed correction value P ₀ corresponding to the vehicle speed V from the fuel consumption table is set. As the fuel consumption table described above, is set to a value higher than the correction value P ₀ read out from the normal table for the same vehicle speed (see FIG. 5), tire setting pressure P will be corrected to enhance.

When the setting of the vehicle speed correction value P ₀ is completed, the process proceeds to step S24, the steering angle correction coefficient k is calculated. This correction coefficient k is
Tire grip force during steering (Cornering power CP)
The tire pressure set in accordance with the vehicle speed is corrected with the steering angle correction coefficient in order to secure the vehicle speed, and is usually set to a value of 1.0 or less. FIG. 6 shows the relationship between the steering angle θ and the steering nucleus correction coefficient k, and this relationship is stored in a storage device in advance as a table. Then, the steering angle correction coefficient k corresponding to the steering angle θ detected by the steering angle sensor 45 is read from the above table. The steering angle correction coefficient curve shown in FIG. 6 may be stored according to the vehicle speed, and the steering angle correction coefficient k may be set according to the steering angle θ and the vehicle speed V.

The controller 10 controls the initial pressure set as described above.
The tire pressure P is calculated by the following equation from P _IN , the vehicle speed correction value P ₀ , and the steering angle correction coefficient k (step S26).

P = k × (P _IN + P ₀ ) The controller 10 controls the opening and closing of the air supply valve 12, the exhaust valve 8, and the control valves 40 to 43 while monitoring the pressure sensor 34 to control the tire pressure of each tire. Adjust to the set value P.

Incidentally, the steering angle correction in the embodiment described above, obtains a correction factor, which has been performed by the multiplying the sum of the initial pressure P _IN and the vehicle speed correction value P _0, Kajikaku correction value corresponding to the steering angle look, may be corrected added or subtracted to this to the sum of the initial pressure P _iN and the vehicle speed correction value P _0.

The steering angle correction uses the steering angle θ detected by the steering angle sensor 45, but the steering angle may be corrected by detecting the steering angular velocity.

Further, when the steering angle sensor is not particularly used, a maximum set pressure at which the vehicle can safely turn may be set in accordance with the vehicle speed, and the tire pressure may not be increased beyond the maximum set pressure.

(Effect of the Invention) As described in detail above, according to the tire pressure control method of the present invention, the remaining fuel in the fuel tank is detected, and when the remaining fuel is less than a predetermined value, the tire pressure is increased. As a result, economical driving becomes possible, and the vehicle can be driven for a long distance with the remaining fuel regardless of the driving technique of the driver.

[Brief description of the drawings]

1 is a flowchart showing a tire pressure control procedure according to the method of the present invention, FIG. 2 is a pneumatic circuit diagram of a tire pressure control device for executing the method of the present invention, FIG. 3 is an enlarged cross-sectional view of a main part near the axle hub of the drive wheel, FIG. 4 is an enlarged cross-sectional view of a main part near the axle hub of the idle wheel, and FIG. 5 is a diagram showing the relationship between the vehicle speed V and the vehicle speed correction value P _0. FIG. 6 is a graph showing the relationship between the steering angle θ and the steering angle correction coefficient k, FIG. 7 is a graph showing the relationship between the tire pressure and the rolling resistance, and FIG. 8 is a graph showing the relationship between the tire pressure and the fuel efficiency. FIG. 9 is a graph showing the relationship between the vehicle speed V, rolling resistance, and fuel efficiency. 3 ... air passage, 4 ... air passage, 10 ... controller, 7 ... exhaust valve, 12 ... air supply valve, 34 ... pressure sensor,
40 to 43: control valve, 44: vehicle speed sensor, 46: fuel sensor, 48, 49: warning light.

Claims (1)

(57) [Claims] In a tire pressure control method for increasing or decreasing the air pressure of a tire during running, detecting the remaining amount of fuel in a fuel tank and increasing the air pressure of the tire when the remaining amount of fuel is less than a predetermined value. A tire pressure control method comprising: