JPH0210722B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tire pressure control device for a vehicle.

Conventional vehicle tire pressure control devices include:
For example, there is one disclosed in Utility Model Publication No. 46-18171. This includes a solenoid valve that fills or releases air from inside the tire, and a pressure switch and a manual switch that operate by detecting the air pressure of the tire to operate the solenoid valve. However, in the case of such conventional vehicle tire pressure control devices, the mechanism was to simply detect and control the tire air pressure, so it was not possible to control the tire air pressure by simply detecting the tire air pressure. In some cases, there has been a problem in that the maneuverability, driving stability, ride comfort, etc. of the vehicle cannot be satisfied.

This invention was made by focusing on these conventional problems, and in addition to the tire air pressure, the load on the tires, and the vibration level when the vehicle is running (vehicle body vertical vibration acceleration or suspension system unsprung mass). The purpose of this technology is to solve the above problems by detecting the RMS (root mean square) value of vertical vibration acceleration, etc.) and vehicle speed, and controlling tire air pressure based on these values.

In general, the maneuverability (turning performance) of a vehicle is determined by the balance between the centrifugal force applied to the vehicle when turning and the cornering force of the tires generated from the front and rear wheels. It shows the rate at which the cornering force of the tire changes with respect to the change in slip angle, and it takes a nearly constant value in a range where the slip angle is small.) Therefore, the larger the cornering power, the smaller the slip angle to produce the same cornering force, and the more the vehicle can turn against a comparable centrifugal force, the more the vehicle can turn with a smaller steering angle and the steering wheel becomes more difficult to turn. It is known for its sharp maneuverability (turning performance). On the other hand, as shown in FIG. 1, it is known that a tire has a characteristic that the air pressure that maximizes its cornering power changes depending on the load applied to the tire.

Therefore, based on the above-mentioned facts, the tire pressure control device of the present invention includes a means for detecting the tire air pressure, a means for detecting the load applied to the tire, and a means for detecting the required cornering power for the tire based on these. and a control means for controlling the air pressure of the tire so that the tire air pressure is controlled so that the cornering power of the tire is around the maximum value with respect to the load applied to the tire. As a result, the tire pressure control device of the present invention can always maintain cornering power near the maximum value even when the load on the vehicle changes, thereby providing excellent vehicle maneuverability (turning characteristics). Can be done.

In general, the running stability of a vehicle is determined by the static margin S=(Cr/Cf+Cr-a/a+b) (here, Cf
, Cr is the cornering power of the front or rear tires, respectively, as shown in Figure 2, and a and b are the vehicle's center of gravity C, from the point of application of the front or rear wheels on the road surface, respectively, as shown in Figure 2. Indicates the distance to G. ) is known to be expressed as That is, when the static margin S is positive,
The point of action of the resultant force of the cornering force generated by the front and rear tires is located behind the center of gravity C and G of the vehicle,
When a vehicle is traveling straight and some disturbance occurs,
It is known that the vehicle has running stability because a restoring moment acts to return the vehicle to its previous state. Further, as shown in FIG. 1, it is known that the cornering power of a tire changes depending on the internal pressure and load of the tire.

Therefore, based on the above facts, the load distribution of each wheel is detected from the tire air pressure and the load applied to the tire, and the tire air pressure is controlled so that the tire obtains cornering power that makes the static margin S positive. In this way, even if the number of passengers or the loading condition changes, the running stability of the vehicle can be improved.

Additionally, the ride quality of a vehicle generally deteriorates when the level of vibration transmitted from the road surface to the vehicle body when the vehicle is running is large. It is known that this vibration transmission from the road surface increases as the tire air pressure increases, and decreases as the tire air pressure decreases.

Therefore, based on the above facts, the tire air pressure is controlled so that cornering power that makes the static margin S positive is obtained based on the tire air pressure, the load on the tires, and the vibration level when the vehicle is running. At the same time, for example, when the level of vibration transmitted from the road surface to the vehicle body is large, such as when driving on rough terrain, the tire air pressure can be corrected to a lower value, thereby improving both the running stability and ride comfort of the vehicle. can.

Additionally, when a vehicle is running at high speed, it is generally necessary to increase the air pressure in the tires compared to when driving normally to prevent standing wave phenomena and the like, thereby increasing safety during high-speed running.

Therefore, based on the above facts, the tire pressure is controlled to obtain the required cornering power based on the tire pressure, the load on the tire, and the vehicle speed, and the tire pressure is set higher when driving at high speed than when driving normally. By controlling the vehicle, it is possible to improve driving stability, especially safety during high-speed driving.

The present invention will be explained below based on the drawings.

3, 4, and 5 are diagrams showing a tire air pressure control device for a vehicle according to an embodiment of the present invention. First, the configuration will be explained. As shown in FIG. 3, the tire air pressure control device 1 of this embodiment controls the air pressure of the front and rear tires 2, 3, 4, and 5 in a vehicle 6 equipped with pneumatic tires 2, 3, 4, and 5 on the front, rear, left, and right sides. means 7 and 8 for detecting the load applied to each tire 2, 3, 4, 5, means 9, 10, 11, 12 for detecting the load applied to each tire 2, 3, 4, 5, and means 13 for detecting the vibration acceleration of each wheel in the vertical direction of the vehicle body. ,1
4, 15, 16, and means 17 for detecting vehicle speed;
Control means 18 that controls the air pressure of the tires 2, 3, 4, 5 based on the signals detected by these
It is equipped with. A means 7 for detecting the air pressure of the front left and right tires 2, 3 is provided in a front wheel pressure measurement chamber 19 connected to the front left and right tires 2, 3, and detects the air pressure of the rear left and right tires 4, 5. The means 8 is provided in a rear wheel pressure measuring chamber 20 that communicates with the rear left and right tires 4 and 5. The means 9, 10, 11, 12 for detecting the loads applied to the respective tires 2, 3, 4, 5 are arranged, for example, between the coil springs of the suspension supporting the respective tires 2, 3, 4, 5 and the vehicle body. The structure is such that a load cell is inserted into the coil spring or the amount of deflection of these coil springs is measured. Means 1 for detecting the vibration acceleration of each wheel in the vertical direction of the vehicle body
3, 14, 15, and 16 have a configuration in which, for example, a vibration accelerometer is provided on a suspension arm that supports each wheel, or the above-mentioned load detecting means 9, 10, 11, and 12 are used together. There is. The means 17 for detecting the vehicle speed is provided at the speedometer cable outlet of the transmission, and is configured to count the rotation of the speedometer cable in pulses and convert it into the vehicle speed. In the figure, a dashed line indicates a signal transmission path between each detection means and the control means 18. 21 indicates a pressurized air system. The pressure air system 21 includes an air compression pump 2 that is driven directly by the engine or by an electric motor.
2. A pressure accumulation chamber 23 in which the pressurized air generated by the air compression pump 22 is accumulated; two 3-position switching valves 24 operated by signals output from the control means 18;
25, the front wheel side or rear wheel side pressure measurement chambers 19, 20 are connected to the pressure accumulation chamber 23 through the three-position switching valves 24, 25, respectively, and the wheels equipped with the front left and right tires 2, 3 are rotatable, respectively. A rotary joint 2 that supports the tires 2 and 3 and connects the inside of the tires 2 and 3 with the front wheel pressure measurement chamber 19 via piping.
6, 27, a rotary joint that similarly rotatably supports the wheels on which rear left and right tires 4, 5 are mounted, and connects the inside of the tires 4, 5 with the rear wheel side pressure measurement chamber 20 via piping. Into 28,
It has 29. The dotted line in the figure shows the path of pressurized air.

As shown in FIGS. 4A, B, and C, the three-position switching valves 24 and 25 have a spring center type configuration,
When a signal to keep the tire air pressure constant is input from the control means 18, no operating force is applied and the pressure measuring chambers 19, 20 and the pressure accumulating chamber are at the neutral first position shown in FIG. 4A due to their own spring force. 23 and the atmosphere 30. Furthermore, when a signal to increase the tire air pressure is input from the control means 18, the three-position switching valves 24 and 25 move to the position shown in FIG. and the pressure accumulation chamber 23 are communicated with each other. In addition, the 3-position switching valve 2
4 and 25, when a signal to reduce the tire air pressure is input from the control means 18, an operating force acts to move them to the position C in FIG. 4, and the pressure measurement chamber 1
9, 20 and the atmosphere 30.

Next, with reference to the block diagram of the control means 18 shown in FIG. 5, the structure of the control means 18 and the operation of the air pressure control device 1 will be explained together. This control means 18 controls the air pressures of the tires 2, 3, 4, and 5 so as to obtain cornering power that makes the static margin S positive even when the wheel load changes, thereby ensuring running stability. When the level of vibration transmitted from the road surface to the vehicle body is large, such as when driving on rough terrain, the tire air pressure is corrected to a lower level to improve ride comfort. That is, the control means 18 controls the load signals of the detection means 9 and 10 for detecting the loads applied to the front left and right tires 2 and 3.
Enter Wf ₁ and Wf ₂ to calculate the front wheel load, Wf = Wf ₁ + Wf ₂
The rear wheel load Wr=Wr 1 is calculated by inputting the load signals Wr ₁ and Wr ₂ from the front wheel load calculation circuit 31 that calculates the load and the detection means 11 and 12 that similarly detects the load applied to the rear left and right tires 4 and _5. +Wr ₂ and a rear wheel load calculation circuit 32 that calculates the front wheel and rear wheel loads calculated by the front wheel and rear wheel load calculation circuits 31 and 32.
Wf and Wr are stored in the memories 33 and 34 as follows when the vehicle is stationary. That is, when a signal indicating that the vehicle speed ν is zero is input to the trigger circuit 35 from the means 17 for detecting the vehicle speed, a memory trigger is generated and the contents of each arithmetic circuit 31 and 32 are input to the memories 33 and 34. The front and rear wheel loads Wf and Wr are stored. 36 is a center of gravity position calculation circuit;
The center of gravity position (load distribution) G of the vehicle is determined from the static front and rear wheel loads Wf and Wr stored in the memories 33 and 34.
=Wr/Wf+Wr (=a/a+b) is calculated and inputted to a circuit 37 for calculating the resultant force action position of cornering force Cf and Cr, which will be described later. 38 is a static margin setting circuit which sets the static margin S (=Cr/Cf+Cr-a/a+b) to a positive value and adjusts its size to select the magnitude of running stability. . The static margin S set by the static margin setting circuit 38 and the center of gravity position (load distribution) G (=a/a+b) are input to the cornering force resultant action position calculation circuit 37, and the static margin Position of resultant force of cornering force required to obtain S (distribution of cornering force between front and rear wheels) C=S+G (=
Cr/Cf+Cr) is calculated. 39 is a turning ability setting circuit, which stores front and rear wheel loads Wf in memories 33 and 34;
Input Wr to find the total load W = Wf + Wr, and then multiply this total load W by a preset coefficient K on an average road surface to obtain the sum of cornering power.
We are looking for Cf + Cr (=KW). Note that this coefficient K may be selected and changed by the driver depending on the road surface. 40 is a cornering power calculation circuit, which calculates the resultant force action position calculation circuit 3 of the cornering force sum Cf + Cr (=KW) set in the turning ability setting circuit 39 and the cornering force.
Position of the resultant force of the cornering force determined in step 7 (distribution of cornering power between the front and rear wheels) C (=
Cr/Cf+Cr) and the cornering power Cf of the front tires 2 and 3 required to obtain the static margin S = (1-C) KW and the rear tires 4,
5's cornering power Cr=CKW is calculated. These (1+C) KW and CKW are used as target values for cornering power depending on the tires installed. Therefore, the cornering power calculation circuit 40 functions as target value calculation means. Reference numeral 41 denotes a tire pressure calculation circuit, which calculates control values for the air pressures Pf and Pr of the front and rear tires 2, 3 and 4, 5 necessary to generate the cornering powers Cf and Cr determined by the cornering power calculation circuit 40. There is. That is, the tire pressure calculation circuit 41 has the tires 2, 3, 4, and 5 mounted on it.
As shown in the figure, a function Pf, r = F (Cf, r Wf, r ) are stored, and the Wf and Wr of the front and rear wheels input from the memories 33 and 34 and the cornering power calculation circuit 4
Cornering power of front and rear wheels input from 0
By substituting Cf and Cr, the front and rear tires 2, necessary to generate these cornering powers Cf and Cr are calculated.
Find the control values for the air pressures Pf and Pr at points 3, 4, and 5. Therefore, the tire pressure calculation circuit 41
functions as a control value calculation means. Note that an air pressure correction circuit 42, which will be described later, may be added to the control value calculation means. Function F sets the upper limit tire air pressure according to wheel loads Wf and Wr, and tires 2, 3,
This protects the tires by preventing excessive air pressure from being supplied to tires 4 and 5. Although the same function F is set for the front and rear tires 2, 3 and 4, 5, different functions F may be stored for each front and rear tire. 42 is an air pressure correction circuit, and if the front or rear tires 2, 3, 4, or 5 have extremely low or high pressures when the load distribution is extremely uneven, the tires will generate abnormal heat and cause trouble. Therefore, the upper and lower limits of the air pressure are set, and the air pressures Pf and Pr are controlled based on the function F of the tire air pressure calculation circuit 41 only within these limits. That is,
The air pressure correction circuit 42 is configured to control the installed tire 2,
3, 4, and 5, when the air pressure Pf or Pr obtained by the function F is between the lower limit air pressure L and the upper limit air pressure H, the air pressure value Pf
Or output Pr as is, and output air pressure Pf or Pr
is less than the lower limit air pressure L, the lower limit air pressure L
A function that outputs the value of the upper limit air pressure H when the air pressure Pf or Pr is greater than or equal to the upper air limit H.
Bf, r=g(Pf, r) is stored, and the tire pressure calculation circuit 41 outputs the tire pressure Pf, Pr obtained as the tire pressure Bf or Br corrected as described above. Further, this air pressure correction circuit 42 changes the upper limit air pressure H of the function g to a lower value h when the level of vehicle body vibration is large. That is, the means 13, 1 for detecting the vibration acceleration of the wheel in the vertical direction of the vehicle body.
4, 15, 16 output vibration acceleration af ₁ , af ₂ ,
Circuits 43, 44, 45, and 46 that calculate the root mean square (RMS) values of ar ₁ and ar ₂ , and the average value Af for each front and rear wheel of the RMS values calculated by these circuits 43, 44, 45, and 46. , circuits 47 and 48 for determining Ar
and these average values Af, Ar and reference levels Afo, Aro
Comparators 49 and 50 are provided to compare the average vibration values Af and Ar of either the front or rear wheels to the reference level.
If larger than Afo and Aro, air pressure correction circuit 42
The upper limit air pressure H of the function g is set to a lower value h.
Note that the function g may be different for each of the front and rear wheels. 51 and 52 are subtractors, which calculate the actual air pressures P'f and P'r of the front and rear tires 2, 3 and 4, 5 detected by the air pressure detecting means 7 and 8.
and the air pressures Bf and Br output by the air pressure correction circuit 42, the differences ef=Bf-P'f and er=Br-P'r are calculated, respectively. 53 and 54 are dead zone setting circuits, which determine the differences Ef=1ef1-l and Er=1er1-l between the absolute values of ef and er and a positive constant l. Judgment circuits 55 and 56 determine whether the three-position switching valve 2 is closed if Ef or Er is zero or negative, respectively.
4 or 25 to the first position, and maintain the air pressures of the front and rear tires 2, 3 or 4, 5 at the same values. On the other hand, the determination circuits 57 and 58 each determine that Ef or Er is positive,
If Ef or Er is positive, sign determination circuits 59, 6
0, 61, and 62 determine the signs of ef and er. The sign discrimination circuits 60 and 62 are respectively ef or
If the sign of er is determined as positive, the actual air pressure
Since P'f or P'r is lower than the air pressure Bf or Br required to obtain the required cornering power Cf or Cr, the three-position switching valve 24 or 25 is set to the third position, and the pressure accumulating chamber 23 and pressure measuring chamber 19 or 20, and the air pressures of the front and rear tires 2, 3 or 4, 5 are increased. Conversely, if the sign discrimination circuits 59 and 61 judge the sign of ef or er to be negative, the actual air pressure Pf or P′r
is higher than the air pressure Bf or Br required to obtain the required cornering power Cf or Cr, so 3
The position switching valve 24 or 25 is set to the first position, the pressure measurement chamber 19 or 20 is communicated with the atmosphere, and the air pressure of the front and rear tires 2, 3 or 4, 5 is lowered. Therefore, the above subtractor 5
1, 52, dead zone setting circuits 53, 54, determination circuits 55, 56, 57, 58, and sign determination circuit 5
9, 60, 61, and 62 function as an operating means. Reference numeral 63 is a warning device, and even if the control means 18 controls the air pressure of the tires 2, 3, 4, and 5 so that the static margin S is positive as described above, the cornering power of the tires actually changes. Since there is a limit to the possible range, the desired static margin S may not be obtained. In this case, a warning is issued to alert the driver. 64 is a cornering power detection circuit that constitutes a part of the warning device 63, and the memory 33 stores the air pressures P'f and P'r of the front and rear tires 2, 3 and 4, 5 detected by the air pressure detecting means 78. , 34 are input, and the actual cornering powers Cf' and Cr' of the tires 2, 3 and 4, 5 are detected. That is,
This circuit 64 has tires 2, 3, 4 mounted on it,
5, functions Cr', r' representing the relationship between cornering powers Cf', Cr' and tire air pressures P'f, P'r that change according to wheel loads Wf, Wr as parameters. = f (P'f, r Wf, r) is stored, and the front and rear wheel loads Wf, Wr from the memories 33 and 34 and the air pressure from the detection means 7 and 8
By substituting Pf and Pr, tires 2, 3
and the cornering power that 4 and 5 actually have
Cf′ and Cr′ are detected. 65 and 66 are warning discrimination circuits for the front and rear wheels, respectively, and detect the cornering power that the tires 2, 3 and 4, 5 actually have, detected by the cornering power detection circuit 64.
Cf', Cr' are compared with the cornering powers Cf, Cr required to satisfy the static margin S determined by the cornering power calculation circuit 40, and if Cf and Cf' are not equal or Cr is Cr' is not equal, a warning device 63 is activated to alert the driver to driving stability.

FIG. 6 is a block diagram of a control means according to another embodiment of the present invention. This control means 18
The system detects the tire air pressure, the load on the tires, and the vehicle speed, and controls the tire air pressure to obtain cornering power that makes the static margin S positive. Air pressure is controlled at a high level to improve running stability, especially at high speeds. That is,
This control means 18 includes means 17 for detecting vehicle speed ν.
It also has a discrimination circuit 67 that increases the function g of the air pressure correction circuit 42 by ΔB as a whole when the vehicle speed ν reaches a constant vehicle speed V or more compared to the value when the vehicle speed is less than V, as shown by the dashed line. Therefore, in this control means 18, when the vehicle speed ν is higher than V, the tire air pressure is increased by ΔB. Other structures and operations are similar to those of the embodiment shown in FIGS. 3, 4, and 5, so the same parts are given the same reference numerals and explanations will be omitted.

As explained above, according to this invention,
The target value of required cornering power is calculated based on the tire air pressure and the load on the tires.
Since the tire pressure is controlled to achieve this target value, even if the vehicle load changes,
The cornering power can always be kept close to the maximum value, which has the effect of making the vehicle's maneuverability excellent. Furthermore, in addition to the above-mentioned effects, the embodiments shown in FIGS. 3, 4, and 5 are equipped with a warning device, so that they have the effect of alerting the driver to the running stability of the vehicle.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between vehicle tire air pressure and cornering power using the load applied to the tires as a parameter. Figure 2 is a schematic diagram of the vehicle to explain the static margin S of the vehicle. Figure 3 is a diagram of this vehicle. A schematic diagram showing a tire pressure control device for a vehicle according to an embodiment of the invention, and FIGS. 4A, B, and C are schematic diagrams showing the configuration and operation of a three-position switching valve of the tire pressure control device for a vehicle according to this embodiment. 5 is a block diagram of the control means of the tire pressure control device for a vehicle according to this embodiment, and FIG. 6 is a block diagram of the tire pressure control means for a vehicle according to another embodiment of the present invention. 2, 3, 4, 5... Tire, 7, 8... Means for detecting air pressure, 9, 10, 11, 12... Means for detecting load applied to tire, 18... Control means, 40... Cornering Power calculation circuit (target value calculation means), 41...Tire pressure calculation circuit (control value calculation means), {51, 52...Subtractor, 5
3, 54...Dead zone setting circuit, 55, 56, 5
7, 58... Judgment circuit, 59, 60, 61, 62
...sign discrimination circuit} (operating means).

Claims (1)

[Claims] 1. In a vehicle equipped with pneumatic tires, a means for detecting the tire air pressure, a means for detecting the load on the tire, and a means for controlling the tire air pressure so that the required cornering power is obtained from the tire based on these. control means, the control means includes target value calculation means for calculating a target value of cornering power according to the tires mounted;
The tire is characterized by comprising a control value calculation means for calculating a control value of the tire air pressure based on the target value and the load applied to the tire, and an operation means for operating the tire air pressure so that the control value is achieved. Tire pressure control device for vehicles.