JPH04154413A - Remote measuring method of tire pressure - Google Patents

Abstract

PURPOSE:To learn accurate tire pressure speedily in any case by connecting a control line to the low pressure side for a short period of time through operation of a pressure control valve before measurement so as to measure tire pressure accurately and speedily. CONSTITUTION:A pressure control valve 355 is in the neutral position and a pressure discharge valve 358 is in the first position at the time of non- operation. Therefore, a control line 351 is shut off from a compressor 352 and an air cylinder 354. On the other hand, the atmospheric pressure is introduced into a tire pressure adjusting valve 300 from the control line 351 to block a passage. Consequently, the inside of a tire 101 is shut off from the outside, and pressure at that time is maintained. I this case, the same operation as that at the time of pressure reduction control is carried out intentionally to shorten equilibrium reaching time after pressure is increased and controlled. That is, after increase and control of pressure ends, the pressure control valve 355 is not only returned to the neutral position from the first position, but also moved to the second position for a short period of time only. Thus, pressure of air in the control line 351 is instantaneously released in the atmosphere via the pressure control valve 355 and a muffler 361.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention enables accurate measurement of the air pressure in the tires of a vehicle (referred to as tire pressure) from a remote location while the vehicle is in motion, and is capable of accurately measuring the air pressure in a vehicle's tires while the vehicle is in motion. The present invention relates to a method for remotely measuring tire pressure, which makes it possible to automatically control the tire pressure with good responsiveness.

[Conventional technology]

The applicant had previously filed an application for a tire pressure adjustment device that remotely controls the tire pressure of a vehicle and freely increases or decreases the tire pressure even while the vehicle is in motion, as disclosed in Japanese Unexamined Patent Publication No. 1984-10.
The application has been published as No. 9109.

This tire pressure adjustment device includes a control line that is switched to a pressure line or a low pressure side by a pressure control valve, a pressure sensor provided on the control line, and a control line that is connected to the control line via a rotating shaft seal part. When automatically controlling the tire pressure of two vehicles using a tire pressure adjustment valve and a pneumatic tire connected to the tire pressure adjustment valve, it is necessary to check the actual measured value of the tire pressure as accurately as possible at any time, even when driving. However, it is very difficult to provide a means for regulating the pressure in each tire itself, so it is necessary to supply pressurized air to the tire at the pressure increase head, and to remove the pressure air from the tire pressure when the pressure is reduced. This means that the tire pressure is estimated by measuring the controlling air pressure (line pressure) using a pressure sensor.

A pressure control valve, which is a switching valve, is provided between the control line and the pressure air supply source. The control line is connected to the atmosphere during B reduction control. Not only when increasing the pressure B, but also when performing pressure reduction control, or even when just measuring the evening tire pressure, high pressure is initially applied to the control line and the pressure is applied to the wheel G of each tire; It is necessary to open the valve and communicate the control line with the inside of each tire. However, except when controlling or measuring tire pressure, the control line is opened to the atmosphere, which allows the tire pressure regulating valve to communicate with the inside of each tire. Since the valve is closed, the high pressure air inside each tire will not leak to the outside.

Note that it is necessary to provide a rotating shaft seal section where the air passage of the control line crosses from the vehicle body side to the rotating tire side, but since the rotating shaft seal section has a sliding seal surface that causes friction, In order to reduce this friction, the sealing surfaces cannot be brought into strong contact and it is necessary to provide a certain amount of clearance. As a result, the rotating shaft seal cannot avoid a small amount of air leakage, but this may be caused by pressure increase or decrease control,
Alternatively, this is only during tire pressure measurement, and in a steady state where the control line is open to the atmosphere, air leakage from the tire does not occur.

[Problem to be solved by the invention]

When increasing, decreasing, or measuring the tire pressure, pressurized air is supplied to the control line, and the control line communicates with the inside of the tire via a tire pressure regulating valve that is opened thereby. Therefore, it seems possible to actually measure the tire pressure by detecting the line pressure with a pressure sensor provided in the control line, but in reality, it is not possible to actually measure the tire pressure that easily.

First of all, as mentioned above, there is inevitably air leakage in the rotating shaft seal, and even if air does not leak from the tire in a steady state, the tire pressure may change. When increasing or decreasing the pressure or measuring the tire pressure, there is a problem that the line pressure is slightly lower than the actual tire pressure because there is a small amount of airflow leaking from the rotary shaft seal.

The bigger problem is that if line pressure is measured immediately after pressure increase control or pressure decrease control, it may take much longer after pressure increase control for line pressure to equilibrate with tire pressure than after pressure decrease control. That's what I understand. Therefore, even if the line pressure is measured before reaching an equilibrium state and corrected by adding the pressure drop due to leakage from the rotary shaft seal to the line pressure, the actual tire pressure cannot be determined.

The time required for line pressure and tire pressure to equilibrate is extremely long after pressure increase control and does not match the time required after pressure decrease control. Therefore, since the tire pressure is measured as different values, it becomes impossible to control the tire pressure responsively and accurately by automatic control. Therefore, there is a need for a means that can quickly and accurately measure tire pressure at a location away from the tire. The problem to be solved by the present invention is to find a method that meets this requirement.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a control line that is switched to a pressure line or a low pressure side by a pressure control valve, a pressure measuring means provided in the control line, and a rotating shaft seal for the control line. In a tire pressure remote control device consisting of a tire pressure regulating valve connected through a tire pressure regulating valve and a pneumatic tire connected to the tire pressure regulating valve, in order to quickly and accurately measure the tire pressure, The pressure in the tire and the pressure in the control line quickly reach equilibrium by previously operating the pressure control valve and connecting the control line to the low pressure side for a short time; The line pressure is measured by the pressure measuring means, and a differential pressure specific to the remote control device caused by air leakage at the rotating shaft seal portion is added to the measured value to obtain an actual measured value of the tire pressure. A method for remotely measuring tire pressure is provided.

[For production]

When depressurization control is in progress, line pressure is lower than tire pressure, so when depressurization control is stopped,
A portion of the high pressure air accumulated in the tire returns to the control line, and even if there is leakage from the rotating shaft seal, the line pressure and tire pressure can reach equilibrium within a short time. .

This can be explained by the small change in pressure applied to the spool valve in the tire pressure control valve and the short stroke of the spool valve.Contrary to this, when pressure increase control is performed Although the line pressure is higher than the tire pressure, when the pressure increase control is stopped, the line pressure is reversed and the line pressure becomes lower, reaching an equilibrium state with the tire pressure. The range of pressure drop until the high pressure in the line becomes lower than the tire pressure is large, and the pressure change acting on the spool valve in the tire pressure control valve is correspondingly large, and the spool valve is in an equilibrium position! It can also be explained that it is necessary to move a long distance. (Refer to the Examples section for details) In the method of the present invention, even after pressure increase control, the high pressure air in the control line is exhausted by communicating with the atmosphere for a short time. This is to intentionally create a pressure state similar to that after pressure reduction control, thereby allowing the tire pressure and line pressure to reach an equilibrium state as quickly as after pressure reduction control.

Therefore, by applying the method of the present invention to any process that takes time to reach equilibrium, regardless of whether it is tire pressure increase or decrease control or tire pressure measurement, tire pressure and line pressure can be rapidly balanced. By measuring the line pressure and adding to it the pressure difference between the tire pressure after equilibrium and the line pressure, which is a nearly constant value, you can quickly and accurately obtain a pressure value that is extremely close to the actual tire pressure. Can be telemetered.

This makes it possible to remotely adjust the tire pressure in response to automatic control.

〔Example〕

The present invention will be explained below with reference to illustrated embodiments.

FIG. 2 illustrates a wheel equipped with a tire pressure regulating device to which the method of the invention is applied.

In this figure, a wheel 10 supporting a tire 101
2 is an axle shaft 201 with a bolt (not shown).
connected to. The bearing case 202 is the carrier 2
03 is fitted into the cylindrical portion 204 of the carrier 2.
It is integrally fixed to 03. A bearing 205 is housed in the bearing case 202, and the axle shaft 2
01 is rotatably supported by a bearing 205.

The outer ring of the bearing 205 is supported by the bearing case 202 and the end face of the cylindrical portion 204 of the carrier, and the inner ring of the bearing 205 is supported by the axle shaft 201 and a nut 206 screwed onto the tip of the axle shaft.

As shown in an enlarged example in FIG.
and seals the control line joint from the outside in the operating state, as will be described below.

The tire pressure regulating valve 300 has a structure as shown in an enlarged example in FIG. The air pressure of the tire 101 is adjusted by releasing it to the outside via the mechanism 350. Pressure mechanism 350 connects carrier 203 via control line 351.
A tire pressure regulating valve 300 connected to the passage 213 in the axle shaft 201 via a hole 211 drilled in the carrier 203 and a rotary shaft seal portion 207 is formed in the center of the outer end surface of the axle shaft 201. The axle shaft 201 is connected to a passage 213 bored in the axle shaft 201 by a pressure tube 301. Therefore, the pressure of the pressure mechanism 350 is
, and the tire pressure regulating valve 30 via the pressure tube 301.
It leads to 0. The tire pressure regulating valve 300 is connected to the tire 101 via a pressure tube 302.

The pressure mechanism 350 takes in air through a filter 353 with a compressor 352 and pressurizes it, accumulates this high pressure air in an air cylinder 354, and operates a pressure control valve 355.
It is configured to supply the tire pressure regulating valve 300 with the tire pressure regulating valve 300. That is, the pressure control valve 355 is connected to the pressure line 356.
is connected to a compressor 352 and an air cylinder 354 via a control line 351, and a tire pressure regulating valve 30 is connected via a control line 351.
Connected to 0. A release line 357 is connected to the middle of the control line 351, and a pressure release valve 358 is connected to the release line 357. (Note that a dryer (not shown) may be provided in the control line 351.) Pressure control valve 3
55 and the pressure release valve 358 are switched and controlled by an electronic control unit (ECU) 37 (l) equipped with a microcomputer.

When inactive, pressure control valve 355 is in the neutral position shown in FIG.
51. When the pressure control valve 355 is in the first position, switched to the left in the figure, the pressure line 356
and a control line 351, whereby high pressure air is supplied to the tire 101 through the tire pressure regulating valve 300. The pressure control valve 355 also connects the control line 351 to the silencer 36 when the pressure control valve 355 is switched to the right in the figure and is in the second position.
1 to the atmosphere.

Pressure release valve 358, when inactive, is connected to the first valve shown in FIG.
The valve is in position f (valve closed state), and the release line 357 is communicated with the atmosphere via the silencer 362. Pressure release valve 358 isolates release line 357 from the atmosphere when switched to the right in the figure and in a second position.

A pressure sensor 365 is provided in the middle of the control line 351 between the connection part with the release line 357 and the wheel. This sensor 365 is connected to ECU 370.

Also connected to the ECU 370 are a vehicle speed sensor 367, a load sensor 368 that detects the weight distribution of the vehicle, a road sensor 369 that detects road surface conditions, and the like.

The ECU 370 includes a pressure sensor 365, as described later.
The pressure control valve 355 and the pressure release valve 358 are switched and controlled according to the output signals of the vehicle speed sensor 367, load sensor 368, and road surface sensor 369.

FIG. 3 shows an example of a detailed structure of the tire pressure regulating valve 300.

A first boat 311 and a second port 312 are formed in the housing 310 . A connector 303 (FIG. 2) of the pressure tube 301 is connected to the first boat 311, and a connector 304 (FIG. 2) of the pressure tube 302 is connected to the second port 312. That is, the first boat 311 is connected to the pressure mechanism 350 and the second port 31
2 is connected to the tire 101. A passage 313 that can communicate with the first and second boats 311 and 312 is formed in the housing 310 . This passage 313 is opened and closed by a first valve mechanism 330 and a second valve mechanism 340.

The first valve mechanism 330 includes a housing 310 and a cover 315 fixed to the housing 310 with bolts 314.
between the diaphragm 331 and the disk 33
2 and a spring 333. The outer peripheral edge of the diaphragm 331 is sandwiched between the housing 310 and the cover 315, and a thick wall portion 334 is formed at the center of the diaphragm 331.
The passageway 3 is connected to and away from the raised portion 316 of the housing 310.
13 is opened and closed. Disk 332 is glued to the back side of thickened portion 334. Spring 333 connects disk 332 and cover 3
15, and the diaphragm 331 is connected to the passage 313.
is biased toward the side that closes it. A variable pressure chamber 321 formed between the diaphragm 331 and the housing 310 is connected to the communication hole 3.
It communicates with the first boat 311 via 17. On the other hand, an atmospheric chamber 322 formed between the diaphragm 331 and the cover 315 communicates with the atmosphere through a communication hole 318 formed in the cover 315, and is always at atmospheric pressure.

Therefore, when high pressure is not introduced into the variable pressure chamber 321, the diaphragm 331 is biased by the spring 333 and closes the passage 313. On the other hand, when the pressure inside the variable pressure chamber 321, that is, the first port 311, is above a predetermined value, the diaphragm 331 is displaced toward the atmospheric chamber 322 against the spring 333,
The passage 313 is opened. As a result, the passage 313 communicates with the first boat 311 via the variable pressure chamber 321 and the communication hole 317.

The second valve mechanism 340 includes a spool valve 342 that is slidably supported in a bore 341 formed in the housing 310 . The opening of the bore 341 is closed by a plug 343. The passage 313 opens approximately at the center of the bore 341, and a second boat 312 is located on the opposite side of the opening of the passage 313.
A communication hole 323 that communicates with is opened.

When the spool valve 342 is in the neutral position, it closes the passage 313 and the communication hole 323, and when it is displaced in the left-right direction, two annular grooves 344 formed on the outer circumferential surface of the spool valve 342 close the passage 313 and the communication hole 323.
, 345, the passage 313 and the communication hole 323 are communicated with each other.

A first chamber 324 and a second chamber 325 are formed within the bore 341 on both end sides of the spool valve 342, and each of these chambers 3
Compression springs 346 and 34 are provided in 24 and 325, respectively.
7 is provided. Further, the first chamber 324 communicates with the passage 313 through a throttle 326, and the second chamber 325 communicates with the second boat 312 through a throttle 327. In this way, the first
The pressure in the passage 313 is introduced into the chamber 324 through a restriction 326, and the pressure in the second boat 312 is introduced into the second chamber 325 through a restriction 327. The spool valve 342 is the first
It is displaced according to the pressure difference between the chamber 324 and the second chamber 325.

Next, the operation of the illustrated example will be explained.

When inactive, pressure control valve 355 is shown in FIG.
is in a neutral position and pressure relief valve 358 is in a first position. Control line 351 therefore connects compressor 35
2 and air cylinder 354. On the other hand, in the tire pressure regulating valve 300, atmospheric pressure is introduced into the variable pressure chamber 321 from the control line 351, and as a result, the diaphragm 331 is biased by the spring 333 and closes the passage 313. In addition, the spool valve 342 is connected to the passage 313 and the communication hole 32.
3 is blocked. Therefore, the inside of the tire 101 is isolated from the outside, and the pressure at that time is maintained.

By the way, when it is necessary to increase the pressure inside the tie 101 due to a change in the vehicle speed or the driving conditions such as the load acting on the vehicle body or the road surface condition, the ECU 370 controls the pressure control valve 3.
55 to the right in the figure. Therefore control line 3
High-pressure air at a predetermined pressure is introduced into the compressor 352 and the air cylinder 354. The high-pressure air is supplied to the tire pressure regulating valve 300 through the pressure line 351, so that high-pressure air at a predetermined pressure is introduced into the first boat 311 and the variable pressure chamber 321, and the diaphragm 331 uses the pressure of this air to move the passage 313. Open. Therefore, the first port 311 and the variable pressure chamber 321 communicate with the passage 313.

As a result, the first chamber 324 of the second valve machine ellipse 340 has the throttle 3
26, and the spool valve 340 is displaced to the left in FIG. 3 due to the difference between this high pressure and the pressure in the second chamber 325 (that is, the pressure in the tire 101). Therefore, the second boat 312 and the passage 313 communicate with each other via the annular groove 345 and the communication hole 323, and high pressure air is fed to the tire 101.

When the pressure inside the tire 101 approaches the pressure of the high pressure air supplied from the control line 351, the first chamber 324 and the second chamber 3
25, the spool valve 342 returns to the neutral position, and the passage 313 and the communication hole 323
will be blocked. The ECU 370 also detects changes in pressure caused by the pressure sensor 365 or changes in the pressure caused by the flow rate sensor 36.
6, it is detected that the pressure in the tire 101 has almost reached the pressure in the control line 351, and the pressure control valve 355 is returned to the neutral position, and the pressure release valve 358 is closed. Switch to the first valve open position (return to the state shown in Figure 2).

As a result, the pressure air in the control line 351 is transferred to the silencer 3.
62 into the atmosphere, the pressure in the first port 311 and the variable pressure chamber 321 rapidly decreases to atmospheric pressure.

On the other hand, due to the aperture effect of the apertures 326 and 327, the first chamber 3
24 and the second chamber 325 is slow, and therefore the spool valve 342 is hardly displaced and maintains a substantially neutral position. During this time, the diaphragm 331
Due to the pressure drop in 21, the spring 333 biases the passage 3.
13 is occluded.

On the other hand, when it is necessary to reduce the pressure inside the tire 101, the EC 11370 first switches the pressure release valve 35 to the second position to shut off the inside of the control line 351 from the excessive pressure, and then the pressure control valve 355 is switched to the first layer, whereby high-pressure air is introduced into the control line 351 once from the daily air line 356. This trans-pressure air is guided to the variable pressure chamber 321 of the tire pressure regulating valve 300, thereby causing the diaphragm 331 to open the passage 313. Then ECU37
0 switches the pressure control valve 355 to the second position 1 and releases a portion of the high pressure air in the control line 351 to the atmosphere through the muffler 361, reducing the pressure to a constant low pressure. The pressure inside the bath line 351 at this time (pressure sensor 3
65) is not equal to atmospheric pressure due to the constriction effect of the conduit, but is lower than the target value of the pressure in the tire 101. Therefore, the pressure in the first chamber 324 reaches the second chamber 324.
25 (ie, the pressure within the tire 101), the spool valve 342 shifts to the right in FIG.

As a result, the passage 313 and the communication hole 323 communicate with each other, and the air in the tire 101 is released from the tire pressure regulating valve 300 and the control line 351 to the atmosphere through the pressure control valve 355 and the muffler 361. In addition, the tire pressure adjustment valve 30
The piping of the control line 351 from the pressure control valve 355 to the pressure control valve 355 is relatively long, and the pipe from the pressure control valve 355 to the silencer 361
Since the flow path area of the piping up to is set small so as to have a throttling effect, the air inside the tire 101 is gradually released into the atmosphere, and the pressure inside the variable pressure chamber 321 does not suddenly drop during this time. Therefore, the state of conduction from the passage 313 to the communication hole 317 is maintained. Needless to say, in order to maintain the pressure in the control line 351 at a predetermined low pressure, not only the conduit throttling effect but also duty control is performed to repeatedly switch the pressure control valve 355 between the second position and the neutral position. Good too.

When the pressure inside the tire 101 approaches the target value in this way, the pressure difference between the first chamber 324 and the second chamber 325 almost disappears, the spool valve 342 returns to the neutral position, and the communication hole 323 and the passage 313 are closed. Cut off.

The ECU 370 has a pressure sensor 365 and a flow rate sensor 366.
It is detected from the output signal that the pressure within the tire 101 has substantially reached the target value, and the pressure control valve 355 is returned to the neutral position, and the pressure release valve 358 is switched to the first position. As a result, the control line 351 is suddenly released to the atmosphere through the muffler 362, the pressure in the variable pressure chamber 321 rapidly decreases and approaches atmospheric pressure, and the diaphragm 331 closes the passage 313. On the other hand, due to the aperture effect of the apertures 326 and 327,
The pressure drop in the first chamber 324 and the second chamber 325 is slow, so the spool valve 342 maintains a substantially neutral position.

Although the detailed structure and operational issues of the rotary shaft seal portion 207 have not been mentioned in the above explanation, the control line 351 is connected to the rotating axle shaft 207 from the hole 211 of the carrier 203, which is a stationary member on the vehicle body side. In order to conduct electrically across the passage 213 of
It is necessary to provide it between 01 and 01.

In FIG. 4 illustrating the structure of the rotary shaft seal portion 207 and FIG. 5 illustrating its operating state, 401 is the carrier 2.
The lip seal is made of an elastic material such as rubber and is fixed in the hole 03 by retaining rings 402 and 403, and has a hole 404 and two lips 405 and 406.

(The lip seal 401 can also be composed of two separate pieces, left and right.) 407 is the axle shaft 201
At the top, retaining rings 408 and 4 are installed to prevent axial movement.
09, the sleeve is rotatably fitted and has one or more holes 410, which are in continuous communication with a passage 213 drilled in the axle shaft 201.

When the pressure of the control line 351 leading to the hole 211 is close to atmospheric pressure, the state is as shown in FIG. 4, and the lips 405 and 406 are not in contact with the surface of the sleeve 407, and a slight gap d is formed. Since there is, Lip Seal 401
There is no friction between the sleeve 407 and the sleeve 40
7 can rotate together with the axle shaft 201. However, when the air pressure p of a predetermined value or more acts on the control line 351, the pressure near the hole 404 increases, so the lip 40
5 and 406 are pushed to opposite sides and follow arrow d in FIG.
The tips of the lips 405 and 406 contact and restrain the outer peripheral surface of the sleeve 407, and the holes 211, 404, and 410 become extensions of the control line 351.
, and a passage 213 form a communication path.

At this time, a slight gap l is provided between the rotating axle shaft 201 and the stationary sleeve 407 restrained by the lip seal 401 in order to reduce friction. Passage 21
Some of the air in 3 leaks.

In addition to the lip-type sealing devices shown in FIGS. 4 and 5, in various actual sealing devices that can be used as the rotary shaft seal portion 207, there is usually some amount of air leakage due to the need to reduce friction. We have no choice but to allow leaks.

Therefore, even if the pressure control valve 355 is returned to the neutral position after pressure increase or decrease control of the tire 101 and the pressure in the control line 351 and the tire 101 are balanced after some time, the control The pressure measured by the pressure sensor 365 on the line 351 does not accurately indicate the air pressure within the tire 101, and a pressure difference of ΔP occurs when equilibrium is reached.

A portion of the pressurized air leaks from the leakage point of the rotating shaft seal portion 207, that is, from the gap 1 of the sleeve 407 in the example shown in FIGS. It indicates low pressure.

Moreover, it has been found that the time required for the pressure to reach equilibrium, that is, the time required to reach equilibrium, is significantly different between tire pressure increase control and tire pressure decrease control. Figure 6(a)
, (b) show the change in pressure over time in each case, where the solid line shows the air pressure in the tire 101, and the broken line shows the pressure sensor 36 in the control line 351.
5 shows the detected pressure. In either case, the pressure control valve 355 is returned to the neutral position at time X to terminate pressure increase or decrease control.

At the time of pressure increase control, as shown in FIG. 6(a), the pressure in the control line 351, which was initially higher than the pressure of the tire 101, is returned to the neutral position 1 of the pressure control valve 355, and the pressure increase control is performed. As it stops, it descends, and due to air leakage from the rotary shaft seal portion 207, the pressure drops below the pressure of the tire 101, and the pressure is balanced at a pressure lower by ΔP.

Since the supply pressure was initially higher than the pressure in the tire 101, a relatively long time, as indicated by Tz, is required to reach equilibrium.

On the other hand, during pressure reduction control, as shown in FIG. 6(b), from the time of pressure reduction control, the control line 35
Since the pressure in tire 101 is lower than the pressure in tire 101, when the pressure control valve 355 is returned to the neutral position and pressure reduction control is stopped, a large amount of air is stored even if there is leakage from the rotary shaft seal portion 207. Due to the pressure air returning from within the tire 101, the control line 351
The pressure settles at a value lower than the tire pressure by ΔP.

As shown in FIG. 7, it has been found that the time to reach equilibrium varies greatly depending on the air pressure of the tire 101, especially in the case of pressure increase control. When tire pressure is relatively low, it takes a considerable amount of time to reach an equilibrium state after pressure increase control.
When the tire pressure is high, it takes a relatively short time. On the contrary,
After pressure reduction control, an equilibrium state is reached in a short, approximately constant period of time, almost regardless of the level of tire pressure.

Next, the manner in which the equilibrium arrival times TZ and Tc change will be analyzed in more detail, including the behavior of the spool valve 342 of the tire pressure regulating valve 300. Except for non-control, the control line 351 is at a pressure sufficiently higher than atmospheric pressure not only during pressure increase control and pressure decrease control, but also when tire pressure is monitored (pressure detection). This pressure keeps the pressure in the variable pressure chamber 321 of the tire pressure regulating valve 300 higher than atmospheric pressure,
The diaphragm 331 is pressed against the spring 333 to establish communication between the passage 313, the first boat 311, and the control line 351. Therefore, under these conditions, a small amount of air always leaks from the rotary shaft seal portion 207. Therefore, the spool valve 342, which was in the equilibrium position as shown in FIG. 8(a) immediately after the control was stopped, is moved to the position shown in FIG. As shown in FIG. When the amount of leaked air is large, the overlap is exceeded as shown in Fig. 8(c), but under normal conditions, the amount of leaked air is small, so the spool valve 342 is slightly opened at position 1. Even so, the valve closes immediately, and balance occurs at the position where the amount of overlap is zero, as shown in FIG. 8(d). At this time, the pressure in the control line 351 detected by the pressure sensor 365 is the first
equal to the pressure in the chamber 324, and the tire pressure is equal to the pressure in the second chamber 32.
Equal to the pressure of 5. i.e. tire pressure and control line 3
The pressure difference ΔP at 51 is formed as a pressure difference across the spool valve 342 located at the position shown in FIG. 8(d). Note that the arrows in FIGS. 8(b) and 8(c) indicate the flow of leaking air.

From the pressure equilibrium state shown in FIG. 8(d), the difference ΔP between the tire pressure and the pressure detected by the pressure sensor 365 is expressed as follows.

ΔP=2K·χ/S However, K is the spring constant of the spring 324 (N/l1l), X is the overlap amount (II) of the spool valve 342, and S is the cross-sectional area of the spool valve 342 (III).

The reason why the times T2 and Tc for reaching equilibrium between the tire pressure and the control line pressure are significantly different after the pressure increase control and after the pressure decrease control can be explained from the behavior of the spool valve 342 of the tire pressure adjustment valve 300 as follows. I can do it.

First, during pressure increase control, as shown on the left side of the three time-lapse graphs in FIG. 9(a), the spool valve 342 is
24 compresses the spring 347 and opens the second chamber 32.
5 side, but due to the stop of pressure increase control, pressure control valve 3
55 returns to the neutral position and the supply of high pressure air to the control line 351 is cut off, the spool valve 342 cuts off the communication between the passage 313 and the communication hole 323, and the spring 3
Return to neutral position where forces 46 and 347 are balanced (middle drawing). However, due to air leakage in the rotary shaft seal portion 207, a small flow of air occurs in the throttle 326, and the pressure in the first chamber 324 is lower than the pressure in the second chamber 325, so as shown in the drawing on the right. Spool valve 342 compresses spring 346 to reach an equilibrium position (same as FIG. 8(d)). In this way, since the spool valve 342 gradually moves through a long stroke that includes blocking the passage midway, the arrival time Tz becomes long.

On the other hand, during pressure reduction control, the spool valve 342 is in the position shown on the left side of FIG.
3 and the communication hole 323, but when the pressure reduction control was stopped, the pressure control valve 355 returned to the neutral position, and the pressure was discharged from the control line 351 through the throttle pipe and the muffler 361 into the atmosphere. When the air flow stops, the pressure in passage 313 and first chamber 324 increases, causing spool valve 342 to move slightly to the left until it reaches the equilibrium position shown in the drawing on the right (same as (d) in FIG. 8). take. The distance traveled during this time is small, and there is no need to block the flow path along the way.
Movement to the equilibrium position ends in borrowed time. Therefore, this arrival time Tc becomes small.

Based on the above considerations, the inventors came up with the idea that in order to shorten the time TZ to reach equilibrium after pressure increase control, the same operation as in pressure reduction control should be added intentionally. That is, after the pressure increase control is completed, the pressure control valve 355 (FIG. 2) is not only returned from the first position to the neutral position, but also subsequently moved to the second position for a short period of time to remove the air in the control line 351. An operation is added to momentarily release the pressure to the atmosphere via the pressure control valve 355 and the muffler 361. This operation
Of course, this can be done automatically according to a command from the ECU 370.

Due to this instantaneous pressure reduction operation, the spool valve 342, which was in the position shown in the left drawing in FIG. Therefore, when the pressure control valve 355 is returned to the neutral position, it can immediately move to the equilibrium position shown in the drawing on the right. As a result, the time T2 to reach equilibrium after pressure increase control is a short time that is not much different from the time Tc to reach equilibrium after pressure decrease control, and in both cases, tire pressure can be detected quickly and both can be automatically controlled. This will allow them to be treated equally. Needless to say, the actual tire pressure is calculated by adding the pressure drop ΔP due to leakage to the detected value of the pressure sensor 365, but such calculation processing is performed within the ECU 370.

FIG. 1 is a block diagram showing the steps of processing and operation for tire pressure measurement corresponding to the characteristics of the method of the present invention. The procedure differs depending on whether the tire pressure is to be measured after increasing the pressure or after decreasing the pressure.When measuring after increasing the pressure, return the pressure control valve 355 to the neutral position as shown in the left column. After that, the tank boat 355 is released to the decompression side and the boat 355 is returned to the neutral position. From now on, the process is the same as when measuring the tire pressure after pressure reduction, and the pressure control valve 355 is placed in the neutral position l for a short time.
For example, after waiting for the pressure to reach an equilibrium state for 0.5 seconds, measure the pressure in the control line 351, add the pressure drop ΔP due to air leakage from the rotating shaft seal portion 207 to this, and then Find the exact pressure inside 101.

Further, FIG. 10 shows an example of the entire tire pressure control procedure executed by the ECU 370 in the form of a flowchart, including the above features of the present invention.

In S (step) 101 of FIG. 10, the target tire pressure PT is changed and set according to changes in load, road conditions, etc.
When O is read, the process advances to 5102 and the pressure release valve 358
is switched to the second position to cut off communication between the control line 351 and the atmosphere, and at the same time, the pressure control valve 355 is switched from the neutral position to the first position to transfer the high pressure air in the pressure line 356 to the control line 351. It is fed into a conduit that passes through the rotating shaft seal portion 207 and reaches the tire pressure regulating valve 300 to increase the pressure. Thereby, the variable pressure chamber 3 of the tire pressure regulating valve 300 shown in FIG.
21 pressure increases, compressing the spring 333 and pushing the diaphragm 331 to the right, high-pressure air enters the passage 313, pressurizes the first chamber 324 through the throttle 3Z3, and causes the spool valve 342 to move to the second chamber. 325 and communicates the passage 313 with the communication hole 323, the inside of the tire 101 communicates with the control line 351 in FIG. 2.

Therefore, the process proceeds to S103, and the process shown in the left column of FIG. The ECU 370 performs the operation of returning to the neutral position again.
By causing the pressure in the control line 351 (line pressure) and the pressure in the tire 101 to quickly reach an equilibrium state, for example, after a short period of about 0.5 degrees, the pressure sensor 365 brings the pressure into equilibrium. By measuring this pressure and adding ΔP to it, an accurate measured tire pressure PTM is obtained.

Next, in S104, the set target tire pressure P
The difference between TO and the measured tire pressure PTM is calculated, and it is determined whether the absolute value is larger than a predetermined value (eg, 5 kPa). If not, the actual tire pressure PTM is the target tire pressure PT.
Assuming that it is approximately equal to O, the process proceeds to 5108 and the control ends. Although not shown, at this time the pressure release valve 358 in FIG. 2 is switched to the second position to release the control line 351 to the atmosphere. As a result, the tire pressure regulating valve 300 becomes fully closed.

When it is determined in step 5104 that the absolute value of the difference is larger than the predetermined value, pressure increase or decrease control is required, and in order to determine which is the case, the process advances to step 8105 and the set target tire pressure 2 is determined. It is determined whether the value obtained by subtracting the measured tire pressure PTM from 0 is positive or negative.

When the result is determined to be positive, the measured tire pressure PTM is smaller than the target tire pressure PTO and pressure increase control is required, so the process advances to 5106 and estimation control at the time of pressure increase is executed.

Estimated control during pressure increase is performed by holding the pressure control valve 355 at the first position and controlling the pressure from the compressor 352 or air cylinder 354.
High pressure air control line 351, rotating shaft seal part 207
, tire pressure adjustment valve 300, and into the tire 101, the line pressure is measured by a pressure sensor 365, and the flow rate is measured by a flow rate sensor 366. From the line pressure and the flow rate, the pressure inside the tire 101 is measured. This continues until the ECU 370 estimates that PTO has reached the target value PTO.

When it is estimated that the target value has been reached, the pressure control valve 355 is returned to the neutral position, the control line 351 is cut off from the pressure line 356, and the flow returns to step 5103 to actually measure the pressure inside the tire 101. Returning, the tire pressure is measured quickly and accurately as described above, and the process then proceeds to 5104, where it is determined whether the target pressure PTO has been reached.

When the subtraction result is determined to be negative in 8105 described above, the measured tire pressure PTM is larger than the target tire pressure PTO and pressure reduction control is required, so the process proceeds to 5107 and estimation control at the time of pressure reduction is executed. be done.

This control involves switching the pressure control valve 355 to the second position to gradually release the pressure air in the control line 351 to the atmosphere, while monitoring the pressure in the control line 351 and the amount of air flowing out using the pressure sensor 365 and flow rate sensor 366. Measure tire 1
The process continues until the ECU 370 estimates that the pressure inside 01 has reached the target value PTO. When it is estimated that the target value has been reached, the pressure control valve 355 is returned to the neutral position, the control line 351 is cut off from the atmosphere, and the process returns to step 5103 to actually measure the pressure inside the tire 101.

In this case, the tire pressure is measured after pressure reduction control, so follow the steps in the right column shown in Figure 1, and after a short time (e.g. 0.5 seconds), without any need for any operation, Pressure sensor 36
The detected value of 5 is read into the ECU 370, and a constant value of differential pressure ΔP is added thereto to obtain the actual tire pressure value PTM.

In the case of pressure reduction control, the pressure in the control line 351 (line pressure) reaches an equilibrium state with the tire pressure as soon as the control is stopped, so the line pressure is lower than the tire pressure by a constant pressure drop ΔP due to leakage. This is because it will be shown.

〔Effect of the invention〕

By using the method of the present invention, an equilibrium state between tire pressure and line pressure can be quickly obtained not only after pressure reduction control but also after pressure increase control or when simply measuring tire pressure. Even in such cases, accurate tire pressure can be quickly determined by measuring the line pressure and adding a certain differential pressure to it.

Thus, the tire pressure telemetry method of the present invention is highly responsive and accurate, making it suitable for incorporation into an automatic control system, thereby allowing smooth automatic control of tire pressure, It becomes possible to remotely control the tire pressure to any desired level.

[Brief explanation of the drawing]

Fig. 1 is a flowchart of the procedure schematically showing the features of the method of the present invention, Fig. 2 is an overall configuration diagram illustrating a tire pressure regulating device to which the method of the present invention is applied, and Fig. 3 is a tire pressure regulating valve. 4 is a sectional view illustrating the steady state of the rotary shaft seal portion, FIG. 5 is a sectional view illustrating the pressurized state of the rotary shaft seal portion shown in FIG. 4, and FIG. 6 is a sectional view illustrating the structure of the rotating shaft seal portion. (a
) (b) is a line showing a comparison of changes in tire pressure and line pressure depending on the condition in order to explain the principle of operation of the present invention, and Fig. 7 is a line showing a comparison of changes in tire pressure and line pressure that vary depending on tire pressure. Line section showing changes in the time to reach equilibrium, Figure 8 (
a) to (d) are cross-sectional views for explaining the operation of the spool valve in the tire pressure regulating valve, and FIGS. FIG. 10 is a sectional view showing the operation of the spool valve, and is a flowchart showing the control procedure of the tire pressure adjusting device when the method of the present invention is used. 207... Rotating shaft seal portion, 300... Tire pressure adjustment valve, 351... Control line, 355... Pressure control valve, 365... Pressure sensor, 358... Pressure release valve, 341... ...Spool valve. Measurement of tire pressure after pressure increase Measurement of tire pressure after pressure reduction Fig.3 5 Figure 201...Axle shaft 207...Rotating shaft part 401...Rip-n-rule 407...Sleeve diagram Tire pressure (kPa) Processing diagram Diagram

Claims (1)

[Claims] a control line that is switched to a pressure line or a low pressure side by a pressure control valve; a pressure measuring means provided in the control line; a tire pressure regulating valve connected to the control line via a rotating shaft seal part; In a tire pressure remote control device consisting of a pneumatic tire connected to the tire pressure regulating valve, in order to quickly and accurately measure the tire pressure, the pressure regulating valve is operated for a short time before measurement. By connecting the control line to the low pressure side, the pressure in the tire and the pressure in the control line quickly reach an equilibrium state, and then the pressure in the control line is measured by the pressure measuring means; A method for remotely measuring tire pressure, characterized in that the actual measured value of the tire pressure is obtained by adding to the measured value a differential pressure specific to the remote control device caused by air leakage at the rotary shaft seal portion.