AU2984901A - Pressure-controlled three-way valve device, transport vehicle having tire inflation pressure control and method for remote pressure-controlling the valve device - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): COL-VEN S.A.

Invention Title: PRESSURE-CONTROLLED THREE-WAY VALVE DEVICE, TRANSPORT VEHICLE HAVING TIRE INFLATION PRESSURE CONTROL AND METHOD FOR REMOTE PRESSURE- CONTROLLING THE VALVE

DEVICE

The following statement is a full description of this invention, including the best method of performing it known to me/us: PRESSURE-CONTROLLED THREE-WAY VALVE DEVICE, TRANSPORT VEHICLE HAVING TIRE INFLATION PRESSURE CONTROL AND METHOD FOR REMOTE PRESSURE-CONTROLLING THE VALVE DEVICE FIELD OF THE INVENTION: The present invention relates to a valve device for installation in a pressurized air or gas pipe, which device may be controlled either by the gas relative pressure applied to one of the ways of the valve device or by the pressure differential between two of its ways. Thus, the condition of the valve device is remote-controllable through a pipe connected to said one of its ways, without any auxiliary control lines, by varying the air pressure applied in the other end of the pipe. The present invention relates in particular to a three-state valve device capable of operatively being in: a closed or locking position, (ii) an open position between a pair of ways, or (iii) an open position between another pair of ways, according to the state of pressure in one of those ways, which becomes a controller for the valve device.

The invention also relates to a method of controlling the positions of the valve 0 00. device through the state of pressure of the pressurized gas conveyed by the installation pipework.

o: The valve device of the present invention is applicable to inflating and deflating pressurized loads, in particular as a chamber valve, as a component for a tire inflation pressure control system in a motor vehicle. Such systems are used in transport vehicles, 0 in particular trucks and buses, since they allow for corrective actions to be taken with S0" regard to the state of inflation of each particular tire and/or tire axle, either automatically or by hand operation by the driver, without the need for stopping the vehicle, thus resulting in an important element for transport safety.

In the aforesaid application, the valve device is interposed between one end of one installation pipe and the air inlet in the tire, replacing or applied onto the tire's conventional tire valve, and allows performing three operations essential to the abovementioned application, namely: (i)to close the air flow when the instalation is depressurized, in order to prevent the vehicle tires from going down, (ii) to allow a flow of air sufficient for inflating a tire or for keeping it inflated, for instance in case of a fiat, so as to avoid stopping the car anywhere, and (iii) to allow for deflating the tires, for example when the road and/or load conditions require to reduce the inflation pressure.

076-00-06 AU108m In this application, the aforesaid controller way, which is provided on one side of the valve device plunger, is connected to the pipework which, in addition to providing the state control pressure, simultaneously provides the inflating air (gas); while a second way, provided on the other side of the plunger, is coupled to the tire inner tube, and the third way may be arranged for venting air from the second way.

BACKGROUND ART In the abovementioned application, in addition to being able to inflate transport vehicle tires in a controlled way and during motion, it is also desirable to have the possibility of reducing the tire pressure, under the control of a remote device, such as 1" 0 described in. Argentine patent application No P96.01.04.874 published on September 1998 (AR 004.085). For such purpose, it is not desirable to use, as the component designated with reference numeral 39 in said document, conventional threeway valves having independent controls, for example solenoid valves, since this would S. require laying control lines to the wheel location, which would complicate the installation and cannot be easily protected against mechanical accidents.

This problem was initially solved by the two-way valve device described in Argentine patent application No P97.01.01607, published on 29th September 1999 (AR 006772), which conventionally comprises a valve body within which a passage extends between two air inlet/outlet ports provided in opposite longitudinal ends of the valve body, a plunger housed in the passage and a spring stress means which stresses the plunger towards a valve seat in the passage for normally closing the passage, that is in the absence of a greater pressure in the installation pipe. Said valve is provided with an opening adjuster which makes it selectively bidirectional to take, under pipe pressure control, the following positions: locked when the installation is depressurized), maximum opening for air flow in the positive direction (inflation), which is reached when the inlet pressure or resultant force on the plunger is sufficient to overcome the stressing spring restoring force, and minimum opening for air return in the opposite direction (deflation). In the latter minimum opening position, the valve device allows a controlled air flow to return through the installation pipework.

076-00-06 AU1 08m 3 SUMMARY OF THE INVENTION: Accordingly, it is an object of the present invention to provide a chamber valve device for use as a component in an air pressure control system for a vehicle tires. It is another object of the present invention to provide a valve device which remains closed when depressurization of the said system occurs, either because of it being turned off or because of a mechanical accident in the installation pipework, (ii) allows an air flow through the installation pipework to inflate the tire, such as to restore a normal or desired inflation pressure, and (iii) allows to vent air for deflating the tire, without the need for passing through the installation pipework.

S. 10 It is a further object of the present invention to provide a valve device such that the state of the valve device may be controlled without the need for end controls in the structure of the valve device, but by means of the resultant force directly applied on the plunger, due to the condition of the installation pipework. It is still an object that the state So of the valve device may be pneumatically controlled by the same air relative pressure existing by the device.

It is yet another object of the present invention to provide a valve device having a simple, robust, unexpensive construction, in view of the number of like devices needed by a multiple-axle loading vehicle as well as the place (the wheel) each device is respectively mounted on, which place is difficult to protect against strokes and vibrations and therefore subject to mechanical accidents, for example as a result of stones raised by the same or another vehicle.

The above and other objects and advantages which will be apparent upon consideration of the following detailed description are provided according to the invention in a pressure-controlled three-way valve device of the type comprising a valve body in which an inlet passage extends between an inlet way and a second way, said passage housing a plunger coupled to a restoring means which stresses said plunger in the direction of the inlet way. According to the invention, the valve body includes an outlet way before which an outlet valve is located which remains closed when the plunger is in one of its respective opposite travel limit positions, such that the outlet valve only opens when said plunger is in an intermediate position.

According to a preferred embodiment, the outlet valve comprises a pair of circumferential steps formed on the plunger outer wall surface, between which is a seal ring made up of two inner circumferential lips respectively in correspondence with the steps, such that in both plunger travel limit positions a predetermined one of those steps 076-00-06 AU 1 08m 4abuts against the corresponding lip, thus closing the outlet way, which lip remains in the open position only by means of respective gaps formed between the seals and their corresponding Seats in the plunger's intermediate position. The inlet passage crosses the plunger longitudinally, passing through an inlet valve normally closed by the elastic restoring means.

The above objects are essentially provided as a result of the plunger actually involving a mobile seat for the inlet valve, thus inserting an intermediate pressure range within which the plunger longitudinal movement is used as a control for the outlet valve.

The present invention also provides a novel method for remotely controlling the 00 10 state of the valve device without any additional control lines, to correct or maintain a desired pressure in the tire, by varying the gas pressure in the conduit coupled to the inlet way. The method comprises the steps of: depressurizing the pipework, to shut the valve device; (ii) pressurizing the pipework at a positive pressure differential (i.e.

S greater than the air pressure in the chamber) range, to open the inlet passage for inflating; and (iii) applying gas to the inlet way at a pressure within a second range, substantially lower than the pressure present in the second way, that is a "negative' differential relative to the second way (for example, initially depressurizing and bringing the inlet way to the desired pressure), to open the venting way and deflate the tire. In the •first case, the valve device will operate to protect the pressure existing in the controlled 20 side, while in the two other cases it will act to restore or correct the pressure of the tire being controlled, bringing it to the value present in the pipework.

S. The present invention is applicable to transport vehicles provided with tires which inflation pressure is controlled by a pressurized air pipework, for connecting each tire being controlled as a pipework load, through a respective valve device according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS: The above and other objects and advantages of the invention as well as the way it may be developed, implemented and practiced will be more apparent upon consideration of the following detailed description of an exemplary embodiment, taken in conjunction with the accompanying drawings, in which: Figures 1, 2 and 3 are longitudinal cross-sectional views of the valve device according to a preferred embodiment of the present invention wherein Figure 1 shows the valve device in the closed position Figure 2 shows the valve device in the inflation position and Figure 3 shows the valve device in the deflated position (iii).

076-00-06 AU108m Figures 4A and 4B are two state of pressure versus time graphs depicting the operation of the valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT: The following detailed description of the preferred embodiment of the valve device of the invention has been developed such that those skilled in the art can reproduce, with the relevant authorization or license, a chamber valve device to control a vehicle tire inflation and deflation which may be used, for example, with the device as defined in the abovementioned Argentine patent application N 0 P96.01.04874, as the component therein designated by reference numeral 39.

S" 10 Construction: Figures 1, 2 and 3 show a cross-sectional view of a two-valve device 11 .*.according to the present invention, in full length. The two-valve device 11 comprises a valve body 13 within whici is an inlet circuit 15A extending longitudinally between two air ways 17A, 17C, implemented in respective longitudinally-opposing ends 19 of the valve body 13. Way 17A is for the inflow of inflating air; accordingly, it is coupled to the pressurizing installation pipework (not shown), from which it receives both the inflating air flow and pressure signals for controlling the valve device 11. In contrast, the way 17C is coupled to the tire chamber (also not shown), such that it behaves as an inflating air inlet I deflating air outlet conduit. A port 17B is provided on one side of the valve body 13 to define a deflating air outlet way in communication with way 17C through an outlet circuit S. The inside of the valve body houses a longitudinally-travelling plunger 21, springstressed in the direction of the end corresponding to the inlet way 17A. Plunger 21 is internally crossed by an axial passage 25 normally closed by an inlet valve comprised of a piston 27 axially slidable within the valve body 13 and stressed by spring 23 against a plunger end, wherein the piston has an axial projection 29 which is introduced into the inner passage 25 of the plunger in order to keep the piston axially centered with respect to the plunger, and a cicumferential lip closing against end 33 of plunger 21, thus normally closing the outlet of the said passage 25. Piston 27 does not seal against the side wall of the valve body 13 but has longitudinal slots allowing for the gas flow.

A circumferential recess 35 is provided on the outer surface of the plunger 21 in which a seal ring 37, arranged against the surface of the valve body 13 inner wall, extends laterally and inwards. This seal ring 37 also has a pair of circumferential lips 076-00-06 AUlO08m 39A, 398 in respective correspondence with the pair of steps 41A, 41B defined by the recess 35. Thus, the travel of plunger 21 is limited by the steps 41 (for generalization, suffixes etc. are omitted in the reference numerals) alternatively abutting against lips 39.

Operation To inflate the tire, pressurized air is applied to the inlet way 17AI at a pressure sufficiently exceeding the tire pressure present in way 17C to push plunger 21 against the spring, until step 41A abuts against lip 398 of seal 37, thus keeping closed the air passage to the venting way 17A. Plunger 21 stops at this travel limit, but the air pressure *10 in inlet way 17A acts on piston 27 breaking the strength of spring 23 to open passage le.: 25, thus allowing for the tires to be inflated.

Thus, a possible pressure drop in the chamber, for example as a result of a flat, *causes a positive pressure differential generating a net resultant on plunger 21 in the :direction of way 17C, sufficient to break the strength of spring 23 and to fully open the inlet circuit 15A, as shown in Figure 1.

The device of the invention is designed to foresee any possible breakage or failure in the installation, in which case the valve device 11 automatically closes during any depressurization of the pipework. Therefore, in the absence of air pressure in the °inlet way 17A, spring 23 stresses the valve piston 27 against plunger 21, thus closing passage 25, as well as plunger to its limit position in the direction of inlet way 17A, wherein the other step 418 abuts against the other lip 398 of seal 37, thus closing the air flow through the deflation circuit 15B, that is isolating the venting way 17B from way 17C coupled to the tire, the three ways of the valve thus remaining locked, as shown in Figure 2.

If the driver decides to reduce the pressure in the tire, it is advisable to first depressurize the pipework, depriving the inlet way 17A of air pressure (ensuring the momentary blocking of all the vehicle tires), and to then increase the pressure to the desired tire calibration pressure. Plunger 21 is then brought to an intermediate position opening respective gaps between both assemblies of lips 39 and steps 41, as shown in Figure 3, thus allowing air venting through passage 158 open in the direction of the outlet way 178. The dynamic state of plunger 21 may be summarized by equation PA.SA Pc. Sc K.X where: PA: air pressure in the inlet side; 076-00-06 AUl 08m 7 SA: cross-sectional area of plunger 21 in the inlet side; Pc: air pressure in the chamber side; Sc: cross-sectional area of plunger 21 in the chamber side; K: elastic constant of spring 23; X: compression of spring 23; By way of simplification, taking into account that Sc SA a is a constant ratio (depending upon the components' geometric parameters such as the diameter of valve lip 31) and defining variable R K.X SA (also constant), the state of equilibrium of plunger 21 in its intermediate position may be characterized by the following equation: PA o Pc R This equation defines the states of operation of the valve device 11 According to this equation to place the plunger in the intermediate position the pressure signal PA in the inlet way 17A should be equal to the sum defined in the right-hand member of equation determined by the tire pressure Pc and the restoring force R of spring 23 semicompressed a length X. In addition, for the inflation operation, •the inlet pressure PA must meet condition PA C Pc RA where: RA is the restoring stress of spring 23 for a compression XA of same, corresponding to butt 39A-41A.

Synthesizing, provided that:: PA C Pc RB, wherein Re R(Xs) for the plunger abutting against lip 39B of seal 37, the seal of lip 39B is closed against step 41 B, thus bringing the two-valve device 11 to the locking condition.

(ii) PA 0( Pc RA, the seal of lip 39A is closed against step 41A, thus allowing the twovalve device 11 to be in a position capable of inflating, the inflation condition being reached by adding an overpressure APA to force piston 27 against spring 23 and open the inflating way (iii) PA C Pc for XB X XA, plunger 21 floats in an intermediate position without any contact with seal 37, the deflating way 15B thus being opened.

In the exemplary embodiment described, a 0,48 and in a first approximation we can neglect R(XA) R(XB) 0 depending on how the spring 23 is selected. Assuming a calibrated pressure of 7 kg/cm 2 (16,5 kPa), it appears that the opening of outlet valve 39-41 takes place in the vicinity of: 076-00-06 AU108m 8 8 PA r Pc 0,48 x 7 kg/cm 2 (16,5 kPa) 3,36 kg/cm 2 (7,92 kPa) This is illustrated in Figures 4A and 4B. Both figures depict the different conditions of the two-valve device 11, separated by constant pressure straight lines, such conditions being the three states as mentioned above and a fourth state for which, in practice, hysteresis is observed between the inflation and deflation states. Therefore, to deflate the loading tire at a slightly lower pressure Pc 2 in the hysteresis region, it is advisable to initially reduce inlet pressure PA to a lower value, for example 45 of the calibration value Pci, ensuring that the device enters the deflation region during a short time interval, and to then increase the inlet pressure PA to the desired level Pc2, as So 10 shown in Figure 4A. Figure 4A shows how the tire pressure is brought to the desired g:o. level Pc2 from a depressurized inlet pipework.

~The operation principles described are accomplished as a result of the plunger 0 21 involving as a matter of fact a mobile seat for inlet valve 27, thus generating an S. 00: intermediate pressure range within which the longitudinal movement of plunger 21 is used as a mobile element for the outlet valve.

V: It will be obvious to one skilled in the art that various modifications and/or 0.0 variations can be made to the invention as shown in the specific embodiment described, without departing from the scope and spirit of the invention. For example, instead of air .o°.t another gas or fluid may be used other than air or mixed with air. The valve device 11 of the invention may also be used in applications such as selectively pumping or purging a gas to and from a load. For example, as a previous step to deflating the load, rather than depressurizing the inlet way 17A, its pressure PA may be reduced to a value low enough such as 45 of pressure Pc in the second way 17C.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

For the purposes of this specification it will be clearly understood that the word "comprising" means "including but not limited to", and that the word "comprises" has a corresponding meaning.

Claims (1)

1. 076-00-06 AU108m to The valve device according to claim 6, characterized in that said plunger and said inlet valve are stressed by the same restoring means in the direction of the inlet way. The valve device according to claim 6 or 7, characterized in that said restoring means comprises a spring resting on said valve body in the vicinity of said second way. The valve device according to claim 8, characterized in that said inlet valve comprises a piston body seated against said spring and axially opposing said plunger, said piston body having an axial projection fitting in said passage which longitudinally crosses the plunger and a circumferential lip fitting in the plunger's opposite end. 10.- A transport vehicle provided with tire inflation pressure control, characterized in that each tire having controlled inflation pressure is coupled to a pressurized air feeding pipe by means of a respective valve device according to any one of the preceding claims. 15 11.- A method for remote-pressure controlling the valve device of any of claims 1 to 9, in which, in order to open its inlet passage, gas is applied to the inlet way at a pressure comprised in a first range, substantially greater than the pressure present in the second way, until stressing the plunger against the corresponding travel limit, characterized in that, in order to open the outlet passage of the valve device by closing the inlet passage of the valve device, gas is applied to the inlet way at a pressure in a second range, substantially lower than the pressure present in the second way, until stressing the plunger to an intermediate position between both travel limits, by opening the outlet valve formed in both butts of the opposite travel limits of the plunger. 12.- A method according to claim 11, the second way being connected to a pneumatic load the pressure of which is to be controlled, characterized in that the pressure of said pneumatic load is reduced to a lower desired pressure by applying said desired pressure to said inlet way. 13.- A method according to claim 12, characterized in that said inlet way is previously depressurized to a pressure substantially lower than said desired pressure and, once the locking of the valve device has been ensured the pressure in said inlet way is increased to said desired pressure. Dated this 23 day of March 2001 COL-YEN S.A. By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia