Tire valve and method for inflating and deflating a motor vehicle tire

Abstract

Tire valve (10) for inflating and deflating a motor vehicle tire, comprising a hollow valve body (12) defining a receiving space (13), wherein the valve body (12) has an inlet opening (18) communicating with the receiving space (13) and an outlet opening (20) arranged axially offset from the inlet opening (18) and communicating with the receiving space (13), a valve bolt (14) axially displaceably received in the receiving space (13) of the valve body (12), a return spring (16) supported on the valve body (12) and acting on the valve bolt (14), wherein the valve bolt (14) is contoured such that in a first position for closing the motor vehicle tire both the inlet opening (18) and the outlet opening (20) are closed,In a second position axially displaced from the first position for emptying the motor vehicle tire, both the inlet opening (18) and the outlet opening (20) are open, and in a third position axially displaced from the first and second positions for filling the motor vehicle tire, the inlet opening (18) is open and the outlet opening (20) is closed.

Description

The invention relates to a tire valve and a method by which a motor vehicle tire can be filled and emptied. The optimal tire pressure for motor vehicles varies depending on the surface and load. For example, on loose surfaces like sand, mud, or similar terrain, the best possible traction is needed, which can be achieved with a very low tire pressure. On a level surface, such as a country road, sufficient traction is achieved even with a higher tire pressure, although a higher tire pressure results in less friction and lower fuel consumption. The optimal tire pressure for a fully loaded truck is higher than for an empty one. Trucks that operate off-road or on construction sites, such as dump trucks, are typically either completely empty or fully loaded, so the difference between the optimal tire pressures is particularly significant for these types of vehicles. It is known to provide two air lines for tire pressure regulation, each controlled by a valve, to supply air from a pressure source via one air line or discharge air via the other, depending on the desired tire pressure. Valves are known in a wide variety of designs. Examples include US 2,989,999 A and JP S63-255,107 A. There is a constant need to make filling and emptying a motor vehicle tire cost-effective with the least possible design effort. The object of the invention is to demonstrate measures that enable cost-effective filling and emptying of a motor vehicle tire with minimal design effort. The problem is solved according to the invention by a tire valve having the features of claim 1 and a method having the features of claim 10. Preferred embodiments of the invention are specified in the dependent claims and the following description, each of which can individually or in combination represent an aspect of the invention. According to the invention, a tire valve for inflating and deflating a motor vehicle tire is provided with a hollow valve body defining a receiving space, wherein the valve body has an inlet opening communicating with the receiving space and an outlet opening arranged axially offset from the inlet opening and communicating with the receiving space, a valve bolt axially displaceable within the receiving space of the valve body, and a return spring supported on the valve body and acting on the valve bolt, wherein the valve bolt is contoured such that in a first position for closing the motor vehicle tire both the inlet opening and the outlet opening are closed.In a second position axially displaced from the first position for emptying the vehicle tire, both the inlet opening and the outlet opening are open, and in a third position axially displaced from the first and second positions for filling the vehicle tire, the inlet opening is open and the outlet opening is closed. Instead of using separate valves for inflating and deflating the tire, a single tire valve is sufficient for both functions. Specifically, the air line connected to the inlet opening, intended for inflating, can also be used for deflating. This is achieved by short-circuiting the inlet and outlet openings via the valve body's receiving chamber in the second position of the valve pin. For the different operating states – "hold," where the tire is sealed in the first position; "deflate," in the second position; and "inflate," in the third position – the valve pin is simply moved axially within the receiving chamber relative to the valve body between these positions.This design utilizes the fact that a pressure source for inflating a vehicle tire within a tire pressure control system can act axially on the valve pin against the spring force of the return spring. This allows the pressure applied to the valve pin to easily move it to the desired position without significant design complexity. Trucks, in particular, are equipped with a pneumatic system whose pressure source can be used to actuate the tire valve and to inflate and deflate the tire. The ability to easily control the three different valve pin positions with a single pressure source enables cost-effective tire inflation and deflation with minimal design effort. A throttling element can be connected to the outlet port to delay the deflation of the vehicle tire and, by means of the slowly decreasing tire pressure, to more easily achieve a desired target pressure. Additionally or alternatively, a silencer can be connected to the outlet port to prevent unnecessary noise emissions during tire deflation. In particular, the silencer can also provide deliberate throttling. The inlet port can be coupled to the inner tube of the vehicle tire, particularly via a rotary feedthrough, so that the tire valve does not need to rotate with the tire. The valve body can be designed, in particular, as a hollow cylinder closed at one end. The return spring can be provided between the valve pin and the closed axial side of the valve body.The return spring is designed, in particular, as a helical spring, especially a compression spring. The valve pin can be inserted into the receiving chamber on the open axial side of the valve body. Optionally, the valve pin can protrude from the valve body on the open axial side. Alternatively, the valve pin can be recessed in the valve body in any position, so that a pressure chamber, at least partially enclosed by the valve body, is formed on the end face of the valve pin facing the open axial side. In particular, a pressure source is applied to one end face of the valve pin to axially displace the valve pin against the spring force of the return spring. The valve pin can thus be pneumatically displaced axially, using a pressure source that is already present in the vehicle. Specifically, a pressure source is provided for generating pneumatic pressure for a pneumatic system, which is already standard in trucks, and this pressure source is also used to displace the valve pin. This allows the design complexity of the tire valve to be kept to a minimum. Preferably, the pressure source communicates with the receiving chamber, at least for the purpose of inflating the vehicle tire. This allows the pressure source to be used not only for moving the valve bolt but also for inflating the vehicle tire. Separate pressure sources can thus be eliminated, thereby minimizing the design complexity. Preferably, the return spring is maximally relaxed in the second position of the valve pin and maximally tensioned in the third position. The pressure source and the return spring can be located on different axial sides of the valve body, thus preventing mutual interference. Particularly when pressure is applied to the axial side facing away from the return spring to inflate the vehicle tire, a particularly high pressure can develop, forcing the valve pin as far as possible into the valve body against the spring force of the return spring. When a reduction in tire pressure is desired, the pressure supplied by a pressure source is typically minimal, allowing the return spring to automatically move to the second position intended for deflation. In particular, the valve pin can be detachably locked to the valve body, specifically using a locking mechanism based on the ballpoint pen principle. This eliminates the need to maintain a certain minimum pressure on the valve pin to close the vehicle tire in the first position. Preferably, a locking device engaging the valve body and the valve bolt is provided, wherein the locking device has a feed sleeve axially supported on the valve body, wherein the feed sleeve, when axially displaced into the valve body, can be abutted with a stop on a rotary ramp of the valve body inclined against the axial direction and circumferentially, wherein, after sliding on the rotary ramp, the stop of the feed sleeve, in a circumferentially rotated position, can be pressed by the return spring with an axial movement component in the direction out of the valve body against a retaining ramp of the valve body following the rotary ramp, wherein, after a further axial displacement of the valve bolt into the valve body, the valve bolt can be rotated circumferentially past the retaining ramp and can be axially displaced by the return spring into a position maximally extended out of the valve body.The locking mechanism can thus actuate the individual positions of the valve pin according to the ballpoint pen principle, through a series of short pressure pulses. In the fully retracted position of the valve pin, particularly the third position intended for filling, a high pressure is already applied, so that axial support of the valve pin by means of the return spring is not necessary in this position. Therefore, it is sufficient if the locking mechanism provides only two locking positions, corresponding in particular to the first and second positions. For the fully extended position of the valve pin, an axial stop can be provided, for example, formed by a cover and / or a radially inwardly projecting extension of the valve body, against which the return spring can push the valve pin past the retaining ramp. Particularly preferably, the inlet opening of a first check valve and / or the outlet opening of a second check valve can be closed, wherein the first check valve and / or the second check valve has a closing element, in particular a spring-loaded ball, that can be displaced by the valve pin. The closing element of the respective check valve can project slightly into the receiving chamber from the radial outside through the inlet opening or the outlet opening, so that, during axial displacement, the valve pin can abut the closing element with a contact surface, in particular an angled one, and lift the closing element from the inlet opening or outlet opening, which acts as a sealing seat, thereby opening the respective check valve. The closing of the inlet opening and the outlet opening is effected by the respective check valve, so that the valve pin does not have to perform a sealing function.This makes the tire valve correspondingly simple and inexpensive to design. In particular, the valve pin has a first radial recess for closing the inlet port and a second radial recess for closing the outlet port, wherein the axial extent of the first recess is smaller than the axial extent of the second recess. Due to the different axial lengths of the recesses, a simple design of the valve pin allows the inlet port to be open one more time than the outlet port in each of the three axially spaced positions of the valve pin. The respective recess is formed, in particular, by a reduction in the diameter of the valve pin, which is essentially cylindrical, compared to its outer diameter, with the axial ends of the recesses preferably being chamfered towards the radial plane.The beveled axial ends of the recesses can each form a contact surface that strikes a closing element, in particular a ball, of the check valves blocking the inlet or outlet opening, in order to open the check valve by displacing the respective closing element in a direction radial to the valve body. Preferably, an annular gap is formed between the valve pin and the valve body to allow air to pass through. The valve pin can be held in the valve body with a significant amount of play, so that this play forms the annular gap. The tight tolerance requirements can reduce manufacturing costs. Air supplied by a pressure source can be directed to the inlet opening via the annular gap. Additionally, air from the vehicle tire can be directed through the annular gap from the inlet opening to the outlet opening. The invention further relates to a method for inflating and deflating a motor vehicle tire, in which a tire valve, which can be designed and further developed as described above, is subjected to an axial pressure acting on the valve pin against a spring force of the return spring, in particular an impulse-like pressure pulse, between the first position, the second position, and the third position, wherein, in particular, the valve body is moved to the position retracted as far as possible into the valve body before the valve body is moved to the position extended as far as possible out of the valve body. The method can be designed and further developed as described above with reference to the tire valve. The three different positions of the valve pin, which can be easily controlled with the aid of a pressure source, enable cost-effective inflation and deflating of a motor vehicle tire with minimal design effort. The invention is now explained by way of example with reference to the accompanying drawings and preferred embodiments, wherein the features shown below can represent an aspect of the invention, either individually or in combination. The drawings show: Fig. 1: a schematic sectional view of a tire valve in a first position, Fig. 2: a schematic sectional view of the tire valve from Fig. 1 in a second position, and Fig. 3: a schematic sectional view of the tire valve from Fig. 1 in a third position. The tire valve 10 shown in Fig. 1 for a motor vehicle tire, in particular of a truck, has a valve body 12 designed as a hollow cylinder closed at one end, in the receiving chamber 13 of which a valve pin 14 is axially displaceable. A return spring 16, designed as a compression spring, is provided between the valve pin 16 and the closed axial side of the valve body 12. The valve body 12 has an inlet opening 18 and an outlet opening 20 offset axially and, in particular, also circumferentially from the inlet opening 18 in its outer surface, each of which can be closed radially from the outside by a closing element 22 designed as a ball. In the first position of the valve pin 14 shown in Fig. 1, both the inlet opening 18 and the outlet opening 20 are closed, so that pressure from the vehicle tire connected to the inlet opening 18 can be maintained. For this purpose, the valve pin 14 has a first recess 24 formed by a reduction in diameter, into which the closing element 22 of the inlet opening 18 can project, so that the closing element 22 can tightly close the inlet opening 18. Correspondingly, the valve pin 14 also has a second recess 26 formed by a reduction in diameter, into which the closing element 22 of the outlet opening 20 can project, so that the closing element 22 can tightly close the outlet opening 20.The valve pin 14 can be held in the first position by pressure provided by a pressure source, which acts on an end face 28 facing away from the return spring 16 and is in equilibrium with the spring force of the return spring 16. Preferably, however, the valve pin 14 is positively locked, in particular latched, in the first position by means of a locking device functioning according to the ballpoint pen principle. When the pressure acting on the end face 28 is reduced, the spring force of the return spring 16 can extend the valve pin 14 further out of the valve body 12, as shown in Fig. 2. For this purpose, a short pressure pulse is applied to the end face 28 beforehand to release the locking device, which functions according to the ballpoint pen principle, and to move it into one of the second positions of the valve pin 14 shown in Fig. 2. During the axial displacement of the valve pin 14 from the first position shown in Fig. 1 to the position shown in Fig. 2, the valve pin 14 is extended by a short pressure pulse.In the second position shown in Fig. 2, an angled contact surface 30 provided at the axial end of the first recess 24 can abut the closing element 22 of the inlet opening 18, so that the closing element 22 can only penetrate into the receiving chamber 13 up to the radially outermost outer surface of the valve pin 14, thereby allowing the inlet opening 18 to be opened against a spring force of a check valve acting on the closing element 22. Simultaneously, during the axial displacement of the valve pin 14 from the first position shown in Fig. 1 to the position shown in Fig. 2, the closing element 22 can be opened against the spring force of a check valve acting on the closing element 22.In the second position shown in Figure 2, a chamfered contact surface 30, provided at the axial end of the second recess 26, abuts the closing element 22 of the outlet opening 20, so that the closing element 22 can only penetrate into the receiving chamber 13 up to the radially outermost outer surface of the valve bolt 14. This allows the outlet opening 20 to be opened against a spring force of a check valve acting on the closing element 22. Air escaping from the vehicle tire via the inlet opening 18 can flow to the outlet opening 20 via an annular gap 32 formed between the valve bolt 14 and the valve body 12, thereby reducing the pressure of the vehicle tire. When a particularly high pressure is applied to the end face 28 of the valve pin 14, the valve pin 14 can be drawn against the spring force of the return spring 16 as far as possible into the valve body 12, as shown in Fig. 3. Due to the significantly greater axial extent of the second recess 26 compared to the first recess 24, in the third position of the valve pin 14 shown in Fig. 3, the inlet opening 18 is open, but not the outlet opening 20. The outlet opening 20 is closed. The pressure, applied in particular by a compressed air source, causes air to flow from the end face 28 of the valve pin 14 through the annular gap 32 formed between the valve pin 14 and the valve body 12 to the inlet opening 18, thereby inflating the vehicle tire and increasing its pressure. Reference symbol list 10 Tire valve 12 Valve body 13 Receptacle 14 Valve bolt 16 Return spring 18 Inlet opening 20 Outlet opening 22 Closing element 24 First recess 26 Second recess 28 End face 30 Contact surface 32 Annular gap

Claims

Tire valve (10) for inflating and deflating a motor vehicle tire, comprising a hollow valve body (12) defining a receiving space (13), wherein the valve body (12) has an inlet opening (18) communicating with the receiving space (13) and an outlet opening (20) arranged axially offset from the inlet opening (18) and communicating with the receiving space (13), a valve bolt (14) axially displaceably received in the receiving space (13) of the valve body (12), a return spring (16) supported on the valve body (12) and acting on the valve bolt (14), wherein the valve bolt (14) is contoured such that in a first position for closing the motor vehicle tire both the inlet opening (18) and the outlet opening (20) are closed,In a second position axially displaced from the first position for emptying the motor vehicle tire, both the inlet opening (18) and the outlet opening (20) are open, and in a third position axially displaced from the first and second positions for filling the motor vehicle tire, the inlet opening (18) is open and the outlet opening (20) is closed. Tire valve (10) according to claim 1 characterized in that a pressure source for axial displacement of the valve bolt (14) against the spring force of the return spring (16) acts on an end face (28) of the valve bolt (14). Tire valve (10) according to claim 2 characterized in that the pressure source communicates with the receiving space (13) at least for filling the motor vehicle tire. Tire valve (10) according to one of claims 1 to 3 characterized in that the return spring (16) is maximally relaxed in the second position of the valve bolt (14) and maximally tensioned in the third position of the valve bolt (14). Tire valve (10) according to one of claims 1 to 4 characterized in that the valve bolt (14) can be detachably locked to the valve body (12). A tire valve (10) according to one of claims 1 to 5, characterized in that a locking device engaging the valve body (12) and the valve bolt (14) is provided, wherein the locking device has a feed sleeve axially supported on the valve body (12), wherein the feed sleeve, when axially displaced into the valve body (12), can be abutted with a stop on a rotating ramp of the valve body (12) inclined against the axial direction and circumferentially, wherein, after sliding on the rotating ramp, the stop of the feed sleeve, in a circumferentially rotated position, can be pressed by the return spring (16) with an axial movement component in the direction out of the valve body (12) against a retaining ramp of the valve body (12) following the rotating ramp.wherein the valve bolt (14) is rotatable in the circumferential direction past the retaining ramp after a further axial displacement of the valve bolt (14) into the valve body (12) and is axially displaceable by the return spring (16) into a position maximally extended from the valve body (12). Tire valve (10) according to one of claims 1 to 6, characterized in that the inlet opening (18) can be closed by a first check valve and / or the outlet opening (20) by a second check valve, wherein the first check valve and / or the second check valve has a closing element (22) that can be displaced from the valve bolt (14). Tire valve (10) according to one of claims 1 to 7 characterized in that the valve bolt (14) has a first radial recess (24) for closing the inlet opening (18) and a second radial recess (26) for closing the outlet opening (20), wherein the axial extent of the first recess (24) is less than the axial extent of the second recess (26). Tire valve (10) according to one of claims 1 to 8 characterized in that an annular gap (32) for the passage of air is formed between the valve bolt (14) and the valve body (12). Method for filling and emptying a motor vehicle tire, wherein a tire valve (10) according to one of claims 1 to 9 is displaced between the first position, the second position and the third position by a pressure acting axially on the valve bolt (14) against a spring force of the return spring (16), wherein in particular the valve body (14) is displaced into the position inserted as far as possible into the valve body (12) before the valve body (14) is displaced into the position extended as far as possible out of the valve body (12).

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