Pneumatic wheel valve

Abstract

The invention relates to a pneumatic wheel valve (3) for filling and emptying a tyre (2) with air. The pneumatic wheel valve (3) comprises: an air inlet (7), which is designed to be connected to a compressed air line (4), within which there is a pneumatic pressure (p); an air outlet (8), which is designed to be connected to a tyre (2) of a motor vehicle; and an emptying connection (9), which is designed to be connected to an non-pressurised environment (14) of the pneumatic wheel valve (3); wherein the pneumatic wheel valve (3) can be pneumatically moved from a filling state into an emptying state; the air inlet (7) is connected to the air outlet (8) when the pneumatic wheel valve (3) is in the filling state; and the air outlet (7) is connected to the emptying connection (9) when the pneumatic wheel valve (3) is in the emptying state.

Description

[0001] ZF Friedrichshafen AG File 300357 Friedrichshafen 2024-10-15

[0002] Pneumatic wheel valve

[0003] The invention relates to a pneumatic wheel valve for filling and emptying a tire with air.

[0004] From DE 10 2018 117 140 A1, a tire valve for inflating and deflating a motor vehicle tire is known. The tire valve comprises 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. Furthermore, the tire valve comprises a valve pin which is axially displaceably mounted in the receiving space of the valve body, and a return spring which is supported on the valve body and engages the valve pin.The valve pin is contoured such that, in a first position for closing the tire, in a second position axially offset from the first for deflation, both the inlet and outlet openings are open, and in a third position axially offset from both the first and second positions for inflation, the inlet opening is open and the outlet opening is closed. This allows for cost-effective inflation and deflation of a tire with minimal design complexity.

[0005] One object of the present invention is to provide a technology that enables the filling and emptying of a tire in an alternative and particularly simple manner. This object is achieved by the subject matter of the independent claims. Advantageous embodiments are the subject of the dependent claims, the following description, and the figures.

[0006] According to the present invention, a pneumatic wheel valve is proposed which operates solely by means of different pneumatic pressure levels, without a detent (locking mechanism), electrical control, or similar device. The pneumatic wheel valve is pneumatically controlled to change its state from an inflation state to a deflation state. When the pneumatic wheel valve is in the inflation state, it can connect a pneumatic line to a tire. Conversely, when the pneumatic wheel valve is in the deflation state, it can connect the tire to an outlet.

[0007] In this sense, according to a first aspect of the invention, a pneumatic wheel valve is provided for filling and emptying a tire with air. The pneumatic wheel valve comprises an air inlet configured to be connected to a compressed air line within which pneumatic pressure prevails. Furthermore, the pneumatic wheel valve comprises an air outlet configured to be connected to a tire of a motor vehicle. The pneumatic wheel valve also comprises a vent port configured to be connected to a pressureless environment surrounding the pneumatic wheel valve. In particular, it is provided that the pneumatic wheel valve can be pneumatically switched from a filling state to a deflation state, with the air inlet being connected to the air outlet when the pneumatic wheel valve is in the filling state.Furthermore, the air outlet is connected to the vent port when the pneumatic wheel valve is in the emptying state. According to one embodiment, the air outlet can also be separated from the vent port when the pneumatic wheel valve is in the filling state. Additionally, the air inlet can be separated from the air outlet when the pneumatic wheel valve is in the emptying state.

[0008] A valve element in the form of a piston spool can ensure that the required function of the pneumatic wheel valve is achieved in any of its possible positions. In this sense, a further embodiment provides that the pneumatic wheel valve also comprises a valve housing and a piston spool. In particular, it is provided that the piston spool can be pneumatically moved within the housing from a filling position to an emptying position, with the pneumatic wheel valve being in the filling state when the piston spool is in the filling position, and being moved into the emptying state when the piston spool is moved to the emptying position.The pneumatic wheel valve may further include a return element, particularly in the form of a mechanical spring. The return element may be located within the valve housing and configured to exert a preload force on the piston. This preload force causes the piston to tend to move into the filling position. Pneumatic pressure can move the piston from the filling position to the emptying position against the preload force of the return element.

[0009] In particular, the pneumatic wheel valve can be configured to move from the filling state to the emptying state when the pneumatic pressure prevailing in the compressed air line exceeds a limit value. Specifically, the piston slide can only be moved from the filling position to the emptying position, so that the pneumatic wheel valve is moved from the filling state to the emptying state, when the pneumatic pressure prevailing in the compressed air line exceeds a certain value, i.e., is high enough to move the piston slide from the filling position to the emptying position against the preload force of the return element.

[0010] In this context, the pneumatic pressure prevailing in the compressed air line can be applied, in particular, to a control port of the valve. Thus, the pneumatic pressure prevailing in the compressed air line is present at the air inlet and at the control port. Via the control port, the pneumatic pressure prevailing in the compressed air line can act on the piston valve, in particular on a first (end) face of the piston valve. The first end face can, in particular, be located away from a second end face of the piston. ZF Friedrichshafen AG File 300357 Friedrichshafen 2024-10-15

[0011] The valve is arranged with the return element located in the area of ​​the second end face and exerting the preload force on the second end face. In a further embodiment, the pneumatic wheel valve also includes a control port designed to be connected to the compressed air line, so that the pneumatic pressure prevailing in the compressed air line acts on the piston valve and moves the piston valve from the filling position to the emptying position when the pneumatic pressure prevailing in the compressed air line exceeds the limit value.

[0012] As mentioned above, a return element, in particular a spring, can hold the piston valve in the filling position. In a further embodiment, a return element exerts a preload force on the piston valve, so that the piston valve is preloaded in the filling position. The prevailing pneumatic pressure in the compressed air line, acting on the piston valve, can move the piston valve from the filling position to the emptying position against the preload force if the prevailing pneumatic pressure in the compressed air line exceeds the limit value.

[0013] When the piston valve is in the inflation position, it is ensured that compressed air is transferred only from the compressed air line to the tire and not vice versa. In another embodiment, the pneumatic wheel valve is designed to allow compressed air to flow from the air inlet to the air outlet, but not to allow compressed air to flow from the air outlet to the air inlet when the pneumatic wheel valve is in the inflation position.

[0014] A check valve can be arranged in a path between the connection to the compressed air line and the tire. In a further embodiment, the pneumatic wheel valve also includes a check valve located between the air inlet and the air outlet (ZF Friedrichshafen AG File 300357, Friedrichshafen, October 15, 2024). The check valve can function as a pneumatic time delay element. For this purpose, the check valve can include a sealing element (for example, a ball) and a spring. To allow pressure to build up in the compressed air line, the check valve allows full flow after a certain time delay. This can be achieved by damping the movement of the sealing element of the check valve, in particular by a damping piston.In this sense, according to a further embodiment, the check valve comprises a valve seat, a sealing element, a return spring, and a damping piston. In particular, it is provided that the sealing element is biased against the valve seat in a closed switching position by the return spring, with the air inlet separated from the air outlet, so that the pneumatic pressure increases upstream of the sealing element in the area of ​​the air inlet and in the pressure line. As soon as the pneumatic pressure is sufficiently high, the sealing element is moved by compressed air flowing into the pneumatic wheel valve via the air inlet, against the bias of the return spring, into an open switching position in which the air inlet is connected to the air outlet. The sealing element is damped by the damping piston during this movement.

[0015] The pneumatic valve according to the first aspect of the invention can be part of a tire pressure monitoring system with a single pneumatically guided pressure line. In this sense, a tire pressure monitoring system for a motor vehicle is provided according to a second aspect of the invention. The tire pressure monitoring system comprises a tire, a pneumatic wheel valve according to the first aspect of the invention, and a compressed air line. The compressed air line can be connected to the air inlet of the pneumatic wheel valve, the air outlet being connected to the tire, and the venting port being connected to a pressureless environment of the pneumatic wheel valve. According to one embodiment, the pneumatic wheel valve is further located on a wheel onto which the tire is mounted. ZF Friedrichshafen AG File 300357 Friedrichshafen 2024-10-15

[0016] In the following, exemplary embodiments of the invention are explained in more detail with reference to the schematic drawing, wherein identical or similar elements are provided with the same reference numeral. Here, [the following is shown]

[0017] Fig. 1 shows a circuit diagram of an exemplary embodiment of a tire pressure monitoring system for a motor vehicle and

[0018] Fig. 2 shows a sectional view of an embodiment of a pneumatic wheel valve for filling and emptying a tire for the tire pressure monitoring system according to Fig. 1.

[0019] Fig. 1 shows a tire pressure monitoring system 1. The tire pressure monitoring system 1 comprises a tire 2 of a motor vehicle (not shown), a pneumatic wheel valve 3, and a compressed air line 4. The tire pressure monitoring system 1, in particular the pneumatic wheel valve 3, can be arranged on or in a wheel (not shown) onto which the tire 2 is mounted. The tire pressure monitoring system 1 is, in particular, a system that has only a single compressed air line 4 for inflating or deflating the tire. The compressed air line 4 is filled with compressed air, and a pneumatic pressure p prevails in the compressed air line 4.

[0020] In the embodiment shown in Figures 1 and 2, the pneumatic wheel valve 3 is a directional control valve that can be switched between two states. To switch the pneumatic wheel valve 3 between these states, it has a piston spool 5 and a valve housing 6. The piston spool 5 can be moved back and forth along its longitudinal axis L within the valve housing 6 in an axial direction x1, x2. The piston spool 5 can be moved into two positions: a filling position and an emptying position. When the piston spool 5 is in the filling position, the pneumatic wheel valve 3 is in the filling state. When the piston spool 5 is in the emptying position, the pneumatic wheel valve 3 is in the emptying state. ZF Friedrichshafen AG File 300357 Friedrichshafen 2024-10-15

[0021] In the illustrated embodiment, the pneumatic wheel valve 3 has four ports 7 to 10. A first port 7 serves as the air inlet, a second port 8 as the air outlet, a third port 9 as the vent port, and a fourth port 10 as the control port. The compressed air line 4 is connected to the air inlet 7. A supply line 11 branches off from the compressed air line 4 and is connected to the control port 10. Thus, the compressed air line 4 is connected to the control port 10. The air outlet 8 is connected to the tire 2. Specifically, a tire line 12 connects the air outlet 8 to a tire valve 13 of the tire 2. The tire 2 can be inflated with compressed air via the tire valve 13. Compressed air can also be released from the tire 2 via the tire valve 13 to deflate the tire 2. The vent port 9 is connected to a pressureless environment 14 of the pneumatic wheel valve 3.In the pressureless environment 14, for example, atmospheric pressure may prevail (e.g. 101,325 Pa at sea level).

[0022] Figures 1 and 2 show the pneumatic wheel valve 3 in its inflated state. When the pneumatic wheel valve 3 is inflated, the air inlet 7 is connected to the air outlet 8. Compressed air from the compressed air line 4 is then directed through the air inlet 7, a check valve 15 of the pneumatic wheel valve 3 (described in more detail below), and the air outlet 8 into the tire line 12. The compressed air flows through the tire line 12 and enters the tire 2 via the tire valve 13, thus filling the tire 2 with compressed air from the compressed air line 4. The check valve 15 prevents compressed air from the tire 2 and the tire line 12 from flowing back through the air outlet 8 to the air inlet 7.Furthermore, the air outlet 8 is separated from the vent port 9, so that no compressed air from the tire 2 and from the tire line 12 can flow via the air outlet 8 to the vent port 9 to escape into the pressureless environment 14 of the pneumatic wheel valve 3.

[0023] The piston valve 5 is pre-tensioned in the filling position by means of a mechanical spring 16. Locking of the piston valve 5 is not necessary. Thus, ZF Friedrichshafen AG File 300357 Friedrichshafen 2024-10-15, the pneumatic wheel valve 3 is in its filling state ("normally open") without any further external influence. The spring 16 generates a pre-tension force F1 (mechanical force) that acts in a first axial direction x1, for example, on an end face of the piston valve 5. The pneumatic pressure p, which prevails in the compressed air line 4, acts on the piston valve 5 via the supply line 11 and the control port 10 such that a pneumatic force F2 is exerted on the piston valve 5. The pneumatic force F2 acts in a second axial direction x2, which is opposite to the first axial direction x1. The pneumatic force F2 thus acts against the preload force F1. In the switching state according to Fig.1. The pneumatic pressure p is below a certain limit value p1 (p <p1 ), sodass die pneumatische Kraft F2 nicht ausreicht, um den Kolbenschieber 5 entgegen der Vorspannkraft F1 der Feder 16 aus der Befüllungsstellung in die Entleerungsstellung zu verschieben. Wenn und / oder sobald der pneumatische Druck p jedoch den bestimmten Grenzwert p1 überschreitet (p> p1), then the pneumatic force F2 is sufficient to move the piston slide 5 from the filling position to the emptying position against the preload force F1 of the spring 16. Thus, the piston slide 5 can be moved purely pneumatically from the filling position to the emptying position, so that the pneumatic wheel valve 3 can also be moved purely pneumatically from the filling state to the emptying state.

[0024] When the pneumatic wheel valve 3 is in the deflation state, the air inlet 7 is not connected to the air outlet 8. Compressed air from the compressed air line 4 is then not directed via the air inlet 7, the check valve 15, and the air outlet 8 into the tire line 12. For example, the piston spool 5 within the valve housing 6 can close off a compressed air path between the check valve 15 and the air outlet 8. Instead, the air outlet 8 is connected to the vent port 9, allowing compressed air from the tire 2 and the tire line 12 to flow via the air outlet 8 to the vent port 9 and escape into the unpressurized environment 14 of the pneumatic wheel valve 3. This allows compressed air to be released from the tire 2. ZF Friedrichshafen AG File 300357 Friedrichshafen 2024-10-15

[0025] The check valve 15 is located between the air inlet 7 and the air outlet 8 in a path between the connection to the compressed air line 4 and the tire 2. In the embodiments shown in Figures 1 and 2, the check valve 15 functions as a pneumatic time delay element. For this purpose, the check valve 15 has a sealing element 17 in the form of a ball and a spring 18, which, for easier differentiation from the spring of the piston spool 5, is referred to as the "return spring". Furthermore, the check valve 15 includes a damping piston 19. As shown in Figure 2, the damping piston 19 contacts the sealing element 17. The damping piston 19 is displaceable in its longitudinal direction. In the closed position shown in Figure 2, the sealing element 17 rests against a valve seat 20 of the check valve 15. In this position, the sealing element 17 is held by a closing force generated by the return spring 18.To move into an open position, the sealing element 17 must overcome the closing force of the return spring. Furthermore, the sealing element 17 must move the damping piston 19, which dampens the movement of the sealing element 17. The sealing element 17 can be moved pneumatically from the closed to the open position. When the sealing element 17 is in the closed position, no compressed air flows from the compressed air line 4 past the sealing element 17 towards the outlet 8. Instead, compressed air accumulates in the compressed air line 4 in front of the sealing element 17, thereby building up the pneumatic pressure p in the compressed air line 4.

[0026] As described above, the pneumatic pressure p moves the piston 5 against the preload force F1 of the spring 16 from the filling position to the emptying position as soon as the pneumatic pressure p exceeds the limit value p1 (p>p1). If the pneumatic pressure p is less than the limit value p1 (p <p1 ), dann befindet sich der Kolbenschieber 5 in der geöffneten Schaltstellung. Ohne das Rückschlagventil 15 würde Druckluft aus der Druckluftleitung 4 sofort über den Lufteingang 7 und den Luftausgang 8 in Richtung des Reifens 2 strömen. Allerdings muss in den durch Fig. 1 und 2 gezeigten Ausführungsbeispielen weiterhin die Schließkraft der Rückschlagfeder 18 des Rückschlagventils 15 überwunden werden. Diese Schließkraft kann beispielsweise durch die Auswahl (Art, Form, Material etc.) und Anordnung der Rückschlagfeder 18 eingestellt werden. ZF Friedrichshafen AG Akte 300357 Friedrichshafen 2024-10-15

[0027] When the piston valve 5 is in the filling position shown in Figures 1 and 2, the air inlet 7 is only connected to the air outlet 8 when the pneumatic pressure p is high enough to overcome the closing force of the return spring 18. This opening pressure value p2 will be (particularly significantly) below the limit value p1 in order to prevent the piston valve 5 from moving into the emptying position (p2). <p1 ). Während der pneumatische Druck p das Dichtungselement 17 aus der geschlossenen Stellung in die geöffnete Stellung bewegt, wird eine Verschiebungsbewegung des Schließelements 17 durch den Dämpfungskolben 19 gedämpft. Im Resultat lässt das Rückschlagventil 15 den Durchfluss von Druckluft aus der Druckluftleitung 4 erst nach einer gewissen Zeitverzögerung in vollem Umfang zu.

[0028] ZF Friedrichshafen AG File 300357 Friedrichshafen 2024-10-15

[0029] Reference mark

[0030] F1 Preload force

[0031] F2 pneumatic force

[0032] L Longitudinal axis p Pneumatic pressure p Limit value x1 First axial direction x2 Second axial direction

[0033] 1 Tire pressure monitoring system

[0034] 2 tires

[0035] 3 pneumatic wheel valve

[0036] 4 Compressed air line

[0037] 5 piston valves

[0038] 6 Valve housings

[0039] 7 Air inlet

[0040] 8 Air outlet

[0041] 9 Vent connection

[0042] 10 Control connection

[0043] 11 Supply line

[0044] 12 Tire line

[0045] 13 Tire valve

[0046] 14 pressureless environment

[0047] 15 Check valve

[0048] 16 springs

[0049] 17 Sealing element

[0050] 18 Return spring

[0051] 19 damping pistons

[0052] 20 Valve seat

Claims

ZF Friedrichshafen AG File 300357 Friedrichshafen 2024-10-15 Patent claims 1. Pneumatic wheel valve (3) for filling and emptying a tire (2) with air, the pneumatic wheel valve (3) comprising: - an air inlet (7) which is designed to be connected to a compressed air line (4) within which a pneumatic pressure (p) prevails, - an air outlet (8) designed to be connected to a tire (2) of a motor vehicle and - a vent connection (9) which is designed to be connected to a pressureless environment (14) of the pneumatic wheel valve (3), wherein - the pneumatic wheel valve (3) can be pneumatically moved from a filling state to an emptying state, - the air inlet (7) is connected to the air outlet (8) when the pneumatic wheel valve (3) is in the filling state, and - the air outlet (7) is connected to the vent port (9) when the pneumatic wheel valve (3) is in the emptying state.

2. Pneumatic wheel valve (3) according to claim 1 , wherein - the air outlet (7) is separated from the vent port (9) when the pneumatic wheel valve (3) is in the filling state, and - the air inlet (7) is separated from the air outlet (8) when the pneumatic wheel valve (3) is in the emptying state.

3. Pneumatic wheel valve (3) according to claim 1 or 2, the pneumatic wheel valve (3) further comprising - a valve housing (6) and - a piston valve (5), wherein - the piston valve (5) can be pneumatically moved within the housing (6) from a filling position to an emptying position, - the pneumatic wheel valve (3) is in the filling state when the piston slide (5) is in the filling position, and ZF Friedrichshafen AG File 300357 Friedrichshafen 2024-10-15 - the pneumatic wheel valve (3) is put into the emptying state when the piston slide (5) is moved into the emptying position.

4. Pneumatic wheel valve (3) according to claim 3, wherein the pneumatic wheel valve (3) is configured to move from the filling state to the emptying state when the pneumatic pressure (p) prevailing in the compressed air line (4) exceeds a limit value (p1 ).

5. Pneumatic wheel valve (3) according to claim 4, the pneumatic wheel valve (3) further comprising a control port (10) which is configured to be connected to the compressed air line (4) such that the pneumatic pressure (p) prevailing in the compressed air line (4) acts on the piston valve (5) and moves the piston valve (5) from the filling position to the emptying position when the pneumatic pressure (p) prevailing in the compressed air line exceeds the limit value (p1 ).

6. Pneumatic wheel valve (3) according to claim 5, wherein - a return element (16) exerts a preload force (F1) on the piston valve (5) so that the piston valve (5) is preloaded in the filling position, and - the prevailing pneumatic pressure (p) in the compressed air line (4), which acts on the piston valve (5), moves the piston valve (5) from the filling position to the emptying position against the preload force (F1 ) when the prevailing pneumatic pressure (p) in the compressed air line (4) exceeds the limit value (p1 ).

7. Pneumatic wheel valve (3) according to one of the preceding claims, wherein the pneumatic wheel valve (3) is configured to - to allow compressed air to flow from the air inlet (7) to the air outlet (8), but - to prevent compressed air from flowing from the air outlet (8) to the air inlet (7) when the pneumatic wheel valve (3) is in the filling state. ZF Friedrichshafen AG File 300357 Friedrichshafen 2024-10-15 8. Pneumatic wheel valve (3) according to claim 7, the pneumatic wheel valve (3) further comprising a check valve (15) which is arranged between the air inlet (7) and the air outlet (8).

9. Pneumatic wheel valve (3) according to claim 8, wherein - the check valve (15) has a valve seat (20), a sealing element (17), a return spring (18) and a damping piston (19), - the sealing element (17) is biased against the valve seat (20) in a closed switching position by the return spring (18), with the air inlet (7) being separated from the air outlet (8), so that the pneumatic pressure (p) in front of the sealing element (17) increases in the area of ​​the air inlet (7) and in the pressure line (4), and - the sealing element (17) is moved by compressed air, which flows into the pneumatic wheel valve (3) via the air inlet (8), against the preload of the return spring (18) and damped by the damping piston (19) into an open switching position in which the air inlet (7) is connected to the air outlet (8) as soon as the pneumatic pressure (p) is high enough.

10. Tire pressure monitoring system (1) for a motor vehicle, comprising the tire pressure monitoring system (1) - one tire (2), - a pneumatic wheel valve (3) according to one of the preceding claims and - a compressed air line (4), wherein - the compressed air line (4) is connected to the air inlet (7) of the pneumatic wheel valve (3), - the air outlet (8) is connected to the tire (2), and - the vent port (9) is connected to a pressureless environment (14) of the pneumatic wheel valve (3).

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