SAFETY VALVE, PNEUMATIC ACTUATOR, AND VEHICLE

Abstract

A safety valve (100) for a pneumatic conduit (798) includes: a valve body (120) with a pressure port (122) pneumatically connected to a pressure side (840) of the pneumatic conduit (798) and a release port (124) pneumatically connected to a release side (860) of the pneumatic conduit (798), a valve piston (140) axially movable along a valve axis (AV) relative to the valve body (120) between a release-side end position (SP1) and a pressure-side end position (SP2), and a valve piston spring (160) to push the valve piston (140) into the pressure-side end position (SP2). A bypass conduit (150) extends through the valve body (120) or the valve piston (140) and, depending on the position of the valve body, permits a release airflow (AF) to flow through the bypass conduit between the pressure port (122) and the release port (124).

Claims

1. A safety valve for a pneumatic conduit (798), the safety valve comprising: a valve body (120), arranged in the pneumatic conduit (798), the valve body including a pressure port (122) pneumatically connected to a pressure side (840) of the pneumatic conduit (798) and a release port (124) pneumatically connected to a release side (860) of the pneumatic conduit (798), a valve piston (140), arranged in the valve body (120) and axially movable along a valve axis (AV) relative to the valve body (120) between a release-side end position (SP1) on an axial side facing the release port (124) and a pressure-side end position (SP2) on another axial side facing the pressure port (122), and a valve piston spring (160) that pushes the valve piston (140) toward the pressure-side end position (SP2), and a bypass conduit (150) that extends through the valve body (120) or the valve piston (140) and that permits a release airflow (AF) to flow between the pressure port (122) and the release port (124).

2. The safety valve according to claim 1, further comprising a pressure-side gasket (130, 130, 130), which inhibits the release airflow (AF) between the pressure port (122) and the release port (124) in an annular gap (146) when the valve piston (140) is in the pressure-side end position (SP2), wherein the annular gap (146) is between a circumferential surface (145) of the valve piston (140) and an inner surface (126) of the valve body (120).

3. The safety valve according to claim 2 further comprising a release-side gasket (134), which inhibits the release airflow (AF) between the pressure port (122) and the release port (124) when the valve piston (140) is in the release-side end position (SP1).

4. The safety valve according to claim 3, wherein the release-side gasket (134) is arranged between a release-side end face (144) of the valve piston (140) and a release-side stop (129) of the valve body (120), and extends axially in the direction of the valve axis (AV).

5. The safety valve according to claim 4, wherein the release-side gasket (134) is arranged on the release-side end face (144), or the release-side gasket (134) is arranged on the release-side stop (129).

6. The safety valve according to claim 1 wherein the valve body (120) includes a valve body lid (125, 125), wherein the valve body lid includes a pressure-side stop (128) and/or the pressure port (122).

7. The safety valve according to claim 6, wherein the valve body lid (125) is releasably connected to the valve body (120), and includes a lid thread (131) that engages a corresponding body thread (132) of the valve body (120).

8. The safety valve according to claim 6, wherein the valve body lid (125) is mounted to the valve body (120) in a positively locking manner in a lid recess (135) by a body rim (133), wherein the body rim (133) is created by a bordering process after inserting the valve body lid (125) into the lid recess (135).

9. The safety valve according to claim 1 wherein the bypass conduit (150) has a circumferentially closed cross section (152), wherein the bypass conduit is a generally cylindrical channel (153), and extends in a substantially axial direction.

10. The safety valve according to claim 2 wherein the bypass conduit (150) has a circumferentially open cross section (154), wherein the bypass conduit is a groove (155) on a circumferential surface (145) of the valve piston (140) or on an inner surface (126) of the valve body (120).

11. The safety valve according to claim 2 wherein the pressure-side gasket (130) is arranged on the pressure-side end face (142) of the valve piston (140), or wherein the pressure-side gasket (130) is arranged on a pressure-side stop (128) of the valve body (120).

12. The safety valve according to claim 10 wherein the pressure-side gasket (130) is arranged in the annular gap (146) and extends radially in a plane perpendicular to the valve axis (VA).

13. The safety valve according to claim 12, wherein the pressure-side gasket (130) is arranged on the circumferential surface (145) of the valve piston (140).

14. A pneumatic actuator (800) comprising: a pneumatic conduit (798) with a pressure side (840) and a release side (860), and a safety valve according to claim 1.

15. A vehicle (1000) comprising a pneumatic actuator (800).

16. The safety valve according to claim 3, wherein the release-side gasket blocks the release port relative to the conduit and the pressure port when the valve piston is at its release-side end position.

17. The safety valve according to claim 12, wherein the pressure side gasket (130) blocks the release airflow between the pressure port and the release port when the valve piston is in the release-side end position and when the valve piston is in the pressure-side end position.

18. The safety valve according to claim 17, wherein the bypass conduit permits the release airflow when the valve piston is between its two end positions.

19. The safety valve according to claim 17, wherein airflow is blocked in the direction from the release port to the pressure port when the valve piston is at the pressure-side end position.

20. The safety valve according to claim 1, wherein the bypass conduit permits the release airflow (AF) to flow from the pressure port (122) to the release port (124) depending on the position of the valve piston, wherein the release airflow (AF) is blocked from flowing through the release port when the valve piston is in the release-side end position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Further advantages, features and details of the present disclosure result from the following description of the preferred embodiments as well as from the drawings, in which:

[0048] FIG. 1 is a cross-sectional side view of a first preferred embodiment of a safety valve according to the present disclosure,

[0049] FIG. 2A is a cross-sectional side view of a second preferred embodiment of a safety valve according to the concept of the present disclosure,

[0050] FIG. 2B is an end view of the second preferred embodiment of FIG. 2A,

[0051] FIG. 3 is a cross-sectional side view of a third preferred embodiment of an aspect of a safety valve according to the concept of the present disclosure,

[0052] FIG. 4 is a cross-sectional side view of a pneumatic actuator in the form of a pneumatic clutch actuator,

[0053] FIG. 5 is an excerpt of another pneumatic actuator with a safety valve, wherein the pneumatic actuator is in the form of a pneumatic transmission actuator,

[0054] FIG. 6 is a schematic view of a vehicle having a pneumatic actuator with a safety valve according to the concept of the present disclosure.

DETAILED DESCRIPTION

[0055] FIG. 1 shows a safety valve 100 according to the first preferred embodiment of the present disclosure. The safety valve 100 includes a valve body 120 and a valve piston 140, which are both in principle rotationally symmetrical with respect to a valve axis VA. The safety valve 100 has on a pressure side 840 a pressure port 122, which is pneumatically connectable to a pressure source for receiving a pressure P. The safety valve 100 is insertable into a pneumatic conduit 798, in particular of a pneumatic actuator 800. For example, the pneumatic conduit 798 can be located in an actuator piston 820 as shown in FIG. 4 or in an electro pneumatic valve module 890 as shown in FIG. 5. In accordance with an exemplary embodiment, the pressure source could be a pressure chamber 846 of a pneumatic actuator 800, such as a pneumatic clutch actuator 802. In another exemplary embodiment, the pressure source could be an inlet that bridges one or more solenoid valves and a compressed air reservoir. By providing a pressure P to the pressure side 840 of actuator piston 820 in a controllable manner, the pneumatic actuator 800 can be selectively actuated.

[0056] The safety valve 100 comprises on a release side 860 a release port 124, which is pneumatically connectable to a release line, in particular to an environment with ambient pressure PE. In the embodiment shown, the release port comprises a first release port 124.1 and a second release port 124.2.

[0057] The valve piston 140 is held within the valve body 120 in an axially movable manner, adapted to move along the valve axis VA between two axial end positions, namely a first, release-side end position SP1 defined by a release-side stop 129, and a second, pressure-side end position SP2 defined by a pressure-side stop 128.

[0058] Between a circumferential surface 145 of the valve piston 140 and an inner surface 126 of the valve body 120, there is an annular gap 146 for providing a certain clearance between the valve body 120 and the valve piston 140 to allow for a relative axial movement between the two.

[0059] The safety valve 100 further includes a valve piston spring 160, which is arranged inside the valve body 120 and is adapted to push the valve piston 140 into the pressure-side end position SP2.

[0060] A pressure P at the pressure port 122 results in a pressure force FP acting on a pressure-side end face 142 of the valve piston 140.

[0061] The valve piston spring 160 is configured such that the valve piston 140 lifts from the pressure-side end position SP2 when the pressure P at the pressure port 122 exceeds a minimum leakage pressure P.sub.LMIN.

[0062] The valve piston spring 160 is further configured such that the valve piston 140 reaches the release-side end position SP1 when the pressure P at the pressure port 122 reaches a maximum leakage pressure P.sub.LMAX.

[0063] The valve piston spring 160 has a spring constant 162, which is adapted to fulfill the valve piston spring's 160 characteristics with respect to the minimum leakage pressure P.sub.LMIN and the maximum leakage pressure P.sub.LMAX.

[0064] According to the concept of the present disclosure, the valve piston 140 includes a bypass conduit 150, which is adapted to permit a release airflow AF from the pressure port 122 to the release port 124. The bypass conduit 150 has a circumferentially closed cross-section 152, meaning that the cross-section of the bypass conduit 150 is completely enclosed by material, here completely enclosed by the valve piston 140. The circumferentially closed cross-section 152 in this embodiment has a circular shape, resulting in a cylindrical channel 153, extending through the center of the valve piston 140 along the valve axis VA from the pressure-side end face 142 to the release-side end face 144.

[0065] On a release-side end face 144 of the valve piston 140, which is arranged opposite of the pressure-side end face 142, the valve piston 140 includes at least one release-side gasket 134, adapted to sealingly close the release port 124 or ports 124.1 and 124.2 when the valve piston 140 is in the release-side end position SP1.

[0066] On a pressure-side end face 142 of the valve piston 140, the valve piston 140 comprises a pressure-side gasket 130, which is adapted to sealingly close the pressure port 122, in particular pneumatically separate the pressure port 124 from the annular gap 146, when the valve piston 140 is in the pressure-side end position SP2. In the embodiment shown, the pressure-side gasket 130 is a sealing ring molded onto the pressure-side end face 142.

[0067] The safety valve 100 further includes a valve body lid 125, which is releasably attached to the valve body 120 by means of a threaded connection. The valve body 120 has on the pressure side 840 a lid recess 135, adapted to hold the valve body lid 125. The lid recess 135 includes on its inner circumferential surface a body thread 132, which is adapted to engage with a corresponding lid thread 131 of the valve body lid 125. The inner end face of the valve body lid 125 facing the valve piston 140 serves as the pressure-side stop 128.

[0068] The safety valve 100 further includes a lid gasket 170, which is adapted to sealingly connect the valve body lid 125 to the valve body 120 when both are mounted together.

[0069] The safety valve 100 functions as follows: when a pressure P in a pneumatic actuator 800, in particular in a pneumatic clutch actuator 802, is below a minimum leakage pressure P.sub.LMIN, an airflow AF can pass from the pressure port 122 through the bypass conduit 150 to the release port 124. When the pressure P reaches or exceeds the minimum leakage pressure P.sub.LMIN, the pressure force FP is high enough to compress the valve piston spring 160 and lift the valve piston 140 from its pressure-side end position SP2. In such condition, the airflow AF is still able to pass from the pressure port 122 via the bypass conduit 150 to the release port 124.

[0070] Once the rising pressure P reaches or exceeds the maximum leakage pressure P.sub.LMAX, the valve piston 140 reaches the release-side end position SP1 and the airflow between the pressure port 122 and the release port 124 is blocked by the release-side gasket 134, 134.1, 134.2, sealing off the release port 124, or ports 124.1, 124.2. In this case, the pressure P at the pressure port 122 and in the pneumatic actuator 800 can further increase, preferably for actuating a pneumatic system 880 such as a pneumatic clutch 882.

[0071] The valve body includes a fixation thread 906 for positively locking the safety valve 100 in the pneumatic conduit 798 at an interface 900 between the valve body 120 and the pneumatic conduit 798.

[0072] FIG. 2A and FIG. 2B show a second preferred embodiment of a safety valve 100 according to the concept of the present disclosure. The safety valve 100 is shown in a schematic cross-sectional side view in FIG. 2A.

[0073] Compared to the first embodiment of the safety valve 100, the second embodiment of the safety valve 100 includes a bypass conduit 150 with a circumferentially open cross-section 154. The term circumferentially open cross-section means that the cross-section of the bypass conduit 150 is not completely enclosed by material, as the bypass conduit 150 extends along a surface, resulting in a channel open on at least one side, such as a groove. In the embodiment shown, the bypass conduit 150 is in the form of a groove 155 extending parallel to the valve axis VA along an inner circumferential surface 126 of the valve body 120. The groove 155 extends from a release-side conduit end 155.1 to a pressure-side conduit end 155.2.

[0074] The axial dimension and arrangement of the groove 155 is such that the pressure-side gasket 130 exceeds the pressure-side conduit end 155.2 when the valve piston 140 travels to the pressure-side end position SP2, and also such that the pressure-side gasket 130 exceeds the release-side conduit end 155.1 when the valve piston 140 travels to the release-side end position SP1. Consequently, no airflow, in particular no release airflow AF, between the pressure port 122 and the release port 124 is possible when the valve piston is either in the release-side end position SP1 or in the pressure-side end position SP2.

[0075] By blocking the release airflow AF also in the pressure-side end position SP2 (in addition to the release-side end position SP1 compared to the first embodiment), the second embodiment advantageously inhibits any airflow AF, also in an opposite direction from the release port 124 to the pressure port 122, for example when the pressure P at the pressure port 122 is below the ambient pressure PE. In this case, the valve piston 140 is in the pressure-side end position SP2, sealing the pressure port 122 and preventing any airflow through the pressure port 122 into the pneumatic actuator 800.

[0076] In other words, the bypass conduit 150 in the form of the groove 155 is only functional (i.e. only permits an airflow) when the valve piston 140 is in between its two end positions SP1, SP2.

[0077] As a further difference to the first embodiment, the safety valve 100 includes [0078] instead of the pressure-side gasket 130 arranged on an end face of the valve piston or the pressure-side stopa pressure-side gasket 130 which is arranged on an outer circumferential surface 145 of the valve piston 140.

[0079] Due to the form of the bypass conduit 150 with the open cross-section 154 and the pressure-side gasket 130 moving relative to the bypass conduit 150, no further gasket, in particular no release-side gasket 134, is needed.

[0080] FIG. 3 shows an excerpt of a third preferred embodiment of a safety valve 100, comprising an alternative pressure-side gasket 130 for sealingly blocking an airflow AF through the annular passage 146. The alternative pressure-side gasket 130 can in particular be used as an alternative to the first embodiment shown in FIG. 1. The alternative pressure-side gasket 130 is attached to alternative valve body lid 125, which in the present embodiment is formed as a washer 127. The washer 127 is mounted to the valve body 120 in a positively locking manner, here axially locked in a lid recess 135 by means of a body rim 133. Preferably, the body rim 133 is created by a bordering process or the like forming process, after the valve body lid 125 is inserted into the lid recess 135.

[0081] In the present embodiment, the alternative pressure-side gasket 130 is molded onto the washer 127. The alternative pressure-side gasket 130 is preferably made of rubber. The alternative pressure-side gasket 130 is overmolded over the washer 127, or as shown here, onto the washer 127.

[0082] FIG. 4 shows a pneumatic actuator 800 in the form of a pneumatic clutch actuator 802. A safety valve 100 according to the concept of the present disclosure, in particular all of the shown embodiments of a safety valve 100, 100, 100 can be applied in the shown pneumatic actuator 800. The pneumatic clutch actuator 802 includes an actuator piston 820, which is axially movable within an actuator body 830. The actuator piston 820 has a pressure side 840 facing a pressure chamber 846 of the pneumatic actuator 800. When a pressure P is applied on the pressure side 840 of the actuator piston 820, an actuation force FA results, acting on the actuator piston 820. Consequently, an actuation is effected by moving the actuator piston 820. The actuator piston 820 has a release side 860 on the opposite side of the pressure side 840. A safety valve 100 according to the concept of the invention is arranged in the actuator piston 820, with its pressure port 122 facing the pressure side 840 and its release port 124 facing the release side 860.

[0083] A safety valve 100 according to the concept of the invention, in particular all of the shown embodiments of a safety valve 100, 100, 100, can be applied in other pneumatic actuators 800, in particular can be arranged in a place other than an actuator piston 820, for example in a receptacle in a housing of the pneumatic actuator 800. In such cases, the safety valve can be pneumatically connected to the pressure side 840 and/or the release side 860 by means of pneumatic passages or conduits, such as a pressure conduit 848 and/or a release conduit 868 as shown in FIG. 5.

[0084] The previous figures illustrate use of safety valve 100, 100 or 100 within pneumatic clutch actuator 802 only for the sake of exemplary illustration. It is noted however, that safety valve 100, 100 or 100 can be used in another pneumatic conduit 798, for instance, as part of a pneumatic transmission actuator 804 (shown in FIG. 5) or gearbox actuator (not shown in any of the figures) where it forms part of an interface between a closed space within said pneumatic transmission or gearbox actuator and atmosphere, in order to relieve pressure from the closed space when a predetermined pressure is achieved. In case of using safety valve 100, 100 or 100 as part of the pneumatic transmission actuator, safety valve 100, 100 or 100 need not be provided as part of an actuator piston (not shown in any of the figures) of the transmission actuator. For instance, safety valve 100 can be part of various inlets and/or outlets within the transmission actuator that interacts with the external atmosphere.

[0085] FIG. 5 shows an excerpt of another example of an electropneumatic actuator 800 with a safety valve 100, wherein the electropneumatic actuator 800 is in the form of a pneumatic transmission or gearbox actuator 804 used in association with a vehicle gearbox (not shown in FIG. 5), in a pneumatic diagram. In the shown embodiment, the safety valve 100 is not arranged in an actuator piston 820, but in an electro pneumatic valve module 890 as a part of the electropneumatic actuator 800. The safety valve 100 (explained in various embodiments) is arranged in a pneumatic conduit 798 in the electro pneumatic valve module 890 (extending from a pressure side 840). The pneumatic conduit 798, and consequently also the safety valve 100, is pneumatically connected to the pressure side 840 by means of a pressure conduit 848. Preferably, the pressure conduit 848 is pneumatically connected to the pressure side 840 of an actuator piston 820, for example of a pneumatic clutch actuator 802 arranged outside of the electro pneumatic valve module 890, as shown here. The pneumatic conduit 798, and consequently also the safety valve 100, is pneumatically connected to a release side 860 by means of a release conduit 868. An exemplary general working principle of pneumatic actuator 800 is discussed herewith.

[0086] In accordance with the present example as shown in FIG. 5, the electropneumatic valve module 890 is controlled by an Electronic Control Unit 890.5, which is configured to at least transmit electronic control signals to individual valves 890.2 and 890.3. Inlet solenoid valves are labeled in FIG. 5 as 890.2 whereas exhaust solenoid valves labeled as 890.3. Both inlet and exhaust solenoid valves 890.2 and 890.3 receive control signals to open/close from ECU 890.5 depending on whether pneumatic clutch actuator 802 needs to be activated or deactivated.

[0087] A pneumatic inlet 890.1 receives pressurized pneumatic air and passes through firstly, inlets of inlet solenoid valves 890.2, which are shown in a closed state in FIG. 5. The outlets of inlet solenoid valves 890.2 lead to both pressure side 840 as well as to inlets of exhaust solenoid valves 890.3. In the illustrated example, exhaust solenoid valves 890.2 are also shown in a closed state. If exhaust solenoid valves 890.3 are in open state, the pressurized air present in the line indicated as pressure side 840 and/or in the outlets of inlet solenoid valves 890.2 are connected to release side or exhaust 860 via exhaust lines 890.4.

[0088] In accordance with the present example, in order to maintain pressure at pressure side 840 (connection line to actuator 802), safety valve 100 is provided at pressure conduit 848. When the residual or remaining pressure in conduit 848 is above a certain threshold, safety valve 100 opens and a connection is established between conduits 848 and 868 and/or release port 124 of safety valve 100. Thereafter said residual or remaining pressure is exhausted at release side 860. In the present example, there are two inlet solenoid valves 890.2 and two exhaust solenoid valves 890.3 are shown for the sake of illustration. However, a simplified construction with one inlet and one exhaust solenoid along with safety valve 100 can also be envisaged by the skilled person.

[0089] FIG. 6 schematically shows a vehicle 1000 in the form of a commercial vehicle 1010, comprising a pneumatic actuator 800 in the form of a pneumatic clutch actuator 802 with a safety valve 100 according to the concept of the invention. The pneumatic clutch actuator 802 includes an actuator piston 820 for actuating a pneumatic system 880 such as a pneumatic clutch 882. The pneumatic clutch actuator 802 is pneumatically connected to a pressurized air supply unit 560.

LIST OF REFERENCE SIGNS (PART OF THE DESCRIPTION)

[0090] 100, 100, 100 safety valve [0091] 120 valve body [0092] 122 pressure port [0093] 124 release port [0094] 124.1 first release port [0095] 124.2 second release port [0096] 125 valve body lid [0097] 126 inner surface of the valve body [0098] 127 washer [0099] 128 pressure-side stop [0100] 129 release-side stop [0101] 130, 130, 130 pressure-side gasket [0102] 131 lid thread [0103] 132 body thread [0104] 133 body rim [0105] 134 release-side gasket [0106] 134.1 first release-side gasket [0107] 134.2 second release-side gasket [0108] 135 lid recess [0109] 140 valve piston [0110] 142 pressure-side end face [0111] 144 release-side end face [0112] 145 circumferential surface of the valve piston [0113] 146 annular gap [0114] 150 bypass conduit [0115] 152 circumferentially closed cross-section [0116] 153 cylindrical channel [0117] 154 circumferentially open cross-section [0118] 155 groove [0119] 155.1 release-side conduit end [0120] 155.2 pressure-side conduit end [0121] 160 valve piston spring [0122] 162 spring constant [0123] 170 lid gasket [0124] 560 pressurized air supply unit [0125] 798 pneumatic conduit [0126] 800 pneumatic actuator [0127] 802 pneumatic clutch actuator [0128] 804 pneumatic transmission actuator [0129] 820 actuator piston [0130] 830 actuator body [0131] 840 pressure side [0132] 846 pressure chamber [0133] 848 pressure conduit [0134] 860 release side [0135] 868 release conduit [0136] 880 pneumatic system [0137] 882 pneumatic clutch [0138] 890 electro pneumatic valve module [0139] 890.1 pneumatic inlet [0140] 890.2 inlet solenoid valves [0141] 890.3 outlet solenoid valves [0142] 890.4 exhaust or outlet lines from outlet solenoid valves 890.3 [0143] 890.5 Electronic Control Unit (ECU) [0144] 900 interface [0145] 906 fixation thread [0146] 1000 vehicle [0147] 1010 commercial vehicle [0148] AF release airflow [0149] FA actuation force [0150] FP pressure force [0151] P pressure [0152] PE ambient pressure [0153] PLMAX maximum leakage pressure [0154] PLMIN minimum leakage pressure [0155] VA valve axis