Self-adjusting relay valve

Abstract

The present disclosure relates to a self-adjusting relay valve, which aims to prevent the problem of insufficient braking force when the vehicle is fully loaded and excessive braking force when the vehicle is empty. The relay valve is characterized in that the piston comprises an inner operating section, an outer annular section and an intermediate annular section in the lower part thereof, the inner operating section is operable to act on an intake and exhaust assembly, through which the intake cavity is communicated with or disconnected from the first annular cavity; a pressure regulating assembly is arranged in the pressure regulating cavity of the lower housing, the pressure regulating cavity is communicated with the first annular cavity and the second annular cavity respectively, and the pressure regulating assembly is capable of communicating or disconnecting the first annular cavity and the second annular cavity by means of a trigger device. The relay valve can automatically adjust the pressure change ratio of the output port and the control port of the relay valve by means of the trigger device and the pressure regulating assembly according to the empty or full load state of the vehicle, thereby preventing the problem of insufficient braking force when the vehicle is fully loaded and excessive braking force when the vehicle is empty.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a self-adjusting relay valve. BACKGROUND

[0002] The relay valve can be generally provided in an automobile brake system. Especially in a brake system of a commercial vehicle, the relay valve can function to shorten the charging and discharging time. Here, the relay valve has an inlet connected to an air reservoir and an outlet connected to a brake chamber. When the brake pedal is depressed, the output air pressure of a foot brake valve is input to a control port of the relay valve as a control pressure, and under the control pressure, an inlet valve is pushed open, so that compressed air from the air reservoir directly enters the brake chamber through the inlet, without passing through the brake valve, which greatly shortens the charging line of the brake chamber and accelerates the charging process of the brake chamber. When the brake is released, the output air pressure of the brake valve is zero, the inlet valve is closed, and the outlet valve is opened, so that the air pressure of the brake chamber is rapidly discharged to the atmosphere through the outlet and the discharge port, thereby accelerating the discharging process of the brake chamber.

[0003] For a conventional relay valve, the output pressure of the outlet is generally linearly increased with the control pressure of the control port, and is not adjustable between the empty load and the full load of the vehicle. If the brake demand for the empty load is considered, the problem of insufficient brake force for the full load can occur, and if the brake demand for the full load is considered, the problem of excessive brake force for the empty load can occur. Especially, if the relay valve is installed on the rear axle of the vehicle and the brake force of the rear axle is excessive due to the relay valve for the empty load, it can cause abnormal wear of the brake, thereby increasing the cost.

[0004] Therefore, there is a need for a relay valve that takes into account the brake demand for the empty load and the full load. SUMMARY

[0005] Therefore, the purpose of the present disclosure is to provide a self-adjusting relay valve that can prevent the problems of insufficient brake force for the full load and excessive brake force for the empty load of the vehicle.

[0006] To this end, according to the present disclosure, a self-adjusting relay valve can include a housing including an upper housing having a control port and a lower housing having an intake port, an output port and an exhaust port; a control cavity defined in the upper housing, a piston being sealingly and reciprocally disposed in the control cavity with respect to the upper housing and dividing the control cavity into an upper cavity above the piston and a lower cavity below the piston, the control port being in communication with the upper cavity; a lower housing cavity defined in the lower housing, an intake-exhaust assembly being sealingly and reciprocally disposed in the lower housing cavity with respect to the lower housing and dividing the lower housing cavity into an intake cavity in communication with the intake port and an exhaust cavity in communication with the exhaust port; wherein the piston includes, at a lower portion thereof, an inner operating section protruding toward the lower housing, an outer annular section and an intermediate annular section between the inner operating section and the outer annular section, thereby defining a first annular cavity by the inner operating section and the intermediate annular section, a second annular cavity by the intermediate annular section and the outer annular section, and a third annular cavity by the outer annular section and an inner wall of the upper housing defining the control cavity; the output port being in communication with the first annular cavity, the intermediate annular section being sealed with respect to the lower housing, such that the first annular cavity and the second annular cavity are not directly communicated when assembled; the inner operating section being operable to act on the intake-exhaust assembly, the intake cavity being in communication with the first annular cavity when the inner operating section acts on the intake-exhaust assembly, and the intake cavity being disconnected from the first annular cavity when the inner operating section does not act on the intake-exhaust assembly; a pressure regulating assembly being disposed in a pressure regulating cavity of the lower housing, the pressure regulating cavity being in communication with the first annular cavity and the second annular cavity, respectively, the pressure regulating assembly being operable to connect or disconnect the first annular cavity and the second annular cavity by means of a trigger device.

[0007] Therefore, the relay valve according to the present disclosure is capable of automatically adjusting the pressure change ratio of the output port and the control port of the relay valve, that is, automatically adjusting the curve of the output pressure with respect to the control pressure, according to the empty or full load state of the vehicle by means of the trigger device and the pressure regulating assembly. Therefore, the relay valve according to the present disclosure is capable of automatically switching between the empty load and the full load of the vehicle, thereby realizing the self-adjusting function of the relay valve, thereby preventing the insufficient braking force when the vehicle is fully loaded and the excessive braking force when the vehicle is empty.

[0008] Preferably, the pressure regulating assembly can include a valve rod in the pressure regulating cavity of the lower housing, the valve rod being movable between a first position in which the valve rod connects the first annular cavity and the second annular cavity and a second position in which the valve rod disconnects the first annular cavity and the second annular cavity by means of the trigger device. Therefore, the pressure regulating assembly can be realized in a simple manner.

[0009] Preferably, the pressure regulating chamber can have a first passage opening in communication with the first annular chamber and a second passage opening in communication with the second annular chamber; the valve stem can be sealed against the pressure regulating chamber by means of a valve stem seal, the valve stem seal being located between the first passage opening and the second passage opening, the valve stem comprising a reduced diameter portion having an outer diameter smaller than an inner diameter of the valve stem seal; in said first position, the reduced diameter portion is opposite the valve stem seal and the valve stem is thus no longer sealed against the pressure regulating chamber, so that the passage of the pressure regulating chamber between the first passage opening and the second passage opening is not blocked and the first annular chamber is thus in communication with the second annular chamber; in said second position, the reduced diameter portion is not opposite the valve stem seal and the valve stem is thus sealed against the pressure regulating chamber, so that the passage of the pressure regulating chamber between the first passage opening and the second passage opening is blocked and the first annular chamber is thus disconnected from the second annular chamber. The pressure regulating assembly can thus be realized in a simple manner.

[0010] Preferably, the valve stem can comprise a trigger section capable of interacting with the trigger device, the trigger section extending through the open first end of the pressure regulating chamber and outside the lower housing. The trigger device can thus be simply associated with the pressure regulating assembly.

[0011] Preferably, the valve stem can also be sealed against the pressure regulating chamber by means of a first additional seal, the first additional seal being arranged in the region between the first passage opening and the first end of the pressure regulating chamber. Gas entering the first passage opening can thus be prevented from leaking.

[0012] Preferably, the pressure regulating chamber can have a third passage opening in communication with the exhaust chamber, the third passage opening being arranged in the region of the closed second end of the pressure regulating chamber; the valve stem can also be sealed against the pressure regulating chamber by means of a second additional seal, the second additional seal being arranged in the region between the second passage opening and the third passage opening; the valve stem can also comprise an additional reduced diameter portion, the additional reduced diameter portion being located between the free end of the valve stem facing the closed second end and the reduced diameter portion, the additional reduced diameter portion having an outer diameter smaller than an inner diameter of the second additional seal, and the spacing between the reduced diameter portion and the additional reduced diameter portion being smaller than the spacing between the valve stem seal and the second additional seal; in said first position, the additional reduced diameter portion is not opposite the second additional seal, whereas in said second position, the additional reduced diameter portion is opposite the second additional seal. Gas entering the second passage opening can thus be prevented from leaking.

[0013] Preferably, the valve stem can also have an enlarged diameter portion, the enlarged diameter portion being located between the reduced diameter portion and the additional reduced diameter portion and adjoining the additional reduced diameter portion. The correct positioning of the valve stem can thus be ensured.

[0014] Preferably, the trigger device can trigger the valve stem of the pressure regulating assembly to move to the first position or the second position according to the change of the vertical distance between the axle and the vehicle frame located above the axle. Thus, the trigger element can trigger the pressure regulating assembly of the relay valve to automatically switch according to the change of the relative position between the vehicle frame and the axle, so that the pressure regulating assembly of the relay valve can automatically adjust the curve of the output pressure of the relay valve with the change of the control pressure.

[0015] Preferably, the trigger device is a pull cable or a pull rod, or a swing lever. In particular, the relay valve can be installed on the vehicle frame above the rear axle of the vehicle on the basis of a conventional relay valve, and is provided with an elastic arm connected with the axle, and the relay valve is connected with the elastic arm through the pull cable or the pull rod. In this way, the relay valve can be switched by the change of the relative position between the vehicle frame and the axle when the vehicle is empty and full, so as to realize the automatic adjustment function of the relay valve.

[0016] Preferably, the outer annular section of the piston is sealed relative to the lower housing by a first seal, or the upper housing is sealed relative to the lower housing by a second seal. In this way, the position of the seal can be changed, so that the adjustable range of the output pressure of the relay valve can be changed. Thus, the relay valve can change the adjustable range of the braking force output by the relay valve as needed.

[0017] Preferably, the ratio of the area of the upper surface of the piston in the upper chamber to the area of the lower surface of the piston in the first annular chamber and on the inner operating section and the intermediate annular section is between 1.3:1 and 1.6:1.

[0018] Preferably, the ratio of the area of the upper surface of the piston in the upper chamber to the area of the lower surface of the piston in the first annular chamber and on the inner operating section and the intermediate annular section is between 1.3:1 and 1.6:1.

[0019] Preferably, the ratio of the area of the upper surface of the piston in the upper chamber to the area of the lower surface of the piston in the first annular chamber and on the inner operating section and the intermediate annular section is between 1.3:1 and 1.6:1. BRIEF DESCRIPTION OF DRAWINGS

[0020] The technical solutions of the present disclosure will be further described below with reference to the drawings. In the drawings:

[0021] Figure 1A and 1B are respectively schematic perspective views of a self-adjusting relay valve according to an embodiment of an embodiment according to the present disclosure;

[0022] Figure 2 is a schematic sectional view of the self-adjusting relay valve of FIG. 1;

[0023] Figure 3AA sectional view of a self-adjusting relay valve according to the present disclosure having a pressure regulating assembly with a valve stem in a first position;

[0024] Figure 3B A sectional view of a self-adjusting relay valve according to the present disclosure having a pressure regulating assembly with a valve stem in a second position; Figure 3A An enlarged view of the pressure regulating assembly in

[0025] Figure 4A A sectional view of a self-adjusting relay valve according to the present disclosure having a pressure regulating assembly with a valve stem in a first position;

[0026] Figure 4B An enlarged view of the pressure regulating assembly in Figure 4A

[0027] Figure 5A A schematic view showing the variation of the output pressure of the relay valve with the control pressure corresponding to the first and second positions of the valve stem in the case of using the first seal;

[0028] Figure 5B A schematic view showing the variation of the output pressure of the relay valve with the control pressure corresponding to the first and second positions of the valve stem in the case of using the second seal;

[0029] Figure 6 A schematic view showing an embodiment of the trigger device according to the present disclosure configured as a pull cable or a pull rod. DETAILED DESCRIPTION

[0030] In the description of the present disclosure, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present disclosure.

[0031] Figure 1A and 1B A schematic perspective view of a self-adjusting relay valve according to an embodiment of the present disclosure is shown. The relay valve can include an inlet port 10, an outlet port 20, an exhaust port 30, and a control port 40. The inlet port 10 can be configured for connection with a reservoir, the outlet port 20 can be configured for connection with a brake chamber, the exhaust port 30 can be configured for communication with the atmosphere, and the control port 40 can be configured for connection with a brake valve and thus can cause the output air pressure of the brake valve to be input as the control pressure of the relay valve. In addition, one or more inlet ports 10 and / or one or more outlet ports 20 can be provided as needed.

[0032] Figure 2 ​A schematic cross-sectional view of the self-adjusting relay valve of Fig. 1 is shown, which is cut through the inlet port 10, the outlet port 20, the exhaust port 30 and the control port 40. The relay valve can comprise a housing 100. In the housing 100 a piston 200 and an inlet / exhaust assembly 300 can be provided. The housing 100 can comprise an upper housing 110 and a lower housing 120. The control port 40 and the piston 200 can be provided in the upper housing 110, and the inlet port 10, the outlet port 20 and the exhaust port 30 and the inlet / exhaust assembly 300 can be provided in the lower housing 120.

[0033] A control chamber is defined in the upper housing 110 of the housing 100. The piston 200 can be sealingly and reciprocatingly arranged in the control chamber of the upper housing 110 relative to the upper housing 110 and thus can divide the control chamber into an upper chamber 111 above the piston 200 and a lower chamber 112 below the piston 200. The control port 40 is in communication with the upper chamber 111, whereby a control pressure from a brake valve can enter the upper chamber 111 via the control port 40 to act on an upper surface of the piston 200.

[0034] The piston 200 can comprise in its lower part an inner operation section 210 protruding into the lower housing 120, an outer annular section 220 and an intermediate annular section 230 between the inner operation section 210 and the outer annular section 220.

[0035] The inner operation section 210 can be located substantially in the center of the piston and can be configured as a cylindrical protrusion. A guide groove 211 can be provided in the inner operation section 210 and a corresponding guide protrusion 113 can be provided on the upper housing 110, whereby the reciprocating movement of the piston 200 in the control chamber can be guided by the guide groove 211 and the guide protrusion 113. The guide protrusion 113 can be sealed relative to the guide groove 211 by means of a sealing, in particular an O-ring.

[0036] The outer annular section 220 can be provided along or near the outer circumference of the piston and can be sealed relative to the inner wall of the upper housing 110 defining the control chamber by means of a sealing, in particular an O-ring.

[0037] In one embodiment, the outer annular section 220 can be sealed relative to the lower housing 120 by means of a first sealing 510, which can be a Y-shaped sealing ring, for example. In an alternative embodiment, no first sealing 510 sealing the outer annular section 220 relative to the lower housing 120 can be provided. In this case, the upper housing 110 can be sealed relative to the lower housing 120 by means of a second sealing, which can be an O-ring, for example. To this end, a recess 520 for accommodating the second sealing can be provided on the lower housing 120 and the second sealing, in particular the O-ring, can be arranged in the recess 520 in order to seal the upper housing 110 relative to the lower housing 120.

[0038] The intermediate annular section 230 can also be sealed relative to the lower housing 120 by a seal.

[0039] The outer annular section 220 and the intermediate annular section 230 can be circular annular closed sections, but can also be closed sections of other shapes.

[0040] A first annular cavity A can be defined by the inner operating section 210 of the piston 200 and the intermediate annular section 230, a second annular cavity B can be defined by the intermediate annular section 230 and the outer annular section 220, and a third annular cavity C can be defined by the outer annular section 220 and the inner wall of the upper housing 110 defining the control cavity. For the embodiment using the first seal 510, the second annular cavity B and the third annular cavity C are disconnected, so that the first annular cavity A can communicate with the second annular cavity B but cannot communicate with the third annular cavity C. For the embodiment using the second seal, the second annular cavity B and the third annular cavity C remain in communication, so that the first annular cavity A can communicate with the second annular cavity B and the third annular cavity C at the same time.

[0041] The intake and exhaust assembly 300 can be sealingly and reciprocally arranged in the lower housing cavity of the lower housing 120 relative to the lower housing 120, and thus can divide the lower housing cavity into an intake cavity 121 communicating with the air intake port 10 and an exhaust cavity 122 communicating with the air exhaust port 30. The intake cavity 121 can communicate with or be disconnected from the first annular cavity A defined by the inner operating section 210 of the piston 200 and the intermediate annular section 230 by means of the intake and exhaust assembly 300.

[0042] The intake and exhaust assembly 300 can adopt the structure for realizing the intake and exhaust function in the existing relay valve. Figure 2 In the embodiment, the intake and exhaust assembly 300 can include a valve 310, a valve body 320, and a return spring 330. A spring accommodating cavity can be formed in the valve body 320, and the return spring 330 can be placed in the spring accommodating cavity and load the valve 310. The valve 310 can be configured as an end cover for the valve body 320 to close the spring accommodating cavity in the valve body 320. The valve 310 can abut against a valve seat 310' on the lower housing 120 by the return spring 330, and can be away from the valve seat 310' by the inner operating section 210 of the piston 200. The valve seat 310' can be formed by the lower housing 120 or be a separate member.

[0043] The inner operating section 210 of the piston 200 is operable to act on the intake and exhaust assembly 300 so as to enable the valve 310 of the intake and exhaust assembly 300 to be lifted off the valve seat 310'. When the valve 310 of the intake and exhaust assembly 300 is lifted off the valve seat 310', compressed gas can enter the first annular chamber A from the gas reservoir via the intake port 10 and the intake chamber 121. The first annular chamber A can be in communication with the delivery port 20 so that when the valve 310 of the intake and exhaust assembly 300 is lifted off the valve seat 310', compressed gas can eventually enter the delivery port 20 and thus reach the brake chamber.

[0044] Further, referring to Figure 3A , 3B and Figure 4A , 4B , a pressure regulating assembly 400 can be provided in the lower housing 120. The first annular chamber A can be put in communication with or disconnected from the second annular chamber B by means of the pressure regulating assembly.

[0045] Figure 3A a sectional view of a self-adjusting relay valve according to the present disclosure with a pressure regulating assembly having a valve stem in a first position is shown, Figure 3B a magnified view of the pressure regulating assembly in Figure 3A is shown. Figure 4A a sectional view of a self-adjusting relay valve according to the present disclosure with a pressure regulating assembly having a valve stem in a second position is shown, Figure 4B a magnified view of the pressure regulating assembly in Figure 4A is shown.

[0046] The pressure regulating assembly 400 can include a valve stem 410. The valve stem 410 can be located in a pressure regulating chamber 123 of the lower housing 120 which is in communication with the first annular chamber A and the second annular chamber B, respectively. The valve stem 410 can be moved between a first position as shown in Figure 3A and 3B corresponding to a position when the vehicle is empty and a second position as shown in Figure 4A and 4B corresponding to a position when the vehicle is fully loaded by means of a triggering device to be described in detail below.

[0047] A first passage opening 1231 which can be in communication with the first annular chamber A and a second passage opening 1232 which can be in communication with the second annular chamber B as well as a third passage opening 1235 which can be in communication with the exhaust chamber 122 are provided in the pressure regulating chamber 123. The pressure regulating chamber 123 can have an open first end 1233 and a closed second end 1234.

[0048] The valve stem 410 can be sealed against the pressure regulating chamber 123 by means of a valve stem seal 401, which is located between the first passage opening 1231 and the second passage opening 1232. The valve stem 410 can comprise a reduced diameter portion 411, which has an outer diameter that is smaller than the inner diameter of the valve stem seal 401.

[0049] The valve stem 410 can further comprise a trigger section 413. The trigger section 413 is capable of interacting with a trigger device, thereby causing the valve stem 410 to move. In this embodiment, the trigger section 413 extends through the open first end 1233 of the pressure regulating chamber 123 and outside the lower housing 120.

[0050] In order to prevent gas from the first annular chamber A from leaking through the open first end 1233 of the pressure regulating chamber 123, the valve stem 410 can be further sealed against the pressure regulating chamber 123 by means of a first additional seal 402. The first additional seal 402 is arranged in the region between the first passage opening 1231 and the first end 1233 of the pressure regulating chamber 123.

[0051] The pressure regulating assembly 400 can further comprise a first sleeve 404, in which the valve stem 401 is guided. The first sleeve 404 can be fixedly arranged with respect to the pressure regulating chamber 123. The first additional seal 402 can be arranged on the first sleeve 404.

[0052] A third passage opening 1235 of the pressure regulating chamber 123 can be arranged in the region of the closed second end 1234 of the pressure regulating chamber 123. Gas between the free end of the valve stem 410 facing the closed second end 1234 and the closed second end 1234 can enter the exhaust chamber 122 through the third passage opening 1235.

[0053] In order to prevent air from the second annular chamber B from leaking through the third passage opening 1235, the valve stem 410 can be further sealed against the pressure regulating chamber 123 by means of a second additional seal 403. The second additional seal 403 can be arranged in the region between the second passage opening 1232 and the third passage opening 1235. The valve stem 410 can further comprise an additional reduced diameter portion 412. The additional reduced diameter portion 412 is located between the free end of the valve stem 410 and the reduced diameter portion 411, and has an outer diameter that is smaller than the inner diameter of the second additional seal 403. The distance between the reduced diameter portion 411 and the additional reduced diameter portion 412 is smaller than the distance between the valve stem seal 401 and the second additional seal 403.

[0054] In addition, the free end of the valve stem 410 facing the closed second end 1234 can be guided in a second sleeve 405. The second sleeve 405 can be fixedly arranged in the pressure regulating chamber 123.

[0055] In the case of a pressure regulating assembly 400 according to the application, the valve stem 410 can be guided in the first sleeve 404 and the second sleeve 405. Figure 3A and 3BIn the first position shown, the diameter-reduced portion 411 is opposite the valve stem seal 401, so gas from the first passage port 1231 can pass through the gap between the diameter-reduced portion 411 and the valve stem seal 401 to the second passage port 1232, thereby communicating the first annular chamber A with the second annular chamber B. Also, in this first position, the additional diameter-reduced portion 412 is not opposite the second additional seal 403. Thus, gas from the first annular chamber A cannot reach the third passage port 1235, but gas between the free end of the valve stem 410 within the pressure regulating chamber 123 and the second end 1234 of the pressure regulating chamber 123 can pass through the third passage port 1235 into the exhaust chamber 122, thereby being discharged to the atmosphere via the exhaust port 30.

[0056] In the second position shown, the diameter-reduced portion 411 is not opposite the valve stem seal 401, so gas from the first passage port 1231 cannot reach the second passage port 1232, thereby disconnecting the first annular chamber A from the second annular chamber B. Also, in this second position, the additional diameter-reduced portion 412 is opposite the second additional seal 403, so gas from the second passage port 1232 can pass through the gap between the additional diameter-reduced portion 412 and the second additional seal 403 to the third passage port 1235, thereby being discharged to the atmosphere via the third passage port 1235, the exhaust chamber 122, and the exhaust port 30. Figure 4A 4B In the second position shown, the diameter-reduced portion 411 is not opposite the valve stem seal 401, so gas from the first passage port 1231 cannot reach the second passage port 1232, thereby disconnecting the first annular chamber A from the second annular chamber B. Also, in this second position, the additional diameter-reduced portion 412 is opposite the second additional seal 403, so gas from the second passage port 1232 can pass through the gap between the additional diameter-reduced portion 412 and the second additional seal 403 to the third passage port 1235, thereby being discharged to the atmosphere via the third passage port 1235, the exhaust chamber 122, and the exhaust port 30.

[0057] The valve stem 410 can also have a diameter-enlarged portion 414 between the diameter-reduced portion 411 and the additional diameter-reduced portion 412 and adjacent the additional diameter-reduced portion 412. Due to this diameter-enlarged portion 414, it is possible to ensure that the additional diameter-reduced portion 412 can move only between the valve stem seal 401 and the second additional seal 403.

[0058] Figure 5A A diagram showing the output pressure of the relay valve as a function of the control pressure corresponding to the first position and the second position of the valve stem 410 in the case where the first seal 510 is used.

[0059] ​The curve L1 of the output pressure of the relay valve as a function of the control pressure corresponds to the curve in the case where the valve stem 410 is in the first position, i.e. the vehicle is empty. Since in the case where the valve stem 410 is in the first position, the first annular chamber A is in communication with the second annular chamber B. In this case, the compressed air from the reservoir acts on the lower surface of the piston 200 in the first annular chamber A and the second annular chamber B and on the inner operating section 210 and the intermediate annular section 230, whereby the ratio of the increased output pressure ΔP2 of the relay valve to the increased control pressure ΔP4 corresponds to the ratio of the area of the upper surface of the piston 200 in the upper chamber 111 to the sum of the areas of the lower surface of the piston 200 in the first annular chamber A and the second annular chamber B and on the inner operating section 210 and the intermediate annular section 230. Thus, for the curve L1, the ratio of the increased output pressure ΔP2 to the increased control pressure ΔP4 is for example between 1.3:1 and 1.6:1, in particular about 1.5:1, i.e. the pressure change ratio of the output port and the control port of the relay valve is between 1.3:1 and 1.6:1, in particular about 1.5:1.

[0060] The curve L2 of the output pressure of the relay valve as a function of the control pressure corresponds to the curve in the case where the valve stem 410 is in the second position, i.e. the vehicle is fully loaded. Since in the case where the valve stem 410 is in the second position, the first annular chamber A is disconnected from the second annular chamber B. In this case, the compressed air from the reservoir acts on the lower surface of the piston 200 only in the first annular chamber A and on the inner operating section 210 and the intermediate annular section 230, whereby the ratio of the increased output pressure ΔP2 of the relay valve to the increased control pressure ΔP4 corresponds to the ratio of the area of the upper surface of the piston 200 in the upper chamber 111 to the sum of the areas of the lower surface of the piston 200 in the first annular chamber A and on the inner operating section 210 and the intermediate annular section 230. Thus, for the curve L2, the ratio of the increased output pressure ΔP2 to the increased control pressure ΔP4 is for example between 2:1 and 4:1, in particular about 3:1, i.e. the pressure change ratio of the output port and the control port of the relay valve is between 2:1 and 4:1, in particular about 3:1.

[0061] Figure 5B A diagram showing the curves of the output pressure of the relay valve as a function of the control pressure corresponding to the first position and the second position of the valve stem 410 in the case where the second sealing member is used.

[0062] The curve L3 of the output pressure of the relay valve as a function of the control pressure corresponds to the curve when the valve stem 410 is in the first position, i.e. the vehicle is in the unloaded position. Since in this case the first annular chamber A is in communication with the second annular chamber B and the third annular chamber C. In this case, the compressed air from the reservoir acts on the lower surface of the piston 200 in the first annular chamber A, the second annular chamber B and the third annular chamber C and on the inner operating section 210, the intermediate annular section 230 and the outer annular section 220, whereby the ratio of the increased output pressure ΔP2 of the relay valve to the increased control pressure ΔP4 corresponds to the ratio of the area of the upper surface of the piston 200 in the upper chamber 111 to the sum of the areas of the lower surface of the piston 200 in the first annular chamber A, the second annular chamber B and the third annular chamber C and on the inner operating section 210, the intermediate annular section 230 and the outer annular section 220. Thus, for the curve L3, the ratio of the increased output pressure ΔP2 to the increased control pressure ΔP4 is for example between 1 : 1 and 1.2: 1, in particular about 1 : 1, i.e. the pressure change ratio of the output port and the control port of the relay valve is between 1 : 1 and 1.2: 1, in particular about 1 : 1.

[0063] The curve L4 of the output pressure of the relay valve as a function of the control pressure corresponds to the curve when the valve stem 410 is in the second position, i.e. the vehicle is in the fully loaded position. Since in this case the first annular chamber A is disconnected from the second annular chamber B and the third annular chamber C. In this case, the compressed air from the reservoir acts on the lower surface of the piston 200 only in the first annular chamber A and on the inner operating section 210 and the intermediate annular section 230, whereby the ratio of the increased output pressure ΔP2 of the relay valve to the increased control pressure ΔP4 corresponds to the ratio of the area of the upper surface of the piston 200 in the upper chamber 111 to the sum of the areas of the lower surface of the piston 200 in the first annular chamber A and on the inner operating section 210 and the intermediate annular section 230. Thus, for the curve L4, the ratio of the increased output pressure ΔP2 to the increased control pressure ΔP4 is for example between 2: 1 and 4: 1, in particular about 3: 1, i.e. the pressure change ratio of the output port and the control port of the relay valve is between 2: 1 and 4: 1, in particular about 3: 1.

[0064] As mentioned above, in order to enable the valve stem 410 of the pressure regulating assembly to move between the first position and the second position, a triggering device 600 is provided. The triggering device can trigger the valve stem 410 to move to the first position or the second position depending on the change of the relative position of the vehicle frame and the vehicle axle. When the vehicle is empty, the vehicle frame is at a relatively high position, and when the vehicle is fully loaded, the vehicle frame is at a relatively low position. Therefore, when the vehicle is empty, the distance between the vehicle frame and the vehicle axle is large, and when the vehicle is fully loaded, the distance between the vehicle frame and the vehicle axle is small. Thus, when the vehicle is empty, the triggering device 600 can trigger the valve stem 410 to move to the first position. In this first position, the pressure change ratio of the output port and the control port of the relay valve is about 1.5:1 or 1:1, in particular. Therefore, the change curve of the output pressure P2 is relatively flat, thereby preventing the emptying braking force from being too large. When the vehicle is fully loaded, the triggering device 600 can trigger the valve stem 410 to move to the second position. In this second position, the pressure change ratio of the output port and the control port of the relay valve is about 3:1, in particular, as mentioned above. Therefore, the change curve of the output pressure P2 is relatively steep, thereby preventing the fully loaded braking force from being insufficient.

[0065] As one embodiment of the triggering device 600, the triggering device 600 can be configured as a pull cable or a pull rod. Figure 6 A schematic diagram showing the embodiment in which the triggering device 600 is configured as a pull cable or a pull rod is shown. In this embodiment, the relay valve according to the present disclosure can be mounted on the vehicle frame above the vehicle axle, and the pressure regulating cavity 123 of the relay valve extends in the vertical direction. The pull cable or the pull rod also extends in the vertical direction, and can be connected to the vehicle axle 620 on one side, for example, through the elastic arm 610, and can be connected to the part of the triggering section 413 of the valve stem 410 of the pressure regulating assembly that protrudes out of the housing 100 of the relay valve on the other side, in particular. Thus, the pull cable or the pull rod can move vertically depending on the change of the relative position of the vehicle frame and the vehicle axle 620. When the vehicle is empty, the vehicle frame moves upwards, and the pull cable or the pull rod moves the valve stem 410 of the pressure regulating assembly to the first position; when the vehicle is fully loaded, the vehicle frame moves downwards, and the pull cable or the pull rod moves the valve stem 410 of the pressure regulating assembly to the second position.

[0066] As an alternative embodiment of the triggering device 600, the triggering device 600 can also be configured as a swing lever.

[0067] The above-described embodiments are merely examples for the purpose of clarity and are not intended to limit the present disclosure. Based on the above description, those skilled in the art can make other different forms of changes or modifications. Here, it is not necessary and impossible to exhaust all the embodiments. The obvious changes or modifications derived therefrom are still within the protection scope of the present disclosure.

Claims

1. A self-adjusting relay valve, Includes a housing (100), which includes an upper housing (110) having a control port (40) and a lower housing (120) having an air inlet (10), an outlet (20) and an exhaust port (30). A control cavity is defined in the upper housing (110), and a piston (200) is disposed in the control cavity in a sealed manner and reciprocally relative to the upper housing (110), dividing the control cavity into an upper cavity (111) above the piston (200) and a lower cavity (112) below the piston (200), and a control port (40) communicates with the upper cavity (111); A lower housing cavity is defined in the lower housing (120), and an intake and exhaust assembly (300) is disposed in the lower housing cavity of the lower housing (120) in a sealing manner and reciprocally movable relative to the lower housing (120), and the lower housing cavity is divided into an intake cavity (121) communicating with an intake port (10) and an exhaust cavity (122) communicating with an exhaust port (30). Its features are, The piston (200) includes, at its lower portion, an inner operating section (210) projecting downward toward the housing (120), an outer annular section (220), and an intermediate annular section (230) located between the inner operating section (210) and the outer annular section (220), thereby defining a first annular cavity (A) by the inner operating section (210) and the intermediate annular section (230), a second annular cavity (B) defined by the intermediate annular section (230) and the outer annular section (220), and a third annular cavity (C) defined by the outer annular section (220) and the inner wall of the upper housing (110) defining a control cavity; The output port (20) is connected to the first annular cavity (A), and the middle annular section (230) is sealed relative to the lower housing (120), so that the first annular cavity (A) and the second annular cavity (B) are not directly connected when assembled; The inner operating section (210) can be operably applied to the intake and exhaust assembly (300). When the inner operating section (210) applies to the intake and exhaust assembly (300), the intake chamber (121) is connected to the first annular chamber (A). When the inner operating section (210) does not apply to the intake and exhaust assembly (300), the intake chamber (121) is disconnected from the first annular chamber (A). A pressure regulating component (400) is provided in the pressure regulating cavity (123) of the lower housing (120). The pressure regulating cavity (123) is connected to the first annular cavity (A) and the second annular cavity (B) respectively. The pressure regulating component (400) can connect or disconnect the first annular cavity (A) and the second annular cavity (B) by means of a triggering device (600). The pressure regulating assembly (400) includes a valve stem (410) located in a pressure regulating chamber (123) of the lower housing (120). The valve stem (410) is movable between a first position and a second position by means of a triggering device (600). In the first position, the valve stem (410) connects a first annular cavity (A) and a second annular cavity (B). In the second position, the valve stem (410) disconnects the first annular cavity (A) and the second annular cavity (B). The triggering device (600) triggers the valve stem (410) of the pressure regulating assembly to move to the first position or the second position according to the change in the vertical distance between the axle and the frame located above the axle.

2. The relay valve according to claim 1, characterized in that, The pressure regulating chamber (123) has a first channel port (1231) communicating with the first annular cavity (A) and a second channel port (1232) communicating with the second annular cavity (B). The valve stem (410) is sealed relative to the pressure regulating chamber (123) by means of a valve stem seal (401). The valve stem seal (401) is located between the first channel port (1231) and the second channel port (1232). The valve stem (410) includes a diameter reduction portion (411), the outer diameter of which is smaller than the inner diameter of the valve stem seal (401). In the first position, the diameter reduction portion (411) is opposite to the valve stem seal (401) and therefore the valve stem (410) is no longer sealed relative to the pressure regulating chamber (123), so the passage of the pressure regulating chamber (123) between the first channel port (1231) and the second channel port (1232) is not blocked and therefore the first annular cavity (A) and the second annular cavity (B) are connected; In the second position, the diameter reduction portion (411) is not opposite to the valve stem seal (401) and therefore the valve stem (410) is sealed relative to the pressure regulating chamber (123), thereby blocking the passage of the pressure regulating chamber (123) between the first channel port (1231) and the second channel port (1232) and thus the first annular cavity (A) is disconnected from the second annular cavity (B).

3. The relay valve according to claim 2, characterized in that, The valve stem (410) includes a trigger section (413) capable of interacting with the triggering device (600), the trigger section (413) extending through the open first end (1233) of the pressure regulating chamber (123) and extending beyond the lower housing (120).

4. The relay valve according to claim 3, characterized in that, The valve stem (410) is also sealed relative to the pressure regulating chamber (123) by means of a first additional seal (402), which is located in the area between the first channel opening (1231) and the first end (1233) of the pressure regulating chamber (123).

5. The relay valve according to claim 2, characterized in that, The pressure regulating chamber (123) has a third channel opening (1235) communicating with the exhaust chamber (122), and the third channel opening (1235) is located in the region of the closed second end (1234) of the pressure regulating chamber (123); The valve stem (410) is also sealed relative to the pressure regulating chamber (123) by means of a second additional seal (403), which is located in the area between the second channel port (1232) and the third channel port (1235); The valve stem (410) also includes an additional diameter reduction portion (412), which is located between the free end of the valve stem (410) facing the closed second end (1234) and the diameter reduction portion (411). The outer diameter of the additional diameter reduction portion (412) is smaller than the inner diameter of the second additional seal (403), and the distance between the diameter reduction portion (411) and the additional diameter reduction portion (412) is smaller than the distance between the valve stem seal (401) and the second additional seal (403). In the first position, the additional diameter reduction portion (412) is not opposite to the second additional seal (403), while in the second position, the additional diameter reduction portion (412) is opposite to the second additional seal (403).

6. The relay valve according to claim 5, characterized in that, The valve stem (410) also has a diameter enlargement portion (414) which is between and adjacent to the diameter reduction portion (411) and the additional diameter reduction portion (412).

7. The relay valve according to claim 1, characterized in that, The triggering device (600) is configured as a cable or a lever, or as a swing arm.

8. The relay valve according to any one of claims 1 to 7, characterized in that, The outer annular segment (220) of the piston (200) is sealed relative to the lower housing (120) by a first seal (510), or the upper housing (110) is sealed relative to the lower housing (120) by a second seal.

9. The relay valve according to any one of claims 1 to 7, characterized in that, The ratio of the area of ​​the upper surface of the piston (200) in the upper cavity (111) to the area of ​​the lower surface of the piston (200) in the first annular cavity (A) and the second annular cavity (B), as well as in the inner operating section (210) and the intermediate annular section (230) is between 1.3:1 and 1.6:

1.

10. The relay valve according to any one of claims 1 to 7, characterized in that, The ratio of the area of ​​the upper surface of the piston (200) in the upper cavity (111) to the area of ​​the lower surface of the piston (200) in the first annular cavity (A) and in the inner operating section (210) and the intermediate annular section (230) is between 2:1 and 4:

1.

11. The relay valve according to any one of claims 1 to 7, characterized in that, The ratio of the area of ​​the upper surface of the piston (200) in the upper cavity (111) to the area of ​​the lower surface of the piston (200) in the first annular cavity (A), the second annular cavity (B) and the third annular cavity (C) and in the inner operating section (210), the middle annular section (230) and the outer annular section (220) is between 1:1 and 1.2:1.

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