A combined service brake and energy storage brake cylinder

Abstract

The application discloses a combined service brake and energy storage brake cylinder, which comprises a shell, a parking brake push rod and a brake piston, the shell is internally provided with a service brake cavity, an energy storage brake cavity and a brake parking cavity, the parking brake push rod is internally provided with a breathing valve, the breathing valve comprises a valve body, an exhaust valve piston, an actuator element, a loading spring and an adjusting spring, the valve body is internally provided with a first cavity, a second cavity and a sealing surface, one end of the actuator element is arranged in the second cavity, the other end penetrates through the valve body and is fixed with the shell, the exhaust valve piston is slidably arranged in the first cavity, the loading spring is connected with the valve body and the exhaust valve piston, so that the exhaust valve piston is pressed against the sealing surface on the side of the second cavity and unidirectionally separates the first cavity and the second cavity, and the adjusting spring is connected with the exhaust valve piston and the actuator element. The application provides a combined service brake and energy storage brake cylinder, and the stroke of the exhaust valve piston in the breathing valve can be reduced.

Description

Technical Field

[0001] This invention relates to the field of automotive parts technology, and in particular to a combined service brake and energy storage brake cylinder. Background Technology

[0002] Spring brake cylinders are commonly used components in automotive braking systems, and the breather valve is a crucial part within them. In existing spring brake cylinders, to match the stroke of the parking brake push rod, the breather valve typically requires a relatively large stroke for the exhaust valve piston. This results in a large breather valve size and a long travel time for the exhaust valve piston to complete its stroke, leading to issues with low sensitivity. Summary of the Invention

[0003] In order to overcome the problem that the exhaust valve piston of the breather valve in the prior art has a large stroke, resulting in low sensitivity of the breather valve, the present invention provides a combined service brake and energy storage brake cylinder, which can reduce the stroke of the exhaust valve piston in the breather valve.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A combined service brake and energy storage brake cylinder includes a housing, a parking brake push rod, and a brake piston fixed to the parking brake push rod. The housing contains a service brake chamber, an energy storage brake chamber, and a parking brake chamber. The parking brake push rod contains a breather valve, which includes a valve body, an exhaust valve piston, an actuator element, a loading spring, and an adjusting spring. The valve body is fixed to the parking brake push rod. The valve body contains a first chamber communicating with the service brake chamber, a second chamber communicating with the energy storage brake chamber, and a sealing surface disposed between the first and second chambers. One end of the actuator element is disposed in the second chamber, and the other end extends out of the valve body and is fixed to the housing. The exhaust valve piston is slidably disposed in the first chamber. The loading spring connects the valve body and the exhaust valve piston, so that the exhaust valve piston presses the sealing surface towards the second chamber and unidirectionally isolates the first and second chambers. The adjusting spring connects the exhaust valve piston and the actuator element.

[0006] In the above technical solution, since the other end of the actuator element protrudes from the valve body and is fixed to the housing, when the parking brake push rod moves, the actuator element will have a relative displacement relative to the valve body, thereby changing the distance between the actuator element and the exhaust valve piston. When the parking brake is released, the actuator element is in a position relatively far away from the first chamber. The exhaust valve piston is pressed against the sealing surface under the combined force of the loading spring and the adjusting spring, thereby isolating the first chamber and the second chamber. At this time, the exhaust valve piston is in a sealed state. In this state, the air pressure in the energy storage brake chamber will generate a thrust on the exhaust valve piston opposite to the spring force of the loading spring. When the thrust generated by the air pressure in the energy storage brake chamber is large enough, it can push the exhaust valve piston away from the sealing surface, making the first chamber and the second chamber connected. When the air pressure in the energy storage brake chamber decreases to an insufficient level to push the exhaust valve piston open, the exhaust valve piston returns to the state of pressing against the sealing surface. When the parking brake is engaged, the parking brake push rod moves to one side relative to the housing, while the actuator element remains fixed relative to the housing. The actuator element moves relative to the first cavity, compressing the adjusting spring. When the adjusting spring is compressed to a certain extent, the spring force generated by the adjusting spring pointing towards the first cavity exceeds the spring force of the loading spring pointing towards the second cavity. This pushes the exhaust valve piston away from the sealing surface, allowing the first and second cavities to connect. Due to the combined action of the loading and adjusting springs, when the exhaust valve piston switches from a sealed state to a connected state, the relative displacement between the actuator element and the valve body causes both the loading and adjusting springs to deform simultaneously. Since the displacement of the exhaust valve piston is equal to the deformation of the loading spring, the displacement of the exhaust valve piston is less than the relative displacement between the actuator element and the valve body. Because the parking brake push rod is connected to external parts, its switching stroke remains essentially unchanged. This design converts a large external stroke change into a small change in the exhaust valve piston's shape, ensuring that the exhaust valve piston does not move too far from the sealing surface in the connected state. Furthermore, the models of the loading spring and adjusting spring can be changed as needed to alter the displacement of the exhaust valve piston in the two states, as well as the clamping force exerted by the exhaust valve piston on the sealing surface when it is in a sealed state, making the above solution applicable to various products.

[0007] Preferably, the end of the exhaust valve piston away from the second cavity is disposed in the first cavity, so that the first cavity generates a pressure on the end face of the exhaust valve piston that is parallel to the sliding direction of the exhaust valve piston.

[0008] In the above technical solution, the exhaust valve piston is subjected to thrust from the air pressure of the first and second chambers, respectively. When the exhaust valve piston is in a sealed state, if the air pressure in the energy storage brake chamber is greater than the air pressure in the service brake chamber, and the pressure difference is large enough, the thrust generated by the pressure difference can push the exhaust valve piston away from the sealing surface, connecting the first and second chambers. Gas will flow from the energy storage brake chamber through the second and first chambers into the service brake chamber to achieve air pressure balance. When the pressure difference between the second and first chambers decreases to an insufficient level to push the exhaust valve piston open, the exhaust valve piston will return to the state of pressing the sealing surface. When the exhaust valve piston is in a sealed state, if the pressure in the service brake chamber is greater than the pressure in the energy storage brake chamber, the pressure difference will only increase the sealing pressure, increasing the sealing effect, and will not push the exhaust valve piston open, thus keeping the vehicle brake chamber and the energy storage brake chamber in a state of isolation. The above solution can depressurize the energy storage brake chamber when the relative pressure difference between the energy storage brake chamber and the service brake chamber is too large.

[0009] Preferably, the outer wall of the exhaust valve piston is provided with an adjustment groove, and the exhaust valve piston is provided with a first communication port and a second communication port that are interconnected. The first communication port is connected to the first cavity through the adjustment groove, and the second communication port is connected to the second cavity.

[0010] In the above technical solution, the adjusting groove can determine the airflow between the first and second chambers. Adjusting grooves of different sizes can be set according to specific needs. Since the airflow velocity through the adjusting groove is limited, when the air pressure difference between the service brake chamber and the energy storage brake chamber is too large, the adjusting groove cannot adjust in time. The air pressure difference will cause the exhaust valve piston to overcome the elastic force and press tightly against the second chamber, thus isolating the first and second chambers. Furthermore, due to the combined action of the loading spring and the adjusting spring, when the exhaust valve piston is in the connected state and the distance between the exhaust valve piston and the sealing surface is relatively close, the exhaust valve piston can quickly move to the sealed position, achieving rapid isolation. When the exhaust valve piston is in the connected state, it is in a state of force balance, requiring only a small pressure difference to move the exhaust valve piston, making the isolation action more sensitive.

[0011] Preferably, the inner wall of the first cavity is provided with an adjustment groove, and the exhaust valve piston is provided with a first communication port and a second communication port that are interconnected. The first communication port is connected to the first cavity through the adjustment groove, and the second communication port is connected to the second cavity.

[0012] In the above technical solution, the adjusting groove can determine the airflow between the first and second chambers. Adjusting grooves of different sizes can be set according to specific needs. Since the airflow velocity through the adjusting groove is limited, when the air pressure difference between the service brake chamber and the energy storage brake chamber is too large, the adjusting groove cannot adjust in time. The air pressure difference will cause the exhaust valve piston to overcome the elastic force and press tightly against the second chamber, thus isolating the first and second chambers. Furthermore, due to the combined action of the loading spring and the adjusting spring, when the exhaust valve piston is in the connected state and the distance between the exhaust valve piston and the sealing surface is relatively close, the exhaust valve piston can quickly move to the sealed position, achieving rapid isolation. When the exhaust valve piston is in the connected state, it is in a state of force balance, requiring only a small pressure difference to move the exhaust valve piston, making the isolation action more sensitive.

[0013] Preferably, a retaining spring is connected between the actuator element and the valve body, so that the actuator element moves toward the first cavity side under the action of the retaining spring.

[0014] Preferably, an O-ring is provided at the position where the exhaust valve piston contacts the sealing surface. The O-ring can increase the sealing effect of the sealing surface.

[0015] Preferably, the actuator element is positioned within the second cavity in a first position and a second position. When the actuator element is in the first position, the exhaust valve piston presses against the sealing surface, separating the first and second cavities. When the actuator element is in the second position, the exhaust valve piston disengages from the sealing surface, connecting the first and second cavities. The actuator element can move between the first and second positions.

[0016] Preferably, when the actuator element is in the first position, the loading spring is in a compressed state and the adjusting spring is in a stretched state.

[0017] In the above technical solution, when the actuator element is in the first position, the spring forces of the loading spring and the adjusting spring on the exhaust valve piston are both directed towards the second cavity, so that the exhaust valve piston presses the cover tightly against the second cavity and unidirectionally isolates the first and second cavities. When the actuator element moves towards the first cavity, the adjusting spring will first recover its deformation, and the exhaust valve piston will not move at this time. When the actuator element moves a certain distance, the adjusting spring is compressed, and the spring force of the adjusting spring can counteract the downward force of the loading spring, the exhaust valve piston will be opened, and the moving distance of the exhaust valve piston after opening is the deformation of the loading spring. This solution can further reduce the displacement of the exhaust valve piston when switching between the two states.

[0018] Preferably, when the actuator element is in the first position, the loading spring is in a compressed state, and the adjusting spring is in a compressed state.

[0019] In the above technical solution, when the actuator element is in the first position, the spring forces of the loading spring and the adjusting spring on the exhaust valve piston are in opposite directions. The magnitude of the spring forces of the two springs can be adjusted to regulate the magnitude of the pressing force of the exhaust valve piston on the sealing surface when it is in a sealed state.

[0020] Preferably, the elastic coefficient of the loading spring is greater than that of the adjusting spring. In the above technical solution, after the actuator element of the exhaust valve piston moves a certain distance, the deformation of the adjusting spring is greater than that of the loading spring, and the moving distance of the exhaust valve piston is the deformation of the loading spring. Therefore, the solution can further reduce the displacement of the exhaust valve piston when switching between the two states.

[0021] Preferably, the first cavity is connected to the service brake cavity through a first channel, and the second cavity is connected to the energy storage brake cavity through a second channel. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the parking brake engagement in this invention;

[0023] Figure 2 This is a schematic diagram of the parking brake in this invention when it is released.

[0024] In the diagram: 1. Housing; 2. Parking brake push rod; 2.1. Brake piston; 3. Service brake chamber; 4. Energy storage brake chamber; 5. Breather valve; 5.1. Valve body; 5.2. Exhaust valve piston; 5.3. Actuator element; 5.4. Loading spring; 5.5. Adjusting spring; 5.6. Holding spring; 5.7. First chamber; 5.8. Second chamber; 5.9. Sealing surface; 6. Brake parking chamber; 7. Adjusting groove. Detailed Implementation

[0025] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0026] Example 1:

[0027] like Figure 1 and Figure 2As shown, a combined service brake and energy storage brake cylinder includes a housing 1, a parking brake push rod 2, and a brake piston 2.1 fixed to the parking brake push rod 2. The housing 1 contains a service brake chamber 3, an energy storage brake chamber 4, and a parking brake chamber 6. The energy storage brake chamber 4 and the parking brake chamber 6 are separated by the brake piston 2.1. The parking brake push rod 2 is inside the housing 1 and slidably connected to it. The energy storage brake chamber 4 and the parking brake chamber 6 are separated by the parking brake push rod 2. The parking brake push rod 2 contains a breather valve 5 for connecting or separating the service brake chamber 3 and the energy storage brake chamber 4. The breather valve 5 includes a valve body 5.1, an exhaust valve piston 5.2, an actuator element 5.3, a loading spring 5.4, and an adjusting spring 5.5. The valve body 5.1... Fixed to the parking brake push rod 2, the valve body 5.1 has a first cavity 5.7 communicating with the service brake cavity 3, a second cavity 5.8 communicating with the energy storage brake cavity 4, and a sealing surface 5.9 disposed between the first cavity 5.7 and the second cavity 5.8. One end of the actuator element 5.3 is disposed in the second cavity 5.8, and the other end protrudes from the valve body 5.1 and is fixed to the housing 1. The exhaust valve piston 5.2 is slidably disposed in the first cavity 5.7. The loading spring 5.4 connects the valve body 5.1 and the exhaust valve piston 5.2 so that the exhaust valve piston 5.2 presses the sealing surface 5.9 against the second cavity 5.8 and unidirectionally isolates the first cavity 5.7 and the second cavity 5.8. The adjusting spring 5.5 connects the exhaust valve piston 5.2 and the actuator element 5.3.

[0028] In the above technical solution, since the other end of the actuator element 5.3 protrudes from the valve body 5.1 and is fixed to the housing 1, when the parking brake push rod 2 moves, the actuator element 5.3 will have a relative displacement relative to the valve body 5.1, thereby changing the distance between the actuator element 5.3 and the exhaust valve piston 5.2. When the parking brake is released, the actuator element 5.3 is in a position relatively far away from the first cavity 5.7. Under the combined force of the loading spring 5.4 and the adjusting spring 5.5, the exhaust valve piston 5.2 presses against the sealing surface 5.9, thereby isolating the first cavity 5.7 and the second cavity 5.8. At this time, the exhaust valve piston 5.2 is in a sealed state. In this state, the air pressure in the energy storage brake cavity 4 will generate a thrust on the exhaust valve piston 5.2 opposite to the elastic force of the loading spring 5.4. When the thrust generated by the air pressure in the energy storage brake cavity 4 is large enough, it can push the exhaust valve piston 5.2 away from the sealing surface 5.9, so that the first cavity 5.7 and the second cavity 5.8 are connected. When the air pressure in the energy storage brake chamber 4 decreases to an insufficient level to push open the exhaust valve piston 5.2, the exhaust valve piston 5.2 returns to the state of pressing the sealing surface 5.9. When the parking brake is engaged, the parking brake push rod 2 moves to one side relative to the housing 1, and the actuator element 5.3 is fixed relative to the housing 1. The actuator element 5.3 moves relative to the first cavity 5.7 and compresses the adjusting spring 5.5. When the adjusting spring 5.5 is compressed to a certain extent, the elastic force generated by the adjusting spring 5.5 pointing towards the first cavity 5.7 is greater than the elastic force of the loading spring 5.4 pointing towards the second cavity 5.8, the exhaust valve piston 5.2 is pushed open and away from the sealing surface 5.9 so that the first cavity 5.7 and the second cavity 5.8 are connected. Due to the combined action of the loading spring 5.4 and the adjusting spring 5.5, when the exhaust valve piston 5.2 switches from a sealed state to a connected state, the relative displacement between the actuator element 5.3 and the valve body 5.1 causes the loading spring 5.4 and the adjusting spring 5.5 to deform simultaneously. The displacement of the exhaust valve piston 5.2 is equal to the deformation of the loading spring 5.4. Therefore, the displacement of the exhaust valve piston 5.2 will be less than the relative displacement between the actuator element 5.3 and the valve body 5.1. Since the parking brake push rod 2 is connected to external parts, the switching stroke cannot be significantly changed. This solution can convert a large change in external stroke into a smaller change in the shape of the exhaust valve piston 5.2, ensuring that the exhaust valve piston 5.2 does not move too far from the sealing surface 5.9 in the connected state. Furthermore, the models of the loading spring 5.4 and the adjusting spring 5.5 can be changed as needed to alter the displacement of the exhaust valve piston 5.2 in the two states, as well as the magnitude of the pressure force exerted by the exhaust valve piston 5.2 on the sealing surface 5.9 in the sealed state. This allows the solution to be applied to various products.

[0029] A retaining spring 5.6 is connected between the actuator element 5.3 and the valve body 5.1 so that the actuator element 5.3 can move towards the first cavity 5.7 under the action of the retaining spring 5.6.

[0030] The first cavity 5.7 is connected to the service brake cavity 3 through a first channel, and the second cavity 5.8 is connected to the energy storage brake cavity 4 through a second channel.

[0031] Preferably, the end of the exhaust valve piston 5.2 away from the second cavity 5.8 is disposed in the first cavity 5.7, so that the first cavity 5.7 generates a pressure on the end face of the exhaust valve piston 5.2 parallel to the sliding direction of the exhaust valve piston 5.2. The loading spring 5.4 is disposed in the first cavity 5.7.

[0032] In the above technical solution, the two ends of the exhaust valve piston 5.2 are respectively subjected to thrust generated by the air pressure from the first chamber 5.7 and the second chamber 5.8. When the exhaust valve piston 5.2 is in a sealed state, if the air pressure in the energy storage brake chamber 4 is greater than the air pressure in the service brake chamber 3 (the air pressure in the first chamber 5.7 is approximately equal to the air pressure in the service brake chamber 3, and the air pressure in the second chamber 5.8 is approximately equal to the air pressure in the energy storage brake chamber 4), and the air pressure difference is large enough, the thrust generated by the pressure difference can push the exhaust valve piston 5.2 away from the sealing surface 5.9, making the first chamber 5.7 and the second chamber 5.8 connected. Gas will flow from the energy storage brake chamber 4 through the second chamber 5.8 and the first chamber 5.7 into the service brake chamber 3 to achieve air pressure balance. When the pressure difference between the second chamber 5.8 and the first chamber 5.7 decreases to an insufficient level to push the exhaust valve piston 5.2 open, the exhaust valve piston 5.2 will return to the state of pressing the sealing surface 5.9. When the exhaust valve piston 5.2 is in a sealed state, if the pressure inside the service brake chamber 3 is greater than the pressure inside the energy storage brake chamber 4, the pressure difference will only increase the sealing force, thus improving the sealing effect. This prevents the exhaust valve piston 5.2 from being pushed open, ensuring that the vehicle brake chamber and the energy storage brake chamber 4 remain isolated. This solution allows for pressure relief of the energy storage brake chamber 4 when the relative pressure difference between it and the service brake chamber 3 is too large.

[0033] The actuator element 5.3 has two positions within the second cavity 5.8: a first position and a second position. In the first position, the exhaust valve piston 5.2 presses against the sealing surface 5.9, separating the first cavity 5.7 from the second cavity 5.8. In the second position, the exhaust valve piston 5.2 disengages from the sealing surface 5.9, connecting the first cavity 5.7 and the second cavity 5.8. The actuator element 5.3 can move between the first and second positions.

[0034] Preferably, the outer wall of the exhaust valve piston 5.2 is provided with an adjustment groove 7, and the exhaust valve piston 5.2 is provided with a first communication port and a second communication port that are interconnected. The first communication port is connected to the first cavity 5.7 through the adjustment groove 7, and the second communication port is connected to the second cavity 5.8.

[0035] Preferably, an O-ring is provided at the position where the exhaust valve piston 5.2 contacts the sealing surface 5.9. The O-ring can increase the sealing effect of the sealing surface 5.9.

[0036] In the above technical solution, the adjusting groove 7 can determine the airflow between the first cavity 5.7 and the second cavity 5.8. Different sizes of adjusting grooves 7 can be set according to specific needs. Since the airflow velocity through the adjusting groove 7 is limited, when the air pressure difference between the service brake cavity 3 and the energy storage brake cavity 4 is too large, the adjusting groove 7 cannot adjust in time. The air pressure difference will cause the exhaust valve piston 5.2 to overcome the elastic force and press tightly against the sealing surface 5.9 on the side of the second cavity 5.8, thus isolating the first cavity 5.7 and the second cavity 5.8. Furthermore, due to the combined action of the loading spring 5.4 and the adjusting spring 5.5, when the exhaust valve piston 5.2 is in the connected state and the distance between the exhaust valve piston 5.2 and the sealing surface 5.9 is relatively close, the exhaust valve piston 5.2 can quickly move to the sealed position, achieving rapid isolation. When the exhaust valve piston 5.2 is in the connected state, it is in a state of force balance, requiring only a small pressure difference to move the exhaust valve piston 5.2, making the isolation action more sensitive.

[0037] Alternatively, in another embodiment, the end of the exhaust valve piston away from the second chamber may not be connected to the first chamber, but rather to the atmosphere or to another independent chamber.

[0038] In another embodiment, the first cavity has an adjustment groove on its inner wall, and the exhaust valve piston has a first communication port and a second communication port that are interconnected. The first communication port is connected to the first cavity through the adjustment groove, and the second communication port is connected to the second cavity.

[0039] Example 2:

[0040] like Figure 1 and Figure 2 As shown, based on Embodiment 1, when the actuator element 5.3 is in the first position, the loading spring 5.4 is in a compressed state and the adjusting spring 5.5 is in a stretched state.

[0041] In the above technical solution, when the actuator element 5.3 is in the first position, the spring forces of the loading spring 5.4 and the adjusting spring 5.5 on the exhaust valve piston 5.2 are both directed towards the second cavity 5.8, so that the exhaust valve piston 5.2 presses the sealing cover 5.9 against the second cavity 5.8 and unidirectionally isolates the first cavity 5.7 and the second cavity 5.8. When the actuator element 5.3 moves towards the first cavity 5.7, the adjusting spring 5.5 will first recover its deformation, and the exhaust valve piston 5.2 will not move at this time. When the actuator element 5.3 moves a certain distance, the adjusting spring 5.5 is compressed, and the spring force of the adjusting spring 5.5 can counteract the downward spring force of the loading spring 5.4, then the exhaust valve piston 5.2 will be opened, and the moving distance of the opened exhaust valve piston 5.2 is equal to the deformation of the loading spring 5.4. This solution can further reduce the displacement of the exhaust valve piston 5.2 when switching between the two states.

[0042] Example 3:

[0043] As shown in the figure, based on Embodiment 1, when the actuator element 5.3 is in the first position, the loading spring 5.4 is in a compressed state, and the adjusting spring 5.5 is in a compressed state.

[0044] In the above technical solution, when the actuator element 5.3 is in the first position, the spring force of the loading spring 5.4 and the adjusting spring 5.5 on the exhaust valve piston 5.2 is in opposite directions. The clamping force of the exhaust valve piston 5.2 on the sealing surface 5.9 when it is in the sealed state can be adjusted by adjusting the spring force of the two springs.

[0045] Example 4:

[0046] As shown in the figure, based on Embodiment 1, the elastic coefficient of the loading spring 5.4 is greater than that of the adjusting spring 5.5. In the above technical solution, after the actuator element 5.3 of the exhaust valve piston 5.2 moves a certain distance, the deformation of the adjusting spring 5.5 is greater than that of the loading spring 5.4, while the moving distance of the exhaust valve piston 5.2 is equal to the deformation of the loading spring 5.4. Therefore, this solution can further reduce the displacement of the exhaust valve piston 5.2 when switching between two states.

Claims

1. A combined service brake and energy storage brake cylinder comprising a housing, a parking brake push rod and a brake piston fixed with the parking brake push rod, a service brake chamber, an energy storage brake chamber and a brake parking chamber are arranged in the housing, characterized in that, The parking brake push rod is internally provided with a breathing valve, the breathing valve comprises a valve body, an exhaust valve piston, an actuator element, a loading spring and an adjusting spring, the valve body is fixed with the parking brake push rod, the valve body is internally provided with a first cavity communicated with a service brake cavity, a second cavity communicated with an energy storage brake cavity and a sealing surface arranged between the first cavity and the second cavity, one end of the actuator element is arranged in the second cavity, the other end penetrates through the valve body and is fixed with the housing, the exhaust valve piston is slidably arranged in the first cavity, the loading spring is connected between the valve body and the exhaust valve piston to press the sealing surface to the side of the second cavity and unidirectionally separate the first cavity and the second cavity, and the adjusting spring is connected between the exhaust valve piston and the actuator element. One end of the exhaust valve piston away from the second cavity is arranged in the first cavity to generate a pressure parallel to the sliding direction of the exhaust valve piston on the end surface of the exhaust valve piston in the first cavity; An adjusting groove is arranged on the outer side wall of the exhaust valve piston or the inner side wall of the first cavity, the exhaust valve piston is provided with a first communicating port and a second communicating port in communication with each other, the first communicating port is communicated with the first cavity through the adjusting groove, and the second communicating port is communicated with the second cavity. The position of the actuator element in the second cavity comprises a first position and a second position, when the actuator element is in the first position, the exhaust valve piston presses the sealing surface and separates the first cavity and the second cavity, and when the actuator element is in the second position, the exhaust valve piston is separated from the sealing surface and communicates the first cavity and the second cavity.

2. A combined service and storage brake cylinder according to claim 1, characterized in that A retaining spring is connected between the actuator element and the valve body to move the actuator element to the side of the first cavity under the action of the retaining spring.

3. A combined service and storage brake cylinder as defined in claim 1, characterized in that An O-shaped sealing ring is arranged at the position where the exhaust valve piston contacts the sealing surface.

4. The combined service and storage brake cylinder of claim 1 wherein, The position of the actuator element in the second cavity comprises a first position and a second position, when the actuator element is in the first position, the exhaust valve piston presses the sealing surface and separates the first cavity and the second cavity, and when the actuator element is in the second position, the exhaust valve piston is separated from the sealing surface and communicates the first cavity and the second cavity.

5. The combined service and storage brake cylinder of claim 1 wherein, When the actuator element is in the first position, the loading spring is in a compressed state, and the adjusting spring is in a stretched state.

6. A combined service and storage brake cylinder as defined in claim 1, characterized in that When the actuator element is in the first position, the loading spring is in a compressed state, and the adjusting spring is in a compressed state.

7. The combined service and storage brake cylinder of claim 1 wherein, The elastic coefficient of the loading spring is greater than that of the adjusting spring.

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