Exhaust device, brake and fork lift truck and method of operation of the exhaust device

Abstract

The present application belongs to the field of mechanical engineering technology, and particularly relates to an actuating mechanism for a brake, in particular to an exhaust device, a brake, a forklift truck and a working method of the exhaust device. The exhaust device is matched with an exhaust plate through an exhaust cylinder, so as to limit the movement of a piston rod of a brake master cylinder. A liquid storage space is arranged to dynamically adjust the limiting distance. The incompressibility of liquid and the compressibility of gas are utilized. When the pedal is stepped on to exhaust, the limit of the movement of the piston rod is limited according to the gas content of the brake fluid discharged into the liquid storage space, so as to adjust the stroke of the brake pedal, that is, to make the brake pedal be stepped on more deeply to discharge deep bubbles. Since the liquid storage space is compressed at this time, the brake master cylinder is also in a liquid discharging state due to the movement of the piston rod, so as to bidirectionally pressurize the brake fluid in the brake system, and further improve the outgassing amount of the bubbles in the brake fluid.

Description

Technical Field

[0001] This invention belongs to the field of mechanical engineering technology, specifically relating to an actuation mechanism for a brake, and more particularly to an exhaust device, a brake, a forklift, and a method for operating the exhaust device. Background Technology

[0002] Before a forklift leaves the factory, brake fluid needs to be added to its braking system. Because forklifts have a heavy load, their braking performance is required to be high. It is especially important to purge the air from the brake system lines during the brake fluid filling process.

[0003] In related technologies, removing air bubbles from brake fluid typically involves manually pressing the brake pedal to allow the brake fluid to flow through the brake fluid lines, thereby expelling all air bubbles. The relevant operational standards require: before testing, remove the reservoir cap and check that the bleed air vent is clear; add brake fluid to the reservoir; locate the bleed screw on the brake cylinder of the wheel requiring bleed air; have someone inside the vehicle slowly depress the brake pedal 5-6 times, then keep the pedal depressed; have someone outside the vehicle loosen the bleed screw with a wrench and observe the brake fluid flow at the bleed screw: when there are no air bubbles and the brake fluid is spraying in a straight line, immediately tighten the bleed screw. Bleeding is complete. During the test drive, brake fluid should be continuously added to maintain the specified level in the reservoir. Finally, tighten the reservoir cap.

[0004] However, after actual operation by the staff, it was found that controlling the pedal depth was difficult. Because the bleed screw of the brake wheel cylinder was in the open state, there was no resistance when the brake fluid flowed, which could easily lead to over-pressing, causing damage to the return spring in the brake master cylinder, thus resulting in subsequent factory failures.

[0005] There is an urgent need to provide an exhaust device and its working method to solve the technical problem of difficulty in controlling the pedal depth when venting the brake in related technologies.

[0006] It should be noted that the information disclosed in this background section is only for understanding the background technology of the present application concept, and therefore, the above description is not considered to constitute prior art information. Summary of the Invention

[0007] This disclosure provides at least one venting device, including: a venting cylinder sleeved on the piston rod of the brake master cylinder; a venting plate disposed inside the venting cylinder to limit the forward movement length of the piston rod; and a fluid storage space between the venting plate and the front end of the venting cylinder; a fluid guide pipe is connected to the front end of the venting cylinder; the fluid guide pipe is configured to communicate with the bleed screw of the brake wheel cylinder; wherein when venting is triggered, the brake fluid in the brake wheel cylinder is pressurized and flows into the fluid storage space through the fluid guide pipe, thereby pushing the venting plate to move and change its position limiting the piston rod.

[0008] In one optional embodiment, the exhaust pipe includes an upper cylinder and a lower cylinder; the lower cylinder has a liquid inlet at its front end; the liquid inlet is configured to communicate with a liquid guide pipe; and the upper cylinder has an exhaust port at its top, and a one-way valve for gas discharge is provided at the exhaust port; wherein when the piston rod moves forward, the brake fluid in the brake wheel cylinder flows into the reservoir through the liquid inlet to increase the pressure in the reservoir, thereby discharging the gas in the reservoir through the exhaust port and pushing the exhaust plate backward.

[0009] In one alternative embodiment, the exhaust plate has a through hole in the center that is adapted to the piston rod of the brake master cylinder; and the exhaust plate is also configured to be pushed by the connecting block at the rear end of the piston rod to compress the reservoir space.

[0010] In one optional embodiment, if the reservoir contains a mixture of brake fluid and gas, the connecting block pushes the exhaust plate to compress the reservoir; that is, if there is gas in the reservoir, the position of the exhaust plate when the gas is compressed to an incompressible state is the limit position of the exhaust plate's movement.

[0011] In one optional implementation, if the reservoir is filled with brake fluid, the vent plate remains stationary to limit its compression of the reservoir; that is, if there is no gas in the reservoir, the position of the vent plate is the limit position of its movement.

[0012] In one alternative embodiment, a spring is provided between the exhaust plate and the front end of the exhaust pipe; and when the spring is in its initial state, the outer wall of the exhaust plate blocks the exhaust port.

[0013] This disclosure also provides at least one brake, including: a master cylinder with the aforementioned venting device sleeved on its piston rod; an oil reservoir disposed above the master cylinder, the oil reservoir being configured to supply brake fluid to the master cylinder; and a wheel cylinder connected to the master cylinder via a pipeline.

[0014] This disclosure also provides at least one forklift, including: the aforementioned brake; and a brake pedal configured to drive a piston rod in a brake master cylinder to move.

[0015] This disclosure also provides at least one method for operating an exhaust device, including: using the above-mentioned exhaust device; wherein the brake wheel cylinder and the exhaust cylinder are connected by a fluid guide pipe; the piston rod is limited by an exhaust plate; and when initially pressed, the piston rod moves forward to squeeze the brake fluid into the reservoir through the fluid guide pipe, thereby pushing the exhaust plate to move and change its position limiting the piston rod; when pressed deeply, the connecting block at the rear end of the piston rod pushes the exhaust plate to further compress the reservoir.

[0016] In one optional embodiment, if there is gas in the liquid storage space, the position of the exhaust plate when the gas is compressed to an incompressible state is the movement limit position of the exhaust plate.

[0017] If there is no gas in the liquid storage space, the position of the vent plate is the limit position of the vent plate's movement.

[0018] The beneficial effects of this invention are that the exhaust device, through the cooperation of the exhaust pipe and the exhaust plate, achieves the movement limit of the brake master cylinder piston rod. Compared with the traditional fixed limit method, the limit distance is dynamically adjusted by the set reservoir space. Utilizing the incompressibility of liquid and the compressibility of gas, when the pedal is pressed to exhaust air, the piston rod movement is limited according to the gas content of the brake fluid discharged into the reservoir space. That is, when the brake fluid discharged into the reservoir space contains gas, the connecting block at the rear end of the piston rod will further compress the reservoir space, thereby increasing the stroke of the brake pedal. This allows the brake pedal to be pressed more deeply to expel deep air bubbles. Furthermore, since the reservoir space is compressed at this time, the brake master cylinder is also in the discharge state due to the movement of the piston rod, thereby bidirectionally pressurizing the brake fluid in the braking system and increasing the amount of air bubbles released from the brake fluid.

[0019] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 A three-dimensional structural schematic diagram of the brake provided in an embodiment of this disclosure is shown;

[0023] Figure 2 An exploded structural diagram of the exhaust device provided in an embodiment of this disclosure is shown;

[0024] Figure 3 A schematic diagram of the internal structure of the exhaust device provided in an embodiment of this disclosure is shown;

[0025] Figure 4 This diagram illustrates the state of the exhaust plate of the exhaust device provided in this embodiment when it retracts.

[0026] Figure 5 This diagram illustrates the state of the exhaust plate of the exhaust device provided in this embodiment when it is moved forward.

[0027] In the picture:

[0028] 1. Exhaust pipe; 10. Exhaust port; 11. Upper cylinder; 12. Lower cylinder; 121. Locking strip; 13. Liquid inlet; 14. Exhaust plate; 140. Locking groove; 15. Spring; 2. Piston rod; 21. Connecting block; 3. Brake master cylinder; 4. Oil reservoir; 5. Liquid guide pipe; 6. Brake wheel cylinder; 7. Bleed screw; 8. Brake pedal. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the figures, the thickness of parts may be exaggerated or reduced for the purpose of effectively depicting the technical content.

[0031] In related technologies, when a forklift is manufactured and ready for shipment, brake fluid needs to be added to the braking system. After the brake fluid is added, air bubbles in the braking system need to be removed to ensure the stability of the braking system. Common methods for removing air bubbles include: vacuum venting, pressurizing the reservoir for venting, and manual venting. For OEMs, manual venting is the mainstream method. Manual venting involves repeatedly pressing the brake pedal to allow the brake fluid to flow and expel air bubbles from the braking system. However, because the bleed screw on the brake wheel cylinder is open and there is no back pressure in the hydraulic system, the operator can easily... The brake pedal is easily pressed too deeply, which can damage the return spring in the master cylinder. To address this, some technologies use a limiter on the brake pedal, either by placing a limiter under the pedal or on the piston rod, to restrict the pedal's depth. However, in practice, it has been found that a fixed limiter cannot accommodate all braking systems, as the air content in the brake fluid varies between systems. If the limiter is too small, it will still cause significant stretching of the return spring; conversely, a large limiter may result in insufficient pedal depth, preventing deep air bubbles from escaping.

[0032] Therefore, how to solve the problem that the fixed limit method cannot meet the air content requirements of the braking system is a technical problem that urgently needs to be solved in this field.

[0033] The defects in the above solutions and the reasons for their occurrence are the results of the inventors' practice and careful research. Therefore, the discovery process of the above problems and the solutions proposed in this disclosure should be considered as the inventors' contributions to this disclosure.

[0034] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0035] See Figure 1 , Figure 1 An exhaust device is shown, comprising: an exhaust pipe 1 sleeved on the piston rod 2 of the master cylinder 3; an exhaust plate 14 disposed inside the exhaust pipe 1 to limit the forward movement of the piston rod 2; and a fluid storage space between the exhaust plate 14 and the front end of the exhaust pipe 1; a fluid guide pipe 5 is connected to the front end of the exhaust pipe 1; the fluid guide pipe 5 is configured to communicate with the bleed screw 7 of the brake wheel cylinder 6; wherein when the brake pedal is pressed to exhaust, the brake fluid in the brake wheel cylinder 6 is pressurized and flows into the fluid storage space through the fluid guide pipe 5, thereby pushing the exhaust plate 14 to move and change its position limiting the piston rod 2.

[0036] Specifically, the exhaust pipe 1 and the exhaust plate 14 are designed to cooperate to limit the movement of the piston rod 2 of the master cylinder 3. Compared with the traditional fixed limiting method, the limiting distance is dynamically adjusted by the set reservoir space. Utilizing the incompressibility of liquid and the compressibility of gas, when the pedal is pressed to bleed air, the piston rod 2 is limited to its movement limit according to the amount of gas in the brake fluid discharged into the reservoir space. That is, when the brake fluid discharged into the reservoir space contains gas, the connecting block 21 at the rear end of the piston rod 2 will further compress the reservoir space, thereby increasing the stroke of the brake pedal 8, so that the brake pedal 8 can be pressed more deeply to expel deep air bubbles.

[0037] See Figure 2 In some embodiments, the exhaust pipe 1 includes an upper cylinder 11 and a lower cylinder 12; the lower cylinder 12 has a liquid inlet hole 13 at its front end; the liquid inlet hole 13 is configured to communicate with the liquid guide pipe 5; and the upper cylinder 11 has an exhaust hole 10 at its top, and a one-way valve for gas discharge is provided at the exhaust hole 10.

[0038] As an optional implementation, the exhaust pipe 1 includes an upper cylinder 11 and a lower cylinder 12, which are connected by a snap-fit ​​mechanism. One cylinder is equipped with a retaining strip 121, and auxiliary sealing patches are used to prevent brake fluid or gas leakage from gaps. Specifically, when venting is required, the upper cylinder 11 and lower cylinder 12 are spliced ​​together, and then the fluid inlet is connected to the fluid guide pipe 5 to begin the venting process.

[0039] See Figure 3 Specifically, the exhaust plate 14 can also be configured to include an upper plate and a lower plate, which are connected by splicing, including but not limited to a slot 140 on one plate and a sealing patch to prevent gas or liquid leakage. The upper plate has a semi-circular hole at its center, and the lower plate has a semi-circular hole at its center. After splicing, they form a through hole that matches the piston rod 2 of the brake master cylinder 3. At the same time, since a connecting block 21 is provided on the rear side of the piston rod 2, as the piston rod 2 continues to move, the connecting block 21 will contact the exhaust plate 14 and push the exhaust plate 14. If there is air in the reservoir at this time, due to the compressibility of the gas, the connecting block 21 will push the exhaust plate 14 to move to slightly compress the reservoir. That is, for the operator, there is a certain resistance to stepping, but it can still be stepped on until the gas is compressed to the point that it cannot be stepped on. At this time, compared with the case where the reservoir is full of brake fluid, the piston rod 2 moves forward more, and the pressure applied to the braking system is greater, which helps to expel deep gas.

[0040] For details, see Figure 4 and Figure 5Because the exhaust pipe 1 has an exhaust port 10, when the piston rod 2 moves but the connecting block 21 does not contact the exhaust plate 14, brake fluid and / or gas from the braking system will flow into the reservoir. The exhaust plate 14 will move backward under the action of the flowing brake fluid and / or gas until the exhaust port 10 opens. When the connecting block 21 pushes the exhaust plate 14 to compress the reservoir, the gas in the reservoir will first be discharged from the exhaust port 10 until the exhaust plate 14 passes the position of the exhaust port 10. At this time, the gas remaining in the reservoir serves as the standard for pedal limit. If there is no gas, due to the incompressibility of the liquid, the exhaust plate 14 will not be able to continue to move, thereby forcibly restricting the operator's pedaling.

[0041] That is, such as Figure 4 As shown, when the piston rod moves forward and the connecting block does not press against the exhaust plate, the brake fluid and / or gas in the braking system flow into the reservoir from direction F1. Subsequently, the exhaust plate is pressed and moves along direction F2, and at this time, some gas can be discharged along direction F3. When the connecting block presses against the exhaust plate, the exhaust plate will move along direction F4 until it avoids the exhaust hole. At this time, the liquid in the reservoir tends to transmit pressure along direction F3.

[0042] In some embodiments, a spring 15 is provided between the exhaust plate 14 and the front end of the exhaust cylinder 1; and when the spring 15 is in the initial state, the outer wall of the exhaust plate 14 blocks the exhaust hole 10.

[0043] See Figure 1 On the other hand, some embodiments also provide a brake, including: a master cylinder 3, on which the above-mentioned venting device is sleeved; an oil reservoir 4, disposed above the master cylinder 3, the oil reservoir 4 being configured to supply brake fluid to the master cylinder 3; and a wheel cylinder 6, the wheel cylinder 6 being connected to the master cylinder 3 via a pipeline.

[0044] See Figure 1 On the other hand, some embodiments also provide a forklift including the aforementioned brake and brake pedal 8, the brake pedal 8 being configured to drive the piston rod in the brake master cylinder to move.

[0045] On the other hand, some embodiments also provide a method of operating the exhaust device, including: using the above-mentioned exhaust device; connecting the brake wheel cylinder 6 and the exhaust cylinder 1 through the fluid guide pipe 5; limiting the forward movement distance of the piston rod 2 by the exhaust plate 14; and when the pedal is pressed to exhaust, the piston rod 2 moves forward to squeeze the brake fluid into the reservoir through the fluid guide pipe 5, thereby pushing the exhaust plate 14 to move to change its position limiting the piston rod 2; when the pedal is pressed deeply, the connecting block 21 at the rear end of the piston rod 2 pushes the exhaust plate 14 to further compress the reservoir.

[0046] In some embodiments, the exhaust stack 1 includes an upper cylinder 11 and a lower cylinder 12; the lower cylinder 12 has a liquid inlet hole 13 at its front end; the liquid inlet hole 13 is configured to communicate with the liquid guide pipe 5; and the upper cylinder 11 has an exhaust hole 10 at its top, and a one-way valve for gas discharge is provided at the exhaust hole 10.

[0047] In some embodiments, the exhaust plate 14 has a through hole in the center that is adapted to the piston rod 2 of the brake master cylinder 3; and the exhaust plate 14 is also configured to be pushed by the rear connecting block 21 of the piston rod 2 to compress the reservoir space.

[0048] In some embodiments, a spring 15 is provided between the exhaust plate 14 and the front end of the exhaust cylinder 1; and when the spring 15 is in the initial state, the outer wall of the exhaust plate 14 blocks the exhaust hole 10.

[0049] In some embodiments, if there is gas in the reservoir, the connecting block 21 pushes the vent plate 14 to compress the reservoir; if the reservoir is full of brake fluid, the vent plate 14 remains stationary to limit the displacement of the connecting block 21.

[0050] In summary, this venting device, through the cooperation of the venting pipe 1 and the venting plate 14, achieves the movement limit of the piston rod 2 of the brake master cylinder 3. Compared with the traditional fixed limit method, the limit distance is dynamically adjusted by the set reservoir space. Utilizing the incompressibility of liquid and the compressibility of gas, when the pedal is pressed to vent, the movement limit of the piston rod 2 is determined according to the gas content of the brake fluid discharged into the reservoir space. That is, when the brake fluid discharged into the reservoir space contains gas, the connecting block 21 at the rear end of the piston rod 2 will further compress the reservoir space, thereby increasing the stroke of the brake pedal 8. This allows the brake pedal 8 to be pressed more deeply to expel deep air bubbles. Furthermore, since the reservoir space is compressed at this time, the brake master cylinder 3 is also in the discharge state due to the movement of the piston rod 2, thereby bidirectionally pressurizing the brake fluid in the braking system and increasing the amount of air bubbles released from the brake fluid.

[0051] In this document, when it is said that the first component is located on the second component, this can mean that the first component can be directly formed on the second component, or that the third component can be inserted between the first component and the second component.

[0052] In this document, when an element or layer is referred to as “located,” “joined to,” “connected to,” “attached to,” or “coupled to” another element or layer, it may be directly located, joined, connected, attached to, or coupled to the other element or layer, or there may be intermediate elements or layers present. Conversely, when an element is referred to as “directly on another element or layer,” “directly joined to,” “directly connected to,” “directly attached to,” or “directly coupled to” another element or layer, there may be no intermediate elements or layers present. Other terms used to describe relationships between elements should be interpreted in a similar manner (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the related listed items.

[0053] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0054] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0055] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence unless expressly indicated herein. Therefore, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer, or segment discussed above may be referred to as a second element, component, region, layer, or segment.

[0056] Spatially relative terms, such as “inside,” “outside,” “below,” “below,” “down,” “above,” “up,” etc., may be used herein to describe the relationship between one element or feature illustrated in the figures and another element or feature. In addition to the orientations depicted in the figures, spatially relative terms may be intended to cover different orientations of the device in use or operation. For example, if the device in the figure is flipped, an element described as “below” or “below” other elements or features would be oriented as “above” other elements or features. Thus, the example term “below” can cover both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein are interpreted accordingly.

[0057] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. An exhaust device, characterized in that, include: An exhaust pipe fitted onto the piston rod of the brake master cylinder; and An exhaust plate installed inside the exhaust pipe to limit the forward movement of the piston rod; as well as A liquid storage space is left between the exhaust plate and the front end of the exhaust pipe; A liquid guide pipe is connected to the front end of the exhaust pipe; The liquid guide tube is configured to connect to the bleed screw of the brake wheel cylinder; in When the exhaust is triggered, the brake fluid in the brake wheel cylinder is pressurized and flows into the reservoir through the guide pipe, thereby pushing the exhaust plate to move and change its position that limits the piston rod. The exhaust stack includes an upper cylinder and a lower cylinder; The lower cylinder has a liquid inlet hole at its front end; The inlet port is configured to communicate with the liquid guide tube; and The top of the upper cylinder is provided with an exhaust port, and a one-way valve for gas discharge is provided at the exhaust port. in When the piston rod moves forward, the brake fluid in the brake wheel cylinder flows into the reservoir through the inlet hole to increase the pressure in the reservoir, thereby expelling the gas in the reservoir through the vent hole and pushing the vent plate backward. The exhaust plate has a through hole in the center that matches the piston rod of the brake master cylinder; and The exhaust plate is also configured to be pushed by the piston rod rear end connecting block to compress the liquid storage space; If the reservoir contains a mixture of brake fluid and gas, the connecting block will push the vent plate to compress the reservoir. If the reservoir is filled with brake fluid, the vent plate remains stationary to limit its compression of the reservoir.

2. The exhaust device as described in claim 1, characterized in that, A spring is provided between the exhaust plate and the front end of the exhaust pipe; and In its initial state, the outer wall of the exhaust plate blocks the exhaust hole.

3. A brake, characterized in that, include: The master cylinder of the brake has an exhaust device as described in claim 1 fitted on its piston rod; and A reservoir, positioned above the master cylinder, is configured to supply brake fluid to the master cylinder; and The brake wheel cylinder is connected to the master brake cylinder via a pipeline.

4. A forklift, characterized in that, include: The brake as described in claim 3; and A brake pedal configured to drive the piston rod in the master cylinder.

5. A method for operating an exhaust device, characterized in that, include: The exhaust device as described in claim 1 is used; in The brake wheel cylinder and the exhaust pipe are connected by a liquid guide tube; The piston rod's forward movement distance is limited by the exhaust plate; as well as When the pedal is initially depressed, the piston rod moves forward to compress the brake fluid into the reservoir through the fluid guide tube, thereby pushing the exhaust plate to move and change its position that limits the piston rod. When the pedal is pressed deeply, the connecting block at the rear end of the piston rod pushes the exhaust plate to further compress the reservoir space.

6. The working method as described in claim 5, characterized in that, If there is gas in the liquid storage space, the position of the exhaust plate when the gas is compressed to an incompressible state is the limit position of the exhaust plate's movement. If there is no gas in the liquid storage space, the position of the vent plate is the limit position of the vent plate's movement.

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