Parking brake system, working method thereof and agricultural machinery

Abstract

The present invention relates to the field of hydraulic braking and discloses a parking brake system and agricultural machinery. The parking brake system includes a parking brake, a first reversing valve, a second reversing valve, and an accumulator. The working oil port of the first reversing valve is connected to the rod chamber of the brake cylinder of the parking brake. The oil inlet of the first reversing valve is connected to the oil inlet oil circuit. The oil return port of the first reversing valve is connected to the oil return oil circuit. In a power-off state, the working oil port of the first reversing valve is connected to the oil return port, and the oil outlet of the second reversing valve is connected to the oil return oil circuit. In a power-off state, the oil inlet and oil outlet of the second reversing valve are connected, and the accumulator is connected to the oil inlet of the second reversing valve. The parking brake system of the present invention can prevent the tires of the agricultural machinery from locking when the power is accidentally lost during driving, and can also enable the agricultural machinery to slow down relatively slowly and smoothly until it stops.

Description

Technical Field

[0001] The present invention belongs to the field of hydraulic braking, and in particular relates to a parking brake system and a working method thereof, and agricultural machinery. Background Art

[0002] The parking brake system of existing agricultural machinery (such as silage loader) usually includes a parking brake and a reversing valve. The reversing valve controls the operation of the parking brake's brake cylinder to switch the parking brake between a braking state and a brake-released state. The specific working method is as follows: when the reversing valve is powered and switched to the first valve position, the spring in the rodless chamber of the brake cylinder is compressed, causing the piston rod to retract, and the parking brake is switched to the brake-released state. When the reversing valve loses power and switches to the second valve position, the spring in the rodless chamber of the brake cylinder resets, causing the piston rod to extend, and the parking brake is switched to the braking state. This working method poses a significant safety hazard. When the agricultural machinery accidentally loses power while driving, the reversing valve will immediately switch to the second valve position, causing the parking brake to immediately switch to the braking state, causing the tires to lock. At this time, safety accidents such as rollover are very likely to occur. Summary of the Invention

[0003] In view of the above-mentioned deficiencies or defects in the prior art, the present invention provides a parking brake system and agricultural machinery, aiming to solve the technical problems of the existing parking brake system of agricultural machinery having major safety hazards and low safety factor.

[0004] To achieve the above object, the present invention provides a parking brake system, comprising:

[0005] parking brake;

[0006] Oil return line, including damping components;

[0007] a first reversing valve, wherein the working oil port of the first reversing valve is connected to the rod chamber of the brake cylinder of the parking brake, the oil return port of the first reversing valve is connected to the oil inlet end of the oil return oil circuit, the working oil port of the first reversing valve being in a power-off state being in communication with the oil return port, and the working oil port of the first reversing valve being in a power-on state being in communication with the oil inlet;

[0008] a second reversing valve and an accumulator, wherein the oil inlet of the second reversing valve is connected to the accumulator, the oil outlet of the second reversing valve is connected to the oil return line, and the connection position is located between the oil inlet end of the oil return line and the damping member, the oil inlet and the oil outlet of the second reversing valve are connected in a de-energized state, and the oil inlet and the oil outlet of the second reversing valve are disconnected in a powered state;

[0009] The oil inlet circuit is connected to the oil inlet of the first reversing valve and the accumulator respectively.

[0010] Optionally, the oil inlet circuit includes:

[0011] Hydraulic pumps;

[0012] a one-way valve, wherein the oil inlet of the one-way valve is connected to the output end of the hydraulic pump;

[0013] One end of the first oil circuit is connected to the oil outlet of the one-way valve, and the other end is connected to the oil inlet of the first reversing valve. The first oil circuit is also connected to the accumulator.

[0014] Optionally, the oil inlet circuit further includes a relief valve, and the relief valve is arranged in parallel with the hydraulic pump.

[0015] Optionally, the damping member is a throttle valve.

[0016] Optionally, the first reversing valve is a proportional valve, and the parking brake system further includes a controller, which is communicatively connected to the first reversing valve and is used to control the flow path opening between the working oil port and the return oil port of the first reversing valve to gradually increase after receiving an emergency stop signal.

[0017] Optionally, the parking brake system also includes a vehicle speed detector, and the controller is communicatively connected to the vehicle speed detector and is used to control the flow path opening between the working oil port and the return oil port of the first reversing valve to gradually increase according to the vehicle speed information detected by the vehicle speed detector after receiving an emergency stop signal.

[0018] Optionally, the vehicle speed detector is a tire speed sensor.

[0019] The present invention also provides an agricultural machine, comprising the above-mentioned parking brake system.

[0020] The present invention also provides a method for operating the parking brake system, comprising the following steps:

[0021] After determining that the agricultural machinery has switched to the driving gear, the first reversing valve and the second reversing valve are switched to the energized state. When the first reversing valve is switched from the energized state to the de-energized state, the second reversing valve is synchronously switched to the de-energized state.

[0022] Optionally, the working method further includes:

[0023] It is determined that the agricultural machinery has stopped suddenly or the hydraulic pump has lost power, and the opening of the flow path between the working oil port and the return oil port of the first reversing valve is controlled to gradually increase.

[0024] Through the above technical solution, the parking brake system of the present invention can be applied to agricultural machinery. When the agricultural machinery accidentally loses power during driving, resulting in a power loss in the parking brake system, the first reversing valve and the second reversing valve are both in a power-off state at the same time. The working oil port of the first reversing valve is connected to the return oil port so that the rod chamber of the brake cylinder of the parking brake is connected to the return oil circuit. At the same time, the oil inlet and oil outlet of the second reversing valve are connected so that the accumulator is connected to the return oil circuit. At this time, under the hydraulic damping action of the damping member, the rod chamber of the brake cylinder can be prevented from instantaneously releasing pressure through the return oil circuit. At the same time, the accumulator can provide hydraulic energy to the brake cylinder through the return oil circuit and the first reversing valve within a period of time, preventing the hydraulic oil in the rod chamber of the brake cylinder from flowing back, thereby avoiding the situation where the parking brake is immediately braked to lock the tire and cause a safety accident when the power is accidentally lost. Moreover, as the hydraulic energy provided by the accumulator gradually decreases, the hydraulic oil in the rod chamber of the brake cylinder will gradually and slowly flow back through the return oil line, and the parking brake will perform parking braking more smoothly and slowly, so that the agricultural machinery can be parked smoothly. That is, when the agricultural machinery loses power accidentally during driving, the parking brake system can prevent the agricultural machinery tires from locking and can make the agricultural machinery slow down more slowly and steadily until it stops. In this way, the safety factor in the event of accidental power failure is effectively further improved.

[0025] Other features and advantages of the present invention will be described in detail in the following detailed description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention.

[0027] In the attached figure:

[0028] Figure 1 Schematic diagram of the structure of a parking brake system in a specific embodiment of the present invention.

[0029] Description of reference numerals:

[0030] 1 Brake cylinder 2 First reversing valve

[0031] 3 Second reversing valve 4 Accumulator

[0032] 5 Hydraulic pump 6 Check valve

[0033] 7 First oil circuit 8 Relief valve

[0034] 9 Second oil circuit 10 Damping element

[0035] 11 Third Oil Line DETAILED DESCRIPTION

[0036] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0038] In the present invention, unless otherwise specified, directional words such as "up, down, top, bottom" are usually used to describe the relative positions of components in the directions shown in the drawings or in the vertical, perpendicular or gravity directions.

[0039] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0040] The present invention first provides a parking brake system.

[0041] In one embodiment, referring to the attached Figure 1 As shown, the parking brake system includes:

[0042] parking brake;

[0043] The oil return circuit includes a damping member 10;

[0044] The first reversing valve 2, the working oil port of the first reversing valve 2 is connected to the rod chamber of the brake cylinder 1 of the parking brake, the return oil port of the first reversing valve 2 is connected to the oil inlet end of the return oil circuit, the working oil port of the first reversing valve 2 in the de-energized state is connected to the return oil port, and the working oil port of the first reversing valve 2 in the energized state is connected to the oil inlet;

[0045] The second reversing valve 3 and the accumulator 4, the oil inlet of the second reversing valve 3 is connected to the accumulator 4, the oil outlet of the second reversing valve 3 is connected to the oil return line, and the connection position is located between the oil inlet end of the oil return line and the damping member 10. In the de-energized state, the oil inlet and the oil outlet of the second reversing valve 3 are connected, and in the energized state, the oil inlet and the oil outlet of the second reversing valve 3 are disconnected;

[0046] The oil inlet circuit is connected to the oil inlet of the first reversing valve 2 and the accumulator 4 respectively.

[0047] The parking brake system of this embodiment can be applied to agricultural machinery. When the agricultural machinery is switched to a driving gear, first reversing valve 2 is energized, and the working oil port of first reversing valve 2 is connected to the oil inlet port, thereby connecting the rod chamber of brake cylinder 1 of the parking brake to the oil inlet circuit. This configuration allows the oil inlet circuit to continuously supply hydraulic energy to brake cylinder 1 through first reversing valve 2, keeping the parking brake in the released state.

[0048] When the agricultural machinery loses power unexpectedly during driving, causing the parking brake system to lose power, the first reversing valve 2 and the second reversing valve 3 are both in a power-off state at the same time. The working oil port of the first reversing valve 2 is connected to the return oil port so that the rod chamber of the brake cylinder 1 of the parking brake is connected to the return oil circuit. At the same time, the oil inlet and oil outlet of the second reversing valve 3 are connected so that the accumulator 4 is connected to the return oil circuit. At this time, under the hydraulic damping action of the damping member 10, the rod chamber of the brake cylinder 1 can be prevented from instantaneously releasing pressure through the return oil circuit. At the same time, the accumulator 4 can provide hydraulic energy to the brake cylinder 1 through the return oil circuit and the first reversing valve 2 for a period of time, so that the rod chamber of the brake cylinder 1 maintains high pressure, preventing the hydraulic oil in the rod chamber of the brake cylinder 1 from flowing back, and avoiding the situation where the parking brake is immediately braked and the tire is locked when power is accidentally lost, thereby causing a safety accident. Moreover, as the hydraulic energy provided by the accumulator 4 gradually decreases, the hydraulic oil in the rod chamber of the brake cylinder 1 will gradually and slowly flow back through the return oil circuit, and the parking brake will perform parking braking more smoothly and slowly, so that the agricultural machinery can be parked smoothly. That is, when the agricultural machinery loses power unexpectedly, the parking brake system can prevent the agricultural machinery tires from locking while allowing the agricultural machinery to slow down more slowly and steadily until it stops. In this way, the safety factor in the event of an accidental power failure is effectively further improved.

[0049] In order to ensure that the second reversing valve 3 can lose power synchronously with the loss of power to the first reversing valve 2, the second reversing valve 3 and the first reversing valve 2 can be set in the same control circuit, or a controller that is respectively communicated with the second reversing valve 3 and the first reversing valve 2 is set. When it is determined that the first reversing valve 2 loses power, the controller promptly controls the second reversing valve 3 to lose power synchronously.

[0050] Specifically, the first reversing valve 2 can be a two-position three-way reversing valve and the valve core has a first valve position and a second valve position. In the de-energized state, the valve core of the first reversing valve 2 is in the first valve position driven by the elastic force of the spring, and the working oil port of the first reversing valve 2 is connected to the return oil port. In the energized state, the valve core of the first reversing valve 2 overcomes the elastic force of the spring under the action of the electromagnet and switches to the second valve position, and the working oil port of the first reversing valve 2 is connected to the oil inlet.

[0051] Specifically, the return oil circuit may also include a second oil circuit 9 and a third oil circuit 11. One end of the second oil circuit 9 is connected to the return oil port of the first reversing valve 2, and the other end is connected to one port of the damping element 10. One end of the third oil circuit 11 is connected to the other port of the damping element 10, and the oil outlet of the second reversing valve 3 is connected to the second oil circuit 9.

[0052] Specifically, the first reversing valve 2 and the second reversing valve 3 may be solenoid reversing valves or electric reversing valves or other valves that can be controlled electrically.

[0053] In this embodiment, the oil inlet circuit is connected to the oil inlet of the first reversing valve 2 and the accumulator 4, respectively. When the first reversing valve 2 is energized, the working oil port of the first reversing valve 2 communicates with the oil inlet. With this arrangement, when the agricultural machine is switched to a driving gear, the first reversing valve 2 is energized, and the working oil port of the first reversing valve 2 communicates with the oil inlet. This allows the accumulator 4 to simultaneously store energy when the rod chamber of the parking brake cylinder 1 is connected to the oil inlet circuit.

[0054] In actual application, the input end of the oil inlet circuit and the output end of the oil return circuit can be connected to the hydraulic oil tank to realize oil supply and oil return.

[0055] In this embodiment, the oil inlet and oil outlet of the second reversing valve 3 are disconnected when the machine is powered. This arrangement prevents some hydraulic oil in the oil inlet circuit from entering the oil return circuit through the second reversing valve 3 when the agricultural machine is switched to a driving gear.

[0056] Specifically, the second reversing valve 3 can be a two-position two-way reversing valve and the valve core has a first valve position and a second valve position. In the de-energized state, the valve core of the second reversing valve 3 is in the first valve position driven by the elastic force of the spring, and the oil inlet and oil outlet of the second reversing valve 3 are connected. In the energized state, the valve core of the second reversing valve 3 overcomes the elastic force of the spring under the action of the electromagnet and switches to the second valve position, and the oil inlet and oil outlet of the second reversing valve 3 are disconnected.

[0057] In one embodiment, the oil inlet circuit includes:

[0058] Hydraulic pump 5;

[0059] A one-way valve 6, the oil inlet of the one-way valve 6 is connected to the output end of the hydraulic pump 5;

[0060] A first oil circuit 7, one end of which is connected to the oil outlet of the one-way valve 6, and the other end of which is connected to the oil inlet of the first reversing valve 2. The first oil circuit 7 is also connected to the accumulator 4;

[0061] In actual application, the input end of the hydraulic pump 5 can be connected to the hydraulic oil tank.

[0062] In this embodiment, when the hydraulic pump 5 stops unexpectedly, the one-way valve 6 can prevent the accumulator 4 from being depressurized, and the hydraulic oil in the brake cylinder 1 from being instantly backflowed and depressurized, thereby maintaining the pressure of the brake cylinder 1 in a short period of time, and preventing the parking brake from being immediately applied and locking the tire when the hydraulic pump 5 stops.

[0063] In one embodiment, the oil inlet circuit further includes a relief valve 8, which is arranged in parallel with the hydraulic pump 5. In this arrangement, the relief valve 8 can prevent the input hydraulic pressure of the hydraulic pump 5 from being too high.

[0064] Specifically, the overflow valve 8 can be a manual adjustment structure or an electric adjustment structure.

[0065] In one embodiment, the damping member 10 is a throttle valve. In this configuration, the hydraulic damping effect is achieved through the throttling action of the throttle valve.

[0066] Of course, in other embodiments, the damping member 10 may also be a speed regulating valve or a damping valve.

[0067] In one embodiment, the first reversing valve 2 is a proportional valve, and the parking brake system also includes a controller, which is communicated with the first reversing valve 2 and is used to control the flow path opening between the working oil port and the return oil port of the first reversing valve 2 to gradually increase after receiving an emergency stop signal.

[0068] As will be appreciated, agricultural machinery is generally equipped with an emergency stop switch, which can be used to quickly shut down the agricultural machinery's engine in an emergency. At this point, the hydraulic pump 5 will also shut down simultaneously. In this embodiment, the first reversing valve 2 is configured as a proportional valve. Upon receiving an emergency stop signal generated by pressing the emergency stop switch, the controller controls the flow path opening between the working oil port and the return oil port of the first reversing valve 2 to gradually increase. With this configuration, based on the characteristics of the proportional valve, after the hydraulic pump 5 shuts down, the first reversing valve 2 can be controlled by the controller to gradually increase the flow path opening between the working oil port and the return oil port, thereby controlling the return oil speed of the brake cylinder 1 and enabling the brake cylinder 1 to release pressure more slowly. This prevents the brake cylinder 1 from releasing pressure instantly, causing the parking brake to immediately apply and lock the tires. This allows the agricultural machinery to smoothly and slowly apply the parking brake even in emergency situations.

[0069] Of course, in some other embodiments, the second reversing valve 3 may also be a servo valve.

[0070] In one embodiment, the parking brake system further includes a vehicle speed detector. The controller is communicatively connected to the vehicle speed detector and is configured to, upon receiving an emergency stop signal, gradually increase the opening of the flow path between the working oil port and the return oil port of the first reversing valve 2 based on vehicle speed information detected by the vehicle speed detector. This arrangement allows the opening of the flow path between the working oil port and the return oil port of the first reversing valve 2 to be adjusted accordingly based on the actual vehicle speed, ensuring that the braking force of the parking brake matches the vehicle speed, further improving the reliability of the smooth and gentle parking brake application of the agricultural machinery in emergency stops.

[0071] In one embodiment, the vehicle speed detector is a tire speed sensor.

[0072] In this embodiment, the vehicle speed detector determines the traveling speed of the agricultural machinery by detecting the rotation speed of the tires of the agricultural machinery.

[0073] Of course, in some other embodiments, the vehicle speed detector may also be a GPS speedometer.

[0074] The present invention further provides an agricultural machine including the parking brake system described above. The specific structure of the parking brake system is similar to that of the above-described embodiments. Since the present agricultural machine utilizes all of the technical solutions of all of the above-described embodiments, it at least possesses all of the beneficial effects brought about by the technical solutions of the above-described embodiments, and therefore, no further details will be given here.

[0075] In addition, the agricultural machinery may be, for example, a forage machine, a tractor, or the like.

[0076] The present invention also provides a working method of the parking brake system.

[0077] In one embodiment, the working method includes the following process:

[0078] After determining that the agricultural machinery is switched to the driving gear, the first reversing valve 2 and the second reversing valve 3 are switched to the energized state. When the first reversing valve 2 is switched from the energized state to the de-energized state, the second reversing valve 3 is synchronously switched to the de-energized state.

[0079] It can be understood that after determining that the agricultural machinery has switched to the driving gear, the first reversing valve 2 is switched to the energized state, and the working oil port of the first reversing valve 2 is connected to the oil inlet so that the rod chamber of the brake cylinder 1 of the parking brake is connected to the oil inlet oil circuit. With this arrangement, the oil inlet oil circuit can continuously provide hydraulic energy to the brake cylinder 1 through the first reversing valve 2, so that the parking brake remains in the brake release state, allowing the agricultural machinery to travel normally.

[0080] During driving, if the agricultural machinery accidentally loses power or other reasons cause the first reversing valve 2 to switch from the energized state to the de-energized state, the second reversing valve 3 will be synchronously switched to the de-energized state. In this way, the accumulator 4 is connected to the return oil circuit. Under the hydraulic damping action of the damping member 10, the rod chamber of the brake cylinder 1 can be prevented from instantaneously releasing pressure through the return oil circuit. At the same time, the accumulator 4 can provide hydraulic energy to the brake cylinder 1 through the return oil circuit and the first reversing valve 2 for a period of time, so that the rod chamber of the brake cylinder 1 maintains high pressure, preventing the hydraulic oil in the rod chamber of the brake cylinder 1 from flowing back, and avoiding the situation where the parking brake is immediately applied to the tire to lock and cause a safety accident when the power is accidentally lost.

[0081] In one embodiment, the working method further includes:

[0082] It is determined that the agricultural machinery has stopped suddenly or the hydraulic pump 5 has lost power, and the opening of the flow path between the working oil port and the return oil port of the first reversing valve 2 is controlled to gradually increase.

[0083] In this embodiment, in order to enable the flow path opening between the working oil port and the return oil port of the first reversing valve 2 to be continuously controlled and adjusted, the first reversing valve 2 can be set as a proportional valve. Based on the characteristics of the proportional valve, after the hydraulic pump 5 stops, the first reversing valve 2 can gradually and slowly increase the flow path opening between the working oil port and the return oil port, thereby controlling the return oil speed of the brake cylinder 1, so that the brake cylinder 1 can be depressurized more slowly, avoiding the situation where the brake cylinder 1 is instantly depressurized and the parking brake is immediately applied to lock the tire, so that the agricultural machinery can also be parked smoothly and slowly in the case of an emergency stop.

[0084] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0085] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0086] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0087] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A parking brake system, characterized in that: The parking brake system comprises: parking brake; An oil return line including a damping member (10); a first reversing valve (2), wherein a working oil port of the first reversing valve (2) is connected to a rod chamber of a brake cylinder (1) of the parking brake, a return oil port of the first reversing valve (2) is connected to an oil inlet end of the return oil circuit, the working oil port of the first reversing valve (2) in a power-off state is communicated with the return oil port, and the working oil port of the first reversing valve (2) in a power-on state is communicated with the oil inlet; a second reversing valve (3) and an accumulator (4), wherein the oil inlet of the second reversing valve (3) is connected to the accumulator (4), and the oil outlet of the second reversing valve (3) is connected to the oil return oil circuit, and the connection position is located between the oil inlet end of the oil return oil circuit and the damping member (10); the oil inlet and the oil outlet of the second reversing valve (3) are connected when the power is off, and the oil inlet and the oil outlet of the second reversing valve (3) are disconnected when the power is on; An oil inlet circuit, connected to the oil inlet of the first reversing valve (2) and the accumulator (4) respectively; The second reversing valve (3) is configured to be de-energized synchronously with the first reversing valve (2), and to be energized synchronously with the first reversing valve (2) in a driving gear state; the damping member (10) is used to limit the instantaneous pressure relief of the rod chamber of the brake cylinder (1) through the oil return line; the accumulator is used to provide hydraulic energy to the brake cylinder (1) through the oil return line and the first reversing valve (2) in a de-energized state, thereby preventing the hydraulic oil in the rod chamber of the brake cylinder (1) from flowing back.

2. The parking brake system according to claim 1, characterized in that: The oil inlet circuit includes: Hydraulic pump (5); a one-way valve (6), wherein the oil inlet of the one-way valve (6) is connected to the output end of the hydraulic pump (5); A first oil circuit (7) has one end connected to the oil outlet of the one-way valve (6) and the other end connected to the oil inlet of the first reversing valve (2). The first oil circuit (7) is also connected to the accumulator (4).

3. The parking brake system according to claim 2, characterized in that: The oil inlet circuit further comprises a relief valve (8), and the relief valve (8) is arranged in parallel with the hydraulic pump (5).

4. The parking brake system according to claim 1, characterized in that: The damping member (10) is a throttle valve.

5. The parking brake system according to claim 1 or 2, characterized in that: The first reversing valve (2) is a proportional valve. The parking brake system further comprises a controller, which is in communication with the first reversing valve (2) and is used to control the flow path opening between the working oil port and the return oil port of the first reversing valve (2) to gradually increase after receiving an emergency stop signal.

6. The parking brake system according to claim 5, characterized in that: The parking brake system further comprises a vehicle speed detector, the controller being in communication with the vehicle speed detector and being used to control the flow path opening between the working oil port and the return oil port of the first reversing valve (2) to gradually increase according to the vehicle speed information detected by the vehicle speed detector after receiving an emergency stop signal.

7. The parking brake system according to claim 6, characterized in that: The vehicle speed detector is a tire speed sensor.

8. An agricultural machine, characterized in that: The agricultural machine comprises a parking brake system according to any one of claims 1 to 7.

9. The operating method of the parking brake system according to any one of claims 1 to 7, characterized in that: The process includes the following: After determining that the agricultural machinery is switched to the driving gear, the first reversing valve (2) and the second reversing valve (3) are switched to the energized state; when the first reversing valve (2) is switched from the energized state to the de-energized state, the second reversing valve (3) is synchronously switched to the de-energized state.

10. The working method according to claim 9, characterized in that: The working method further comprises: It is determined that the agricultural machinery has stopped suddenly or the hydraulic pump (5) has lost power, and the opening of the flow path between the working oil port and the return oil port of the first reversing valve (2) is controlled to gradually increase.

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