Brake hydraulic system of tractor trailer

Abstract

The utility model provides a tractor trailer brake hydraulic system which comprises an oil pump, a trailer brake oil cylinder and a foot brake valve, a one-way valve is arranged on an outlet oil way of the oil pump, an outlet of the one-way valve is provided with a brake main way and a first pressure relief branch way, the outlet end of the brake main way is provided with a brake branch way and a release branch way, and the brake branch way is connected with the trailer brake oil cylinder; a brake release valve is arranged on the release branch; the first pressure relief branch is connected with a pilot control valve, and an outlet of the pilot control valve is connected with an overflow valve; the outlet end of the foot brake valve is connected with one end of a valve element of the pilot control valve. According to the utility model, the parking brake of the trailer is realized through the trailer brake oil cylinder; oil liquid enters a trailer brake oil cylinder through the one-way valve, the brake main path and the brake branch path, and brake release is achieved. The pilot control valve is controlled to be closed through the foot brake valve, and temporary braking of the trailer is achieved. The tractor trailer is braked immediately after parking and released immediately after running, and operation convenience and timeliness are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of tractor trailer brake systems, in particular to a tractor trailer brake hydraulic system. Background Art

[0002] As the application field of tractors gradually expands, the application of trailers is becoming more and more common. The trailer braking system is a necessary configuration. In general trailers, the brakes are divided into air brakes and hydraulic brakes, which have different adaptability regions. The development of hydraulic brakes is relatively difficult, and there are few supporting components available. At present, the brakes of trailers are mostly configured separately. When preparing for driving, after the engine is started, the brakes of the tractor head and the trailer need to be released respectively; when parking, the tractor head and the trailer need to be braked in time. Since it is difficult to take care of both ends at the same time, the timeliness and convenience of operation are poor; at the same time, the impact is large when parking, and the operating comfort is poor. Utility Model Content

[0003] The technical problem to be solved by the utility model is: how to realize the function of braking a tractor trailer when it is parked and releasing the brake when it is driving, so as to improve the convenience and timeliness of operation.

[0004] The technical solution of the utility model to solve the above technical problems is as follows:

[0005] The utility model provides a tractor trailer brake hydraulic system, comprising an oil pump, a trailer brake oil cylinder, and a foot brake valve, wherein an inlet of the oil pump is provided with an oil tank, an outlet oil circuit of the oil pump is provided with a one-way valve, an outlet of the one-way valve is provided with a brake main circuit and a first pressure relief branch, an outlet end of the brake main circuit is provided with a brake branch and a release branch, the brake branch is connected to the trailer brake oil cylinder; the release branch is connected to the oil tank, and a brake release valve is provided on the release branch; the first pressure relief branch is connected to a pilot control valve, the outlet of the pilot control valve is connected to a relief valve, and the outlet of the relief valve is connected to the oil tank; the outlet end of the foot brake valve is connected to one end of a valve core of the pilot control valve.

[0006] The beneficial effects of the utility model are:

[0007] With the utility model, the trailer parking brake is initially realized through the trailer brake cylinder; when driving, under the action of the overflow valve, the brake main circuit maintains oil pressure, and the oil enters the trailer brake cylinder through the one-way valve, the brake main circuit and the brake branch circuit, realizing brake release; when temporarily braking, the foot brake valve controls the pilot control valve to close, releases the pressure holding effect of the overflow valve, and increases the oil pressure entering the trailer brake cylinder from the brake main circuit, realizing temporary braking of the trailer; when preparing to shut down, the brake release valve releases the oil pressure in the trailer brake cylinder, realizing the trailer returning to the initial parking brake state. Thus, the function of braking when the tractor trailer is parked and releasing when driving is realized, improving the convenience and timeliness of operation.

[0008] On the basis of the above technical solution, the present invention can also be improved as follows.

[0009] Furthermore, a flow valve is provided on the oil circuit from the oil pump to the one-way valve, the inlet of the flow valve is connected to the outlet of the oil pump, the first outlet of the flow valve is connected to the inlet of the one-way valve, and the second outlet of the flow valve is provided with an external oil circuit.

[0010] When the trailer is in driving state, after the brakes are released, part of the pressure oil output by the oil pump flows out through the second outlet of the flow valve and the external oil line, so as to facilitate the oil supply to other systems on the tractor.

[0011] Furthermore, a second pressure relief branch is provided on the oil circuit from the oil pump to the flow valve, and the second pressure relief branch is connected to the second inlet of the pilot control valve.

[0012] In the driving state, part of the pressure oil in front of the pilot control valve passes through the first pressure relief branch, and part of the pressure oil after the pilot control valve passes through the second pressure relief branch. Both the first pressure relief branch and the second pressure relief branch are stabilized by the overflow valve, which improves the pressure stability of the main brake circuit and has good reliability.

[0013] Furthermore, the valve core of the pilot control valve is provided with a left position, a middle position and a right position. When the left position is working, the first inlet and the second inlet of the pilot control valve are both connected to the outlet of the pilot control valve; when the middle position is working, the first inlet of the pilot control valve is connected to the outlet of the pilot control valve, and the second inlet is closed; when the right position is working, the first inlet and the second inlet of the pilot control valve are both closed;

[0014] The outlet end of the foot brake valve is connected to the right working end of the valve core of the pilot control valve; the main brake circuit is also connected to the left working end of the valve core of the pilot control valve through a branch circuit.

[0015] In the temporary braking state, the pilot oil pushes the valve core of the pilot control valve to the right position through the foot brake valve. The first inlet and the second inlet of the pilot control valve are closed, and the main braking circuit can establish a higher oil pressure. The pressure oil pushes the plunger of the trailer brake cylinder to extend, so that the trailer is in a temporary braking state; the brake pressure oil acts on the left end of the valve core of the pilot control valve. When the brake pressure fluctuates and the pressure is high, the brake pressure oil pushes the valve core to move to the middle position to work, so that part of the pressure oil output by the oil pump is released through the pilot brake valve and the relief valve to avoid brake locking; when the braking is abnormal and the pressure is too high, the brake pressure oil pushes the valve core to move to the left position to work, and the first pressure relief branch and the second pressure relief branch both release pressure through the relief valve, which plays a role in rapid pressure relief; it is convenient to protect the trailer brake cylinder and trailer brakes.

[0016] Furthermore, the outlet of the oil pump is also provided with a safety branch, the safety branch is connected to the oil tank, and a safety valve is provided on the safety branch.

[0017] When the outlet pressure of the oil pump is too high, part of the oil is released to the oil tank through the safety valve, which improves the safety of the hydraulic system.

[0018] Furthermore, a brake solenoid valve is provided at the outlet end of the main brake circuit, and the brake solenoid valve is a normally open valve.

[0019] When the engine is ready to shut down, the brake release valve is opened and the brake solenoid valve is closed, which is convenient for cutting off the pressure oil in the main brake circuit, ensuring that the pressure oil in the trailer brake cylinder quickly returns to the tank through the release branch, thereby improving the timeliness of the trailer returning to the parking brake state.

[0020] Furthermore, the valve core of the brake solenoid valve is provided with a normally open working position and a one-way working position. When the normally open working position is working, the inlet and outlet of the brake solenoid valve are connected; when the one-way working position is working, the brake solenoid valve can make the pressure oil flow from the trailer brake cylinder to the main brake circuit in one direction.

[0021] When ready to shut down, the brake solenoid valve switches to the one-way working position to cut off the pressure oil in the main brake circuit; at the same time, when the oil pump is turned off, the oil in the trailer's brake cylinder can also be depressurized in one direction through the brake solenoid valve, which improves the timeliness of the trailer's return to the parking brake state.

[0022] Furthermore, the brake release valve is a normally closed solenoid valve; a normally closed working position and a release working position are provided on the valve core of the brake release valve.

[0023] When ready to shut down, the brake release valve switches to the release working position, and the oil in the trailer brake cylinder returns to the tank through the release working position, making it easier to control the trailer back to the parking brake state; when the brake release valve loses power, it returns to the normally closed working position, restoring the hydraulic system to its initial state, making it easier to operate next time.

[0024] Furthermore, a throttling channel and a one-way channel are provided on the release working position, and the throttling channel and the one-way channel are connected in parallel with each other; the one-way channel enables oil to flow from the trailer brake cylinder to the oil tank in one direction.

[0025] The throttling channel makes it easy to control the oil return speed of the trailer brake cylinder to avoid impact; when the pressure of the trailer brake cylinder is high, the oil can be quickly returned through the one-way channel, which is convenient for rapid pressure relief and improves the timeliness of the trailer returning to the parking state.

[0026] Furthermore, the trailer brake cylinder includes a cylinder body and a plunger, wherein the cylinder body is provided with a piston, one end of the plunger extends into the cylinder body and is provided with a conical head, the large end diameter of the conical head is larger than the diameter of the plunger, and the small end of the conical head is in contact with the piston; a first spring is sleeved on the plunger, and when the first spring is compressed and deformed, the elastic force of the first spring can push the conical head to move toward the piston; a second spring is provided at one end of the piston away from the plunger, and when the second spring is compressed and deformed, the elastic force of the second spring can push the piston to move toward the plunger; an oil interface is also provided on the cylinder body, the oil interface is connected to the cavity where the conical head is located, and the brake branch is connected to the oil interface.

[0027] In the initial state, the elastic force of the second spring overcomes the elastic force of the first spring, so that the plunger extends to achieve parking brake of the trailer; when the oil interface inputs pressurized oil, since the piston is affected by the oil pressure over a larger area, the oil pressure and the elastic force of the first spring jointly overcome the elastic force of the second spring, so that the piston compresses the second spring to move, thereby retracting the plunger to achieve trailer braking contact; when the pressurized oil input by the oil interface builds up a higher pressure, the oil pressure can overcome the elastic force of the first spring, thereby pushing the plunger out to achieve temporary braking of the trailer; the hydraulic connection is convenient and the operation is easy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the utility model in the initial state.

[0029] Figure 2 It is a schematic diagram of the structure of the utility model in driving state.

[0030] Figure 3 It is a schematic diagram of the structure of the utility model in a temporary braking state.

[0031] Figure 4 The utility model is a schematic diagram of the structure in the flameout state.

[0032] In the accompanying drawings, the technical features represented by the reference numerals are as follows:

[0033] 1-Oil pump; 2-Trailer brake cylinder; 3-Pilot control valve; 4-Overflow valve; 5-Foot brake valve; 6-Check valve; 7-Brake release valve; 8-Oil tank; 9-Tractor brake cylinder; 10-Flow valve; 11-External oil line; 12-Safety valve; 13-Brake solenoid valve; 14-Cylinder body; 15-Piston; 16-Plunger. DETAILED DESCRIPTION

[0034] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0035] This utility model refers to Figure 1-4 .

[0036] The utility model provides a tractor trailer brake hydraulic system, comprising an oil pump 1, a trailer brake oil cylinder 2, and a foot brake valve 5, wherein an inlet of the oil pump 1 is provided with an oil tank 8, an outlet oil circuit of the oil pump 1 is provided with a one-way valve 6, an outlet of the one-way valve 6 is provided with a brake main circuit and a first pressure relief branch, an outlet end of the brake main circuit is provided with a brake branch and a release branch, the brake branch is connected to the trailer brake oil cylinder 2; the release branch is connected to the oil tank 8, and a brake release valve 7 is provided on the release branch; the first pressure relief branch is connected to a pilot control valve 3, an outlet of the pilot control valve 3 is connected to a relief valve 4, and an outlet of the relief valve 4 is connected to the oil tank 8; the outlet end of the foot brake valve 5 is connected to one end of a valve core of the pilot control valve 3.

[0037] principle:

[0038] The trailer brake cylinder 2 is an original structure on the trailer, used to push the trailer brake to work, and belongs to the prior art; wherein, when there is no pressure oil input to the trailer brake cylinder 2, its own internal elastic force can push the plunger 16 to extend; when pressure oil is input, the pressure oil can overcome the elastic force inside the trailer brake cylinder 2, so that the plunger 16 retracts; when the pressure of the pressure oil input is further increased, the pressure oil can push the plunger 16 to extend. The foot brake valve 5 is an original structure on the tractor brake system, and the tractor brake system is the prior art; wherein, the inlet end of the foot brake valve 5 is provided with a pilot oil source, and the outlet end of the foot brake valve 5 is also connected to the tractor brake cylinder 9. When the brake pedal is stepped on, the brake pedal drives the foot brake valve 5 to open, and the pilot oil enters the tractor brake cylinder 9 through the foot brake valve 5 to achieve the braking of the tractor.

[0039] Under the setting of the utility model, when the foot brake valve 5 is opened, the pilot oil also pushes the valve core of the pilot control valve 3 through the foot brake valve 5 to move, so that the pilot control valve 3 is closed, thereby cutting off the passage from the first pressure relief branch to the overflow valve 4. The working state of the utility model is as follows:

[0040] In the initial state, if Figure 1As shown: the brake release valve 7 is in a closed state; the oil pump 1 is closed, and the plunger 16 of the trailer brake cylinder 2 extends out under the action of its own elastic force and acts on the brake of the trailer, so that the trailer is in a parking brake state.

[0041] When driving, Figure 2 As shown (the direction of the arrow is the direction of oil flow): the engine starts, the oil pump 1 works, and the pressure oil of the oil pump 1 passes through the one-way valve 6, part of which enters the main brake circuit, and part of which enters the first pressure relief branch; in the first pressure relief branch, the oil flows out through the pilot control valve 3 and the relief valve 4, and under the action of the relief valve 4, the main brake circuit maintains a certain oil pressure. In the main brake circuit, the oil enters the trailer brake cylinder 2 through the brake branch, causing the plunger 16 of the trailer brake cylinder 2 to retract, and the trailer brake is released.

[0042] In temporary braking state, such as Figure 3 As shown (the direction of the arrow is the direction of oil flow): the brake pedal is depressed, the foot brake valve 5 is opened, and while the tractor is braked, the pilot oil also pushes the valve core of the pilot control valve 3 through the foot brake valve 5 to move, so that the pilot control valve 3 is closed, the first pressure relief branch is cut off, and the pressure holding effect of the relief valve 4 is released. The outlet oil of the one-way valve 6 all flows to the main brake circuit. The main brake circuit can establish a higher oil pressure, and the pressure oil pushes the plunger 16 of the trailer brake cylinder 2 to extend, so that the trailer is in a temporary braking state.

[0043] Note: The pilot control valve 3 is a multi-way valve, and the pilot oil at both ends of the valve core of the multi-way valve has independent oil return paths, which belongs to the existing technology, and its specific structure has nothing to do with the technical problem solved by the utility model.

[0044] In the ready-to-turn-off state, Figure 4 As shown (the arrow direction is the oil flow direction): the brake release valve 7 is opened, the release branch is connected, and the pressure oil in the trailer brake cylinder 2 is quickly returned to the oil tank 8 through the release branch. Under the action of its own elastic force, the plunger 16 of the trailer brake cylinder 2 extends and acts on the trailer brake, so that the trailer returns to the parking brake state. At this time, the engine can be turned off and the brake release valve 7 returns to the closed state.

[0045] In summary, by adopting the utility model, the trailer parking brake is initially realized through the trailer brake cylinder 2; when driving, under the action of the overflow valve 4, the brake main circuit maintains oil pressure, and the oil enters the trailer brake cylinder 2 through the one-way valve 6, the brake main circuit and the brake branch circuit, realizing the brake release; when temporarily braking, the foot brake valve 5 controls the pilot control valve 3 to close, releases the pressure holding effect of the overflow valve 4, and increases the oil pressure entering the trailer brake cylinder 2 from the brake main circuit, realizing the temporary braking of the trailer; when preparing to shut down, the brake release valve 7 releases the oil pressure in the trailer brake cylinder 2, realizing the trailer returning to the initial parking brake state. Thus, the function of braking when the tractor trailer is parked and releasing when driving is realized, improving the convenience and timeliness of operation.

[0046] Furthermore, a flow valve 10 is provided on the oil circuit from the oil pump 1 to the one-way valve 6, the inlet of the flow valve 10 is connected to the outlet of the oil pump 1, the first outlet of the flow valve 10 is connected to the inlet of the one-way valve 6, and the second outlet of the flow valve 10 is provided with an external oil circuit 11.

[0047] In the driving state, after the brakes of the trailer are released, part of the pressure oil output by the oil pump 1 flows out through the second outlet of the flow valve 10 and the external oil line 11, so as to facilitate the oil supply to other systems on the tractor.

[0048] Furthermore, a second pressure relief branch is provided on the oil circuit from the oil pump 1 to the flow valve 10 , and the second pressure relief branch is connected to the second inlet of the pilot control valve 3 .

[0049] In the driving state, part of the pressure oil in front of the pilot control valve 3 passes through the first pressure relief branch, and part of the pressure oil after the pilot control valve 3 passes through the second pressure relief branch. Both the first pressure relief branch and the second pressure relief branch are stabilized by the overflow valve 4, which improves the pressure stability of the main braking circuit and has good reliability.

[0050] Furthermore, the valve core of the pilot control valve 3 is provided with a left position, a middle position and a right position. When the left position is working, the first inlet and the second inlet of the pilot control valve 3 are both connected to the outlet of the pilot control valve 3; when the middle position is working, the first inlet of the pilot control valve 3 is connected to the outlet of the pilot control valve 3, and the second inlet is closed; when the right position is working, the first inlet and the second inlet of the pilot control valve 3 are both closed;

[0051] The outlet end of the foot brake valve 5 is connected to the right working end of the valve core of the pilot control valve 3; the brake main circuit is also connected to the left working end of the valve core of the pilot control valve 3 through a branch circuit.

[0052] Note: Different groove channels are set for the left station, middle station and right station. When the valve core moves, it can control the left station, middle station or right station to move to the interface position of the pilot control valve 3. Any station works when it is in the interface position.

[0053] In the temporary braking state, the pilot oil pushes the valve core of the pilot control valve 3 to move to the right position for operation through the foot brake valve 5. The first inlet and the second inlet of the pilot control valve 3 are both closed, and the main braking circuit can establish a higher oil pressure. The pressure oil pushes the plunger 16 of the trailer brake cylinder 2 to extend, so that the trailer is in a temporary braking state; the brake pressure oil acts on the left end of the valve core of the pilot control valve 3. When the brake pressure fluctuates and the pressure is high, the brake pressure oil pushes the valve core to move to the middle position for operation, so that part of the pressure oil output by the oil pump 1 is depressurized through the pilot brake valve and the relief valve 4 to avoid brake locking; when the braking is abnormal and the pressure is too high, the brake pressure oil pushes the valve core to move to the left position for operation, and the first pressure relief branch and the second pressure relief branch both relieve pressure through the relief valve 4, which plays a role of rapid pressure relief; it is convenient to protect the trailer brake cylinder 2 and the trailer brake.

[0054] Furthermore, the outlet of the oil pump 1 is also provided with a safety branch, the safety branch is connected to the oil tank 8, and a safety valve 12 is provided on the safety branch.

[0055] When the outlet pressure of the oil pump 1 is too high, part of the oil is released to the oil tank 8 through the safety valve 12, thereby improving the safety of the hydraulic system.

[0056] Furthermore, a brake solenoid valve 13 is provided at the outlet end of the brake main circuit, and the brake solenoid valve 13 is a normally open valve.

[0057] In the state of preparing to shut down, when the brake release valve 7 is opened, the brake solenoid valve 13 is closed, which is convenient for cutting off the pressure oil in the main brake circuit, ensuring that the pressure oil in the trailer brake cylinder 2 quickly returns to the oil tank 8 through the release branch, thereby improving the timeliness of the trailer returning to the parking brake state.

[0058] Furthermore, the valve core of the brake solenoid valve 13 is provided with a normally open working position and a one-way working position. When the normally open working position is working, the inlet and outlet of the brake solenoid valve 13 are connected; when the one-way working position is working, the brake solenoid valve 13 can make the pressure oil flow from the trailer brake cylinder 2 to the main brake circuit in one direction.

[0059] Note: The brake solenoid valve 13 is a two-position one-way valve, which is a prior art; in the normally open working position, a valve channel is provided on the valve core; in the one-way working position, a one-way valve 6 is provided in the valve channel.

[0060] In the state of preparing to shut down the engine, the brake solenoid valve 13 switches to the one-way working position to cut off the pressure oil in the main brake circuit; at the same time, when the oil pump 1 is turned off, the oil in the trailer brake cylinder 2 can also be depressurized in one direction through the brake solenoid valve 13, thereby improving the timeliness of the trailer returning to the parking brake state.

[0061] Furthermore, the brake release valve 7 is a normally closed solenoid valve; the valve core of the brake release valve 7 is provided with a normally closed working position and a release working position.

[0062] Note: The brake release valve 7 can also be connected to the parking lever of the tractor. When the parking lever is pulled, the brake release valve 7 is controlled to the release working position.

[0063] In the state of preparing to shut down, the brake release valve 7 switches to the release working position, and the oil in the trailer brake cylinder 2 returns to the oil tank 8 through the release working position, which is convenient for controlling the trailer to return to the parking brake state; when the brake release valve 7 loses power, it returns to the normally closed working position, so that the hydraulic system returns to the initial state, which is convenient for the next operation.

[0064] Furthermore, a throttling channel and a one-way channel are provided on the release working position, and the throttling channel and the one-way channel are connected in parallel with each other; the one-way channel enables the oil to flow from the trailer brake cylinder 2 to the oil tank 8 in one direction.

[0065] The throttling channel can be used to control the oil return speed of the trailer brake cylinder 2 to avoid impact; when the pressure of the trailer brake cylinder 2 is high, the oil can be quickly returned through the one-way channel to facilitate rapid pressure relief, thereby improving the timeliness of the trailer returning to the parking state.

[0066] Furthermore, the trailer brake cylinder 2 includes a cylinder body 14 and a plunger 16. A piston 15 is provided in the cylinder body 14. One end of the plunger 16 extends into the cylinder body 14 and is provided with a conical head. The large end diameter of the conical head is larger than the diameter of the plunger 16, and the small end of the conical head is in contact with the piston 15. A first spring is sleeved on the plunger 16. When the first spring is compressed and deformed, the elastic force of the first spring can push the conical head to move toward the piston 15. A second spring is provided at one end of the piston 15 away from the plunger 16. When the second spring is compressed and deformed, the elastic force of the second spring can push the piston 15 to move toward the plunger 16. An oil interface is also provided on the cylinder body 14. The oil interface is connected to the cavity where the conical head is located, and the brake branch is connected to the oil interface.

[0067] In the initial state, the elastic force of the second spring overcomes the elastic force of the first spring, so that the plunger 16 extends, realizing the parking brake of the trailer; when the oil interface inputs the pressurized oil, since the piston 15 is affected by the oil pressure over a larger area, the oil pressure and the elastic force of the first spring jointly overcome the elastic force of the second spring, so that the piston 15 compresses the second spring to move, thereby retracting the plunger 16, realizing the braking contact of the trailer; when the pressurized oil input by the oil interface builds up a higher pressure, the oil pressure can overcome the elastic force of the first spring, thereby pushing the plunger 16 to extend, realizing the temporary braking of the trailer; the hydraulic connection is convenient and the operation is convenient.

[0068] In the description of the present invention, it should be understood that if there are descriptive terms indicating orientation, direction or positional relationship, such as: "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., the orientation or positional relationship indicated in this specification is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of understanding the present invention and simplifying the description, and does not indicate or imply that the referred part, element or whole must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0069] In addition, if there are order description terms, such as "first", "second", etc., their purpose in this specification is to facilitate understanding or simplify description. For example, in order to distinguish multiple technical features of the same type or function, but they have to be mentioned separately, this specification may use prefix or suffix order description terms to distinguish them. Therefore, it cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0070] In the present utility model, if the terms describing the relative functional relationship of the structures are used, such as "install", "connect", "connect", "fix", etc., they should be understood in a broad sense unless otherwise clearly specified and limited. For example, "install", "connect", "connect", etc. can be a fixed connection, a detachable connection, or an integrated one; can be a mechanical connection or an electrical connection; can be a direct connection or an indirect connection through an intermediate medium, can be the internal connection of two elements or the interaction relationship between two elements; "fix" can be an integrated fixation or a detachable fixation through fasteners; can be a direct fixation or a fixation through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above-mentioned descriptive terms in the present utility model can be understood according to the specific circumstances, the context, the coherence of the context, etc.

[0071] In the present invention, if there are descriptive terms with subsidiary or connecting meanings, for example, the first feature is "on" or "below" the second feature, unless otherwise clearly specified and limited, it should not be interpreted in a restrictive manner. For example, "on" or "below" can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above descriptive terms in the present invention can be understood according to the specific circumstances, the context, the coherence of the context, etc.

[0072] Furthermore, the first feature being “above”, “above”, and “above” the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being “below”, “below”, and “below” the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0073] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means 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 utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments, examples and features of the different embodiments and examples described in this specification without contradiction, and these combinations or combinations shall all fall within the scope summarized by the utility model.

[0074] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are illustrative and cannot be construed as limitations on the present invention. A person skilled in the art can change, modify, replace and modify the above embodiments within the scope of information available from public channels and in combination with the technical inspiration provided by the present application documents.

Claims

1. A tractor trailer brake hydraulic system, characterized in that: The invention comprises an oil pump (1), a trailer brake oil cylinder (2), and a foot brake valve (5); the inlet of the oil pump (1) is provided with an oil tank (8); the outlet oil circuit of the oil pump (1) is provided with a one-way valve (6); the outlet of the one-way valve (6) is provided with a braking main circuit and a first pressure relief branch; the outlet end of the braking main circuit is provided with a braking branch and a release branch; the braking branch is connected to the trailer brake oil cylinder (2); the release branch is connected to the oil tank (8), and the release branch is provided with a brake release valve (7); the first pressure relief branch is connected to a pilot control valve (3); the outlet of the pilot control valve (3) is connected to a relief valve (4), and the outlet of the relief valve (4) is connected to the oil tank (8); the outlet end of the foot brake valve (5) is connected to one end of the valve core of the pilot control valve (3).

2. The tractor trailer brake hydraulic system according to claim 1, characterized in that: A flow valve (10) is also provided on the oil circuit from the oil pump (1) to the one-way valve (6); the inlet of the flow valve (10) is connected to the outlet of the oil pump (1); the first outlet of the flow valve (10) is connected to the inlet of the one-way valve (6); and the second outlet of the flow valve (10) is provided with an external oil circuit (11).

3. The tractor trailer brake hydraulic system according to claim 2, characterized in that: A second pressure relief branch is also provided on the oil circuit from the oil pump (1) to the flow valve (10), and the second pressure relief branch is connected to the second inlet of the pilot control valve (3).

4. The tractor trailer brake hydraulic system according to claim 3, characterized in that: The valve core of the pilot control valve (3) is provided with a left position, a middle position and a right position. When the left position is working, the first inlet and the second inlet of the pilot control valve (3) are both connected to the outlet of the pilot control valve (3); when the middle position is working, the first inlet of the pilot control valve (3) is connected to the outlet of the pilot control valve (3), and the second inlet is closed; when the right position is working, the first inlet and the second inlet of the pilot control valve (3) are both closed; the outlet end of the foot brake valve (5) is connected to the end of the valve core of the pilot control valve (3) at the right position; the main brake circuit is also connected to the end of the valve core of the pilot control valve (3) at the left position through a branch circuit.

5. The tractor trailer brake hydraulic system according to claim 1, characterized in that: The outlet of the oil pump (1) is also provided with a safety branch, the safety branch is connected to the oil tank (8), and a safety valve (12) is provided on the safety branch.

6. The tractor trailer brake hydraulic system of claim 1, characterized in that: The outlet end of the main braking circuit is also provided with a braking solenoid valve (13), and the braking solenoid valve (13) is a normally open valve.

7. The tractor trailer brake hydraulic system according to claim 6, characterized in that: The valve core of the brake solenoid valve (13) is provided with a normally open working position and a one-way working position. When the normally open working position is in operation, the inlet and outlet of the brake solenoid valve (13) are connected; when the one-way working position is in operation, the brake solenoid valve (13) can allow the pressure oil to flow from the trailer brake cylinder (2) to the brake main circuit in one direction.

8. The tractor trailer brake hydraulic system of claim 1, characterized in that: The brake release valve (7) is a normally closed electromagnetic valve; a normally closed working position and a release working position are provided on the valve core of the brake release valve (7).

9. The tractor trailer brake hydraulic system according to claim 8, characterized in that: The release working position is provided with a throttling channel and a one-way channel, which are connected in parallel with each other; the one-way channel enables oil to flow from the trailer brake oil cylinder (2) to the oil tank (8) in one direction.

10. The tractor trailer brake hydraulic system of claim 1, wherein: The trailer brake oil cylinder (2) comprises a cylinder body (14) and a plunger (16). A piston (15) is arranged in the cylinder body (14). One end of the plunger (16) extends into the cylinder body (14) and is provided with a conical head. The diameter of the large end of the conical head is larger than the diameter of the plunger (16), and the small end of the conical head contacts the piston (15). A first spring is sleeved on the plunger (16). When the first spring is compressed and deformed, the elastic force of the first spring can push the conical head to move in the direction of the piston (15). A second spring is arranged at one end of the piston (15) away from the plunger (16). When the second spring is compressed and deformed, the elastic force of the second spring can push the piston (15) to move in the direction of the plunger (16). The cylinder body (14) is also provided with an oil interface. The oil interface is communicated with the cavity where the conical head is located, and the brake branch is connected to the oil interface.

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