Tractor hydraulic system and tractor

Abstract

The invention belongs to the field of agricultural machinery, and discloses a tractor hydraulic system and a tractor, and the tractor hydraulic system comprises a service braking hydraulic loop which comprises a braking valve used for controlling a brake; the chassis control hydraulic loop comprises a chassis control valve group; and the priority valve group is used for pumping the hydraulic oil passing through the priority valve group to the brake valve when the real-time brake pressure of the service brake hydraulic circuit is not higher than a set upper threshold value, and switching and pumping the hydraulic oil to the chassis control valve group or returning the hydraulic oil when the real-time brake pressure is not lower than a set lower threshold value. According to the tractor chassis control system, through interconnection of the priority valve set and the chassis control valve set, interconnection of a tractor chassis brake system, a clutch control system and a lubricating system is achieved, the system is more compact, and energy consumption is lower; after the system preferentially ensures that the system has the service braking capacity, parking braking is activated, and the driving process is safer and more reliable. And besides, the system is compact, the pipeline arrangement of the whole vehicle system is simplified, and the energy loss of the system is reduced.

Description

Technical Field

[0001] The present application belongs to the field of agricultural machinery, and in particular, relates to a tractor hydraulic system and a tractor. Background Art

[0002] Tractors generally use brake cylinders for braking. As the horsepower of tractors increases, the requirements for braking force and brake control also increase, and the brake system gradually adopts hydraulic drive. However, with the increase of system functions and hydraulic control circuits in tractors, the number of hydraulic components has also increased significantly, occupying a large space, and the main pump drives the various hydraulic systems in parallel, which inevitably leads to problems in oil distribution and system energy consumption. For example, it is difficult to meet the oil demand of the brake system under special working conditions, and the energy consumption of the hydraulic pump is wasted. Summary of the invention

[0003] The purpose of the present application is to provide a tractor hydraulic system and a tractor to improve the braking performance of the tractor and reduce the energy consumption of the system.

[0004] To achieve the above objectives, the present application provides a tractor hydraulic system, comprising: a service brake hydraulic circuit, including brake valves for controlling the brakes; Chassis control hydraulic circuit, including chassis control valve group; The priority valve group is used to pump the hydraulic oil through the priority valve group to the brake valve when the real-time brake pressure of the service brake hydraulic circuit is not higher than a set lower threshold value, and to switch the hydraulic oil to be pumped to the chassis control valve group or return oil when the real-time brake pressure is not lower than a set upper threshold value.

[0005] In some embodiments, the priority valve group has a main oil inlet, a first oil outlet and a second oil outlet and includes: A first-level priority valve, which is a hydraulically controlled valve and is used to control the main oil inlet to switch and connect to the first oil outlet or the second oil outlet; The pressure control valve is the pilot valve of the first-level priority valve.

[0006] In some embodiments, the pressure control valve has at least a first valve position and a second valve position and comprises: An oil return port and a control connection port, located on a first side of a valve body of the pressure control valve, the control connection port being hydraulically connected to a control end of the first-level priority valve; a brake connection port, located at a second side of the valve body of the pressure control valve and hydraulically connected to the first oil outlet; Wherein, in the first valve position, the oil return port is cut off, and the brake connection port is communicated with the control connection port; in the second valve position, the brake connection port is cut off, and the control connection port is communicated with the oil return port.

[0007] In some embodiments, the pressure control valve is a hydraulically controlled valve and includes a first hydraulically controlled end and a second hydraulically controlled end provided with a control spring, and the first hydraulically controlled end and the second hydraulically controlled end are both hydraulically connected to the first oil outlet; Wherein, the control spring is used to drive the valve core so that the pressure control valve is located at the first valve position, and the valve core action area of ​​the second hydraulic control end is larger than the valve core action area of ​​the first hydraulic control end.

[0008] In some embodiments, the primary priority valve has at least a left valve position and a right valve position and comprises: A priority valve oil inlet, connected to the main oil inlet; a first working oil port and a second working oil port, the first working oil port being connected to the first oil outlet, and the second working oil port being used to be connected to the second oil outlet; Wherein, in the left valve position, the priority valve oil inlet is connected to the first working oil port and the second working oil port is cut off, and in the right valve position, the priority valve oil inlet is connected to the second working oil port and the first working oil port is cut off.

[0009] In some embodiments, the first-level priority valve is a hydraulically controlled valve and includes a left control end and a right control end provided with a compression spring, the left control end is hydraulically connected to the control connection port, and the right control end is hydraulically connected to the first oil outlet.

[0010] In some embodiments, the priority valve assembly further has a third oil outlet and includes: A secondary priority valve, used for controlling the second working oil port to switch and connect to the second oil outlet or the third oil outlet; Wherein, the tractor hydraulic system further comprises a chassis lubrication hydraulic oil circuit, and the chassis lubrication hydraulic oil circuit is connected between the third oil outlet and the hydraulic oil tank.

[0011] In some embodiments, the secondary priority valve is a hydraulically controlled valve and is pilot-connected to the LS feedback oil port of the chassis control valve group; And / or, a one-way valve is provided at the first working oil port to prevent the oil from the first oil outlet from flowing back; And / or, the chassis control valve group includes a brake control valve and a plurality of clutch control valves connected in parallel.

[0012] In some embodiments, the tractor hydraulic system further comprises: A main pump is used to pump hydraulic oil to the priority valve group.

[0013] In some embodiments, the priority valve group includes an electronically controlled pressure switching valve, the service brake hydraulic circuit is provided with a pressure sensor for detecting real-time brake pressure, and the tractor hydraulic system includes a controller, which is configured to switch and control the electronically controlled pressure switching valve according to the real-time brake pressure detected by the pressure sensor.

[0014] In addition, the present application also provides a tractor, which includes the tractor hydraulic system described in the present application.

[0015] In the tractor and its hydraulic system of the present application, by designing a priority valve group and associating it with a chassis control valve group, priority interconnection between the service brake hydraulic circuit and the chassis control hydraulic circuit is achieved, which reduces the pipeline layout and makes the system more compact; wherein, the priority valve group is used to make the hydraulic oil through the priority valve group be pumped to the brake valve first when the real-time braking pressure of the service brake hydraulic circuit is not higher than the set lower threshold value, and when the real-time braking pressure is not lower than the set upper threshold value, the hydraulic oil is switched to be pumped to the chassis control valve group or return oil; this priority oil supply control not only ensures higher safety, reliability and braking performance of the braking system, but also avoids excessive workless return of hydraulic oil, reduces system energy loss, and reduces energy consumption.

[0016] Other advantages of the present application and the technical effects of the preferred embodiments will be further described in the following specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide an understanding of the present application and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present application but do not constitute a limitation to the present application. In the accompanying drawings: Figure 1 A hydraulic principle diagram of a tractor hydraulic system according to a specific embodiment of the present application; Figure 2 for Figure 1 The hydraulic principle diagram of the priority valve group in; Figure 3 for Figure 1 Hydraulic schematic diagram of the chassis control valve group.

[0018] Description of Reference Numerals DETAILED DESCRIPTION

[0019] The specific implementation of the present application is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present application and is not intended to limit the present application. It should be noted that, in the absence of conflict, the implementations in the present application and the features in the implementations can be combined with each other.

[0020] The tractor and the tractor hydraulic system of the present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0021] The present application discloses a novel tractor hydraulic system. Figures 1 to 3 As shown, in a specific embodiment, the tractor hydraulic system includes: A service brake hydraulic circuit, comprising a brake valve 5 for controlling a brake 6; A chassis control hydraulic circuit, comprising a chassis control valve group 10; The priority valve group 3 is used to pump the hydraulic oil through the priority valve group 3 to the brake valve 5 when the real-time brake pressure of the service brake hydraulic circuit is not higher than the set lower threshold value, and to switch the hydraulic oil to be pumped to the chassis control valve group 10 or return oil when the real-time brake pressure is not lower than the set upper threshold value.

[0022] It can be seen that the newly designed priority valve group 3 in the present application needs to adjust the direction of hydraulic oil pumping according to the real-time brake pressure. When the real-time brake pressure is lower than the set lower threshold, that is, when the brake pressure is insufficient, the hydraulic oil is controlled to be pumped to the brake valve 5 first, and when the real-time brake pressure reaches the set upper threshold, that is, when the brake pressure is too large, the hydraulic oil can be controlled to be pumped to the chassis control valve group 10 or return oil as appropriate. When the real-time brake pressure is between the threshold interval between the set upper threshold and the set lower threshold, the priority valve group 3 remains in the existing reversing valve position. In this way, complex, priority chassis hydraulic system control, including brake and clutch control, can be achieved through the priority valve group 3. Among them, by designing the priority valve group 3 and interconnecting it with the chassis control valve group 10, the priority interconnection between the service brake hydraulic circuit and the chassis control hydraulic circuit is achieved, the oil supply of the brake hydraulic circuit is prioritized, and on this basis, the oil is supplied to the chassis control valve group 10.

[0023] Compared with the brake hydraulic circuit and chassis control hydraulic circuit that are not interconnected in the prior art, the tractor hydraulic system of the present application realizes system interconnection, reduces pipeline layout, and makes the system more compact. Moreover, the hydraulic oil is supplied to the brake valve 5 first through the priority valve group 3, and then to the chassis control valve group 10. This priority oil supply control not only ensures the safety and reliability of the brake system, but also avoids excessive hydraulic oil return without work, reduces system energy loss, and reduces energy consumption. After the system has the priority to ensure the driving braking capability, the parking brake is activated, which is safer and more reliable during driving. In addition, the filling of the brake hydraulic circuit in the prior art is often controlled by a high-precision and expensive filling valve. The present application uses the priority valve group 3 instead of the filling valve to control the filling of the brake hydraulic circuit, which is more cost-effective.

[0024] The design of priority valve group 3 realizes the chassis hydraulic system control with priority. Figure 2 In one embodiment, the priority valve group 3 adopts the structure of a hydraulically controlled valve group. The priority valve group 3 has a main oil inlet P, a first oil outlet A and a second oil outlet B and includes: The first-level priority valve 301 is a hydraulically controlled valve and is used to control the main oil inlet P to switch to the first oil outlet A or the second oil outlet B; The pressure control valve 302 is a pilot valve of the first-stage priority valve 301 .

[0025] It can be seen that the first-level priority valve 301 is used for switching control to selectively deliver the hydraulic oil of the main oil inlet P to the first oil outlet A or the second oil outlet B. The pressure control valve 302 serves as a pilot control valve of the first-level priority valve 301 and is used for pilot control of the switching action of the first-level priority valve 301. Figure 2 As shown, both the first-level priority valve 301 and the pressure control valve 302 can adopt the structure of hydraulic control valves to realize the above-mentioned function of the priority valve group 3, that is, to adjust the hydraulic oil pumping direction according to the real-time braking pressure.

[0026] To realize hydraulic pilot control of the primary priority valve 301, the pressure control valve 302 has at least a first valve position and a second valve position and includes: The oil return port T1 and the control connection port L1 are located on the first side of the valve body of the pressure control valve 302 , and the control connection port L1 is hydraulically connected to the control end of the first-level priority valve 301 ; The brake connection port L0 is located at the second side of the valve body of the pressure control valve 302 and is hydraulically connected to the first oil outlet A; In the first valve position, the oil return port T1 is cut off, and the brake connection port L0 is connected to the control connection port L1; in the second valve position, the brake connection port L0 is cut off, and the control connection port L1 is connected to the oil return port T1.

[0027] It can be seen that the pressure control valve 302 is at least a two-position three-way valve as shown in the figure, and of course it can also have more valve positions and oil ports. Among them, in the first valve position, the brake connection port L0 is connected with the control connection port L1, so that the pressure oil of the first oil outlet A is guided to the left control end of the first-level priority valve 301 shown in the figure, so that the first-level priority valve 301 shown in the figure switches to the left valve position, that is, the hydraulic oil of the main oil inlet P is delivered to the first oil outlet A, and the oil supply of the service brake hydraulic circuit is prioritized. In the second valve position of the pressure control valve 302, the control connection port L1 is connected with the return oil port T1, that is, the left control end of the first-level priority valve 301 shown in the figure is relieved, and the first-level priority valve 301 switches to the right valve position, that is, the hydraulic oil of the main oil inlet P is delivered to the second oil outlet B, or the oil is returned through the third oil outlet D to be explained below.

[0028] The pressure control valve 302 may be a solenoid valve to control the control connection port L1 to selectively connect to the brake connection port L0 or the oil return port T1. In this embodiment, the pressure control valve 302 is in the form of a hydraulically controlled valve and includes a first hydraulically controlled end (i.e., the left end of the valve body shown in the figure) provided with a control spring and a second hydraulically controlled end (i.e., the right end of the valve body shown in the figure), and both the first hydraulically controlled end and the second hydraulically controlled end are hydraulically connected to the first oil outlet A.

[0029] Among them, the control spring is used to drive the valve core so that the pressure control valve 302 is located in the first valve position, that is, the pressure control valve 302 can be maintained in the first valve position shown in the figure in the non-working state or the initial state, and the oil pressure at the left control end of the first priority valve 301 can be gradually established. At the same time, the valve core action area of ​​the second hydraulic control end is larger than the valve core action area of ​​the first hydraulic control end. Therefore, even if the first hydraulic control end and the second hydraulic control end are both hydraulically connected to the first oil outlet A, the hydraulic force acting on the valve core by the second hydraulic control end is also larger than the hydraulic force acting on the valve core by the first hydraulic control end. When the oil pressure at the first oil outlet A gradually increases, the difference in hydraulic pressure at both ends of the pressure control valve 302 gradually increases. After the oil pressure at the first oil outlet A is large enough (that is, reaches the above-mentioned set upper threshold value) to overcome the spring force of the control spring, the pressure control valve 302 will be switched from the first valve position to the second valve position, that is, the control connection port L1 is connected to the oil return port T1, so that the first priority valve 301 is switched to the right valve position and no longer supplies oil to the first oil outlet A. Similarly, once the oil pressure of the first oil outlet A drops to the above-mentioned set lower threshold, the difference in liquid pressure at both ends of the pressure control valve 302 is insufficient to overcome the spring force of the control spring, which will cause the pressure control valve 302 to switch from the second valve position to the first valve position, and the oil of the first oil outlet A is guided to the left control end of the first-level priority valve 301, gradually building up pressure, prompting the first-level priority valve 301 to switch to the left valve position, that is, switching to a state where oil is supplied to the first oil outlet A first.

[0030] It should be noted that the parameters such as the size of the control spring provided at the left end of the pressure control valve 302 shown in the figure, the difference between the valve core action area of ​​the second hydraulic control end and the first hydraulic control end, etc. can be tested and adjusted according to the specific application environment and control requirements. Similarly, the set lower threshold and set upper threshold corresponding to the real-time brake pressure of the above-mentioned service brake hydraulic circuit can also be set and adjusted according to the specific working conditions.

[0031] See also Figure 2 The primary priority valve 301 also has at least a left valve position and a right valve position and includes: The oil inlet of the priority valve is connected with the main oil inlet P; A first working oil port A1 and a second working oil port B1, the first working oil port A1 is connected to the first oil outlet A, and the second working oil port B1 is used to connect to the second oil outlet B; Among them, in the left valve position, the priority valve oil inlet is connected to the first working oil port A1 and the second working oil port B1 is cut off, and in the right valve position, the priority valve oil inlet is connected to the second working oil port B1 and the first working oil port A1 is cut off.

[0032] It can be seen that the first-level priority valve 301 is also at least a two-position three-way valve, and of course it can also have more valve positions and oil ports. In the left valve position shown in the figure, the hydraulic oil of the main oil inlet P is delivered to the first working oil port A1, that is, the hydraulic oil is preferentially supplied to the service brake hydraulic circuit. In the right valve position shown in the figure, the hydraulic oil of the main oil inlet P is delivered to the second oil outlet B to supply the chassis control hydraulic circuit, or return oil through the third oil outlet D to be described below.

[0033] In this embodiment, the first-level priority valve 301 is a hydraulically controlled valve controlled by the pressure control valve 302. The first-level priority valve 301 includes a left control end and a right control end provided with a compression spring. The left control end is hydraulically connected to the control connection port L1, and the right control end is hydraulically connected to the first oil outlet A. Figure 2 As shown. Among them, the compression spring can be a weak spring, that is, a spring with a small elastic modulus, so that the first-level priority valve 301 can be in the left valve position in the normal or initial state. In this way, in the normal or initial state, the hydraulic oil of the main oil inlet P is preferentially delivered to the first working oil port A1 through the left valve position of the first-level priority valve 301, that is, the service brake hydraulic circuit is preferentially supplied with oil. The main valve core of the first-level priority valve 301 is controlled by a weak spring, the system pressure loss is lower, and the system is more energy-saving and environmentally friendly.

[0034] In particular, the priority valve group 3 may also have a third oil outlet D and include: The secondary priority valve 304 is used to control the second working oil port B1 to switch to connect to the second oil outlet B or the third oil outlet D; The tractor hydraulic system further includes a chassis lubrication hydraulic oil circuit, which is connected between the third oil outlet D and the hydraulic oil tank 15 .

[0035] See also Figure 1 Through the priority valve group 3, the priority valve group 3 and the chassis control valve group 10 are interconnected, and the tractor's service brake hydraulic circuit, chassis control hydraulic circuit and chassis lubrication hydraulic oil circuit are interconnected, making the system more compact and lower in energy consumption.

[0036] When the first priority valve 301 is switched to the right valve position, the second priority valve 304 can control the hydraulic oil of the main oil inlet P to flow to the second oil outlet B or the third oil outlet D, that is, to flow to the chassis control hydraulic circuit or the chassis lubrication hydraulic circuit.

[0037] In this embodiment, the secondary priority valve 304 also adopts the form of a hydraulically controlled valve. Figure 2 In the secondary priority valve 304 shown, when the feedback pressure of the control oil port C is large and the valve core is switched to the upper valve position, the hydraulic oil of the main oil inlet P flows to the third oil outlet D, and then flows to the hydraulic oil tank 15 through the radiator 12 and the lubrication system 14. Among them, the back pressure valve 13 mainly plays the role of protecting the radiator 12.

[0038] Figure 2 The control port C can be connected to Figure 3 The pressure feedback port Ls of the chassis control valve group 10, that is, the secondary priority valve 304 is a hydraulically controlled valve and is pilot-connected to the LS feedback oil port of the chassis control valve group 10. When the oil pressure of the chassis control hydraulic circuit is sufficient, the hydraulic oil of the main oil inlet P can be controlled to flow to the third oil outlet D and flow back to the hydraulic oil tank 15 through the lubrication system 14.

[0039] in addition, Figure 2 The priority valve group 3 in the embodiment may include, in addition to the primary priority valve 301, the pressure control valve 302 and the secondary priority valve 304, a one-way valve 305 provided at the first working oil port A1 for preventing the oil from the first oil outlet A from flowing back, and a first safety valve 303 for controlling the maximum pressure of the first oil outlet A.

[0040] See also Figure 3As an example, the chassis control valve group 10 may include a brake control valve 1001 and a plurality of clutch control valves connected in parallel, including but not limited to the first clutch control valve 1002 for controlling the first clutch 7, the second clutch control valve 1003 for controlling the second clutch 8, and the third clutch control valve 1004 for controlling the third clutch 9. The hydraulic oil of the priority valve group 3 flows out from the second oil outlet B and flows to each clutch control valve connected in parallel through the oil port Pin and the inlet check valve 1007, wherein the inlet check valve 1007 is used to maintain a certain pressure in the valve group without leakage. The second safety valve 1006 is used to control the maximum value of the oil inlet pressure of the chassis control valve group 10, that is, to ensure that the pressure of the chassis control valve group is within the allowable use range, which plays a protective role. The hydraulic oil of each clutch can return oil through the oil port R. In addition, the oil port P0 of the chassis control valve group 10 can be connected to the second accumulator 11 as an auxiliary pressure source of the control system to ensure sufficient system pressure and flow. The pressure reducing valve 1005 in the chassis control valve group 10 is used to ensure that the outlet pressure of the P4 port meets the clutch operating conditions.

[0041] In addition, the tractor hydraulic system of this embodiment further includes a main pump 1 for pumping hydraulic oil to the priority valve group 3. It can be seen that the service brake hydraulic circuit and the chassis control hydraulic circuit, which are interconnected through the priority valve group 3, share the main pump 1, so that the main pump can be used with maximum efficiency, energy consumption can be improved, and the number of pumps can be reduced. In other words, the chassis control valve group 10 and the brake valve 5 share a pressure source, which can achieve reliable chassis fluid system control, including brake and clutch control, reduce pipeline layout, and make the system more compact.

[0042] Specifically, see Figures 1 to 3 , the hydraulic oil is sucked out from the hydraulic oil tank 15 by the main pump 1, and enters the oil inlet of the priority valve group 3 after passing through the filter 2, giving priority to ensuring that the service brake hydraulic circuit has sufficient oil, and can enter the chassis control valve group 10 only after the brake oil is sufficient. When the pressure of the chassis control valve group 10 rises to the set pressure, the secondary priority valve 304 in the priority valve group 3 can be controlled to bypass and unload through the pressure feedback port Ls, and the unloaded oil returns to the hydraulic oil tank 15 after passing through the radiator 12 and the lubrication system 14.

[0043] After the main pump 1 works, it first ensures that the service brake pressure is sufficient before releasing the parking brake. The service brake can be realized by controlling the on and off of the brake valve 5. The first accumulator 4 is used as a reserve pressure source for the brake system. It is connected to the inlet of the brake valve 5 to ensure that the brake system uses oil while achieving multiple braking. The left and right brake chambers of the brake 6 are respectively connected to the pressure oil of the service brake and the parking brake. The parking brake is released after the right chamber is filled with oil, and the service brake is controlled by the left chamber filled with oil.

[0044] See also Figure 2The priority valve group 3, the oil enters from the P port, and after the pressure oil passes through the first-level priority valve 301 and the one-way valve 305, it is prioritized to ensure that the oil flows out from the A port. When the pressure at the A port increases to the set upper threshold value P1, the pressure control valve 302 controls the left chamber of the first-level priority valve 301 to control the oil to communicate with the T1 port and unload, causing the first-level priority valve 301 to switch to the right position as shown in the figure, at this time, the P port is connected to the B port; when the C port control pressure reaches a larger set value P3, the second-level priority valve 304 switches to the lower position as shown in the figure, at this time, the P port is connected to the D port.

[0045] The initial position of the first-level priority valve 301 is as follows: Figure 2 As shown, the left spring is a weak spring, which only ensures the initial position of the valve core in the initial state as shown in the figure. The left and right sides of the pressure control valve 302 have different force areas. When the brake system pressure (i.e., the pressure at port A) increases to the set upper threshold value P1, the valve core of the pressure control valve 302 moves left and switches to the right valve position, so that the left control pressure of the first-level priority valve 301 is unloaded. At this time, the system pressure only needs to overcome the spring force and F 右 >F 弹簧 ; When the pressure at port A drops to the set lower threshold value P2, F 右 <F 弹簧 , the pressure control valve 302 returns to the initial left position shown in the figure, and the first-level priority valve 301 is pushed to the left position shown in the figure under the action of hydraulic pressure; when the system pressure rises to the set upper threshold value P1, the above actions are repeated.

[0046] The initial state of the secondary priority valve 304 is the state shown in the figure, which is connected to the remote control source through port C. When the pressure of port C is P3, the secondary priority valve 304 connects port P with port D. Among them, the one-way valve 305 mainly plays a role in maintaining pressure, and the first safety valve 303 is mainly used to prevent the system from exceeding the rated working pressure and plays a protective role.

[0047] exist Figure 3 In the chassis control valve group 10, the first clutch 7 can be a differential lock clutch, the second clutch 8 can be a PTO clutch, and the third clutch 9 can be a four-wheel drive clutch. The brake control valve 1001 is an electromagnetic switch valve, which controls the on and off of the pressure oil at the P1 port in the chassis control valve group 10 by the electromagnets at both ends of the relay. The first clutch control valve 1002 is a normally open electromagnetic switch valve, and the initial state is as follows Figure 3 As shown, after the electromagnet is energized, pressure oil flows out of the P2 port. The second clutch control valve 1003 is a pressure-controlled electric proportional valve. In the initial state, no pressure oil flows out of the P3 port. The output pressure control is achieved by controlling the input flow of the proportional valve. The third clutch control valve 1004 is an electromagnetic switch valve. In the initial state, no pressure oil flows out of the P4 port. After the electromagnet is energized, pressure oil flows out of the P4 port.

[0048] Alternatively, the priority valve group 3 may also be electrically controlled, that is, include an electrically controlled pressure switch valve, the service brake hydraulic circuit is provided with a pressure sensor for detecting the real-time brake pressure (i.e., the oil pressure of the first oil outlet A), and the tractor hydraulic system includes a controller (not shown), which is configured to switch and control the electrically controlled pressure switch valve according to the real-time brake pressure detected by the pressure sensor. It can be understood by those skilled in the art that the priority valve group 3 may also achieve the purpose of the present application in the form of an electrically controlled valve.

[0049] In addition, the present application also protects a tractor, which includes a tractor hydraulic system according to the present application. In the tractor of the present application, the interconnection of the tractor chassis brake system, clutch control system and lubrication system is realized through the interconnection of the priority valve group and the chassis control valve group. The system is compact and has low energy consumption. After the system has the priority to ensure the driving braking capability, the parking brake is activated, which makes the driving process safer and more reliable. Moreover, the system structure is more compact, the pipeline layout of the whole vehicle system is simplified, and the energy loss of the system is also reduced.

[0050] In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0051] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0052] 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 present application. 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 may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0053] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A tractor hydraulic system, characterized in that: The tractor hydraulic system comprises: A service brake hydraulic circuit, comprising a brake valve (5) for controlling a brake (6); A chassis control hydraulic circuit, comprising a chassis control valve group (10); The priority valve group (3) is used to, when the real-time brake pressure of the service brake hydraulic circuit is not higher than a set lower threshold value, cause the hydraulic oil pumped through the priority valve group (3) to be delivered to the brake valve (5), and when the real-time brake pressure is not lower than a set upper threshold value, cause the hydraulic oil to be switched to be pumped to the chassis control valve group (10) or return oil.

2. The tractor hydraulic system according to claim 1, characterized in that: The priority valve group (3) has a main oil inlet (P), a first oil outlet (A) and a second oil outlet (B) and comprises: The first-level priority valve (301) is a hydraulically controlled valve and is used to control the main oil inlet (P) to switch and connect to the first oil outlet (A) or the second oil outlet (B); The pressure control valve (302) is a pilot valve of the first-level priority valve (301).

3. The tractor hydraulic system according to claim 2, characterized in that: The pressure control valve (302) has at least a first valve position and a second valve position and comprises: An oil return port (T1) and a control connection port (L1) are located on a first side of a valve body of the pressure control valve (302), and the control connection port (L1) is hydraulically connected to a control end of the first-level priority valve (301); A brake connection port (L0), located on a second side of the valve body of the pressure control valve (302) and hydraulically connected to the first oil outlet (A); Wherein, in the first valve position, the oil return port (T1) is cut off, and the brake connection port (L0) is connected to the control connection port (L1); in the second valve position, the brake connection port (L0) is cut off, and the control connection port (L1) is connected to the oil return port (T1).

4. The tractor hydraulic system according to claim 3, characterized in that: The pressure control valve (302) is a hydraulically controlled valve and comprises a first hydraulically controlled end and a second hydraulically controlled end provided with a control spring, wherein the first hydraulically controlled end and the second hydraulically controlled end are both hydraulically connected to the first oil outlet (A); The control spring is used to drive the valve core so that the pressure control valve (302) is located at the first valve position, and the valve core action area of ​​the second hydraulic control end is larger than the valve core action area of ​​the first hydraulic control end.

5. The tractor hydraulic system according to claim 3 or 4, characterized in that: The first-level priority valve (301) has at least a left valve position and a right valve position and comprises: a priority valve oil inlet port, connected to the main oil inlet port (P); A first working oil port (A1) and a second working oil port (B1), wherein the first working oil port (A1) is connected to the first oil outlet (A), and the second working oil port (B1) is used to connect to the second oil outlet (B); Wherein, in the left valve position, the priority valve oil inlet is connected to the first working oil port (A1) and the second working oil port (B1) is blocked, and in the right valve position, the priority valve oil inlet is connected to the second working oil port (B1) and the first working oil port (A1) is blocked.

6. The tractor hydraulic system according to claim 5, characterized in that: The first-level priority valve (301) is a hydraulically controlled valve and comprises a left control end and a right control end provided with a compression spring, the left control end being hydraulically connected to the control connection port (L1), and the right control end being hydraulically connected to the first oil outlet (A).

7. The tractor hydraulic system according to claim 5, characterized in that: The priority valve assembly (3) also has a third oil outlet (D) and comprises: A secondary priority valve (304), used for controlling the second working oil port (B1) to switch and connect to the second oil outlet (B) or the third oil outlet (D); The tractor hydraulic system further comprises a chassis lubrication hydraulic oil circuit, wherein the chassis lubrication hydraulic oil circuit is connected between the third oil outlet (D) and the hydraulic oil tank (15).

8. The tractor hydraulic system according to claim 7, characterized in that: The secondary priority valve (304) is a hydraulically controlled valve and is pilot-connected to the LS feedback oil port of the chassis control valve group (10); And / or, a one-way valve (305) is provided at the first working oil port (A1) for preventing oil from flowing back from the first oil outlet (A); And / or, the chassis control valve group (10) comprises a brake control valve (1001) and a plurality of clutch control valves connected in parallel with each other.

9. The tractor hydraulic system according to claim 1, characterized in that: The tractor hydraulic system also includes: The main pump (1) is used to pump hydraulic oil to the priority valve group (3).

10. The tractor hydraulic system according to claim 1, characterized in that: The priority valve group (3) comprises an electrically controlled pressure switch valve, the service brake hydraulic circuit is provided with a pressure sensor for detecting real-time brake pressure, and the tractor hydraulic system comprises a controller, wherein the controller is configured to switch and control the electrically controlled pressure switch valve according to the real-time brake pressure detected by the pressure sensor.

11. A tractor, characterized in that: The tractor comprises a tractor hydraulic system according to any one of claims 1 to 10.

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