Electro-hydraulic control HST hydraulic system of tractor

Abstract

The utility model provides a tractor electro-hydraulic control HST hydraulic system which comprises an oil supplementing pump, a walking pump and a walking motor, and the walking pump and the walking motor are in loop connection through a pipeline. An oil supplementing branch and a control branch are arranged at an outlet of the oil supplementing pump; the oil supplementing branch is connected with a first one-way valve and a second one-way valve through branches, an outlet of the first one-way valve is connected with one end of the walking motor, and an outlet of the second one-way valve is connected with the other end of the walking motor. The control branch is connected with an electromagnetic reversing valve, the electromagnetic reversing valve is connected with a plunger mechanism, and the output end of the plunger mechanism is connected with a control switch of the walking pump. According to the utility model, the oil replenishing pump supplies oil to the control branch, and the electromagnetic directional valve controls the output direction of the oil, so that the output end of the plunger mechanism is controlled to continuously move; the control switch for controlling the walking pump realizes advancing and retreating state control and continuous speed control of the HST system; and the operation convenience is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of tractor HST systems, in particular to an electro-hydraulic controlled HST hydraulic system for a tractor. Background Art

[0002] The HST system is a hydraulically driven travel system for tractors. The hydraulic pump delivers pressure oil to the hydraulic motor, which drives the wheels to travel. The forward and reverse rotation of the hydraulic pump determines the direction of its own pressure oil output, which in turn determines the direction of rotation of the output shaft of the hydraulic motor, thus enabling the tractor to travel and reverse.

[0003] As the application field of tractors expands, users have higher requirements for the speed control of the whole machine, not only to achieve continuous speed control, but also to make the operation more convenient and comfortable. At present, the commonly used HST system on the market can only control the forward and reverse rotation of the travel hydraulic motor, but cannot accurately control the speed. Therefore, its speed control depends on the gear shifting mechanism at the output end of the travel hydraulic motor, which has poor continuity of speed control and inconvenient operation. Utility Model Content

[0004] The technical problem to be solved by the utility model is: how to realize the speed continuity control of the HST system and improve the convenience of operation.

[0005] The technical solution of the utility model to solve the above technical problems is as follows:

[0006] The utility model provides an electro-hydraulic controlled HST hydraulic system for a tractor, comprising an oil replenishment pump, a travel pump and a travel motor, wherein the travel pump and the travel motor are connected to form a loop through a pipeline; an oil replenishment branch and a control branch are arranged at the outlet of the oil replenishment pump; the oil replenishment branch is respectively connected to a first check valve and a second check valve through branches, the outlet of the first check valve is connected to one end of the travel motor, and the outlet of the second check valve is connected to the other end of the travel motor; the control branch is connected to an electromagnetic reversing valve, the electromagnetic reversing valve is connected to a plunger mechanism, and the output end of the plunger mechanism is connected to a control switch of the travel pump.

[0007] The beneficial effects of the utility model are:

[0008] By adopting the utility model, the original oil replenishment pump is used to supply oil to the control branch, and the oil output direction is controlled by the electromagnetic reversing valve, so as to control the continuous movement of the output end of the plunger mechanism; the control switch of the travel pump is controlled by the output end of the plunger mechanism, so as to realize the forward and backward state control and the continuous speed control of the HST system; the speed accuracy is high, the impact feeling is reduced, and the comfort is good; when operating, it is only necessary to electrically control the working state of the electromagnetic reversing valve, so as to improve the convenience of operation.

[0009] On the basis of the above technical solution, the present invention can also be improved as follows.

[0010] Further, the plunger mechanism includes a reversing plunger, a servo reversing valve and a variable plunger, the plunger rod of the reversing plunger is connected to the control end of the servo reversing valve, the first interface of the servo reversing valve is connected to the left chamber of the variable plunger, the second interface of the servo reversing valve is connected to the right chamber of the variable plunger, and the plunger rod of the variable plunger is connected to the control switch of the travel pump;

[0011] The control branch is also connected to the pressure oil port of the servo reversing valve and the pressure oil port of the electromagnetic reversing valve through branches; the first interface of the electromagnetic reversing valve is connected to the left chamber of the reversing plunger, and the second interface of the electromagnetic reversing valve is connected to the right chamber of the reversing plunger.

[0012] The movement of the reversing plunger is controlled by the electromagnetic reversing valve, the reversing plunger controls the switching state of the servo reversing valve, the servo reversing valve controls the movement of the variable plunger, and the variable plunger controls the forward or backward movement of the travel pump, thereby realizing the forward and backward state control and continuous speed control of the travel pump; the movement amplitude of the control end of the servo reversing valve is controlled by the reversing plunger, which is convenient for controlling the opening of the servo reversing valve, and then controlling the oil pressure entering the variable plunger; the oil pressure of the variable plunger is balanced with the reset elastic force of the travel pump, which is convenient for stably controlling the toggle amplitude of the variable plunger on the control switch of the travel pump, thereby accurately controlling the speed of the travel pump.

[0013] Furthermore, the valve core of the solenoid reversing valve is provided with a left position, a middle position and a right position. When working in the right position, the pressure oil port of the solenoid reversing valve is connected with the first interface, and the return oil port is connected with the second interface; when working in the middle position, the pressure oil port, the return oil port, the first interface and the second interface of the solenoid reversing valve are all closed; when working in the right position, the pressure oil port of the solenoid reversing valve is connected with the second interface, and the return oil port is connected with the first interface.

[0014] By switching the working position of the electromagnetic reversing valve, the oil in the control branch enters the left chamber of the reversing plunger from the first interface or enters the right chamber of the reversing plunger from the second interface; when the electromagnetic reversing valve works in the middle position, the reversing plunger can maintain its position; it is convenient to dynamically control the movement position of the reversing plunger, with high control accuracy and easy operation.

[0015] Furthermore, the valve core of the servo reversing valve is provided with a left position, a middle position and a right position. When the right position is working, the pressure oil port of the servo reversing valve is connected with the first interface, and the return oil port is connected with the second interface; when the middle position is working, the pressure oil port, the return oil port, the first interface and the second interface of the servo reversing valve are all closed; when the right position is working, the pressure oil port of the servo reversing valve is connected with the second interface, and the return oil port is connected with the first interface.

[0016] By switching the working position of the servo reversing valve, the oil in the control branch can flow out from the first interface or the second interface; when the servo reversing valve works in the middle position, the variable plunger can maintain its position; it is convenient to dynamically control the movement position of the variable plunger, with high control accuracy and easy operation.

[0017] Furthermore, a spring is provided in the left cavity and the right cavity of the reversing plunger respectively, one end of the spring abuts against the cylinder body of the reversing plunger, and the other end abuts against the piston of the reversing plunger.

[0018] When the oil charge pump is not working, the electromagnetic reversing valve can be switched to the left or right position at will, and the piston of the reversing plunger can be pushed back to its original position by the spring.

[0019] Furthermore, it also includes an oil tank, and the inlet of the oil replenishment pump, the oil return port of the electromagnetic reversing valve and the oil return port of the servo reversing valve are respectively connected to the oil tank.

[0020] It is convenient for oil recycling and reduces costs.

[0021] Furthermore, a filter is provided on the branch from the control branch to the electromagnetic reversing valve.

[0022] The cleanliness of the oil entering the electromagnetic reversing valve is ensured to avoid clogging of the electromagnetic reversing valve.

[0023] Furthermore, the outlet of the oil replenishment pump is also provided with a relief valve, and the outlet of the relief valve is connected to the oil tank.

[0024] During operation, the oil replenishment pump works continuously, and part of the oil overflows continuously through the overflow valve, which is convenient for ensuring that the oil and oil pressure in the circuits of the travel pump and the travel motor are sufficient and reliable; at the same time, it avoids excessive pressure on the outlet pipeline of the oil replenishment pump and improves safety.

[0025] Furthermore, it also includes a first overload oil replenishing valve, the inlet of the first overload oil replenishing valve is connected to the outlet of the first one-way valve, and the outlet of the first overload oil replenishing valve is connected to the inlet of the first one-way valve.

[0026] The first overload oil replenishing valve is connected in parallel with the first one-way valve. When the travel pump operates at high speed and the pressure on the outlet side of the first one-way valve is too high, part of the oil can overflow through the first overload oil replenishing valve, which is convenient for protecting the hydraulic pipeline and improving safety.

[0027] Furthermore, it also includes a second overload oil replenishing valve, the inlet of the second overload oil replenishing valve is connected to the outlet of the second one-way valve, and the outlet of the second overload oil replenishing valve is connected to the inlet of the second one-way valve.

[0028] The second overload oil replenishing valve is connected in parallel with the second one-way valve. When the travel pump operates at high speed and the pressure on the outlet side of the second one-way valve is too high, part of the oil can overflow through the second overload oil replenishing valve, which is convenient for protecting the hydraulic pipeline and improving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the utility model in the oil replenishing state.

[0030] Figure 2 It is a structural schematic diagram of the utility model in the forward state.

[0031] Figure 3 It is a structural schematic diagram of the utility model in the backward state.

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

[0033] 1- oil replenishment pump; 2- travel pump; 3- travel motor; 4- first one-way valve; 5- second one-way valve; 6- electromagnetic reversing valve; 7- reversing plunger; 8- servo reversing valve; 9- variable plunger; 10- spring; 11- oil tank; 12- filter; 13- overflow valve; 14- first overload oil replenishment valve; 15- second overload oil replenishment valve. 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 1-3 ,In addition to the component symbols in the figure, the arrows indicate the direction of oil flow.

[0036] The utility model provides an electro-hydraulic controlled HST hydraulic system for a tractor, comprising an oil replenishment pump 1, a travel pump 2, and a travel motor 3, wherein the travel pump 2 and the travel motor 3 are connected to form a loop through a pipeline; an outlet of the oil replenishment pump 1 is provided with an oil replenishment branch and a control branch; the oil replenishment branch is respectively connected to a first non-return valve 4 and a second non-return valve 5 through branches, the outlet of the first non-return valve 4 is connected to one end of the travel motor 3, and the outlet of the second non-return valve 5 is connected to the other end of the travel motor 3; the control branch is connected to an electromagnetic reversing valve 6, the electromagnetic reversing valve 6 is connected to a plunger mechanism, and the output end of the plunger mechanism is connected to a control switch of the travel pump 2.

[0037] principle:

[0038] The travel pump 2 is a prior art product, and its control switch is a button or handle that can be toggled in both directions. When it is toggled forward, the travel pump 2 rotates forward; when it is toggled backward, the travel pump 2 rotates reversely. The toggling amplitude determines the output displacement of the travel pump 2, and the output displacement determines the horsepower and speed of the travel motor 3. In the existing tractor, the operating handle is connected to the control switch of the travel pump 2 through a connecting rod mechanism, and the operator toggles the operating handle to control the tractor to move forward and backward. The electromagnetic reversing valve 6 is a prior art product. In addition to the pressure oil port and the return oil port, it has at least two interfaces. The valve core movement of the electromagnetic reversing valve 6 can control the output direction of the hydraulic oil, and the output direction of the hydraulic oil determines the movement direction of the plunger. In the plunger mechanism, the plunger is the name of a prior art product, and the structure includes a cylinder body and a piston. The piston is provided with a plunger rod, and the plunger rod extends out of the cylinder body and serves as an output end; the plunger rod is connected to the control switch of the travel pump 2 through a mechanical structure, and the movement position of the plunger rod determines the toggling amplitude and toggling direction of the control switch.

[0039] The working process of the utility model is as follows:

[0040] In the oil replenishment state, if Figure 1 As shown: the oil of the oil replenishment pump 1 enters the oil replenishment branch; through the first check valve 4 and / or the second check valve 5, the oil is replenished to the circuit of the travel pump 2 and the travel motor 3 to ensure that the oil volume and oil pressure in the circuit are sufficient. When moving forward and backward, the oil replenishment pump 1 maintains the oil replenishment pressure and can continuously replenish oil to the low-pressure side of the circuit through this path. At the same time, the oil of the oil replenishment pump 1 enters the control branch to control the forward and backward status of the tractor.

[0041] In the forward state, Figure 2 As shown: the electromagnetic reversing valve 6 switches to the first working position, and the oil in the control branch enters the left chamber of the plunger mechanism from the electromagnetic reversing valve 6 (taking the left chamber filled with oil corresponding to the forward movement as an example), and at the same time, the oil in the right chamber of the plunger returns from the electromagnetic reversing valve 6; the oil pushes the output end of the plunger mechanism to move right, and the output end switches the control switch of the travel pump 2 to the forward state. When deceleration is required, the electromagnetic reversing valve 6 can refer to the backward state to move the output end of the plunger mechanism to the left, reducing the control switch switching amplitude of the travel pump 2. When the required speed is reached, the electromagnetic reversing valve 6 switches back to the middle position, and the output end of the plunger mechanism maintains the position, thereby maintaining the control switch switching amplitude of the travel pump 2.

[0042] In the backward state, Figure 3As shown: the electromagnetic reversing valve 6 switches to the second working position, and the oil in the control branch enters the right chamber of the plunger mechanism from the electromagnetic reversing valve 6, while the oil in the left chamber of the plunger returns from the electromagnetic reversing valve 6; the oil pushes the output end of the plunger mechanism to move left, and the output end switches the control switch of the travel pump 2 to the backward state. When deceleration is required, the electromagnetic reversing valve 6 can refer to the forward state to move the output end of the plunger mechanism to the right, reducing the control switch switching amplitude of the travel pump 2. When the required speed is reached, the electromagnetic reversing valve 6 switches back to the middle position, and the output end of the plunger mechanism maintains the position, thereby maintaining the control switch switching amplitude of the travel pump 2.

[0043] In summary, the utility model is adopted to utilize the original oil replenishment pump 1 to provide oil to the control branch, and the oil output direction is controlled by the electromagnetic reversing valve 6, so as to control the continuous movement of the output end of the plunger mechanism; the control switch of the travel pump 2 is controlled by the output end of the plunger mechanism, so as to realize the forward and backward state control and the continuous speed control of the HST system; the speed accuracy is high, the impact feeling is reduced, and the comfort is good; when operating, it is only necessary to electronically control the working state of the electromagnetic reversing valve 6, which improves the convenience of operation.

[0044] Further, the plunger mechanism includes a reversing plunger 7, a servo reversing valve 8 and a variable plunger 9, the plunger rod of the reversing plunger 7 is connected to the control end of the servo reversing valve 8, the first interface of the servo reversing valve 8 is connected to the left chamber of the variable plunger 9, the second interface of the servo reversing valve 8 is connected to the right chamber of the variable plunger 9, and the plunger rod of the variable plunger 9 is connected to the control switch of the travel pump 2;

[0045] The control branch is also connected to the pressure oil port of the servo reversing valve 8 and the pressure oil port of the electromagnetic reversing valve 6 through branches; the first interface of the electromagnetic reversing valve 6 is connected to the left chamber of the reversing plunger 7, and the second interface of the electromagnetic reversing valve 6 is connected to the right chamber of the reversing plunger 7.

[0046] Note: The servo reversing valve 8 is a reversing valve, which is a prior art; the reversing valve switches the working position by the axial movement of the valve core relative to the cylinder barrel. Therefore, when the valve core is fixedly installed, the cylinder barrel is its control end; when the cylinder barrel is fixedly installed, the valve core is its control end.

[0047] In the forward state, the first interface of the electromagnetic reversing valve 6 outputs oil to the left chamber of the reversing plunger 7, and the right chamber of the reversing plunger 7 returns oil from the electromagnetic reversing valve 6; the oil pushes the plunger rod of the reversing plunger 7 to move right, and the plunger rod of the reversing plunger 7 drives the control end of the servo reversing valve 8 to move right, so that the servo reversing valve 8 switches the working position; the first interface of the servo reversing valve 8 outputs oil to the left chamber of the variable plunger 9, and the right chamber of the variable plunger 9 returns oil through the servo reversing valve 8; the oil pushes the plunger rod of the variable plunger 9 to move right, and the plunger rod of the variable plunger 9 serves as the output end to turn the travel pump 2 control switch to the forward state.

[0048] In the backward state, the second interface of the electromagnetic reversing valve 6 outputs oil to the right chamber of the reversing plunger 7, and the left chamber of the reversing plunger 7 returns oil from the electromagnetic reversing valve 6; the oil pushes the plunger rod of the reversing plunger 7 to move left, and the plunger rod of the reversing plunger 7 drives the control end of the servo reversing valve 8 to move left, so that the servo reversing valve 8 switches the working position; the second interface of the servo reversing valve 8 outputs oil to the right chamber of the variable plunger 9, and the left chamber of the variable plunger 9 returns oil through the servo reversing valve 8; the oil pushes the plunger rod of the variable plunger 9 to move left, and the plunger rod of the variable plunger 9 serves as the output end to turn the travel pump 2 control switch to the backward state.

[0049] The movement of the reversing plunger 7 is controlled by the electromagnetic reversing valve 6, the reversing plunger 7 controls the switching state of the servo reversing valve 8, the servo reversing valve 8 controls the movement of the variable plunger 9, and the variable plunger 9 controls the forward or backward movement of the walking pump 2, thereby realizing the forward and backward state control and continuous speed control of the walking pump 2; the movement amplitude of the control end of the servo reversing valve 8 is controlled by the reversing plunger 7, so as to control the opening of the servo reversing valve 8, and then control the oil pressure entering the variable plunger 9; the oil pressure of the variable plunger 9 is balanced with the reset elastic force of the walking pump 2, so as to stably control the amplitude of the variable plunger 9 to move the control switch of the walking pump 2, thereby accurately controlling the rotation speed of the walking pump 2.

[0050] Furthermore, the valve core of the solenoid reversing valve 6 is provided with a left position, a middle position and a right position. When working in the right position, the pressure oil port of the solenoid reversing valve 6 is connected with the first interface, and the return oil port is connected with the second interface; when working in the middle position, the pressure oil port, the return oil port, the first interface and the second interface of the solenoid reversing valve 6 are all closed; when working in the right position, the pressure oil port of the solenoid reversing valve 6 is connected with the second interface, and the return oil port is connected with the first interface.

[0051] Note: The valve core of the reversing valve moves relative to the cylinder barrel, which can move any workstation to the interface position of the cylinder barrel, so that the workstation works.

[0052] By switching the working position of the electromagnetic reversing valve 6, the oil in the control branch enters the left chamber of the reversing plunger 7 from the first interface or enters the right chamber of the reversing plunger 7 from the second interface; when the electromagnetic reversing valve 6 works in the middle position, the reversing plunger 7 can maintain its position; it is convenient to dynamically control the movement position of the reversing plunger 7, with high control accuracy and easy operation.

[0053] Furthermore, the valve core of the servo reversing valve 8 is provided with a left position, a middle position and a right position. When the right position is working, the pressure oil port of the servo reversing valve 8 is connected with the first interface, and the return oil port is connected with the second interface; when the middle position is working, the pressure oil port, the return oil port, the first interface and the second interface of the servo reversing valve 8 are all closed; when the right position is working, the pressure oil port of the servo reversing valve 8 is connected with the second interface, and the return oil port is connected with the first interface.

[0054] By switching the working position of the servo reversing valve 8, the oil in the control branch can flow out from the first interface or the second interface; when the servo reversing valve 8 works in the middle position, the variable plunger 9 can maintain its position; it is convenient to dynamically control the movement position of the variable plunger 9, with high control accuracy and easy operation.

[0055] Furthermore, a spring 10 is provided in the left cavity and the right cavity of the reversing plunger 7 , respectively. One end of the spring 10 abuts against the cylinder body of the reversing plunger 7 , and the other end abuts against the piston of the reversing plunger 7 .

[0056] Note: The cylinder and piston structure of the reversing plunger 7 is the prior art. The variable plunger 9 can be reset by means of the reset elastic force of the travel pump 2; in addition, the variable plunger 9 can also adopt the same structure as the reversing plunger 7, that is, springs 10 are respectively provided in the left cavity and the right cavity, one end of the spring 10 abuts against the cylinder of the variable plunger 9, and the other end abuts against the piston of the variable plunger 9.

[0057] When the oil replenishment pump 1 is not working, the electromagnetic reversing valve 6 is switched to the left position or the right position at will, and the piston of the reversing plunger 7 can be pushed to reset by the spring 10.

[0058] Furthermore, it also includes an oil tank 11, and the inlet of the oil replenishment pump 1, the oil return port of the electromagnetic reversing valve 6 and the oil return port of the servo reversing valve 8 are respectively connected to the oil tank 11.

[0059] It is convenient for oil recycling and reduces costs.

[0060] Furthermore, a filter 12 is provided on the branch from the control branch to the electromagnetic reversing valve 6 .

[0061] The cleanliness of the oil entering the electromagnetic reversing valve 6 is ensured, and the electromagnetic reversing valve 6 is prevented from being blocked.

[0062] Furthermore, a relief valve 13 is provided at the outlet of the oil replenishment pump 1 , and the outlet of the relief valve 13 is connected to the oil tank 11 .

[0063] During operation, the oil replenishment pump 1 works continuously, and part of the oil continues to overflow through the overflow valve 13, so as to ensure that the oil and oil pressure in the circuits of the travel pump 2 and the travel motor 3 are sufficient and have good reliability; at the same time, excessive pressure on the outlet pipeline of the oil replenishment pump 1 is avoided, thereby improving safety.

[0064] Furthermore, it also includes a first overload oil replenishing valve 14 , the inlet of the first overload oil replenishing valve 14 is connected to the outlet of the first one-way valve 4 , and the outlet of the first overload oil replenishing valve 14 is connected to the inlet of the first one-way valve 4 .

[0065] The first overload oil replenishing valve 14 is connected in parallel with the first one-way valve 4. When the travel pump 2 operates at a high speed and the outlet pressure of the first one-way valve 4 is too high, part of the oil can overflow through the first overload oil replenishing valve 14, which is convenient for protecting the hydraulic pipeline and improving safety.

[0066] Furthermore, it also includes a second overload oil replenishing valve 15 , the inlet of the second overload oil replenishing valve 15 is connected to the outlet of the second one-way valve 5 , and the outlet of the second overload oil replenishing valve 15 is connected to the inlet of the second one-way valve 5 .

[0067] The second overload oil replenishing valve 15 is connected in parallel with the second one-way valve 5. When the travel pump 2 operates at a high speed and the outlet pressure of the second one-way valve 5 is too high, part of the oil can overflow through the second overload oil replenishing valve 15, which is convenient for protecting the hydraulic pipeline and improving safety.

[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 electro-hydraulic controlled HST hydraulic system, characterized by: The invention comprises an oil replenishment pump (1), a travel pump (2), and a travel motor (3), wherein the travel pump (2) and the travel motor (3) are connected to form a loop through a pipeline; the outlet of the oil replenishment pump (1) is provided with an oil replenishment branch and a control branch; the oil replenishment branch is respectively connected to a first one-way valve (4) and a second one-way valve (5) through branches, the outlet of the first one-way valve (4) is connected to one end of the travel motor (3), and the outlet of the second one-way valve (5) is connected to the other end of the travel motor (3); the control branch is connected to an electromagnetic reversing valve (6), the electromagnetic reversing valve (6) is connected to a plunger mechanism, and the output end of the plunger mechanism is connected to the control switch of the travel pump (2).

2. The tractor electro-hydraulic control HST hydraulic system according to claim 1, characterized in that: The plunger mechanism comprises a reversing plunger (7), a servo reversing valve (8) and a variable plunger (9); the plunger rod of the reversing plunger (7) is connected to the control end of the servo reversing valve (8); the first interface of the servo reversing valve (8) is connected to the left chamber of the variable plunger (9); the second interface of the servo reversing valve (8) is connected to the right chamber of the variable plunger (9); and the plunger rod of the variable plunger (9) is connected to the control switch of the travel pump (2); The control branch is also connected to the pressure oil port of the servo reversing valve (8) and the pressure oil port of the electromagnetic reversing valve (6) through branches; the first interface of the electromagnetic reversing valve (6) is connected to the left chamber of the reversing plunger (7), and the second interface of the electromagnetic reversing valve (6) is connected to the right chamber of the reversing plunger (7).

3. The tractor electro-hydraulic control HST hydraulic system according to claim 2, characterized in that: The valve core of the electromagnetic reversing valve (6) is provided with a left position, a middle position and a right position. When the electromagnetic reversing valve (6) is in operation in the right position, the pressure oil port of the electromagnetic reversing valve (6) is communicated with the first interface, and the return oil port is communicated with the second interface; when the electromagnetic reversing valve (6) is in operation in the middle position, the pressure oil port, the return oil port, the first interface and the second interface are all closed; when the electromagnetic reversing valve (6) is in operation in the right position, the pressure oil port of the electromagnetic reversing valve (6) is communicated with the second interface, and the return oil port is communicated with the first interface.

4. The tractor electro-hydraulic control HST hydraulic system according to claim 2, characterized in that: The valve core of the servo reversing valve (8) is provided with a left position, a middle position and a right position. When the right position is working, the pressure oil port of the servo reversing valve (8) is connected to the first interface, and the return oil port is connected to the second interface; when the middle position is working, the pressure oil port, the return oil port, the first interface and the second interface of the servo reversing valve (8) are all closed; when the right position is working, the pressure oil port of the servo reversing valve (8) is connected to the second interface, and the return oil port is connected to the first interface.

5. The tractor electro-hydraulic control HST hydraulic system according to claim 2, characterized in that: A spring (10) is provided in the left cavity and the right cavity of the reversing plunger (7), respectively. One end of the spring (10) abuts against the cylinder body of the reversing plunger (7), and the other end abuts against the piston of the reversing plunger (7).

6. The tractor electro-hydraulic control HST hydraulic system according to claim 2, characterized in that: It also comprises an oil tank (11), and the inlet of the oil replenishment pump (1), the oil return port of the electromagnetic reversing valve (6) and the oil return port of the servo reversing valve (8) are respectively connected to the oil tank (11).

7. The tractor electro-hydraulic control HST hydraulic system according to claim 2, characterized in that: A filter (12) is also provided on the branch from the control branch to the electromagnetic reversing valve (6).

8. The tractor electro-hydraulic control HST hydraulic system according to claim 1, characterized in that: The outlet of the oil replenishment pump (1) is also provided with a relief valve (13), and the outlet of the relief valve (13) is connected to the oil tank (11).

9. The tractor electro-hydraulic control HST hydraulic system according to claim 1, characterized in that: It also comprises a first overload oil replenishing valve (14), the inlet of the first overload oil replenishing valve (14) is connected to the outlet of the first one-way valve (4), and the outlet of the first overload oil replenishing valve (14) is connected to the inlet of the first one-way valve (4).

10. The tractor electro-hydraulic control HST hydraulic system according to claim 9, characterized in that: It also comprises a second overload oil replenishing valve (15), the inlet of the second overload oil replenishing valve (15) is connected to the outlet of the second one-way valve (5), and the outlet of the second overload oil replenishing valve (15) is connected to the inlet of the second one-way valve (5).

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