Tractor HST Automatic Adjustable Hydraulic Control System

Abstract

This invention relates to the field of hydraulic control system technology, specifically the HST automatic adjustment hydraulic control system for tractors. It includes a hydraulic pump, a hydraulic motor, a first spool valve, and a second spool valve. The hydraulic pump's two outlets are connected to the hydraulic motor via oil supply lines. Both outlets are also connected to a high-pressure oil circuit. A first shuttle valve is connected to this high-pressure oil circuit, and its outlet is connected to the left valve ports of both the first and second spool valves. A low-pressure oil circuit connects the two oil supply lines, and a second shuttle valve is connected to this low-pressure oil circuit. The outlet of the second shuttle valve is connected to the right valve port of the first spool valve. This invention solves the problems of traditional devices that can only be electrically controlled and cannot achieve automatic adjustment, have low intelligence, low operating efficiency, increased power loss, reduced hydraulic pump variable stability, poor comfort, complex operation, and wasted power.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic control system technology, specifically to the HST automatic adjustment hydraulic control system for tractors. Background Technology

[0002] The HST system is the hydraulic drive system for a tractor. It uses a hydraulic pump to deliver pressurized oil to a hydraulic motor, which in turn drives the wheels. The forward and reverse rotation of the hydraulic pump determines the direction of its pressurized oil output, which in turn determines the direction of rotation of the hydraulic motor's output shaft, thus enabling the tractor to move forward and backward.

[0003] As the application areas of tractors expand, users have higher requirements for the speed control of the whole machine. They not only need to achieve continuous speed control, but also need to make the operation more convenient and comfortable.

[0004] A prior art patent with publication number CN222277062U discloses a solution including a replenishing pump, a travel pump, and a travel motor. The travel pump and the travel motor are connected in a loop via pipelines. The outlet of the replenishing pump has a replenishing branch and a control branch. The replenishing branch is connected to a first check valve and a second check valve via branch lines. 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 directional valve, which is connected to a plunger mechanism. The output end of the plunger mechanism is connected to the control switch of the travel pump. Using this invention, the replenishing pump supplies oil to the control branch, and the electromagnetic directional valve controls the oil output direction, thereby controlling the continuous movement of the output end of the plunger mechanism. The control switch of the travel pump enables forward and backward state control and continuous speed control of the HST system, improving operational convenience.

[0005] As existing devices are used, the shortcomings of this technology have gradually become apparent, mainly in the following aspects:

[0006] Existing devices can only be electrically controlled and cannot achieve automatic adjustment. They have low intelligence, low operating efficiency, increased power loss, reduced hydraulic pump variable stability, and have disadvantages such as poor comfort, complicated operation, power waste, and poor fuel economy.

[0007] In conclusion, the existing technology obviously has inconveniences and defects in practical use, so it is necessary to improve it. Utility Model Content

[0008] In view of the shortcomings of the existing technology, this utility model solves the problems of traditional technology where the device can only be electrically controlled and cannot achieve automatic adjustment, has low intelligence, low operating efficiency, increased power loss, reduced hydraulic pump variable stability, poor comfort, complicated operation, and wasted power.

[0009] To solve the above problems, this utility model provides the following technical solution:

[0010] The tractor HST automatic adjustable hydraulic control system includes a hydraulic pump, a hydraulic motor, a first spool valve, and a second spool valve. The oil outlets at both ends of the hydraulic pump are connected to the hydraulic motor via oil supply lines. The oil outlets at both ends of the hydraulic pump are also connected to a high-pressure oil circuit. A first shuttle valve is connected to the high-pressure oil circuit. The oil outlet of the first shuttle valve is connected to the left valve port of both the first and second spool valves. A low-pressure oil circuit is connected between the two oil supply lines. A second shuttle valve is connected to the low-pressure oil circuit. The oil outlet of the second shuttle valve is connected to the right valve port of the first spool valve.

[0011] As an optimized solution, the oil inlet of the first spool valve is connected to the bottom oil chamber of the variable piston of the hydraulic pump, and the oil inlet of the second spool valve is connected to the top oil chamber of the variable piston of the hydraulic pump.

[0012] As an optimized solution, each of the oil supply lines is connected to a speed regulating valve between the hydraulic pump and the low-pressure oil circuit.

[0013] As an optimized solution, each of the oil supply lines is connected in parallel with a system overflow valve, and the outlet ends of the two system overflow valves are connected to the oil replenishment line, which is connected with an oil replenishment overflow valve.

[0014] As an optimized solution, hydraulic motor detection ports are provided on both sides of the hydraulic motor.

[0015] As an optimized solution, the oil outlet of the first shuttle valve is also connected to the oil inlet of the first slide valve.

[0016] As an optimized solution, the hydraulic pump includes a variable displacement piston pump.

[0017] As an optimized solution, the hydraulic motor includes a fixed displacement piston motor.

[0018] As an optimized solution, the oil outlets of the first and second slide valves are connected to the oil tank.

[0019] As an optimized solution, the outlet end of the oil replenishment overflow valve is connected to the oil tank.

[0020] Compared with the prior art, the beneficial effects of this utility model are:

[0021] Two spool valves, two shuttle valves, two speed control valves, and connected pipelines or channels constitute a control valve group; each of the two shuttle valves draws out a stream of oil in the system circuit to provide the pressure required by the hydraulic pump variable mechanism for the two sets of spool valves; the first shuttle valve draws out high-pressure oil, and the second shuttle valve draws out low-pressure oil. At the same time, the high-pressure oil drawn out by the first shuttle valve is led to the left valve port of the two spool valves, and the low-pressure oil drawn out by the second shuttle valve is led to the right valve port of the first spool valve; the movement of the first spool valve is controlled by the high-pressure oil on both sides and the spring force;

[0022] Both spool valves have damping holes on their right sides to prevent pressure shocks caused by violent fluctuations when the valve core moves, ensuring the stability of the hydraulic system and mechanism, and also preventing pressure blockage when the valve core moves.

[0023] The two speed control valves set in this scheme are electronically controlled throttle valves, which can adjust the main oil circuit pressure, thereby controlling the first slide valve, and then controlling the hydraulic pump variable piston to achieve hydraulic pump flow control.

[0024] This solution sets up two detection ports, M1 and M2, on both sides of the motor to monitor system pressure and motor operation.

[0025] In this scheme, the hydraulic pump and hydraulic motor are preferably variable displacement piston pump and fixed displacement piston motor to ensure high transmission efficiency;

[0026] This solution preferably uses two sets of speed control valves to achieve bidirectional speed regulation; two sets of two-position slide valves enable electronic automatic two-dimensional adjustment while ensuring adjustment stability.

[0027] Existing technologies only offer electronic control adjustment. This patent, however, achieves automatic adjustment on top of electronic control adjustment of hydraulic pump flow, making it more intelligent and improving operating efficiency, reducing power loss, and enhancing the stability of hydraulic pump variables, thus improving system operating stability. This makes tractor operation simpler, more intelligent, and more comfortable, while also improving fuel economy. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0029] Figure 1 This is a schematic diagram of the structure of this utility model.

[0030] In the diagram: 1-Hydraulic pump; 2-Hydraulic motor; 3-High-pressure oil circuit; 4-Low-pressure oil circuit; 5-Oil supply line; 6-Second shuttle valve; 7-Speed ​​control valve; 8-System relief valve; 9-Maintenance oil circuit; 10-Maintenance relief valve; 11-Hydraulic motor detection port; 12-First shuttle valve; 13-First slide valve; 14-Second slide valve; 15-Oil tank. Detailed Implementation

[0031] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0032] like Figure 1 As shown, the tractor HST automatic adjustable hydraulic control system includes a hydraulic pump 1, a hydraulic motor 2, a first slide valve 13, and a second slide valve 14. The oil outlets at both ends of the hydraulic pump 1 are connected to the hydraulic motor 2 through oil supply lines 5. The oil outlets at both ends of the hydraulic pump 1 are also connected to a high-pressure oil line 3. A first shuttle valve 12 is connected to the high-pressure oil line 3. The oil outlet of the first shuttle valve 12 is connected to the left valve port of the first slide valve 13 and the second slide valve 14, respectively. A low-pressure oil line 4 is connected between the two oil supply lines 5. A second shuttle valve 6 is connected to the low-pressure oil line 4. The oil outlet of the second shuttle valve 6 is connected to the right valve port of the first slide valve 13.

[0033] The inlet of the first slide valve 13 is connected to the bottom oil chamber of the variable piston of the hydraulic pump 1, and the inlet of the second slide valve 14 is connected to the top oil chamber of the variable piston of the hydraulic pump 1.

[0034] Each oil supply line 5 is connected to a speed control valve 7 between the hydraulic pump 1 and the low-pressure oil line 4.

[0035] Each oil supply line 5 is connected in parallel with a system overflow valve 8. The outlet ends of the two system overflow valves 8 are connected to the oil replenishment line 9, and the oil replenishment line 9 is connected with an oil replenishment overflow valve 10.

[0036] Hydraulic motor detection ports 11 are provided on both sides of the hydraulic motor 2.

[0037] The oil outlet of the first shuttle valve 12 is also connected to the oil inlet of the first slide valve 13.

[0038] Hydraulic pump 1 includes a variable displacement piston pump.

[0039] Hydraulic motor 2 includes a fixed displacement piston motor.

[0040] The oil outlets of the first slide valve 13 and the second slide valve 14 are connected to the oil tank 15.

[0041] The outlet end of the oil replenishment overflow valve 10 is connected to the oil tank 15.

[0042] The working ports of the first and second spool valves are connected to each other. The inlet port is a high-pressure oil source provided by the hydraulic pump, forming a parallel working oil circuit on the left side. At the same time, the return port is a series oil circuit, which then passes through two damping holes and connects to the oil tank, forming a circulation path for the oil.

[0043] The control ports of the first and second spool valves are also interconnected. The left control branch is a branch of the high-pressure oil in the working oil circuit, which is also connected in parallel. The right control branch is also connected in parallel, and each of them is connected to the oil tank after passing through a damping orifice. At the same time, the right branch of the second spool valve is directly connected to the return port of the first spool valve.

[0044] The working principle of this device is as follows:

[0045] Two slide valves, two shuttle valves, two speed control valves 7, and connected pipelines or channels constitute a control valve group; each of the two shuttle valves draws out a stream of oil in the system circuit to provide the pressure required by the variable mechanism of the hydraulic pump 1 for the two sets of slide valves; the first shuttle valve 12 draws out high-pressure oil, and the second shuttle valve 6 draws out low-pressure oil. At the same time, the high-pressure oil drawn out by the first shuttle valve 12 is led to the left valve port of the two slide valves, and the low-pressure oil drawn out by the second shuttle valve 6 is led to the right valve port of the first slide valve 13; the movement of the first slide valve 13 is controlled by the high-pressure oil on both sides and the spring force;

[0046] Both spool valves have damping holes on their right sides to prevent pressure shocks caused by violent fluctuations when the valve core moves, ensuring the stability of the hydraulic system and mechanism, and also preventing pressure blockage when the valve core moves.

[0047] The two speed control valves 7 set in this scheme are electronically controlled throttle valves, which can adjust the pressure of the main oil circuit, thereby controlling the first slide valve 13, and then controlling the variable piston of the hydraulic pump 1 to achieve flow control of the hydraulic pump 1.

[0048] This solution sets up two detection ports, M1 and M2, on both sides of the motor to monitor system pressure and motor operation.

[0049] In this scheme, hydraulic pump 1 and hydraulic motor 2 are preferably variable displacement piston pump and fixed displacement piston motor, respectively, to ensure high transmission efficiency;

[0050] This solution preferably uses two sets of speed control valves 7 to achieve bidirectional speed regulation; two sets of two-position slide valves to achieve electronic automatic two-dimensional adjustment while ensuring adjustment stability.

[0051] The hydraulic pump 1 is driven by the engine and connected to the speed control valve 7 via a pipeline. The hydraulic pump 1 is then connected to the oil inlet of the hydraulic motor 2. A replenishment circuit is provided on the pipelines of the two system relief valves 8. One end of the replenishment circuit is connected to the system circuit G port, and the other end is connected to the oil tank 15 via the replenishment relief valve 10. This design includes two spool valves as displacement control valves for the hydraulic pump 1: the first spool valve 13 and the second spool valve 14. A first shuttle valve 12 connects the oil circuits on both sides of the motor to those on both sides of the hydraulic pump 1. A second shuttle valve 6 connects the inlet and return oil circuits after the system circuit speed control valve 7. The inlet of the two spool valves is supplied with oil by the first shuttle valve 12, and the return oil is connected to the oil tank 15.

[0052] When the tractor engine starts, hydraulic pump 1 operates at its maximum displacement. At this time, the hydraulic system pressure gradually increases. The pressure oil from the first shuttle valve 12 overcomes the spring force and pushes the two slide valves to the right, operating in the left position. High-pressure oil then enters the variable piston, pushing it to move and reducing the displacement of hydraulic pump 1. Meanwhile, high-pressure oil from the second shuttle valve 6 is led to the right valve port of the first slide valve 13. The combined force of this oil and the spring force acts on the valve port. When the pressure exceeds the pressure on the left side, the first slide valve 13 will move to the left. The pressure at both valve ports gradually balances during the valve core movement, and the displacement of hydraulic pump 1 stabilizes. When the load on the tractor increases during operation, the pressure of hydraulic pump 1 increases, and the pressure of the oil led out by the first shuttle valve 12 rises, pushing the slide valve into the left position. The variable piston of hydraulic pump 1 discharges oil, and the displacement of hydraulic pump 1 decreases until both ends are balanced. At this time, the output torque of hydraulic motor 2 increases, and the speed decreases. When the load on the tractor decreases, the output pressure of hydraulic pump 1 decreases. Under the action of the second shuttle valve 6 and the differential valve, the slide valve enters the right position, and the variable piston of hydraulic pump 1 enters, increasing the displacement of hydraulic pump 1 until both ends are balanced. At this time, the output torque of hydraulic motor 2 decreases, and the speed increases. During stable operation of the tractor, the pressure of the oil led out by the speed regulating valve 7 and the first shuttle valve 12 in the regulating circuit changes accordingly, and the first slide valve 13 also actuates accordingly, realizing electronic speed control regulation.

[0053] The second slide valve 14 has a self-adjusting dynamic pressure difference at both ends. It will finely adjust the valve core position and change the valve port flow according to the pressure transmitted from both ends of the variable piston. This controls the position and speed of the variable piston of hydraulic pump 1, ensuring the stability of hydraulic pump 1 and avoiding hydraulic shock.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model, and they should all be covered within the scope of the claims and specification of this utility model.

Claims

1. A tractor HST automatic adjustable hydraulic control system, characterized in that: The system includes a hydraulic pump (1), a hydraulic motor (2), a first slide valve (13), and a second slide valve (14). The oil outlets at both ends of the hydraulic pump (1) are connected to the hydraulic motor (2) through oil supply lines (5). The oil outlets at both ends of the hydraulic pump (1) are also connected to a high-pressure oil circuit (3). A first shuttle valve (12) is connected to the high-pressure oil circuit (3). The oil outlet of the first shuttle valve (12) is connected to the left valve ports of the first slide valve (13) and the second slide valve (14). A low-pressure oil circuit (4) is connected between the two oil supply lines (5). A second shuttle valve (6) is connected to the low-pressure oil circuit (4). The oil outlet of the second shuttle valve (6) is connected to the right valve port of the first slide valve (13).

2. The tractor HST automatic adjustment hydraulic control system according to claim 1, characterized in that: The inlet of the first slide valve (13) is connected to the bottom oil chamber of the variable piston of the hydraulic pump (1), and the inlet of the second slide valve (14) is connected to the top oil chamber of the variable piston of the hydraulic pump (1).

3. The tractor HST automatic adjustment hydraulic control system according to claim 2, characterized in that: Each of the oil supply lines (5) is connected to a speed control valve (7) between the hydraulic pump (1) and the low-pressure oil line (4).

4. The tractor HST automatic adjustment hydraulic control system according to claim 3, characterized in that: Each of the oil supply lines (5) is connected in parallel with a system overflow valve (8), and the outlet ends of the two system overflow valves (8) are connected to the oil replenishment line (9), and the oil replenishment line (9) is connected with an oil replenishment overflow valve (10).

5. The tractor HST automatic adjustment hydraulic control system according to claim 4, characterized in that: Hydraulic motor detection ports (11) are provided on both sides of the hydraulic motor (2).

6. The tractor HST automatic adjustment hydraulic control system according to claim 5, characterized in that: The oil outlet of the first shuttle valve (12) is also connected to the oil inlet of the first slide valve (13).

7. The tractor HST automatic adjustment hydraulic control system according to claim 6, characterized in that: The hydraulic pump (1) includes a variable displacement piston pump.

8. The tractor HST automatic adjustment hydraulic control system according to claim 7, characterized in that: The hydraulic motor (2) includes a fixed displacement piston motor.

9. The tractor HST automatic adjustment hydraulic control system according to claim 8, characterized in that: The oil outlets of the first slide valve (13) and the second slide valve (14) are connected to the oil tank (15).

10. The tractor HST automatic adjustment hydraulic control system according to claim 9, characterized in that: The outlet end of the oil replenishment overflow valve (10) is connected to the oil tank (15).

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