Hydrostatic transmission and its shifting system

Abstract

The present invention provides a hydrostatic transmission and a shifting system thereof, comprising an electromagnetic reversing valve group, a two-speed hydraulically controlled transmission, a closed variable pump, a two-point variable motor, an oil tank, a controller and a pressure sensor, wherein the electromagnetic reversing valve group is communicatively connected to the controller and controls high and low speeds and parking brakes respectively under the control of the controller, the two-speed hydraulically controlled transmission provides two speed ratios, the closed variable pump is communicatively connected to the controller and is controlled by proportional current, the two-point variable motor is communicatively connected to the controller and switches between full displacement and half displacement under the control of the controller, the controller is communicatively connected to the pressure sensor, the pressure sensor measures the pressure of the transmission system, the closed variable pump draws oil from the oil tank and supplies oil to the two-point variable motor and the two-speed hydraulically controlled transmission. The present invention can increase the driving speed range of the whole vehicle without increasing too much cost.

Description

Technical Field

[0001] The present invention generally relates to the field of engineering machinery, and in particular to a hydrostatic transmission and a shifting system thereof. Background Art

[0002] In mining machinery, hydrostatic transmission is a very important chassis transmission mode, which has the advantages of simple layout, high reliability, large transmission torque, and stepless speed change. Common hydrostatic transmission systems are used in construction machinery such as forklifts and trolleys, and the vehicle speed is generally low. Summary of the invention

[0003] A main purpose of the present invention is to overcome at least one defect of the above-mentioned prior art and to provide a hydrostatic transmission and shifting system thereof which can increase the speed range of the whole vehicle without increasing too much cost and which is easy and safe to operate.

[0004] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme:

[0005] According to one aspect of the present invention, a hydrostatic transmission and a shifting system thereof are provided, comprising an electromagnetic reversing valve group, a two-speed hydraulically controlled transmission, a closed variable pump, a two-point variable motor, a fuel tank, a controller and a pressure sensor, wherein the electromagnetic reversing valve group is communicatively connected to the controller and controls high and low speeds and parking brakes respectively under the control of the controller, the two-speed hydraulically controlled transmission provides two speed ratios, the closed variable pump is communicatively connected to the controller and is controlled by proportional current, the two-point variable motor is communicatively connected to the controller and switches between full displacement and half displacement under the control of the controller, the controller is communicatively connected to the pressure sensor, the pressure sensor measures the pressure of the transmission system, the closed variable pump draws oil from the fuel tank and supplies oil to the two-point variable motor and the two-speed hydraulically controlled transmission.

[0006] According to an embodiment of the present invention, the electromagnetic reversing valve group includes a gearbox high-low gear switching solenoid valve and a parking brake solenoid valve, and the gearbox high-low gear switching solenoid valve and the parking brake solenoid valve control high and low speed and parking brake respectively.

[0007] According to an embodiment of the present invention, the two-speed hydraulically controlled transmission provides two speed ratios through high and low speed control oil ports.

[0008] According to one embodiment of the present invention, the closed variable pump is steplessly regulated by a proportional solenoid valve.

[0009] According to an embodiment of the present invention, the two-point variable displacement motor controls the displacement of the pump through a two-point displacement control solenoid valve, so as to switch between full displacement and half displacement under the control of the controller.

[0010] According to one embodiment of the present invention, the system further comprises an oil suction filter disposed at the inlet of the system oil circuit.

[0011] According to one embodiment of the present invention, the system further comprises a high-pressure filter disposed at the oil outlet of the system.

[0012] According to an embodiment of the present invention, the system further comprises a parking brake, and the parking brake is connected to the oil tank via the electromagnetic reversing valve group.

[0013] According to an embodiment of the present invention, the system is applied to mining machinery.

[0014] It can be seen from the above technical solution that the advantages and positive effects of the hydrostatic transmission and the shifting system thereof of the present invention are:

[0015] 1) The transmission system of the present invention adopts "closed pump + two-point variable motor + two-speed gearbox". Compared with the common mining machinery "closed pump + two-point variable motor + transfer case" solution, it greatly increases the range of the system's stepless speed change without increasing too much cost, and enhances the adaptability of the system. It can meet the low-speed and high-torque requirements (0-10km / h) underground, and can also meet the high-speed and low-torque requirements (0-30km / h) on the road.

[0016] 2) The shift system is easy to operate and safe. The forward first and second gears, the reverse first and second gears, and the neutral gear are controlled by a shift combination switch, which is easy to operate; the high and low speeds of the two-speed hydraulic transmission are rarely switched (generally, low speed is used underground, high speed is used on the road, and the car must be stopped to shift gears), so it is controlled by a rocker switch, which is easy to operate and can effectively avoid misoperation.

[0017] 3) The controller can receive the engine load signal and calculate the power consumption of the hydrostatic transmission system. When the load of the hydrostatic transmission system exceeds the set value (such as 70% of the total engine power), the controller will automatically reduce the displacement of the closed pump to reduce the power of the vehicle, protect the engine and prevent stalling. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Various objects, features and advantages of the present invention will become more apparent by considering the following detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. The accompanying drawings are merely exemplary illustrations of the present invention and are not necessarily drawn to scale. In the accompanying drawings, the same reference numerals always refer to the same or similar parts. Among them:

[0019] Figure 1 Schematic diagram of a hydrostatic transmission and a shifting system thereof according to the present invention shown in an exemplary embodiment. DETAILED DESCRIPTION

[0020] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present invention will be comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar structures, and thus their detailed description will be omitted.

[0021] In the following description of different examples of the present invention, reference is made to the accompanying drawings, which form a part of the present invention and in which different exemplary structures, systems and steps that can implement multiple aspects of the present invention are shown by way of example. It should be understood that other specific schemes of components, structures, exemplary devices, systems and steps can be used, and structural and functional modifications can be made without departing from the scope of the present invention. Moreover, although the terms "top", "bottom", "front", "rear", "side", etc. may be used in this specification to describe different exemplary features and elements of the present invention, these terms are used herein only for convenience, such as according to the direction of the examples described in the accompanying drawings. Nothing in this specification should be construed as requiring a specific three-dimensional orientation of the structure to fall within the scope of the present invention.

[0022] Figure 1 FIG. 1 is a schematic diagram of a hydrostatic transmission and a shifting system of the present invention shown in an exemplary embodiment. Figure 1 As shown, the hydrostatic transmission and shifting system of this embodiment include an electromagnetic reversing valve group 1, a two-speed hydraulically controlled transmission 2, a closed variable pump 3, a two-point variable motor 4, an oil tank 7, a controller 8 and a pressure sensor 9.

[0023] Among them, the electromagnetic reversing valve group 1 is connected to the controller 8 by communication, and controls the high and low speed and parking brake respectively under the control of the controller 8. The two-speed hydraulic control gearbox 2 provides two speed ratios, and the closed variable pump 3 is connected to the controller 8 by communication and controlled by proportional current. The two-point variable motor 4 is connected to the controller 8 by communication, and switches between full displacement and half displacement under the control of the controller 8. The controller 8 is connected to the pressure sensor 9 by communication, and the pressure sensor 9 measures the pressure of the transmission system. The closed variable pump 3 draws oil from the oil tank 7 and supplies oil to the two-point variable motor 4 and the two-speed hydraulic control gearbox 2.

[0024] In this embodiment, the electromagnetic reversing valve group 1 includes a gearbox high-low gear switching electromagnetic valve 1.1 and a parking brake electromagnetic valve 1.2, which control high and low speeds and parking brakes respectively.

[0025] In this embodiment, the two-speed hydraulically controlled transmission 2 provides two speed ratios through high and low speed control oil ports. In this embodiment, the closed variable pump 3 realizes stepless regulation through a proportional solenoid valve 3.1. In this embodiment, the two-point variable motor 4 controls the displacement of the pump through a two-point displacement control solenoid valve 4.1, so as to switch between full displacement and half displacement under the control of the controller 8.

[0026] In this embodiment, the system further includes an oil suction filter 5, which is arranged at the inlet of the system oil circuit. In this embodiment, the system further includes a high-pressure filter 6, which is arranged at the outlet of the system oil circuit. In this embodiment, the system further includes a parking brake, which is connected to the oil tank 7 through an electromagnetic reversing valve group.

[0027] In this embodiment, the system is applied to mining machinery. In this embodiment, the controller 8 controls the operation of the hydrostatic system through electrical signals. It receives signals from various operating devices for conversion, and then outputs signals to control the operation of other components. The pressure sensor 9 measures the pressure of the transmission system and feeds back to the controller 8. When the power of the transmission system exceeds the system set pressure, the controller 8 controls the closed variable pump 3 to reduce the flow rate to avoid engine stalling and protect the engine.

[0028] In this embodiment:

[0029] 1. The vehicle can only be started when it is parked (controller controlled). Before shifting gears, the parking brake solenoid valve 1.2 is energized, and the pilot oil of the closed variable pump 3 enters from the P port of the solenoid reversing valve 1 and flows out from the B port, releasing the parking brake.

[0030] 2. High-low speed switching: When the gearbox high-low gear switching solenoid valve 1.1 is not energized, the pilot oil of the closed variable pump 3 passes through the P port of the electromagnetic reversing valve 1, through the A1 port to the low-speed control port of the two-speed hydraulic control gearbox 2, so that it is in a low-speed gear state; conversely, when the gearbox high-low gear switching solenoid valve 1.1 is energized, the pilot oil of the closed variable pump 3 passes through the P port of the electromagnetic reversing valve 1, through the B1 port to the high-speed control port of the two-speed hydraulic control gearbox 2, so that it is in a high-speed gear state.

[0031] 3. Switching between the first and second gears: When the electromagnetic reversing valve 4.1 of the two-point variable motor 4 is not energized, the two-point variable motor 4 is in a full displacement state, which is the first gear; when the electromagnetic reversing valve 4.1 is energized, the two-point variable motor 4 is in a half displacement state, which is the second gear.

[0032] 4. Forward and reverse stepless speed change and neutral gear: When the proportional solenoid valve 3.1 of the closed variable pump 3 is not energized, the displacement of the closed variable pump 3 is zero and it is in neutral gear; when the coil of the proportional solenoid valve 3.1A port receives proportional current, the closed variable pump 3A port starts to discharge oil, and the flow rate is proportional to the current size, and the hydraulic oil flows to the A port of the two-point variable motor 4, pushing it to rotate forward, at this time the whole vehicle starts to move forward, and the size of the current controls the vehicle speed; conversely, when the coil of the proportional solenoid valve 3.1B port receives proportional current, the closed variable pump 3B port starts to discharge oil, and the flow rate is proportional to the current size, and the hydraulic oil flows to the B port of the two-point variable motor 4, pushing it to reverse, at this time the whole vehicle starts to move backward, and the size of the current controls the vehicle speed.

[0033] 5. The forward first and second gears, the reverse first and second gears, and the neutral gear are controlled by a shift combination switch, which is easy to operate. The high and low speed shift is controlled by a rocker switch, which can effectively avoid misoperation.

[0034] It can be seen from the above technical solution that the advantages and positive effects of the hydrostatic transmission and the shifting system thereof of the present invention are:

[0035] 1) The transmission system of the present invention adopts "closed pump + two-point variable motor + two-speed gearbox". Compared with the common mining machinery "closed pump + two-point variable motor + transfer case" solution, it greatly increases the range of the system's stepless speed change without increasing too much cost, and enhances the adaptability of the system. It can meet the low-speed and high-torque requirements (0-10km / h) underground, and can also meet the high-speed and low-torque requirements (0-30km / h) on the road.

[0036] 2) The shift system is easy to operate and safe. The forward first and second gears, the reverse first and second gears, and the neutral gear are controlled by a shift combination switch, which is easy to operate; the high and low speeds of the two-speed hydraulic transmission are rarely switched (generally, low speed is used underground, high speed is used on the road, and the car must be stopped to shift gears), so it is controlled by a rocker switch, which is easy to operate and can effectively avoid misoperation.

[0037] 3) The controller can receive the engine load signal. When the load of the hydrostatic transmission system exceeds the set value (such as 70% of the total engine power), the controller will automatically reduce the displacement of the closed pump to reduce the vehicle power, protect the engine and prevent stalling.

[0038] Those skilled in the art should understand that the specific structures and processes shown in the above specific embodiments are only exemplary and not restrictive. Moreover, those skilled in the art can combine the various technical features shown above in various possible ways to form new technical solutions, or make other changes, which are all within the scope of the present invention.

Claims

1. A hydrostatic transmission and a shifting system thereof, It is characterized in that It includes an electromagnetic reversing valve group, a two-speed hydraulically controlled transmission, a closed variable pump, a two-point variable motor, a fuel tank, a controller and a pressure sensor. The electromagnetic reversing valve group is communicatively connected to the controller and controls high and low speeds and parking brakes respectively under the control of the controller. The two-speed hydraulically controlled transmission provides two speed ratios. The closed variable pump is communicatively connected to the controller and controlled by proportional current. The two-point variable motor is communicatively connected to the controller and switches between full displacement and half displacement under the control of the controller. The controller is communicatively connected to the pressure sensor , the pressure sensor measures the pressure of the transmission system, the closed variable pump draws oil from the oil tank and supplies oil to the two-point variable motor and the two-speed hydraulically controlled gearbox, the electromagnetic reversing valve group includes a gearbox high-low gear switching solenoid valve and a parking brake solenoid valve, the gearbox high-low gear switching solenoid valve and the parking brake solenoid valve respectively control high and low speed and parking brake; before shifting gears, the parking brake solenoid valve is energized, the pilot oil of the closed variable pump enters from the P port of the electromagnetic reversing valve and flows out from the B port, the parking brake is released, and when the gearbox high-low gear switching solenoid valve is not energized, the closed variable pump The pilot oil of the variable displacement pump passes through the P port of the electromagnetic reversing valve, through the A1 port to the low-speed control port of the two-speed hydraulic control transmission, so that it is in the low-speed gear state; on the contrary, when the high-low gear switching solenoid valve of the transmission is energized, the pilot oil of the closed variable displacement pump passes through the P port of the electromagnetic reversing valve, through the B1 port to the high-speed control port of the two-speed hydraulic control transmission, so that it is in the high-speed gear state. When the electromagnetic reversing valve of the two-point variable motor is not energized, the two-point variable motor is in the full displacement state, which is the first gear at this time; when the electromagnetic reversing valve is energized, the two-point variable motor is in the half-displacement state, which is the second gear at this time. When the proportional valve of the closed variable pump is energized, the two-point variable motor is in the half-displacement state, which is the second gear at this time. When the solenoid valve is not energized, the closed variable pump displacement is zero and is in neutral; when the coil of the proportional solenoid valve port A receives proportional current, the closed variable pump port A starts to discharge oil, and the flow rate is proportional to the current size, and the hydraulic oil flows to the port A of the two-point variable motor, pushing it to rotate forward. At this time, the whole vehicle starts to move forward, and the current size controls the vehicle speed; conversely, when the coil of the proportional solenoid valve port B receives proportional current, the closed variable pump port B starts to discharge oil, and the flow rate is proportional to the current size, and the hydraulic oil flows to the port B of the two-point variable motor, pushing it to reverse. At this time, the whole vehicle starts to move backward, and the current size controls the vehicle speed.

2. The hydrostatic transmission and shifting system thereof as claimed in claim 1, It is characterized in that The two-speed hydraulically controlled transmission provides two speed ratios via high and low speed control oil ports.

3. The hydrostatic transmission and shifting system thereof as claimed in claim 1, It is characterized in that The closed variable pump is steplessly regulated by a proportional solenoid valve.

4. The hydrostatic transmission and shifting system thereof as claimed in claim 1, It is characterized in that The two-point variable displacement motor controls the displacement of the pump through a two-point displacement control solenoid valve, so as to switch between full displacement and half displacement under the control of the controller.

5. The hydrostatic transmission and shifting system thereof according to any one of claims 1 to 4, It is characterized in that The system also includes an oil suction filter, which is arranged at the inlet of the system oil circuit.

6. The hydrostatic transmission and shifting system thereof according to any one of claims 1 to 4, It is characterized in that The system also includes a high-pressure filter, which is arranged at the outlet of the system oil circuit.

7. The hydrostatic transmission and shifting system thereof according to any one of claims 1 to 4, It is characterized in that The system further comprises a parking brake, and the parking brake is connected to the oil tank through the electromagnetic reversing valve group.

8. The hydrostatic transmission and shifting system thereof according to any one of claims 1 to 4, It is characterized in that The system is applied to mining machinery.

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