Continuously variable speed pump-motor cam combined control system

Abstract

The invention discloses an infinitely variable speed pump-motor cam combined control system which comprises a two-way variable pump-motor mechanism and a cam driving mechanism. The two-way variable pump-motor mechanism comprises two two-way variable pump-motors which are conducted through a main oil way, and the tilt cylinder is used for controlling the two-way variable pump-motors to supply hydraulic oil to the main oil way; the cam driving mechanism comprises a first cam driving assembly, a second cam driving assembly and a control oil way. The two-way variable pump-motor comprises the pump working condition and the motor working condition, the two-way variable pump-motor is a variable motor under the motor working condition, output of different displacements under the motor working condition is achieved by controlling the oil supply amount of the two-way variable pump-motor under the pump working condition to the main oil way, and large-displacement output can be achieved. The rotary driving element and the tilt cylinder are driven to rotate through the control oil way, switching of the stations of the reversing valve is achieved through rotation of the cam, the tilt cylinder rotates reversely, and the tilt angle of the tilt cylinder is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of control systems, and in particular relates to a stepless speed-variable pump-motor cam combined control system. Background Art

[0002] In heavy-duty mobile equipment, such as tractors, bulldozers, skid loaders, etc., they often face low-speed and high-load conditions when working. Unlike the gear shifting of cars, low-speed conditions are generally predictable, and the gear can be switched in advance. The automatic shifting technology is also very mature. The heavy-duty mobile equipment's heavy-load conditions are often unpredictable, and the load changes are large and last for a long time, which places extremely high demands on the stability of the entire transmission system. The core issue is the need for a stable, economical and efficient continuously variable transmission system, which in short is good low-speed traction characteristics.

[0003] A solution similar to the present invention is a hydrostatic continuously variable transmission (HST), which changes the displacement of the pump motor through an operating mechanism. The hydrostatic continuously variable transmission (HST) is a closed loop formed by a combination of multiple functional hydraulic components. It is directly connected in series in the chassis travel power transmission chain (in a semi-feeding combine harvester, it is on the travel gearbox) through a transmission method, and the displacement and direction of the plunger pump are controlled by the control console to change the output of the motor. However, due to structural reasons, the HST variable mechanism is inside the pump motor, the pump cannot achieve a large swing angle, and the motor is a fixed displacement motor, the working conditions are limited, and a large displacement output cannot be achieved. Summary of the invention

[0004] The object of the present invention is to provide a continuously variable speed pump-motor cam combined control system to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides a continuously variable speed pump-motor cam combined control system, comprising:

[0006] A bidirectional variable pump-motor mechanism, the bidirectional variable pump-motor mechanism includes two bidirectional variable pump-motors communicated through a main oil circuit, the bidirectional variable pump-motors each include a rotatably arranged swing cylinder, the swing cylinder is used to control the bidirectional variable pump-motor to supply hydraulic oil to the main oil circuit; the bidirectional variable pump-motor includes a pump operating condition and a motor operating condition, and the operating conditions of the two bidirectional variable pump-motors are different;

[0007] A cam driving mechanism, the cam driving mechanism includes a first cam driving assembly, a second cam driving assembly and a control oil circuit; the first cam driving assembly and the second cam driving assembly have the same structure and both include a cam, a cam driving element and a rotation driving element, the rotation driving element is detachably connected to the swing cylinder, a reversing valve is connected between the rotation driving element and the control oil circuit, the control oil circuit drives the rotation driving element to work, the cam driving element drives the cam to rotate, based on the rotation of the cam, the reversing valve switches the working position to control the reversing rotation of the rotation driving element.

[0008] Optionally, the rotary drive element includes a first hydraulic cylinder and a second hydraulic cylinder, and the telescopic working end of the first hydraulic cylinder and the telescopic working end of the second hydraulic cylinder are respectively rotatably connected to two opposite ends of the swing cylinder and are arranged on both sides of the rotation point of the swing cylinder.

[0009] Optionally, it also includes a rotating flange, which is detachably connected to the swing cylinder, and the telescopic working end of the first hydraulic cylinder and the telescopic working end of the second hydraulic cylinder are both rotatably connected to the rotating flange, and the telescopic working end of the first hydraulic cylinder and the telescopic working end of the second hydraulic cylinder are respectively arranged on both sides of the rotation point of the swing cylinder and the rotating flange.

[0010] Optionally, the reversing valve is a three-position four-way reversing valve, a second oil inlet pipe and a second oil outlet pipe are connected between the three-position four-way reversing valve and the control oil circuit, and the three-position four-way reversing valve is respectively connected to the first hydraulic cylinder and the second hydraulic cylinder; the valve core of the three-position four-way reversing valve has a first conducting position, an intermediate position and a second conducting position:

[0011] When the valve core of the three-position four-way reversing valve is in the first conducting position, the first hydraulic cylinder is connected to the second oil inlet pipe, and the second hydraulic cylinder is connected to the second oil outlet pipe;

[0012] When the three-position four-way reversing valve is in the middle position, no hydraulic oil flows between the first hydraulic cylinder and the second hydraulic cylinder;

[0013] When the valve core of the reversing valve is in the second conducting position, the first hydraulic cylinder is connected to the second oil outlet pipe, and the second hydraulic cylinder is connected to the second oil inlet pipe;

[0014] Based on the rotation of the cam, the valve core of the reversing valve is switched between the first conducting position, the middle position and the second conducting position.

[0015] Optionally, the first cam driving assembly and the second cam driving assembly both further include a cam variable rod, which is rotatably connected to the valve core of the three-position four-way reversing valve; based on the rotation of the cam, the cam variable rod swings within a preset plane, so that the valve core of the three-position four-way reversing valve switches between the first conduction position, the middle position and the second conduction position.

[0016] Optionally, the cam driving element includes a camshaft, which is detachably connected to the cam, and the cam is spirally extended along its own axis on the outer circumference to form a guide groove, the cam and the cam variable rod are rotatably connected in the guide groove, and the camshaft is driven by a motor.

[0017] Optionally, the main oil circuit is connected to a first oil inlet pipe and a first oil outlet pipe, the main oil circuit includes a first oil circuit and a second oil circuit, a one-way valve is connected between the first oil circuit and the first oil inlet pipe, and between the second oil circuit and the first oil inlet pipe, the first oil circuit and the second oil circuit are respectively connected to the first oil outlet pipe; the two ends of the bidirectional variable pump-motor are respectively connected to the first oil circuit and the second oil circuit.

[0018] Optionally, a first high-pressure relief valve is provided between the first oil circuit and the second oil circuit, the overflow port of the high-pressure relief valve is connected to a shuttle valve, the shuttle valve is connected to a solenoid valve and a high-pressure sensor, and the solenoid valve is connected to an oil return port.

[0019] Optionally, a flushing valve is provided between the first oil circuit and the first oil outlet pipe, and between the second oil circuit and the first oil outlet pipe.

[0020] Optionally, the bidirectional variable pump-motor mechanism also includes a third bidirectional variable pump-motor, and the third bidirectional variable pump-motor includes a rotatably arranged third swing cylinder, and the third swing cylinder is used to control the third bidirectional variable pump-motor to supply hydraulic oil to the main oil circuit, and a synchronous rotating rod is connected between the third swing cylinder and the adjacent swing cylinder.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] The present invention provides a continuously variable speed pump-motor cam combined control system, wherein the bidirectional variable pump-motor in the present invention includes two working conditions, namely, a pump working condition and a motor working condition. In the pump working condition, the bidirectional variable pump-motor is controlled by the swing cylinder to supply hydraulic oil to the main oil circuit, that is, hydraulic oil is supplied to the bidirectional variable pump-motor in other motor working conditions, and the bidirectional variable pump-motor in the motor working condition outputs power to the outside. The bidirectional variable pump-motor in the present invention is a variable motor in the motor working condition, and the output of different displacements in the motor working condition is achieved by controlling the oil supply of the bidirectional variable pump-motor in the pump working condition to the main oil circuit, and a large displacement output can be achieved.

[0023] The cam drive element drives the cam cylinder to rotate through the cam drive element, thereby supplying hydraulic oil to the main oil circuit, and drives the cam to rotate through the cam drive element to realize the switching of the reversing valve position, and then realizes the control of the reversing rotation of the rotary drive element, so that the swivel cylinder rotates in the opposite direction and the swivel angle of the swivel cylinder is increased. The cam drive mechanism directly switches the position of the reversing valve, reduces the number of control elements for large-displacement pumps in large systems, reduces the number of control valve bodies, reduces the interference of flow pulsation on the valve caused by valve opening and closing or working condition switching in the hydraulic circuit, reduces the interference of the valve on the system, increases the stability of the system, and enables the system to have stable large-displacement output. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 This is a schematic diagram of the stepless speed-changing pump-motor-cam combined control system of the present invention;

[0026] Among them, 11, the first two-way variable pump-motor, 12, the second two-way variable pump-motor, 13, the third two-way variable pump-motor, 21, the first three-position four-way reversing valve, 22, the second three-position four-way reversing valve, 31, the first hydraulic cylinder A, 32, the second hydraulic cylinder A, 33, the first hydraulic cylinder B, 34, the second hydraulic cylinder B, 41, the first cam variable rod, 42, the second cam variable rod, 51, the first rotating flange, 52, the second rotating flange, 53, the third rotating flange, 54, the synchronous rotating rod, 61, the motor, 62, the camshaft, 63, the first cam, 64, the second cam, 71, the first oil inlet pipe, 72, the first oil outlet pipe, 73, the second oil inlet pipe, 74, the second oil inlet pipe, 75, the one-way valve, 76, the high-pressure relief valve, 77, the shuttle valve, 78, the solenoid valve, 79, the first high-pressure sensor, 80, the second high-pressure sensor, 81, the flushing valve. DETAILED DESCRIPTION

[0027] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0028] The invention provides a continuously variable speed pump-motor-cam combined control system, comprising a bidirectional variable pump-motor mechanism and a cam driving mechanism.

[0029] The bidirectional variable pump-motor mechanism includes two bidirectional variable pump-motors connected through the main oil circuit. Both bidirectional variable pump-motors include a rotatable swing cylinder, which is used to control the bidirectional variable pump-motor to supply hydraulic oil to the main oil circuit. The bidirectional variable pump-motor includes a pump working condition and a motor working condition, and the working conditions of the two bidirectional variable pump-motors are different. The cam drive mechanism includes a first cam drive assembly, a second cam drive assembly and a control oil circuit. The first cam drive assembly and the second cam drive assembly have the same structure and both include a cam, a cam drive element and a rotation drive element. The rotation drive element is detachably connected to the swing cylinder. A reversing valve is connected between the rotation drive element and the control oil circuit. The control oil circuit drives the rotation drive element to work, and the cam drive element drives the cam to rotate. Based on the rotation of the cam, the reversing valve switches the position to control the reversing rotation of the rotation drive element.

[0030] The bidirectional variable pump-motor in the present invention includes two working conditions: pump working condition and motor working condition. In the pump working condition, the bidirectional variable pump-motor is controlled by the swing cylinder to supply hydraulic oil to the main oil circuit, that is, hydraulic oil is supplied to the bidirectional variable pump-motor in other motor working conditions, and the bidirectional variable pump-motor in the motor working condition outputs power to the outside. The bidirectional variable pump-motor in the present invention is a variable motor in the motor working condition. By controlling the oil supply amount of the bidirectional variable pump-motor in the pump working condition to the main oil circuit, the output of different displacements in the motor working condition can be achieved, and large displacement output can be achieved.

[0031] The cam drive element drives the cam cylinder to rotate through the cam drive element, thereby supplying hydraulic oil to the main oil circuit, and drives the cam to rotate through the cam drive element to realize the switching of the reversing valve position, and then realizes the control of the reversing rotation of the rotary drive element, so that the swivel cylinder rotates in the opposite direction and the swivel angle of the swivel cylinder is increased. The cam drive mechanism directly switches the position of the reversing valve, reduces the number of control elements for large-displacement pumps in large systems, reduces the number of control valve bodies, reduces the interference of flow pulsation on the valve caused by valve opening and closing or working condition switching in the hydraulic circuit, reduces the interference of the valve on the system, increases the stability of the system, and enables the system to have stable large-displacement output.

[0032] In this embodiment, the two bidirectional variable pump-motors are respectively the first bidirectional variable pump-motor 11 and the second bidirectional variable pump-motor 12, the two reversing valves are respectively the first reversing valve and the second reversing valve, the two cams are respectively the first cam 63 and the second cam 64, the two rotating drive elements are respectively the first rotating drive element and the second rotating drive element, the first rotating drive element is detachably connected to the swing cylinder of the first bidirectional variable pump-motor 11, and the second rotating drive element is detachably connected to the swing cylinder of the second bidirectional variable pump-motor 12; based on the rotation of the first cam 63, the first reversing valve switching position controls the first rotating drive element to drive the swing cylinder to reverse rotation; based on the rotation of the second cam 64, the second reversing valve switching position controls the second rotating drive element to drive the swing cylinder to reverse rotation; in this embodiment, the control oil circuit provides hydraulic oil to the first reversing valve and the second reversing valve respectively and recovers excess hydraulic oil.

[0033] The rotating drive element in this embodiment is driven to work by the control oil circuit, driving the swing cylinder to rotate so as to realize the bidirectional variable pump-motor to supply hydraulic oil to the main oil circuit. The drive element can adopt an integrated structure or a split structure. When the drive element adopts an integrated structure, it includes a structural shell, and two chambers that are not connected to each other are arranged inside the shell. The sub-shells of the two chambers can rotate relative to the structural shell to ensure that the swing cylinder can rotate normally. Telescopic rods are slidably arranged in the two chambers. The two telescopic rods are respectively rotatably connected to the two opposite ends of the swing cylinder and are arranged on both sides of the rotation point of the swing cylinder. The two chambers are connected to the reversing valve on the side away from the telescopic rod. Hydraulic oil is injected into one of the chambers through the control oil circuit, and the hydraulic oil in the other chamber flows out and returns to the control oil circuit, thereby realizing the driving of the swing cylinder to rotate.

[0034] Preferably, the driving element adopts a split structure, and the rotating driving element includes a first hydraulic cylinder and a second hydraulic cylinder. The telescopic working end of the first hydraulic cylinder and the telescopic working end of the second hydraulic cylinder are respectively rotatably connected to the two opposite ends of the swing cylinder and are arranged on both sides of the rotation point of the swing cylinder; the control oil circuit injects oil into one of the hydraulic cylinders through the reversing valve, and the hydraulic oil in the other hydraulic cylinder flows out to the control circuit, thereby achieving the purpose of extending the telescopic working end of one hydraulic cylinder and retracting the telescopic working end of the other hydraulic cylinder, thereby driving the swing cylinder to rotate around its rotation point. The hydraulic cylinder has a simple structure and is easy to control.

[0035] Moreover, the first hydraulic cylinder and the second hydraulic cylinder have the same structure, both of which include a hydraulic cylinder body, an oil storage chamber is provided inside the hydraulic cylinder body, the oil storage chamber is provided with an oil port, and the oil port is communicated with the internal oil circuit of the reversing valve; a piston is slidably provided inside the hydraulic cylinder body, the piston of the first hydraulic cylinder is the first piston, and the piston of the second hydraulic cylinder is the second piston, the first piston and the second piston are respectively connected to the swing cylinder for rotation, and are arranged on both sides of the swing cylinder rotation point. In this embodiment, the two rotation drive elements are respectively the first rotation drive element and the second rotation drive element, the first rotation drive element includes the first hydraulic cylinder A31 and the second hydraulic cylinder A32, and the second rotation drive element includes the first hydraulic cylinder B33 and the second hydraulic cylinder B34.

[0036] A further optimized solution further includes a rotating flange, which is detachably connected to the swing cylinder, and the telescopic working end of the first hydraulic cylinder and the telescopic working end of the second hydraulic cylinder are both rotatably connected to the rotating flange, and the telescopic working end of the first hydraulic cylinder and the telescopic working end of the second hydraulic cylinder are respectively arranged on both sides of the rotation point of the swing cylinder and the rotating flange. In this embodiment, the rotating drive element is provided with two groups, namely the first rotating drive element and the second rotating drive element, so there are two rotating flanges, namely the first rotating flange 51 and the second rotating flange 52, the first rotating flange 51 and the swing cylinder of the first two-way variable pump-motor 11 are detachably connected, and the second rotating flange 52 and the swing cylinder of the second two-way variable pump-motor 12 are detachably connected. The rotating flange is rigidly connected to the swing cylinder by nuts or screws, so that the rotating flange and the swing cylinder can move synchronously, that is, the rotating flange and the swing cylinder can rotate synchronously with the swing cylinder rotation point, and the telescopic working ends of the first hydraulic cylinder and the second hydraulic cylinder are respectively rotatably connected to the rotating flange and are respectively arranged on both sides of the rotation point, ensuring that the changes in the oil inlet and outlet of the first hydraulic cylinder and the second hydraulic cylinder can rotate the rotating flange, thereby driving the swing cylinder to rotate.

[0037] The reversing valve in this embodiment can be a two-position four-way reversing valve, a three-dimensional four-way reversing valve or a four-position four-way reversing valve, etc. When the reversing valve is a two-position four-way reversing valve, a second oil inlet pipe 73 and a second oil outlet pipe 74 are connected between the two-position four-way reversing valve and the control oil circuit, and the valve core has a first conduction position and a second conduction position: when the valve core of the reversing valve is in the first conduction position, the first hydraulic cylinder and the second oil inlet pipe 73 are connected, and the second hydraulic cylinder and the second oil outlet pipe 74 are connected; when the valve core of the reversing valve is in the second conduction position, the first hydraulic cylinder and the second oil outlet pipe 74 are connected, and the second hydraulic cylinder and the second oil inlet pipe 73 are connected; based on the rotation of the cam, the valve core of the two-position four-way reversing valve is switched between the first conduction position and the second conduction position.

[0038] A further optimized solution is that the reversing valve is a three-position four-way reversing valve, and a second oil inlet pipe 73 and a second oil outlet pipe 74 are connected between the three-position four-way reversing valve and the control oil circuit, and the three-position four-way reversing valve is respectively connected to the first hydraulic cylinder and the second hydraulic cylinder; the valve core of the three-position four-way reversing valve has a first conducting position, an intermediate position and a second conducting position: when the valve core of the three-position four-way reversing valve is in the first conducting position, the first hydraulic cylinder and the second oil inlet pipe 73 are connected, and the second hydraulic cylinder and the second oil outlet pipe 74 are connected; when the three-position four-way reversing valve is in the intermediate position, no hydraulic oil flows between the first hydraulic cylinder and the second hydraulic cylinder; when the valve core of the reversing valve is in the second conducting position, the first hydraulic cylinder and the second oil outlet pipe 74 are connected, and the second hydraulic cylinder and the second oil inlet pipe 73 are connected; based on the rotation of the cam, the valve core of the reversing valve is switched between the first conducting position, the intermediate position and the second conducting position. In this embodiment, two three-position four-way reversing valves are provided, namely a first three-position four-way reversing valve 21 and a second three-position four-way reversing valve 22. The first three-position four-way reversing valve 21 is connected to the first rotary drive element, and the second three-position four-way reversing valve 22 is connected to the second rotary drive element.

[0039] The three-position four-way reversing valve has three working positions. In the first conducting position and the second conducting position, the oil inlet and outlet conditions of the first hydraulic cylinder and the second hydraulic cylinder change. When the three-position four-way reversing valve is in the middle position, no hydraulic oil enters or exits the first hydraulic cylinder and the second hydraulic cylinder, the swing angle of the swing cylinder of the two-way variable pump is zero degrees, and no hydraulic oil flows out of the two-way variable pump, which facilitates the precise control of the rotation direction of the two-way variable pump and the control of the flow rate of the two-way variable pump.

[0040] The first cam driving assembly and the second cam driving assembly can use the cam to directly drive the reversing valve to move, or the cam can drive other components to move and then drive the reversing valve to move, so as to realize the switching of the reversing valve core at different positions. When the cam is used to directly drive the reversing valve to move, the following structure can be used: the eccentric radius of each part of the cam is different, that is, the cam adopts a shape with different aspect ratios, such as an elliptical structure, and the outer circumference of the cam is provided with grooves with different aspect ratios, such as an elliptical groove, and a sliding member is embedded in the groove and slidably connected, and the sliding member is rotatably connected with the valve core of the reversing valve, and the valve core is slidably arranged inside the reversing valve, and the plane where the sliding member is located is in the same plane as the plane where the valve core moves, and the cam is arranged on one side of the reversing valve, and the reversing valve is detachably connected to the entire device. When working, the cam rotates, and since the outer circumference of the cam is provided with grooves with different aspect ratios, the rotation of the cam drives the sliding member and the valve core to slide, and the sliding direction is consistent with the sliding direction of the valve core and the reversing valve, so as to realize the switching of the first conduction position and the second conduction position of the reversing valve.

[0041] Preferably, when the cam drives other components to move and then drives the reversing valve to move, the cam driving mechanism also includes a cam variable rod, which is rotatably connected to the valve core of the three-position four-way reversing valve; based on the rotation of the cam, the cam variable rod swings in a preset plane, so that the valve core of the three-position four-way reversing valve switches between the first conduction position, the middle position, and the second conduction position. In this embodiment, two cam variable rods are provided, namely, a first cam variable rod 41 and a second cam variable rod 42, the first cam variable rod 41 is rotatably connected to the first three-position four-way reversing valve 21, and the second cam variable rod 42 is rotatably connected to the second three-position four-way reversing valve 22.

[0042] The three-position four-way reversing valve is rotatably installed inside the system, and the three-position four-way reversing valve can rotate relative to each other, so that the valve core and the three-position four-way reversing valve are offset to adapt to the position change caused by the rotation of the cam variable rod, and ensure that the cam variable rod can rotate normally. The cam variable rod is driven to rotate by the cam driving element. Since the valve core is slidably arranged inside the reversing valve, the cam variable rod drives the valve core to move inside the reversing valve, thereby realizing the switching of the valve core of the three-position four-way reversing valve between the first conduction position, the middle position and the second conduction position. In this embodiment, the valve core is fixedly connected with a driving rod, and one end of the driving rod is rotatably connected with a pin shaft, and the pin shaft is rotatably connected with the cam variable rod, thereby realizing the rotation connection between the valve core and the cam variable rod. Of course, the rotation connection between the valve core and the cam variable rod can also be realized by other methods, for example, the valve core is fixedly connected with a driving bracket, and the driving bracket is parallel to the movement plane of the valve core, that is, the driving bracket and the movement plane of the valve core are in two parallel planes, and the driving bracket and the cam variable rod are rotatably connected through the pin shaft or other components, ensuring that the cam variable rod can switch the working position of the three-position four-way reversing valve.

[0043] The cam driving element can choose direct drive or indirect drive to realize the rotation of the cam variable rod; for example, when the cam driving element chooses indirect drive, the cam driving element includes a motor, the output shaft of the motor is detachably connected to the camshaft, the camshaft is detachably connected to the cam, and other transmission mechanisms such as a deflection wheel and a connecting rod are arranged between the cam and the cam variable rod to convert the rotational motion of the cam into the rotational motion of the cam variable rod, and the cam variable rod can only rotate within the moving plane of the valve core.

[0044] In a further optimized solution, the cam driving element includes a camshaft 62, which is detachably connected to the cam. The cam is spirally extended along its own axis to form a guide groove on the outer circumference of the cam. The cam and the cam variable rod are rotatably connected in the guide groove, and the camshaft 62 is driven by a motor 61. In this embodiment, a group of cam driving elements are provided, and the first cam 63 and the second cam 64 can be detached and sleeved on the camshaft 62, and the first cam 63 and the second cam 64 are driven to rotate simultaneously by a camshaft 62. The camshaft 62 is driven to rotate by the motor 61, and the rotation of the camshaft 62 drives the cam to rotate. Since the cam and the cam variable rod are rotatably connected in the guide groove, the guide groove is annular and inclinedly arranged on the circumference of the cam, and the cam variable rod is rotatably connected to the valve core of the reversing valve, the cam variable rod has a position limit, ensuring that the cam variable rod can only rotate in the moving plane of the valve core. There are fewer direct drive elements, more sensitive driving, and more convenient operation. Preferably, one end of the camshaft 62 is detachably connected to the output shaft of the motor 61 via a coupling, and the other end of the camshaft 62 is rotatably connected to the mounting seat via a bearing, ensuring that the camshaft 62 can only rotate along its axis.

[0045] To further optimize the solution, a sliding groove is provided at one end of the cam variable rod away from the cam driving element, and a pin is rotatably connected to the rotating flange, and the pin is movably arranged in the sliding groove. The cam driving element drives the cam variable rod to rotate, and the changes in the oil inlet and outlet of the first hydraulic cylinder and the second hydraulic cylinder drive the rotating flange to rotate. The rotating flange can drive the pin to move in the sliding groove to ensure that the movement of the two will not interfere or get stuck, and ensure that the cam variable rod and the rotating flange can rotate independently. Through the connection between the cam variable rod and the rotating flange, it is ensured that the cam variable rod can only move within the plane of the valve core movement, and the rotation angle of the rotating flange and the swing cylinder is limited by the setting of the sliding groove.

[0046] In this embodiment, the main oil circuit is connected with the first oil inlet pipe 71 and the first oil outlet pipe 72, and the main oil circuit includes the first oil circuit and the second oil circuit. A one-way valve 75 is connected between the first oil circuit and the first oil inlet pipe 71, and between the second oil circuit and the first oil inlet pipe 71. The first oil circuit and the second oil circuit are respectively connected with the first oil outlet pipe 72; the two ends of the bidirectional variable pump-motor are respectively connected with the first oil circuit and the second oil circuit. Since the bidirectional variable pump-motor in this embodiment is a bidirectional structure, the two ends of the bidirectional variable pump-motor are respectively connected with the first oil circuit and the second oil circuit in the main oil circuit. When the bidirectional variable pump-motor is in pump working condition, one of the oil circuits provides hydraulic oil to the bidirectional variable pump-motor, and the bidirectional variable pump-motor provides high-pressure hydraulic oil to the other oil circuit.

[0047] The first oil inlet pipe 71 enters from ES, and the first oil outlet pipe 72 flows out from AS. The first oil inlet pipe 71 provides hydraulic oil to the first oil circuit and the second oil circuit respectively through two one-way valves 75, and the excess hydraulic oil of the first oil circuit and the second oil circuit flows out from the first oil outlet pipe 72. In this embodiment, the first oil inlet pipe 71 and the first oil outlet pipe 72 are normally in a sealed state. When the hydraulic oil in the main circuit is reduced, the hydraulic oil is supplied to the main oil circuit through the first oil inlet pipe 71, so that the main oil circuit can work normally.

[0048] Further optimization scheme, a high-pressure relief valve 76 is arranged between the first oil circuit and the second oil circuit, the overflow port of the high-pressure relief valve 76 is connected to a shuttle valve 77, the shuttle valve 77 is connected to a solenoid valve 78 and a high-pressure sensor, and the solenoid valve 78 is connected to an oil return port. The high-pressure relief valve 76 serves as a system pressure guarantee. When the system exceeds the limit pressure, the excess hydraulic oil is transmitted to the shuttle valve 77 through the overflow port. The shuttle valve 77 is a straight-stroke valve, which is a valve that combines a valve body and an actuator. The high-pressure sensor measures the pressure of the hydraulic oil in the shuttle valve 77, and controls its opening through the solenoid valve 78 to flow the excess hydraulic oil in the shuttle valve 77 back to the oil return port. In this embodiment, two high-pressure sensors are arranged, namely a first high-pressure sensor 79 and a second high-pressure sensor 80. The first high-pressure sensor 79 is used to detect the pressure of the hydraulic oil in the shuttle valve 77, and the second high-pressure sensor 80 is used to measure the pressure of the hydraulic oil in the main oil circuit.

[0049] When the whole system is working, it is necessary to establish the working oil pressure required by the load. First, the solenoid valve 78 is energized, the engine speed signal of the whole machine is input, and the solenoid valve 78 has different openings to adjust the starting pressure in the main oil circuit to prevent excessive pressure, excessive speed fluctuations, and engine flameout. The pressure in the main oil circuit is slowly accumulated to achieve a smooth start of the entire cylindrical cam variable pump control system.

[0050] Further optimization scheme, flushing valves 80 are provided between the first oil circuit and the first oil outlet pipe 72, and between the second oil circuit and the first oil outlet pipe 72. The flushing valves 80 in this embodiment can be provided separately, or a flushing valve 80 can be shared. When the whole system continues to work for a long time, the oil temperature of the high-pressure circuit will become higher and higher. The hydraulic oil is supplied to the main oil circuit through the first oil inlet pipe 71, and the excess hydraulic oil flows out through the flushing valve 80 and the first oil outlet pipe 72, so that the replacement of the hydraulic oil reduces the temperature of the main oil circuit and improves the stability of the whole system.

[0051] Further optimizing the scheme, the bidirectional variable pump-motor mechanism also includes a third bidirectional variable pump-motor 13, and the third bidirectional variable pump-motor 13 also includes a pump working condition and a motor working condition. The third bidirectional variable pump-motor 13 includes a third swing cylinder that is rotatably arranged, and the third swing cylinder is used to control the third bidirectional variable pump-motor 13 to supply hydraulic oil to the main oil circuit. A synchronous rotating rod 54 is connected between the third swing cylinder and the adjacent swing cylinder. In this embodiment, the first bidirectional variable pump-motor 11, the second bidirectional variable pump-motor 12 and the third bidirectional variable pump-motor 13 are arranged in parallel, that is, the two ends of the first bidirectional variable pump-motor 11, the second bidirectional variable pump-motor 12 and the third bidirectional variable pump-motor 13 are respectively connected to the first oil circuit and the second oil circuit. In this embodiment, the third swing cylinder is detachably connected to the third rotating flange 53, and the third rotating flange 53 is arranged in parallel with the second rotating flange 52, and the third rotating flange 53 is arranged flush with one end of the second rotating flange 52, and the third rotating flange 53 and the second rotating flange 52 are connected at this end through a synchronous rotating rod 54 to ensure that when the second swing cylinder rotates, the third swing cylinder is driven to rotate synchronously.

[0052] like Figure 1 The stepless speed pump-motor cam combined control system shown in the figure describes the working process by taking the initial swing angles and corresponding displacements of the first bidirectional variable pump-motor 11, the second bidirectional variable pump-motor 12 and the third bidirectional variable pump-motor 13 (arranged from left to right) as examples: zero displacement (0°), maximum forward displacement (45°), and maximum reverse displacement (45°). In this application scenario, the shape of the second cam 64 is changed so that in the initial state of this embodiment, no matter whether the camshaft 62 rotates clockwise or counterclockwise, the second cam variable rod 42 will drive the second three-position four-way reversing valve 22 to move right, so that the second three-position four-way reversing valve 22 switches to the first conduction position (left position). The working process is described as follows:

[0053] When the motor 61 drives the camshaft 62 to rotate counterclockwise, the starting swing angles and corresponding displacements of the first bidirectional variable pump-motor 11, the second bidirectional variable pump-motor 12 and the third bidirectional variable pump-motor 13 (arranged from left to right) are: zero displacement (0°), maximum forward displacement (45°), and maximum reverse displacement (45°). The motor 61 drives the camshaft 62 to rotate counterclockwise, and the valve core of the first three-position four-way reversing valve 21 moves rightward, so that the first three-position four-way reversing valve 21 switches to the first conducting position (left position), the first hydraulic cylinder A31 takes in oil, the second hydraulic cylinder A32 presses oil, the first piston in the first rotating drive element extends, the second piston shortens, the first rotating flange 51 and the first swing cylinder swing counterclockwise, thereby increasing the swing angle of the first bidirectional variable pump-motor 11 to a maximum of 45° (at this time, the first bidirectional variable pump-motor 11 is in pump working condition), generating a high-pressure flow output to be supplied to the second bidirectional variable pump-motor 12 and the third bidirectional variable pump-motor 13 (at this time, the second bidirectional variable pump-motor 12 and the third bidirectional variable pump-motor 13 are in motor working condition). At the same time, the rotation of the second cam variable rod 42 will drive the second three-position four-way reversing valve 22 to move rightward, so that the second three-position four-way reversing valve 22 switches to the first conduction position (left position), so that the first hydraulic cylinder of the second rotary drive element enters oil, the second hydraulic cylinder discharges oil, the first piston in the second rotary drive element extends, and the second piston shortens, driving the second rotary flange 52 to rotate, thereby driving the second two-way variable pump-motor 12 to reduce the second rotation swing angle, to a minimum of 0°. At the same time, through the connection of the synchronous rotation rod 54, the rotation of the second two-way variable pump-motor 12 swing cylinder will simultaneously drive the third two-way variable pump-motor 13 swing cylinder to rotate, so that the swing angle of the third two-way variable pump-motor 13 is synchronously reduced to a controllable value (which can be adjusted according to the actual layout relationship). When the swing angles of the first bidirectional variable pump-motor 11, the second bidirectional variable pump-motor 12 and the third bidirectional variable pump-motor 13 (arranged from left to right) move to the maximum swing angle, zero position, and minimum swing angle respectively, at this moment, the third bidirectional variable pump-motor 13 can be switched to the pump operating state, and the first bidirectional variable pump-motor 11 can be switched to the motor operating state (optional).

[0054] When the motor 61 drives the camshaft 62 to rotate clockwise, the initial swing angles and corresponding displacements of the first bidirectional variable pump-motor 11, the second bidirectional variable pump-motor 12 and the third bidirectional variable pump-motor 13 (arranged from left to right) are: zero displacement (0°), maximum forward displacement (45°), and maximum reverse displacement (45°). The motor 61 drives the camshaft 62 to rotate clockwise, and the valve core of the first three-position four-way reversing valve 21 moves to the left, so that the first three-position four-way reversing valve 21 switches to the second conducting position (right position), the first hydraulic cylinder A31 discharges oil, and the second hydraulic cylinder A32 enters oil, the first piston in the first rotating drive element shortens, and the second piston extends, and the first rotating flange 51 and the first swing cylinder swing clockwise, thereby increasing the swing angle of the first bidirectional variable pump-motor 11 to a maximum of -30° (at this time, the first bidirectional variable pump-motor 11 is in pump working condition), generating a high-pressure flow output to be supplied to the second bidirectional variable pump-motor 12 and the third bidirectional variable pump-motor 13 (at this time, the second bidirectional variable pump-motor 12 and the third bidirectional variable pump-motor 13 are in motor working condition). At the same time, the rotation of the second cam variable rod 42 will drive the second three-position four-way reversing valve 22 to the left position, so that the first hydraulic cylinder of the second rotary drive element enters oil and the second hydraulic cylinder discharges oil, driving the corresponding piston to produce displacement, driving the second rotary flange 52 to rotate, thereby driving the second two-way variable pump-motor 12 to reduce the second rotation swing angle, and the minimum angle is the minimum angle. At the same time, through the connection of the synchronous rotation rod 54, the rotation of the second two-way variable pump-motor 12 swing cylinder will simultaneously drive the third two-way variable pump-motor 13 swing cylinder to rotate, so that the swing angle of the third two-way variable pump-motor 13 is synchronously reduced to a controllable value (which can be adjusted according to the actual layout relationship). When the swing angles of the first bidirectional variable pump-motor 11, the second bidirectional variable pump-motor 12 and the third bidirectional variable pump-motor 13 (arranged from left to right) respectively move to the maximum reverse swing angle, the minimum swing angle (not equal to zero degrees), and the minimum swing angle 2 (slightly larger than the minimum swing angle when the cam rotates counterclockwise), at this moment, the third bidirectional variable pump-motor 13 is still in the motor operating condition, and the first bidirectional variable pump-motor 11 is still in the pump operating condition (optional).

[0055] The present invention also includes other situations, which are not listed here. The starting swing angles and corresponding displacements of the first bidirectional variable pump-motor 11, the second bidirectional variable pump-motor 12 and the third bidirectional variable pump-motor 13 (arranged from left to right) can be set according to actual conditions.

[0056] The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for a person skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

[0057] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0058] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0059] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A stepless speed variable pump-motor cam joint control system, characterized in that: include: A bidirectional variable pump-motor mechanism, the bidirectional variable pump-motor mechanism includes two bidirectional variable pump-motors communicated through a main oil circuit, the bidirectional variable pump-motors each include a rotatably arranged swing cylinder, the swing cylinder is used to control the bidirectional variable pump-motor to supply hydraulic oil to the main oil circuit; the bidirectional variable pump-motor includes a pump operating condition and a motor operating condition, and the operating conditions of the two bidirectional variable pump-motors are different; A cam driving mechanism, the cam driving mechanism includes a first cam driving assembly, a second cam driving assembly and a control oil circuit; the first cam driving assembly and the second cam driving assembly have the same structure and both include a cam, a cam driving element and a rotation driving element, the rotation driving element is detachably connected to the swing cylinder, a reversing valve is connected between the rotation driving element and the control oil circuit, the control oil circuit drives the rotation driving element to work, the cam driving element drives the cam to rotate, based on the rotation of the cam, the reversing valve switches the working position to control the reversing rotation of the rotation driving element.

2. The continuously variable speed pump-motor cam combined control system according to claim 1, characterized in that: The rotary drive element comprises a first hydraulic cylinder and a second hydraulic cylinder, wherein the telescopic working end of the first hydraulic cylinder and the telescopic working end of the second hydraulic cylinder are respectively rotatably connected to two opposite ends of the swing cylinder and are arranged on both sides of the rotation point of the swing cylinder.

3. The continuously variable speed pump-motor cam combined control system according to claim 2, characterized in that: The rotary drive element also includes a rotary flange, which is detachably connected to the swing cylinder. The telescopic working end of the first hydraulic cylinder and the telescopic working end of the second hydraulic cylinder are both rotatably connected to the rotary flange. The telescopic working end of the first hydraulic cylinder and the telescopic working end of the second hydraulic cylinder are respectively arranged on both sides of the rotation point of the swing cylinder and the rotary flange.

4. The continuously variable speed pump-motor cam combined control system according to claim 2, characterized in that: The reversing valve is a three-position four-way reversing valve, a second oil inlet pipe and a second oil outlet pipe are connected between the three-position four-way reversing valve and the control oil circuit, and the three-position four-way reversing valve is respectively connected to the first hydraulic cylinder and the second hydraulic cylinder; the valve core of the three-position four-way reversing valve has a first conducting position, a middle position and a second conducting position: When the valve core of the three-position four-way reversing valve is in the first conducting position, the first hydraulic cylinder is connected to the second oil inlet pipe, and the second hydraulic cylinder is connected to the second oil outlet pipe; When the three-position four-way reversing valve is in the middle position, no hydraulic oil flows between the first hydraulic cylinder and the second hydraulic cylinder; When the valve core of the reversing valve is in the second conducting position, the first hydraulic cylinder is connected to the second oil outlet pipe, and the second hydraulic cylinder is connected to the second oil inlet pipe; Based on the rotation of the cam, the valve core of the reversing valve is switched between the first conducting position, the middle position and the second conducting position.

5. The stepless speed change pump-motor cam combined control system according to claim 4, characterized in that: The first cam driving assembly and the second cam driving assembly both further include a cam variable rod, which is rotationally connected to the valve core of the three-position four-way reversing valve; based on the rotation of the cam, the cam variable rod swings within a preset plane, so that the valve core of the three-position four-way reversing valve switches between the first conduction position, the middle position and the second conduction position.

6. The continuously variable speed pump-motor cam combined control system according to claim 1, characterized in that: The cam driving element includes a camshaft, which is detachably connected to the cam. The cam is spirally extended along its own axis to form a guide groove on the outer circumference. The cam is rotatably connected to the cam variable rod in the guide groove. The camshaft is driven by a motor.

7. The continuously variable speed pump-motor cam combined control system according to claim 1, characterized in that: The main oil circuit is connected with a first oil inlet pipe and a first oil outlet pipe, and the main oil circuit includes a first oil circuit and a second oil circuit. A one-way valve is connected between the first oil circuit and the first oil inlet pipe, and between the second oil circuit and the first oil inlet pipe. The first oil circuit and the second oil circuit are respectively connected with the first oil outlet pipe; both ends of the bidirectional variable pump-motor are respectively connected with the first oil circuit and the second oil circuit.

8. The continuously variable speed pump-motor cam combined control system according to claim 7, characterized in that: A high-pressure relief valve is provided between the first oil circuit and the second oil circuit, an overflow port of the high-pressure relief valve is connected to a shuttle valve, the shuttle valve is connected to a solenoid valve and a high-pressure sensor, and the solenoid valve is connected to an oil return port.

9. The continuously variable speed pump-motor cam combined control system according to claim 7, characterized in that: Flushing valves are provided between the first oil circuit and the first oil outlet pipe, and between the second oil circuit and the first oil outlet pipe.

10. The continuously variable speed pump-motor cam combined control system according to claim 1, characterized in that: The bidirectional variable pump-motor mechanism also includes a third bidirectional variable pump-motor, and the third bidirectional variable pump-motor includes a third rotatable swing cylinder. The third swing cylinder is used to control the third bidirectional variable pump-motor to supply hydraulic oil to the main oil circuit, and a synchronous rotating rod is connected between the third swing cylinder and the adjacent swing cylinder.

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