CN116241426A

CN116241426A - Hydraulic system's oil pressure electric control mechanism and variable pump

Info

Publication number: CN116241426A
Application number: CN202211093976.9A
Authority: CN
Inventors: 王德超
Original assignee: Nanjing Zhuoyi Control Technology Co ltd
Current assignee: Ningbo Shunxin Hydraulic Technology Co.,Ltd.
Priority date: 2022-09-08
Filing date: 2022-09-08
Publication date: 2023-06-09
Anticipated expiration: 2042-09-08
Also published as: CN116241426B

Abstract

The utility model relates to an oil pressure electric control mechanism of a hydraulic system, which comprises a valve body and a valve core, wherein the valve core is arranged in a valve core cavity of the valve body, a motor is arranged on the valve body, and an output shaft of the motor is directly or indirectly connected with the valve core to drive the valve core to rotate or move; the method is characterized in that: the valve is characterized in that a piston cavity is further formed in the valve body, a piston is arranged in the piston cavity, the piston cavity is divided into a left pressure cavity and a right pressure cavity, the area of a left stress surface of the piston, acted by pressure oil in the left pressure cavity, is larger than that of a right stress surface of the piston, the piston is provided with a rack part, and a gear meshed with the rack part is arranged on an output shaft of the motor. The hydraulic electric control mechanism of the hydraulic system is simple and reasonable in structure and does not need to adopt a pressure sensor. The utility model also relates to a variable displacement pump.

Description

Hydraulic system's oil pressure electric control mechanism and variable pump

Technical Field

The utility model belongs to the field of fluid transmission and control, and particularly relates to an oil pressure electric control mechanism and a variable pump of a hydraulic system.

Background

The variable displacement pump is a pump of variable displacement. The variable pump can be a single-acting vane pump, a radial plunger pump or an axial plunger pump, and is widely used in the hydraulic transmission fields of metallurgy, mines, engineering machinery, ships, civil aviation ground equipment and the like. The variable pump radial plunger pump comprises a piston eccentric type and a shaft eccentric type, and the axial plunger type comprises a swash plate type and an inclined shaft type. The bidirectional variable displacement pump is a pump, and is a method of changing displacement by changing a variable displacement mechanism such as a tilting direction or a compression ratio of a swash plate of an axial plunger pump, etc., with a rotation direction of a prime mover unchanged. If the original direction is northeast-southwest, the northwest-southeast direction is changed, the original oil suction port of the variable pump is changed into an oil outlet, and the original oil outlet is changed into an oil suction port, namely the flow direction of liquid flow is changed. In a closed circuit, the direction of rotation of the load is changed, for example, a swash plate pump rotates a swash plate and a cylinder body, oil is absorbed on one side of a plunger in the cylinder body, and oil is pressed on one side.

The variable plunger pump controls the angle of the sloping cam plate by the control mechanism by depending on the outlet pressure, thereby controlling the stroke of the plunger and achieving the purpose of controlling the flow; the variable vane pump controls the eccentric amount of the eccentric ring by the control mechanism by depending on the outlet pressure so as to achieve the purpose of controlling the flow; that is, variable pump systems of different kinds can control the variable size by the stroke amount of the mechanism of the variable, for example: when the variable plunger swash plate is perpendicular to the input shaft, the pump discharge flow is zero when the variable vane pump eccentric amount is 0.

However, the existing pressure control and flow control are realized through various complex oil ways, various problems can occur in the pollution degree of oil liquid, the existing closed loop system is unstable, the existing closed loop system is realized by a feedback mechanism such as an expensive servo valve, a pressure sensor, a flow sensor and the like, the pressure sensor needs to be continuously regulated through complex software operation to control the required pressure, the response speed of the pressure sensor depends on the complex algorithm and calculation speed of the feedback and chip operation of the sensor and the comprehensive response of the control mechanism, the requirement on the control system is higher, the cost is relatively higher, and a pressure sensor component is added, so that a certain fault rate is increased. The existing pressure feedback mechanism can be further improved. Various valves (such as reversing valves) and variable pumps are commonly applied in the liquid-gas transmission industry, one of the cores in the reversing valves and the variable pumps is a valve core (also called a piston) stroke control mechanism, and the reversing valves always use the thrust generated after the electromagnetic coil is electrified to drive the valve core of the reversing valve to move so as to realize hydraulic or pneumatic reversing, so that the running direction of a hydraulic or pneumatic executive component is changed. The existing electromagnetic reversing valve has the following defects: 1. the electromagnetic valve is required to be commutated, electromagnetic force is required to be always pushed, the power-losing valve core is reset, but in some occasions, pressure is required to be kept all the time, at the moment, the reversing valve is required to be kept in a reversing state all the time, heating and power consumption can be generated when the electromagnetic coil is electrified for a long time, and the service life of the coil is greatly shortened. 2. The electromagnetic coil can only push the valve core with small diameter, the valve core with large diameter needs to be pushed by controlling hydraulic pressure and hydraulic pressure through the electromagnetic valve, and the response time of the electro-hydraulic reversing valve is prolonged due to the two-stage conversion. 3. The common electromagnetic valve or the electrohydraulic reversing valve only has a plurality of states of opening, closing and reversing, can not realize the control of the opening degree, and has limited application range.

One of the chinese utility models patent No. zl201220164212.X (bulletin No. CN 202579037U) discloses a piston stroke control mechanism, which includes a limit switch, a limit screw, a guide key, and other limit devices. The method is characterized in that: an upper flange is arranged at the upper end of the variable housing, the motor base is fixed on the upper flange by screws, the pull rod is connected with the variable nut by screws, the screw rod is connected with a motor shaft of the servo motor by taper pins, an upper limit switch and a lower limit switch are arranged on the motor base of the servo motor, and the upper limit screw and the lower limit screw are connected with the variable nut by a limit bracket and a guide key.

The motor of the patent drives displacement through a screw rod. According to the transmission ratio, the motor rotates for a plurality of turns, the screw rod can advance for 1mm, the motor setting speed is too high, the step loss is caused by insufficient torque, the variable speed is very slow due to proper speed, the stroke of the variable valve core of the variable pump is usually about 20mm, and the maximum stroke variable can be completed in a few seconds by using the stepping motor.

In view of the above, the existing valve element travel control mechanism for valves and variable displacement pumps needs to be further improved.

Disclosure of Invention

The first technical problem to be solved by the utility model is to provide an oil pressure electric control mechanism of a hydraulic system which has a simple and reasonable structure and does not need to adopt a pressure sensor aiming at the prior art.

The technical scheme adopted by the utility model for solving the first technical problem is as follows: the oil pressure electric control mechanism of the hydraulic system comprises a valve body and a valve core, wherein the valve core is arranged in a valve core cavity of the valve body, a motor is arranged on the valve body, and an output shaft of the motor is directly or indirectly connected with the valve core to drive the valve core to rotate or move; the method is characterized in that: the valve is characterized in that a piston cavity is further formed in the valve body, a piston is arranged in the piston cavity, the piston cavity is divided into a left pressure cavity and a right pressure cavity, the area of a left stress surface of the piston, acted by pressure oil in the left pressure cavity, is larger than that of a right stress surface of the piston, the piston is provided with a rack part, and a gear meshed with the rack part is arranged on an output shaft of the motor.

Preferably, the piston is divided into a left section, a middle section and a right section, the left section extends into the left pressure chamber, the right section extends into the right pressure chamber, and the rack part is arranged in the middle section. The structure can enable the left pressure cavity and the right pressure cavity to be independent of each other, pressure oil in the left pressure cavity and the right pressure cavity cannot enter a piston cavity part where an output shaft of the motor is located, and rotation of the motor is not affected by the pressure oil.

Further improved, an axially-through connecting flow passage is arranged in the piston, and the connecting flow passage is used for communicating the left pressure cavity with the right pressure cavity. The structure can simplify the oil way, and only one way of oil way is communicated with the left pressure cavity or the right pressure cavity, and can be the pressure oil with the same oil pressure communicated with the two sides of the left pressure cavity and the right pressure cavity. If the connecting flow passage is not provided, the pressure oil passage is divided into two paths and is respectively communicated with the left pressure cavity and the right pressure cavity.

Further improved, the valve core cavity comprises an upper pressure cavity positioned at the upper end of the valve core; the valve core is provided with a pressure oil port and an oil return port, and also comprises a rotating shaft which extends into the upper pressure cavity and is inserted into the valve core, an output shaft of the motor is connected with the rotating shaft so as to drive the rotating shaft to rotate, and a chute which is always communicated with the upper pressure cavity is arranged on the peripheral wall of the rotating shaft; the rotation of the rotating shaft can enable the chute to be communicated with one of the pressure oil port and the oil return port so that the valve core moves upwards or downwards, and the valve core stops moving under the state that the pressure oil port and the oil return port are blocked with the chute. Wherein the chute has a certain length and is arranged along the peripheral wall of the rotating shaft to form a spiral groove.

The valve element stroke control mechanism has the following advantages.

1. The rotary shaft is driven to rotate, so that the chute is communicated with one of the pressure oil port and the oil return port, and the oil pressure in the upper pressure cavity is changed; when the pressure oil port (for example, the rotating shaft positively rotates the chute and the pressure port is communicated with the chute), the oil pressure of the upper pressure cavity is increased, so that the force of the pressure oil acting downwards on the valve core is increased, the valve core can move downwards (the opening between the chute and the oil port can be slowly reduced to 0 along with the downward movement amount), and the valve core stops; when the oil return port is communicated with the chute, the oil pressure of the upper pressure cavity is reduced, so that the force of the pressure oil acting downwards on the valve core is reduced, and the valve core can be stopped by moving upwards (the opening degree is reduced to 0 in the same way). The larger the rotation angle is, the larger the opening is, the larger the movement amount is, the rotation angle amount of the rotation shaft is converted into the up-and-down movement amount of the valve core, the control mechanism can control the maximum stroke displacement of the valve core by only controlling the rotation shaft to rotate within the range of about 100 degrees or even smaller angle, the speed time can be often completed within a few milliseconds, the control mechanism has good dynamic response characteristics, no complex algorithm is used, the mechanical automatic tracking is realized only by using a mature servo motor or a stepping motor, and in addition, the core components of the control mechanism are the rotation shaft and the valve core, so the control mechanism has simple mutual matching relation, low cost and simple and reasonable structure.

2. The force required for driving the rotation shaft to rotate is small and negligible, for example, a servo motor can be adopted to easily drive the valve core to rotate, and even if the valve core with a large diameter is driven, the energy consumption is small, and the energy is saved.

3. When the valve core moves to the set position, the pressure oil port and the oil return port are blocked with the chute, the upper pressure cavity is not filled with oil or drained with oil, the upper end and the lower end of the valve core are stressed and balanced, the valve core can be kept at the set position without always supplying power, and the situation that the electromagnetic coil is always in an electric state is avoided in the traditional electromagnetic valve to keep the set position of the valve core is avoided.

4. The intermittent forward or reverse rotation of the rotating shaft is a decomposition action so as to fully show the axial movement process and principle of the valve core, thereby facilitating the thorough understanding of the utility model by those skilled in the art; in practical applications, of course, the rotation of the rotary shaft may be continuous, and the displacement of the spool may be continuous, based on a pre-designed program and given parameters. Therefore, the displacement of the valve core can be precisely controlled by controlling the rotation angle of the rotating shaft.

5. The rotary shaft can be conveniently driven to rotate, if the servo motor is adopted, the motor can accurately control the rotation angle of the motor, the motor can rapidly control the whole control stroke, the motor only needs to rotate by 100 degrees or less, the rotation angle can be accurately controlled through the encoder, the rotation angle of the motor can be converted into the position of the valve core moving up and down through the rotary shaft, the current valve core position can be read through the rotary encoder, the stroke of the valve core is controlled, and the precision of the control mechanism is improved.

6. Of course, the hydraulic electric control mechanism of the hydraulic system can be used in other fields or products, such as variable plunger pumps, variable gear pumps, variable vane pumps, hydraulic valves, hydraulic cylinders and hydraulic transformers.

7. The opening degree (flow control) of the hydraulic valve core is controlled and decided to be increased through a certain angle of rotation of the motor, namely the motor rotates (limiting torque) - - - - - - - - > drives the pilot valve core (rotating shaft) - - - - - > main valve core opening degree to be increased- - - > pressure to be larger than motor limiting torque- - > the piston pushes the motor to reversely rotate- - - - - > pilot and main valve core reducing opening degree- - - > pressure to be reduced to be balanced; this is done: control motor torque upper limit= (pressure control) and control motor rotation angle upper limit= (opening control) (flow control).

The above is a specific way of acting the valve core. Of course, the output shaft of the motor can be connected with a transmission screw rod, and the transmission screw rod is connected with the valve core in a transmission way. The output shaft of the motor is directly connected with the valve core, and the rotation of the output shaft of the motor drives the valve core to rotate, so that the application scene can be a traditional hydraulic switch valve.

As an improvement, a thrust mechanism which acts on the valve core to enable the valve core to move upwards is also included. The thrust mechanism is arranged, so that pressure difference can be formed at the upper end and the lower end of the valve core more easily, after the oil is discharged and discharged from the upper pressure cavity, the valve core can move upwards better under the action of the thrust mechanism, and when the oil is fed into the upper pressure cavity for pressurization, the force of the upper pressure cavity acting on the valve core is larger than the force of the thrust mechanism acting on the valve core, so that the valve core moves downwards better.

Alternatively, the thrust mechanism is a spring acting on the lower end of the valve core, and when the pressure oil port is communicated with the chute, the force acting on the valve core by the upper pressure cavity is larger than the force acting on the valve core by the spring, and the valve core moves downwards; when the oil return port is communicated with the chute, the force of the upper pressure cavity acting on the valve core is smaller than the force of the spring acting on the valve core, and the valve core moves upwards; the upward movement or the downward movement of the valve core can enable the pressure oil port and the oil return port to be blocked with the chute. The spring is adopted to provide upward thrust for the valve core, and the valve has the advantages of simple structure and low cost.

Preferably, the thrust mechanism is a lower pressure cavity positioned at the lower end of the valve core, and the lower pressure cavity is connected with the oil inlet. The thrust mechanism is favorable for oil pressure supply, and the oil inlet is formed in the valve body, so that the design is more reasonable. The oil pressure is adopted to provide upward thrust for the valve core, so that the valve has the advantage of high precision control, and the high control precision can be maintained even if the valve is used for a long time. The pressure oil of the upper pressure cavity and the pressure oil of the lower pressure cavity can be provided by the same pressure oil way and are divided into two paths which are respectively connected into the upper pressure cavity and the lower pressure cavity from the outside of the valve core. Or may be provided by different pressure oil paths. The key is that when oil is fed into the upper pressure cavity and the lower pressure cavity, a pressure difference is formed, so that the valve core can be controlled to move upwards or downwards by changing the pressure difference.

Further improved, the valve core is internally provided with a connecting flow passage used for communicating the pressure oil port and the lower pressure cavity, and the area of the pressure oil in the upper pressure cavity acting on the upper stress surface of the valve core is larger than that of the pressure oil in the lower pressure cavity acting on the lower stress surface of the valve core. The structure can ensure that the oil pressure of the upper pressure cavity and the oil pressure of the lower pressure cavity are provided by the same oil port, so that the channel inside the valve body can be simplified better; after the pressure oil in the lower pressure cavity enters the upper pressure cavity through the connecting flow channel, the pressure in the upper pressure cavity is equal to the pressure in the lower pressure cavity, and the pressure difference is easily generated at the two ends of the valve core due to the difference of the areas of the stress surfaces, so that the movement of the valve core can be controlled. The oil pressure is adopted to provide upward thrust for the valve core, the control precision is high, the control precision can be kept even if the valve core is used for a long time, the oil pressure is easy to generate balance at two ends of the valve core, the valve core is effectively ensured to be kept at a certain set position, namely, the connecting flow passage and the oil return opening are in a blocking state with the chute, the pressure oil does not enter the upper pressure cavity any more, meanwhile, the upper pressure cavity is not communicated with the oil return opening, the upper pressure cavity does not enter oil nor drain, the valve core moves to the limit position, the hydraulic oil of the upper pressure cavity cannot be compressed any more, and therefore the stress of the upper end and the lower end of the valve core reaches balance, so that the valve core is kept at the set position.

Specifically, based on the area difference of the stress surfaces, when the pressure oil port is communicated with the chute, pressure oil enters the upper pressure cavity, the force of the upper pressure cavity acting on the valve core is larger than the force of the lower pressure cavity acting on the valve core, and the valve core moves downwards; when the oil return port is communicated with the chute, the pressure oil is discharged out of the upper pressure cavity, the oil pressure is reduced, the force of the upper pressure cavity acting on the valve core is smaller than the force of the lower pressure cavity acting on the valve core, and the valve core moves upwards; the upward movement or the downward movement of the valve core can enable the pressure oil port and the oil return port to be blocked with the chute.

If the oil inlet is directly communicated with the lower pressure cavity, when the pressure of the oil inlet is unstable, certain fluctuation is generated, the fluctuation can be directly reflected in the lower pressure cavity, the pressure is increased or reduced, the stress balance of the valve core is broken, the valve core or the axial movement is adjusted, the upper pressure cavity is further communicated with the connecting flow channel or the oil return port until the valve core is rebalanced, the valve core stroke control is unstable, and the valve core stroke control is further improved according to the current situation. After the pressure reaches the balance, even if the pressure of the oil inlet fluctuates to a certain extent, if the pressure of the oil inlet decreases to a certain extent, the pressure oil in the lower pressure cavity cannot reversely flow to the oil inlet due to the existence of the check valve, so that the valve core still keeps balance.

Preferably, the lower end of the lower pressure cavity is provided with a plug for sealing, and the one-way valve is arranged in an inner cavity of the plug. The structure can be used for arranging the one-way valve in the plug in advance, and then the plug provided with the one-way valve is directly arranged at the lower end opening of the lower pressure cavity, so that the assembly is more convenient.

Preferably, in a state that the chute is blocked from both the pressure oil port and the oil return port, the pressure oil port and the oil return port are respectively positioned at two sides of the chute. Therefore, the rotary shaft can rotate in one direction to enable the chute to be communicated with the pressure oil port and the connecting runner, and rotate in the opposite direction to enable the chute to be communicated with the oil return port. The control is facilitated, the motor can rotate in a smaller angle range, and the axial movement of the valve core is realized. The digital control is easy to realize through a circuit for controlling the rotation of the motor. The motor integrated control circuit can control the rotating shaft through input signals.

If the valve core moves axially beyond the design range, the control mechanism may be damaged, as an improvement, the outer wall of the valve core is provided with an outer stop shoulder, the inner wall of the valve core cavity is provided with an inner stop shoulder, and the inner stop shoulder forms a block for the outer stop shoulder when the valve core moves downwards to the limit position. The gear of the inner retaining shoulder and the gear of the outer retaining shoulder are matched to restrain the limit movement position of the valve core, so that safety is improved.

Compared with the prior art, the oil pressure electric control mechanism of the hydraulic system has the advantages that:

1. the oil pressure electric control mechanism can control the torque force of the motor, can be used for sensing and feeding back the current pressure, saves a pressure sensor and effectively reduces the cost.

2. The motor only needs to output controllable torsion, the purpose of pressure control can be achieved without calculation, and the response is extremely fast, because the mechanical feedback is forced to rotate reversely.

3. The feedback pressure can not be too big, otherwise the output shaft rotation of motor receives the resistance too big, leads to the motor to be unable to normally work, if want to make the resistance little, then must do very little with the area of atress of piston, this can make piston processing inconvenient, and with the fracture, for solving this problem, we will left the pressure oil in the pressure chamber the area of the left atress face of piston be greater than the area of the right atress face of piston that the pressure oil in the pressure chamber of right side acted on, form feedback pressure through pressure difference, only need control left atress face and right atress face area difference can, can do big with the piston cross-sectional area like this, ensure that piston processing is convenient, and bulk strength strengthens.

The second technical problem to be solved by the utility model is to provide a variable pump which has a simple and reasonable structure and does not need to adopt a pressure sensor aiming at the prior art.

The utility model solves the second technical problem by adopting the technical proposal that: a variable displacement pump comprising a variable head, characterized in that: the variable head is connected with the valve core in a swinging way, so that the axial movement of the valve core drives the variable head to swing. The variable valve core is connected with the valve core in a swinging way through a ball head structure. The ball head structure can enable the axial movement of the valve core to drive the variable head to swing more easily.

Compared with the prior art, the variable pump has the advantages that: the variable pump can realize the control of output pressure without arranging a pressure sensor, effectively reduces the cost, controls the swing angle of the variable head through the axial movement amplitude of the valve core, has good dynamic response characteristic by adopting the valve core stroke control mechanism, and can accurately control the displacement of the valve core by controlling the rotation angle of the rotating shaft.

Drawings

FIG. 1 is a schematic perspective view of a variable displacement pump according to an embodiment of the present utility model;

FIG. 2 is a schematic diagram showing a second perspective structure of an embodiment of the variable displacement pump of the present utility model;

FIG. 3 is a cross-sectional view of an embodiment of the variable displacement pump of the present utility model (with a chute in communication with the return port);

FIG. 4 is a cross-sectional view taken along A-A of FIG. 3; FIG. 5 is a B-B cross-sectional view of FIG. 3;

FIG. 6 is a cross-sectional view of a variable displacement pump of the present utility model showing both the chute and the pressure port and the return port blocked;

FIG. 7 is a C-C cross-sectional view of FIG. 3;

FIG. 8 is a cross-sectional view of an embodiment of the variable displacement pump of the present utility model (chute in communication with the pressure port);

FIG. 9 is a D-D sectional view of FIG. 8;

FIG. 10 is a sectional view taken along E-E of FIG. 8;

FIG. 11 is a schematic perspective view of a rotary shaft according to the present utility model;

FIG. 12 is a schematic perspective view of a piston according to the present utility model;

FIG. 13 is a schematic perspective view of a valve core according to the present utility model;

FIG. 14 is a schematic diagram showing a three-dimensional structure of a valve core according to the present utility model;

fig. 15 is a schematic view of the hydraulic principle of the present utility model.

Detailed Description

The utility model is described in further detail below with reference to the embodiments of the drawings.

As shown in fig. 1 to 15, a preferred embodiment of the variable displacement pump of the present utility model employing a spool stroke control mechanism is shown.

The variable pump comprises a variable head and an oil pressure electric control mechanism of a hydraulic system, wherein the variable head 2 is in swinging connection with the valve core 3, so that the axial movement of the valve core 3 drives the variable head 2 to swing. The variable valve 2 and the valve core 3 are connected in a swinging way through a ball head structure. The remainder of the variable displacement pump refers to existing variable displacement pump configurations.

The oil pressure electric control mechanism of the hydraulic system comprises a valve body 1 and a valve core 3, wherein the valve core 3 is arranged in a valve core cavity of the valve body 1 and can axially move, a motor 7 is arranged on the valve body 1, the motor 7 is preferably a servo motor, and an output shaft 71 of the motor 7 is indirectly connected with the valve core 3 to drive the valve core 3 to move.

As shown in fig. 7 and 15, a piston chamber is further provided in the valve body 1, the piston chamber and the spool chamber are independent from each other, a piston 8 is provided in the piston chamber, the piston 8 can move left and right, the piston chamber is divided into a left pressure chamber 9a and a right pressure chamber 9b, the area of a left stress surface 8a of the piston 8 acted by pressure oil in the left pressure chamber 9a is larger than the area of a right stress surface 8b of the piston 8 acted by pressure oil in the right pressure chamber 9b, the piston 8 has a rack portion 821, and a gear 72 meshed with the rack portion 821 is provided on an output shaft 71 of the motor 7. The piston 8 is divided into a left section 81, a middle section 82 and a right section 83, wherein the left section 81 extends into the left pressure cavity, the right section 83 extends into the right pressure cavity, and the rack portion 821 is arranged in the middle section 82.

As a modification, an axially penetrating engagement flow passage 84 is provided in the piston 8, and the engagement flow passage 84 communicates the left pressure chamber 9a with the right pressure chamber 9 b.

The valve core 3 in this embodiment is columnar, a sealing ring is arranged between the periphery of the valve core and the valve core cavity, the valve body 1 is internally provided with the valve core cavity, the valve core 3 is arranged in the valve core cavity and can axially move, the valve core 3 only moves up and down and cannot rotate to be optimal, for example, a certain section of the cross section of the valve core 3 is in a non-circular structure, and the cross section of a section of the valve core cavity at a corresponding position is also in a non-circular structure, so that the valve core 3 can only move up and down. The valve core 3 is provided with a pressure oil port P and an oil return port T, and specifically, the valve core 3 divides a valve core cavity into an upper pressure cavity 11 and a lower pressure cavity 12. The valve further comprises a thrust mechanism acting on the valve core 3 to enable the valve core 3 to move upwards, wherein the thrust mechanism in the embodiment is a lower pressure cavity 12 positioned at the lower end of the valve core 3, and the lower pressure cavity 12 is connected with an oil inlet 14 of the valve body 1. The outer wall of the valve core 3 is provided with an outer stop shoulder 33, the inner wall of the valve core cavity is provided with an inner stop shoulder 13, and when the valve core 3 moves downwards to the limit position, the inner stop shoulder 13 forms a stop for the outer stop shoulder 33.

The rotary valve further comprises a rotary shaft 5 which extends into the upper pressure cavity 11 and is inserted into the valve core 3, a bearing can be arranged between the rotary shaft 5 and the inner hole wall of the valve body 1, and the rotary friction force of the rotary shaft 5 is reduced. The top surface of case 3 is opened and is supplied rotation axis 5 male jack, is equipped with motor 7 on the valve body 1, and the output of motor 7 peg graft in rotation axis 5's upper end and be in the same place through the pin joint, can set up the universal joint between motor 7's output shaft and the rotation axis 5, can eliminate the error and guarantee good concentricity to can drive rotation axis 5 rotation.

The peripheral wall of the rotary shaft 5 is provided with a chute 51 which is always communicated with the upper pressure chamber 11, and the chute 51 is a chute structure having a certain length and being inclined along the peripheral wall of the rotary shaft 5, thereby having a certain spiral shape. The rotation of the rotating shaft 5 enables the chute 51 to be communicated with the pressure oil port P and the oil return port T alternatively, or enables the chute 51 to be blocked from the pressure oil port P and the oil return port T; when the pressure oil port P is communicated with the chute 51, pressure oil enters the upper pressure cavity 11, the force of the upper pressure cavity 11 acting on the valve core 3 through the pressure oil is larger than the force of the lower pressure cavity 12 acting on the valve core 3 through the pressure oil, and the valve core 3 moves downwards; when the oil return port T is communicated with the chute 51, the upper pressure cavity 11 starts to discharge oil, the oil pressure is reduced, the force acting on the valve core 3 by the upper pressure cavity 11 is smaller than the force acting on the valve core 3 by the lower pressure cavity 12, and the valve core 3 moves upwards; the up-and-down movement of the valve core 3 can block the pressure oil port P and the oil return port T from the chute 51.

The pressure oil port P in this embodiment is communicated with the lower pressure cavity 12, the valve core 3 is provided with a connecting flow channel 31 for communicating the pressure oil port P with the lower pressure cavity 12, the rotation of the rotation shaft 5 can enable the chute 3 to be alternatively communicated with the pressure oil port P and the oil return port T, or enable the chute 3 to be blocked from the pressure oil port P and the oil return port T, the area of the pressure oil in the upper pressure cavity 11 acting on the upper stress surface 3a of the valve core 3 is larger than the area of the pressure oil in the lower pressure cavity 12 acting on the lower stress surface 3b of the valve core 3, the axial movement of the valve core 3 can enable the pressure oil port P and the oil return port T to be blocked from the chute 51, so that oil is neither fed nor discharged from the upper pressure cavity 11, and the upper pressure and the lower pressure of the valve core are balanced. In a state where both the pressure oil port P and the oil return port T are blocked from the chute 51, inlet ends of the pressure oil port P and the oil return port T are located at both sides of the chute 51, respectively.

The oil inlet 14 communicates with said lower pressure chamber 12 via a non-return valve 4. The lower end of the lower pressure cavity 12 is provided with a plug 6 for sealing, and the one-way valve 4 is arranged in the inner cavity of the plug 6.

Of course, the thrust mechanism may also be a spring acting on the lower end of the spool 3, and as a preferred spring may be placed in the lower pressure chamber 12. When the pressure oil port P is communicated with the chute 51, the force of the upper pressure cavity 11 acting on the valve core 3 through pressure oil is larger than the force of the spring acting on the valve core 3, and the valve core 3 moves downwards; when the oil return port T is communicated with the chute 51, the force of the upper pressure cavity 11 acting on the valve core 3 is smaller than the force of the spring acting on the valve core 3, and the valve core 3 moves upwards; the upward movement or the downward movement of the valve core 3 can cause the pressure oil port P and the oil return port T to be blocked from the chute 51. This embodiment is not shown in the drawing.

The working principle and the working process of the variable pump are as follows:

1. by controlling the motor 7 to rotate forward, the output control of the valve or variable displacement pump is made to increase the flow rate linearly, and the flow rate is made to decrease the flow rate linearly in reverse.

2. The output pressure to be controlled is loaded on the motor 7 through the gear 72 and the rack portion 821 of the piston 8, and is opposed to the torque of the motor 7, and when the thrust of the piston 8 is greater than the torque of the motor 7, it is reversed, so that the flow output of the variable displacement pump or valve is reduced, and the required output pressure is reduced.

3. By controlling the torque of the motor 7. When the output pressure acts on the piston 8, it is generated

1) Thrust Ft < torque Fd of motor 7, motor 7 is rotated forward to the desired angular position

2) Thrust Ft > torque Fd of motor 7, motor 7 is reversed, the displacement is reduced to reduce the pressure until ft=fd is balanced, i.e. torque control of motor 7 effects control of the pressure.

When the motor 7 drives the rotary shaft 5 to rotate forward by an angle, as shown in fig. 3-6, the chute 51 on the rotary shaft 7 is communicated with the oil return port T, the pressure oil in the upper pressure cavity 11 is discharged through the chute 51 and the oil return port T, the upper pressure cavity 11 is depressurized, and the pressure oil of the oil inlet 14 flows to the lower pressure cavity 12 through the one-way valve 4, so that the valve core 3 moves upwards under the action of oil pressure. The larger the angle by which the rotary shaft 5 rotates in this direction, the greater the distance by which the spool 3 moves upward. When the motor 7 stops working, the valve core 3 moves up to the chute 3 to be blocked with the pressure oil port P and the oil return port T, as shown in fig. 6, the upper pressure cavity 11 is not decompressed any more, no pressure oil can enter again, the force of the upper pressure cavity 11 acting on the valve core 3 and the force of the lower pressure cavity 12 acting on the valve core 3 are just balanced, and the valve core 3 is kept at the position.

On the contrary, when the motor 7 drives the rotary shaft 5 to reversely rotate by an angle, as shown in fig. 8 to 10, the chute 51 on the rotary shaft 7 is communicated with the pressure oil port P, the pressure oil of the oil inlet 14 flows to the lower pressure cavity 12 through the one-way valve 4, and simultaneously flows to the upper pressure cavity 11 after passing through the connecting flow passage 31 and the chute 51, so that the pressures in the upper pressure cavity 11 and the lower pressure cavity 12 reach the same, but the area of the pressure oil in the upper pressure cavity 11 acting on the upper stress surface 3a of the valve core 3 is larger than the area of the pressure oil in the lower pressure cavity 12 acting on the lower stress surface 3b of the valve core 3, and a differential is formed under the condition that the pressures are the same, namely the downward pressure applied to the valve core 3 is larger than the upward pressure, and the valve core 3 moves downwards axially. The larger the angle by which the rotary shaft 5 rotates in this direction, the greater the distance by which the spool 3 moves downward. When the motor 7 stops working, the valve core 3 moves down to the chute 3 and is blocked by the pressure oil port P and the oil return port T, the upper pressure cavity 11 does not have pressure oil to enter again and does not release pressure, the force of the upper pressure cavity 11 acting on the valve core 3 through the pressure oil and the force of the lower pressure cavity 12 acting on the valve core 3 through the pressure oil are just balanced, and the valve core 3 is kept at the position.

According to the variable pump, the swing angle of the variable head 2 is changed, the swing angle of the variable head 2 is driven by the axial movement of the valve core 3, and finally the flow rate of oil discharged by the variable pump in unit time (namely the displacement of the pump) is realized. Which is a conventional design of variable displacement pump.

The intermittent forward or reverse rotation of the rotary shaft 5 is a decomposition action to fully exhibit the up-and-down movement process and principle of the valve core 3, so that the present utility model is well understood by those skilled in the art; in practice, of course, the rotation of the rotary shaft 5 may be continuous, and the displacement of the valve core 3 may be continuous, based on a pre-designed program and given parameters. Therefore, the displacement of the valve core 3 can be precisely controlled by the rotation angle of the motor 7 to the rotation shaft 5.

It should be noted that, in the description of the present embodiment, the directions or positional relationships indicated by the terms "front, rear", "left, right", "inner, outer", "upper, lower", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the apparatus or element to be referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model. The terms "mounted," "connected," "coupled," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

Claims

1. The oil pressure electric control mechanism of the hydraulic system comprises a valve body (1) and a valve core (3), wherein the valve core (3) is arranged in a valve core cavity of the valve body (1), a motor (7) is arranged on the valve body (1), and an output shaft (71) of the motor (7) is directly or indirectly connected with the valve core (3) to drive the valve core (3) to rotate or move; the method is characterized in that: still be equipped with the piston chamber in valve body (1), be equipped with piston (8) in the piston chamber, the piston chamber divide into left pressure chamber (9 a) and right pressure chamber (9 b), the area that the pressure oil in left pressure chamber (9 a) acted on left stress surface (8 a) of piston (8) is greater than the area that the pressure oil in right pressure chamber (9 b) acted on right stress surface (8 b) of piston (8), piston (8) have rack portion (821), be equipped with on output shaft (71) of motor (7) with gear (72) of rack portion (821) meshing.

2. The oil pressure electric control mechanism of a hydraulic system according to claim 1, characterized in that: the piston (8) is divided into a left section (81), a middle section (82) and a right section (83), the left section (81) stretches into the left pressure cavity, the right section (83) stretches into the right pressure cavity, and the rack part (821) is arranged in the middle section (82).

3. The oil pressure electric control mechanism of a hydraulic system according to claim 1, characterized in that: an axially-through connecting flow passage (84) is arranged in the piston (8), and the connecting flow passage (84) communicates the left pressure cavity (9 a) with the right pressure cavity (9 b).

4. The oil pressure electric control mechanism of a hydraulic system according to claim 1, characterized in that: the valve core cavity comprises an upper pressure cavity (11) positioned at the upper end of the valve core (3); the valve core (3) is provided with a pressure oil port (P) and an oil return port (T), and further comprises a rotating shaft (5) which extends into the upper pressure cavity (11) and is inserted into the valve core (3), an output shaft of the motor (7) is connected with the rotating shaft (5) so as to drive the rotating shaft (5) to rotate, and a chute (51) which is always communicated with the upper pressure cavity (11) is arranged on the peripheral wall of the rotating shaft (5); the rotation of the rotating shaft (5) can enable the chute (51) to be communicated with one of the pressure oil port (P) and the oil return port (T) so that the valve core moves upwards or downwards, and the valve core stops moving under the state that the pressure oil port (P) and the oil return port (T) are blocked with the chute (51).

5. The oil pressure electric control mechanism of a hydraulic system according to claim 4, wherein: and a thrust mechanism acting on the valve core to enable the valve core to move upwards.

6. The oil pressure electric control mechanism of a hydraulic system according to claim 8, wherein: the thrust mechanism is a spring acting on the lower end of the piston (3), when the pressure oil port (P) is communicated with the chute (51), the force acting on the piston (3) by the upper pressure cavity (11) is larger than the force acting on the piston (3) by the spring, and the piston (3) moves downwards; when the oil return port (T) is communicated with the chute (51), the force of the upper pressure cavity (11) acting on the piston (3) is smaller than the force of the spring acting on the piston (3), and the piston (3) moves upwards; the upward movement or the downward movement of the piston (3) can enable the pressure oil port (P) and the oil return port (T) to be blocked with the chute (51).

7. The oil pressure electric control mechanism of a hydraulic system according to claim 5, wherein: the thrust mechanism is a lower pressure cavity (12) positioned at the lower end of the piston (3), and the lower pressure cavity (12) is connected with an oil inlet (14) of the valve body (1). The piston (3) is internally provided with a connecting flow passage (31) for communicating the pressure oil port (P) and the lower pressure cavity (12), and the area of the pressure oil in the upper pressure cavity (11) acting on the upper stress surface (3 a) of the piston (3) is larger than the area of the pressure oil in the lower pressure cavity (12) acting on the lower stress surface (3 b) of the piston (3); when the pressure oil port (P) is communicated with the chute (51), the force of the upper pressure cavity (11) acting on the valve core (3) is larger than the force of the lower pressure cavity (12) acting on the valve core (3), and the valve core (3) moves downwards; when the oil return port (T) is communicated with the chute (51), the force of the upper pressure cavity (11) acting on the valve core (3) is smaller than the force of the lower pressure cavity (12) acting on the valve core (3), and the valve core (3) moves upwards; the upward movement or the downward movement of the valve core (3) can enable the pressure oil port (P) and the oil return port (T) to be blocked with the chute (51).

8. The oil pressure electric control mechanism of a hydraulic system according to claim 6, wherein: the oil inlet (14) is communicated with the lower pressure cavity (12) through a one-way valve (4).

9. The oil pressure electric control mechanism of a hydraulic system according to claim 4, wherein: under the state that chute (51) and pressure hydraulic fluid port (P) and oil return port (T) all block, pressure hydraulic fluid port (P) and oil return port (T) are located respectively the both sides of chute (51) the outer wall of case (3) has outer fender shoulder (33), the inner wall in valve core chamber has interior fender shoulder (13), moves to extreme position under case (3), interior fender shoulder (13) form the stopper to outer fender shoulder (33).

10. Variable displacement pump, including variable head (2), its characterized in that: the hydraulic electric control mechanism according to any one of claims 1 to 9 is further included, and the variable head (2) is connected with the valve core (3) in a swinging way, so that the axial movement of the valve core (3) drives the variable head (2) to swing.