CN115256317A

CN115256317A - Automatic oil return mechanism and hydraulic tool

Info

Publication number: CN115256317A
Application number: CN202210924299.4A
Authority: CN
Inventors: 翟艳英; 刘丽静; 周明涛
Original assignee: Beijing Tianze Electric Power Group Co ltd
Current assignee: Beijing Tianze Electric Power Group Co ltd
Priority date: 2022-08-03
Filing date: 2022-08-03
Publication date: 2022-11-01

Abstract

The invention relates to the technical field of hydraulic pressure, and discloses an automatic oil return mechanism and a hydraulic tool. The hydraulic tool comprises the automatic oil return mechanism and is also provided with a motor, a hydraulic pump, an oil tank, a piston and a working head, wherein the motor is used for driving the hydraulic pump, the hydraulic pump is used for pumping hydraulic liquid in the oil tank into a working cavity of the piston to drive the piston to move, and the working head moves between an opening position and a closing position through the movement of the piston to perform a pressing or cutting action. The invention can automatically operate and automatically return oil and release pressure by one-key pressing operation, and has high automation degree.

Description

Automatic oil return mechanism and hydraulic tool

Technical Field

The invention relates to the technical field of hydraulic pressure, in particular to an automatic oil return mechanism and a hydraulic tool.

Background

Hydraulic crimping and/or cutting tools are commonly used to perform predetermined connection operations, such as for crimping connectors on electrical wires or hydraulic pipes and for crimping rivets, or for cutting operations, such as cutting electrical wires during installation and maintenance of electrical systems.

Such tools typically include an electric motor powered by an electric battery and hydraulic conduits that increase the hydraulic fluid pressure acting on the piston to move the piston against the bias of a compression spring. A piston is connected to the working head (the working head includes a movable jaw and a fixed jaw), and the piston actuates the movable jaw to move the movable jaw relative to the fixed jaw of the tool during a pressing operation. The jaws can be shaped and/or provided with interchangeable auxiliary elements in order to adapt to a specific object, such as an electrical contact to be pressed or a metal bar to be cut.

When the compaction or cutting is finished, the pressure of hydraulic liquid acting on the piston needs to be relieved, and the hydraulic liquid flows back to the oil tank from the working chamber of the piston through the return channel so as to reset the working head to an open state. The method adopted in the prior technical scheme is as follows: install the backwash valve additional on the return channel, the last correlation of backwash valve is provided with manual returning means, the backwash valve can close and open the return channel, in the normality, the backwash valve closes the return channel under the effort of the spring of self always, so that realize the pressure increase of hydraulic fluid in the working chamber of piston, when needs pressure release, stir or press manual returning means, can make the backwash valve overcome the effort of spring and shift out to the outside in order to open the return channel, make high-pressure hydraulic fluid in the working chamber of piston can flow back in the oil tank.

The technical problems in the technical scheme are as follows: the manual returning device needs to be pushed or pressed until the working head is reset to the initial opening position, so that the tool is complex to operate and inconvenient to use, the labor intensity is increased, the automation degree is low, and the use experience of a user is reduced.

In view of the above, it is desirable to develop a new type of return device and hydraulic tool to solve the above technical problems.

Disclosure of Invention

The invention aims to make up for the defects of the prior art, and provides an automatic oil return mechanism and a hydraulic tool, which are simple and convenient to operate, high in automation degree and capable of achieving automatic oil return.

In order to solve the technical problems, the invention adopts the following technical scheme:

in a first aspect, the present invention provides an automatic oil return mechanism, comprising a return valve, a swing rod, a driver, a first sensor, a second sensor, a controller and a power supply;

the return valve is used for controlling the opening and closing of a return channel of the hydraulic liquid, and the return valve in a non-hydraulic liquid return state enables the return channel to be in a closed state under the action of a spring;

the first end of the swing rod is hinged to the outside of the return channel through a first shaft, and the swing rod is movably connected with the return valve; when the swing rod swings around the first shaft to a first position, the swing rod drives the backflow valve to overcome the acting force of the spring to completely open the backflow channel; when the swing rod swings around the first shaft to a second position, the swing rod drives the backflow valve and completely closes the backflow channel under the action of the spring;

the driver is used for driving the swing rod to swing between the first position and the second position around the first shaft;

the first sensor is used for detecting the position of the swing rod;

the second sensor is used for detecting at least one working parameter in the process of pressurizing hydraulic liquid and the process of releasing pressure;

the controller controls the starting of the driver according to the feedback information of the second sensor, and the controller controls the closing of the driver according to the feedback information of the first sensor;

the power supply supplies power to the first sensor, the second sensor, and the controller.

Further, the driver comprises a motor and a cam, the motor is arranged outside the return channel and is powered by the power supply, the cam is arranged at the output end of the motor, and the cam is in contact with the second end of the swing rod; under the drive of the motor, the cam rotates and drives the swing rod to swing between the first position and the second position around the first shaft.

Further, the driver comprises a hydraulic cylinder, a cylinder body of the hydraulic cylinder is hinged to the outside of the backflow channel through a third shaft, and a hydraulic cylinder shaft of the hydraulic cylinder is hinged to the second end of the swing rod through a fourth shaft; the swing rod swings around the first shaft between the first position and the second position under the driving of the hydraulic cylinder.

Further, the operating parameters include a maximum pressure value of the hydraulic fluid during pressurization and a minimum pressure value of the hydraulic fluid during depressurization.

Further, in the process of pressurizing the hydraulic fluid, if the maximum pressure value of the hydraulic fluid collected by the second sensor is equal to or greater than a first parameter preset in the controller, information is fed back to the controller, the controller controls the driver to start and drives the backflow valve to open the backflow channel by using the swing rod, so that pressure relief is realized; in the process of releasing the pressure of the hydraulic fluid, if the minimum pressure value of the hydraulic fluid collected by the second sensor is equal to or less than a second parameter preset in the controller, feeding back information to the controller, controlling the driver to start by the controller, and driving the backflow valve to close the backflow channel by using the swing rod to complete pressure relief;

in the process of pressure relief of hydraulic fluid, the driver can drive the swing rod to swing from the second position to the first position after being started, in the process, if the position of the swing rod, which is acquired by the first sensor, is located at the first position, information is fed back to the controller, and then the controller controls the driver to close, so that the swing rod and the backflow valve are relatively fixed, and the backflow channel is always in the maximum opening state; after hydraulic fluid pressure relief is completed, the driver can drive the swing rod to swing from the first position to the second position after being started, in the process, if the position of the swing rod acquired by the first sensor is located at the second position, information is fed back to the controller, the controller controls the driver to be closed, so that the swing rod and the backflow valve are reset to be in a static state, and the backflow channel is always in a closed state, and the next working cycle is started conveniently.

Further, automatic oil return mechanism still includes the oil return pole, the first end of oil return pole articulates through the second shaft the outside of backward flow passageway, the cover is equipped with the torsional spring just on the second shaft the torsional spring is connected the second shaft with between the oil return pole under the effort of torsional spring the second end of oil return pole with the second end contact of pendulum rod, just the oil return pole is configured into: when no external force intervenes the oil return rod makes the pendulum rod can not drive the reflux valve is opened the backward flow passageway, when external force intervenes the oil return rod is ordered about and winds the second shaft swing, so that the pendulum rod can drive the reflux valve is opened completely the backward flow passageway.

Furthermore, the swing rod and the oil return rod are oppositely arranged and encircle the periphery of the return channel.

Furthermore, a high-pressure needle valve is further arranged on the reflux valve.

In a second aspect, the present invention provides a hydraulic tool, comprising an electric motor, a hydraulic pump, an oil tank, a piston and a working head, wherein the electric motor is used for driving the hydraulic pump, the hydraulic pump is used for pumping hydraulic liquid in the oil tank into a working cavity of the piston so as to drive the piston to move, and the working head is mutually moved between an opening position and a closing position through the movement of the piston so as to execute a pressing or cutting action; the hydraulic tool further comprises the automatic oil return mechanism, the motor is powered by the power supply through the controller, when the controller receives a starting instruction and the first sensor detects that the swing rod is located at the second position, the controller controls the power supply to supply power to the motor, the motor starts to work, and when the controller receives a closing instruction and/or the first sensor detects that the swing rod is not located at the second position, the controller controls the power supply not to supply power to the motor, and the motor does not work; the return passage is provided between the working chamber of the piston and the oil tank.

Further, the hydraulic tool also comprises a positioner for realizing the positioning of the spatial position of the hydraulic tool.

Further, the motor is turned on and off by a button integrated on the hydraulic tool, or the motor is turned on and off by a remote controller.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention designs an automatic oil return mechanism, which mainly adopts the principle that a driver drives a swing rod to drive a return valve to open or close a return channel, and adopts a first sensor, a second sensor and a controller to realize automatic setting.

2. The invention is designed with the oil return rod which is used as a manual return mechanism for driving the swing rod to act, and when the pressure boosting process is suddenly interrupted (sudden power failure or manual operation suspension is possible) or the automatic oil return mechanism fails, the oil return rod can be stirred or pressed to drive the swing rod to swing so as to drive the return valve to open the return channel, so that the working head can be reset to the open position.

3. The invention is provided with the swing rod for driving the reflux valve to open or close the reflux channel and the oil return rod for manually controlling the motion of the swing rod, the swing rod and the oil return rod are oppositely arranged and surround the periphery of the reflux channel, the structural design is reasonable, and the whole device is more compact.

Drawings

In order that the advantages of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings.

Fig. 1 is a schematic perspective view of an angle according to a first embodiment of the present invention;

fig. 2 is a schematic perspective view of another angle according to a first embodiment of the present invention;

fig. 3 is a schematic diagram of an internal structure of a second embodiment of the present invention.

The reference numbers are as follows:

1-a storage battery, 2-a controller, 3-a motor, 4-a hydraulic pump, 5-an oil tank, 6-a piston, 7-a working head, 8-a return valve, 9-a swing rod, 10-a motor, 11-a cam, 12-a pressure sensor, 13-a fixed rod, 14-an oil return rod, 15-a button and 16-a high-pressure needle valve.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that embodiments of the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring embodiments of the present invention.

In the following description, a detailed structure will be presented for a thorough understanding of embodiments of the invention. It is apparent that the implementation of the embodiments of the present invention is not limited to the specific details familiar to those skilled in the art. The following detailed description of preferred embodiments of the invention, however, the invention is capable of other embodiments in addition to those detailed.

In the description of the present invention, the term "a and/or B" means all possible combinations of a and B, such as a alone, B alone or a and B, and the term "at least one a or B" or "at least one of a and B" means similar to "a and/or B" and may include a alone, B alone or a and B; the singular forms "a", "an" and "the" may include the plural forms as well; the terms "inboard", "outboard", "longitudinal", "lateral", "upper", "lower", "top", "bottom", and the like, indicate an orientation or positional relationship based on that shown in the drawings, which is for convenience only to describe the invention and does not require that the invention be constructed and operated in a particular orientation and, therefore, should not be construed as limiting the invention; the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Embodiments of the invention are described in further detail below with reference to the accompanying drawings:

example one

As shown in fig. 1 to 3, the present embodiment provides an automatic oil return mechanism, which includes a return valve 8, a swing link 9, a driver, a first sensor (not shown), a second sensor, a controller 2, and a power supply.

In this embodiment, the return valve 8 is mounted on a return channel for the hydraulic liquid, which return channel is formed between the working chamber of the piston 6 and the tank 5, the return valve 8 being able to control the opening and closing of the return channel, and the return valve 8, under the force of a spring, brings the return channel into a closed state in the non-return state of the hydraulic liquid (i.e. when the hydraulic liquid does not need to return from the working chamber of the piston 6 to the tank 5).

The swing rod 9 is designed to be a bending rod with smooth transition at the transition part, the swing rod 9 is wound outside the backflow channel as close as possible, a fixed rod 13 is fixedly connected outside the backflow channel, the first end of the swing rod 9 is hinged to the first end of the fixed rod 13 through a first shaft, the swing rod 9 is further movably connected with the backflow valve 8, and the movable connection means that when the swing rod 9 swings around the first shaft, the swing rod 9 can drive the backflow valve 8 to reciprocate so as to open or close the backflow channel. When the swing rod 9 swings around the first shaft to the first position, the swing rod 9 drives the backflow valve 8 to overcome the acting force of the spring to completely open the backflow channel; when the swing rod 9 swings around the first shaft to the second position, the swing rod 9 drives the backflow valve 8 and completely closes the backflow channel under the action of the spring.

The driver is electrically connected with the controller 2 and is controlled by the controller 2 to open and close, and the driver is used for driving the swing rod 9 to swing between the first position and the second position around the first shaft. The driver includes but is not limited to the following two ways:

preferably, as shown in fig. 1 and 2, the driver may be a motor 10 and a cam 11, the motor 10 is disposed outside the return channel, the motor 10 is preferably, but not limited to, a stepping motor, a main body of the motor 10 is fixed outside the return channel through a connecting disc, the motor 10 may be directly powered by a power supply, the cam 11 is fixedly disposed at an output end of the motor 10, an outer contour of the cam 11 is in contact with a second end of the swing link 9, wherein for better contact between the cam 11 and the second end of the swing link 9 and better power transmission, a planar contact plate is designed at the second end of the swing link 9, and the cam 11 is in contact with a plane of the planar contact plate; under the drive of the motor 10, the cam 11 rotates and drives the oscillating bar 9 to oscillate between the first position and the second position around the first axis.

Preferably, the driver can also be a hydraulic cylinder, a cylinder body of the hydraulic cylinder is hinged to the outside of the backflow channel through a third shaft, and a hydraulic cylinder shaft of the hydraulic cylinder is hinged to the second end of the swing rod 9 through a fourth shaft; the swing rod 9 swings around the first shaft between the first position and the second position under the driving of the hydraulic cylinder. By optimizing the design, the power of the hydraulic cylinder can be designed to be supplied by the hydraulic pump 4 and the oil tank 5 in the second embodiment below under the control of the controller 2.

The second sensor is electrically connected to the controller 2, and the controller 2 controls the activation of the driver based on the feedback information of the second sensor. The second sensor is adapted to detect at least one operating parameter during pressurization and depressurization of the hydraulic fluid. As shown in fig. 1 and 2, the second sensor can be a pressure sensor 12, the operating parameters required to be detected by the pressure sensor 12 include a maximum pressure value of the hydraulic fluid during pressurization and a minimum pressure value of the hydraulic fluid during depressurization, and the pressure sensor 12 is installed on the return channel and is used for detecting a pressure value of the hydraulic fluid in the operating chamber of the piston 6. The pressure value of the hydraulic liquid collected by the pressure sensor 12 is compared with the preset parameter in the controller 2 to judge whether the pressure of the working cavity of the piston 6 needs to be released or whether the pressure of the working cavity of the piston 6 is released; if the maximum pressure value of the hydraulic fluid collected by the pressure sensor 12 in the pressurization process is equal to or greater than a first parameter preset in the controller 2, feeding back the information to the controller 2, controlling the driver to start by the controller 2, and driving the backflow valve 8 to open a backflow channel by using the swing rod 9 to realize pressure relief; if the minimum pressure value of the hydraulic fluid collected by the pressure sensor 12 in the pressure relief process is equal to or less than a second parameter preset in the controller 2, the information is fed back to the controller 2, the controller 2 controls the driver to start and drives the backflow valve 8 to close the backflow channel by using the swing rod 9, so that the pressure relief is completed. In summary, the feedback information from the pressure sensor 12 can indicate the starting time of the drive. Of course, the second sensor is not limited to the pressure sensor 12, nor is the operating parameter limited to the maximum pressure value of the hydraulic liquid during pressurization and the minimum pressure value of the hydraulic liquid during depressurization; the sensor is primarily used to detect a limit parameter for determining the starting time of the drive, and accordingly, the operating parameter can also be set to the same type of parameter as the limit parameter detected by the second sensor.

The first sensor is electrically connected to the controller 2, and the controller 2 controls the closing of the actuator according to the feedback information of the first sensor. The first sensor is used for detecting the position of the swing rod 9, and mainly detects the first position and the second position of the swing rod 9. The first sensor may be a position sensor, which is a sensor that senses the position of the object and converts it into a usable output signal, which may include a touch sensor and a proximity sensor, and which is preferably a magnetic switch. The magnetic switch collects the position of the swing rod 9 and compares the position with position data preset in the controller 2 to judge whether the swing rod 9 swings in place; in the process of pressure relief, the driver drives the swing rod 9 to swing from the second position to the first position after being started, if the position of the swing rod 9 acquired by the magnetic switch is at the first position, information is fed back to the controller 2, the controller 2 controls the driver to close, so that the swing rod 9 and the backflow valve 8 are relatively fixed, and the backflow channel is always in the maximum opening state; after the pressure relief is finished, the driver can drive the swing rod 9 to swing from the first position to the second position after being started, in the process, if the position of the swing rod 9 collected by the magnetic switch is located at the second position, information is fed back to the controller 2, the controller 2 controls the driver to be closed, so that the swing rod 9 and the backflow valve 8 are reset to be in a static state, and the backflow channel is always in a closed state, and the next working cycle is started conveniently. In summary, the feedback information via the magnetic switch can indicate the closing time of the drive.

The power supply supplies power to the motor 10, the first sensor, the second sensor and the controller 2 in the driver, and the power supply can be the storage battery 1 or an external power supply unit connected through a flexible cable or directly supplied by a power supply main.

In this embodiment, the automatic oil return mechanism further includes an oil return rod 14, and the oil return rod 14 is integrally similar to an arc rod and surrounds the outside of the return channel as closely as possible. The first end of oil return rod 14 passes through the second shaft and articulates the second end at dead lever 13, and the second shaft sets up with dead lever 13 relatively fixed, and the cover is equipped with torsion spring (not shown in the figure) and torsion spring connection between second shaft and oil return rod 14 on the second shaft, and the second end of oil return rod 14 contacts with the plane contact plate on the second end of pendulum rod 9 under the effort of torsion spring, and oil return rod 14 is configured as: when no external force intervenes, the oil return rod 14 enables the swing rod 9 not to drive the return valve 8 to open the return channel, and when the external force intervenes, the oil return rod 14 is driven and swings around the second shaft, so that the swing rod 9 can drive the return valve 8 to completely open the return channel. The oil return rod 14 is used as a manual return mechanism for driving the swing rod 9 to move, and when sudden interruption occurs in the pressurization process (sudden power failure or manual operation suspension may occur) or the automatic oil return mechanism fails, the oil return rod 14 can be directly pulled or pressed by a hand to drive the swing rod 9 to swing so as to drive the return valve 8 to open the return channel, so that the working head 7 can be reset to the open position. In order to facilitate the use of the oil return rod 14, a toggle block protruding outward is further designed on the oil return rod 14. In addition, the swing rod 9 and the oil return rod 14 are arranged oppositely and surround the periphery of the return channel, so that the structural design is reasonable, and the whole device is more compact.

In the present embodiment, as shown in fig. 1 and fig. 2, the return valve 8 is further provided with a high pressure needle valve 16, the high pressure needle valve 16 is provided to ensure that the maximum pressure value in the working chamber of the piston 6 does not exceed the maximum pressure-bearing value of the tool, and when the maximum pressure value in the working chamber of the piston 6 reaches the start rating of the high pressure needle valve 16, the high pressure needle valve 16 is automatically opened and depressurized.

Example two

As shown in fig. 1 to 3, the present embodiment provides a hydraulic tool including the automatic oil return mechanism described in the first embodiment. Specifically, the hydraulic tool comprises a controller 2, a motor 3, a hydraulic pump 4, an oil tank 5, a piston 6, a working head 7, a return valve 8, a swing rod 9, a driver, a magnetic switch, a sensor and a power supply, wherein the motor 3, the driver, the first sensor and the second sensor are powered by the power supply through the controller 2. Wherein the electric motor 3 is used for driving the hydraulic pump 4, the hydraulic pump 4 is used for pumping the hydraulic liquid in the oil tank 5 into the working cavity of the piston 6 to drive the piston 6 to move, and the working head 7 is mutually moved between an opening position and a closing position through the action of the piston 6 to execute a pressing or cutting action. And the motor 3 is powered by the power supply through the controller 2, when the controller 2 receives a starting instruction and the first sensor detects that the swing rod 9 is located at the second position, the controller 2 controls the power supply to supply power to the motor 3, so that the motor 3 starts to work, and when the controller 2 receives a closing instruction and/or the first sensor detects that the swing rod 9 is not located at the second position, the controller 2 controls the power supply not to supply power to the motor 3, so that the motor 3 does not work.

In this embodiment, the hydraulic tool further includes a positioner (not shown) for positioning the spatial position of the hydraulic tool, so that the hydraulic tool is provided with a 4G positioning function.

In this embodiment, the electric motor 3 is turned on and off by a button 15 integrated in the hydraulic tool, or the electric motor 3 is turned on and off by a remote controller. Through the design of the remote controller and the long-distance lengthened operating rod, the hydraulic tool can complete high-altitude shearing and other operations or other operations at high altitude and at long distance.

The automatic oil return mechanism is designed, operation can be automatically carried out and oil return and pressure relief can be automatically carried out through one-key pressing operation, the automation degree is high, the design is reasonable, the structure is compact, the use is convenient and fast, the use experience of a user can be improved, and the competitiveness of a product is enhanced.

While there have been shown and described what are at present considered the fundamental principles and essential features of the invention and its advantages, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. An automatic oil return mechanism is characterized by comprising a return valve, a swing rod, a driver, a first sensor, a second sensor, a controller and a power supply;

the first end of the swing rod is hinged to the outside of the return channel through a first shaft, and the swing rod is movably connected with the return valve; when the oscillating bar oscillates to a first position around the first shaft, the oscillating bar drives the backflow valve to overcome the acting force of the spring and completely open the backflow channel; when the swing rod swings around the first shaft to a second position, the swing rod drives the backflow valve and completely closes the backflow channel under the action of the spring;

the first sensor is used for detecting the position of the swing rod;

the second sensor is used for detecting at least one working parameter in the process of pressurizing and depressurizing the hydraulic liquid;

2. The automatic oil return mechanism of claim 1 wherein the driver includes a motor disposed outside the return channel and powered by the power source and a cam disposed at an output end of the motor, the cam contacting the second end of the rocker lever; under the drive of the motor, the cam rotates and drives the swing rod to swing between the first position and the second position around the first shaft.

3. The automatic oil return mechanism of claim 1 wherein the actuator comprises a hydraulic cylinder, a cylinder body of the hydraulic cylinder is hinged outside the return channel by a third shaft, and a cylinder shaft of the hydraulic cylinder is hinged at the second end of the swing link by a fourth shaft; the swing rod swings around the first shaft between the first position and the second position under the driving of the hydraulic cylinder.

4. The automatic oil return mechanism of claim 1 wherein the operating parameters include a maximum pressure value of the hydraulic fluid during pressurization and a minimum pressure value of the hydraulic fluid during depressurization.

5. The automatic oil return mechanism of claim 4,

in the process of pressurizing the hydraulic fluid, if the maximum pressure value of the hydraulic fluid acquired by the second sensor is equal to or greater than a first parameter preset in the controller, feeding information back to the controller, controlling the driver to start by the controller, and driving the backflow valve to open the backflow channel by using the oscillating bar so as to realize pressure relief; in the pressure relief process of the hydraulic fluid, if the minimum pressure value of the hydraulic fluid acquired by the second sensor is equal to or less than a second parameter preset in the controller, feeding information back to the controller, controlling the driver to start by the controller, and driving the backflow valve to close the backflow channel by using the swing rod to complete pressure relief;

6. The automatic oil return mechanism of claim 1, further comprising an oil return rod, wherein a first end of the oil return rod is hinged to the outside of the return channel through a second shaft, a torsion spring is sleeved on the second shaft and connected between the second shaft and the oil return rod, a second end of the oil return rod is in contact with a second end of the swing rod under the action of the torsion spring, and the oil return rod is configured to: when no external force intervenes the oil return rod makes the pendulum rod can not drive the reflux valve is opened the backward flow passageway, when external force intervenes the oil return rod is ordered about and winds the second shaft swing, so that the pendulum rod can drive the reflux valve is opened completely the backward flow passageway.

7. The automatic oil return mechanism of claim 6 wherein the rocker and the oil return rod are disposed opposite to each other and surround the periphery of the return channel.

8. The automatic oil return mechanism of claim 1 wherein the return valve is further provided with a high pressure needle valve.

9. A hydraulic tool comprises an electric motor, a hydraulic pump, an oil tank, a piston and a working head, wherein the electric motor is used for driving the hydraulic pump, the hydraulic pump is used for pumping hydraulic liquid in the oil tank into a working cavity of the piston to drive the piston to move, the working head is moved between an opening position and a closing position through the movement of the piston to execute a pressing or cutting action, the hydraulic tool is characterized by further comprising the automatic oil return mechanism as claimed in any one of claims 1 to 8, wherein the electric motor is powered by the power supply through the controller, when the controller receives a starting instruction and the first sensor detects that the swing rod is located at the second position, the controller controls the power supply to supply power to the electric motor, so that the electric motor starts to operate, and when the controller receives a closing instruction and/or the first sensor detects that the swing rod is not located at the second position, the controller controls the power supply not to supply power to the electric motor, so that the electric motor does not operate; the return passage is provided between the working chamber of the piston and the oil tank.

10. A hydraulic tool as in claim 9 further comprising a positioner for effecting positioning of the spatial position of the hydraulic tool.

11. A hydraulic tool as in claim 9 wherein the motor is turned on and off using a button integrated into the hydraulic tool or a remote control.