CN221858279U - Lubricating oil duplex filter - Google Patents

Abstract

The utility model discloses a lubricating oil double filter, comprising: a filter head, a first filter tank, a second filter tank, a switching valve and a balancing valve core; the first filter tank and the second filter tank are both installed at the upper end of the filter head; the valve body of the switching valve is rotatably connected in the filter head and its side wall can correspond to the oil inlet of the first filter tank or the second filter tank; the lower part of the switching handle is hinged on the outer wall of the valve body; a valve cavity is opened in the valve body, and an oil through port is opened on the side wall of the valve body and connects the valve cavity with the oil inlet of the first filter tank or the oil inlet of the second filter tank; the balancing valve core is elastically connected to the inner wall of the valve cavity; the switching end face of the switching handle is an inclined surface arranged at an angle to the moving direction of the balancing valve core, and the other end of the balancing valve core penetrates the side wall of the valve body and abuts against the switching end face to push or release the balancing valve core to open or block the oil through port. The lubricating oil double filter designed by the utility model can reduce the switching torque, reduce the difficulty of operation, and has a simple and compact structure, reduces its volume, and improves its impact and vibration resistance.

Description

A lubricating oil double filter

Technical Field

The utility model relates to the technical field of lubricating oil filtering, and more specifically to a lubricating oil double filter.

Background Art

The filter can filter out impurities in the lubricating oil. However, as the filter is used, it will gradually become clogged, which will reduce the filter's flow performance and even cause the filter to be clogged. In order to avoid the filter's flow performance being reduced and clogged, the filter needs to be cleaned every once in a while. When cleaning the filter, the filter needs to be disassembled and cleaned before being reinstalled and put into use, which greatly reduces the work efficiency. Therefore, by combining two filters to form a double filter, the two filters can work independently without interfering with each other. When one filter is clogged, the other filter can still operate normally to ensure the normal operation of the system.

However, the existing duplex filter has the following problems:

1) Due to the certain pressure difference between the two filters, it is necessary to overcome greater resistance when switching, which makes the operation more difficult and may also cause oil leakage, environmental pollution and other problems;

2) Two filters are usually switched by a combination of two three-way valves, six-way valves, cylindrical valves, cone valves, etc. The structure is complex, the volume is large, and the impact and vibration resistance is poor;

3) Existing filters usually use filter screens for simple filtering, which has poor filtering effect;

Therefore, how to provide a lubricating oil double filter that can reduce switching torque, reduce operating difficulty, and has a simple and compact structure, reduces its volume, improves its ability to resist impact and vibration, and can effectively intercept impurities in the lubricating oil to ensure the quality of the lubricating oil is a problem that technical personnel in this field urgently need to solve.

Utility Model Content

In view of this, the utility model provides a lubricating oil duplex filter, which can reduce switching torque, reduce operating difficulty, and has a simple and compact structure, reduces its volume, improves its ability to resist impact and vibration, and can effectively intercept impurities in the lubricating oil to ensure the quality of the lubricating oil.

In order to achieve the above purpose, the utility model adopts the following technical solutions:

A lubricating oil duplex filter comprises: a filter head, a first filter tank, a second filter tank, a switching valve and a balancing valve core;

The filter head has an oil inlet channel and an oil outlet channel;

The first filter tank and the second filter tank are both installed at the upper end of the filter head and are both provided with an oil inlet connected to the oil inlet channel and an oil outlet connected to the oil outlet channel; the switching valve comprises a valve body and a switching handle, the valve body is rotatably connected in the oil inlet channel and its side wall can correspond to close the oil inlet of the first filter tank or the second filter tank; the lower part of the switching handle is hinged to the outer wall of the valve body through a pin shaft;

A valve cavity connected to the oil inlet channel is provided in the valve body, and an oil port is provided on the side wall of the valve body and connects the valve cavity with the oil inlet of the first filter tank or the oil inlet of the second filter tank; one end of the balancing valve core is elastically connected to the inner wall of the valve cavity along the axial direction of the oil port; the switching end face of the switching handle is an inclined surface arranged at an angle to the moving direction of the balancing valve core, and the other end of the balancing valve core penetrates the side wall of the valve body and abuts against the switching end face of the switching handle to push or release the balancing valve core to open or block the oil port.

Through the above technical scheme, the utility model provides a lubricating oil double filter, which realizes the blocking switching of the oil inlet of the first filter tank and the oil inlet of the second filter tank by rotating the switching handle to drive the valve body to rotate, thereby realizing the switching of the first filter tank and the second filter tank, and the structure is simple and easy to use; by installing the balancing valve core inside the valve body of the switching valve, when it is necessary to switch the filter tank, the switching handle is swung downward, and the lower part of the switching end surface of the switching handle moves upward accordingly and pushes the balancing valve core to move to open the oil port, and the lubricating oil in the oil inlet channel enters the filter tank corresponding to the oil inlet blocked by the valve body through the oil port, and the switching handle is released, the balancing valve core returns to its original position and blocks the oil port. Through the setting of this structure, the pressure difference between the two filter tanks can be reduced when the first filter tank and the second filter tank are switched, the switching torque is reduced, the difficulty of operation is reduced, and the switching is easy and the reliability is high.

Furthermore, the valve body has a fan-shaped blocking block, and rotating the switching handle can drive the blocking block to rotate to correspondingly close the oil inlet of the first filter tank or the second filter tank, thereby realizing the switching of the oil circuit.

Preferably, the balancing valve core includes a valve plug, a return spring, a core body and a ejector pin, the valve plug is connected to the open end of the valve cavity by a thread and a connecting hole connected to the oil inlet channel is formed on its end face; the return spring is located inside the valve cavity and one end of the return spring is fixedly connected to the valve plug; the core body is fixed to the other end of the return spring and it seals the oil passage; one end of the ejector pin is fixed to the other end of the core body, and the other end of the ejector pin passes through the side wall of the valve body and abuts against the switching end face of the switching handle.

Furthermore, four communicating holes may be provided.

Furthermore, the ejector pin and the valve body are sealed by a sealing ring.

Furthermore, an annular stage is formed inwardly at a position of the valve body side wall corresponding to the core body, and an oil port is opened on the annular stage. The core body has a conical structure, and the end connected to the ejector pin is a small head end and extends into the annular stage, and the end connected to the return spring is a large head end and its diameter is smaller than the diameter of the valve cavity. The side wall of the core body abuts against the inner hole of the annular stage to prevent lubricating oil from entering it.

Preferably, a mounting hole is provided on the side wall of the filter head and a mounting ring plate is formed by a protrusion at the edge of the outer wall corresponding to the mounting hole. The valve body is rotatably connected to the mounting ring plate and one end of the valve body extends into the oil inlet channel to rotate and correspondingly block the oil inlet of the first filter tank or the second filter tank. The outer wall is sealed and connected to the inner wall of the mounting ring plate by a pressure ring.

Furthermore, the pressure ring and the mounting ring plate, as well as the pressure ring and the valve body are sealed by sealing rings.

Furthermore, a first limiting groove corresponding to the first filter tank and a second limiting groove corresponding to the second filter tank are opened on the mounting ring plate, and a limiting block adapted to the first limiting groove and the second limiting groove is fixed on the switching handle to limit the switching handle to prevent the switching handle from moving.

Preferably, the first filter tank and the second filter tank both include a tank body, a magnetic component and a filter element, the tank body is fixed at the upper end of the filter head; the oil inlet and the oil outlet are both opened on the tank body; the magnetic component and the filter element are fixed in sequence inside the tank body from bottom to top and correspondingly formed inside the tank body are a connected magnetic adsorption filter section and a solid impurity filter section, the inlet of the magnetic adsorption filter section is connected to the oil inlet, and the outlet of the solid impurity filter section is connected to the oil outlet.

Furthermore, the tank body and the filter head are sealed by a sealing ring.

Furthermore, the magnetic component includes a hollow cylinder and a magnetic rod. The hollow cylinder is fixed at the bottom of the tank body and the magnetic adsorption filter section is between its outer wall and the inner wall of the tank body; the magnetic rod is located in the magnetic adsorption filter section and is fixed to the outer wall of the hollow cylinder.

Furthermore, the filter element includes a support frame and filter material, the support frame is fixed on the upper end of the hollow cylinder; the filter material is wrapped on the side surface of the support frame, the outer side surface and the inner wall of the tank body are the inlet of the solid impurity filter section and are connected to the outlet of the magnetic adsorption filter section, the inner cavity of the support frame is the outlet of the solid impurity filter section and the lower end is connected to the inner cavity of the hollow cylinder, the oil outlet is opened at the bottom of the tank body and is connected to the inner cavity of the hollow cylinder. The filter material is arranged in a pleated structure. The filter element and the magnetic component are sealed by a sealing ring.

Furthermore, an assembly shaft is provided at the upper end of the hollow cylinder, and the support frame is fixed at the upper end of the assembly shaft.

Through the arrangement of the above structure, when the lubricating oil is working, it enters the magnetic adsorption filter section through the oil inlet and adsorbs the iron-based metal particles in the lubricating oil through the magnetic rod, then enters the solid impurity filter section, and flows to the inner cavity of the supporting frame through the filtering material from the outside to the inside to intercept the solid impurities in the lubricating oil, and then flows to the oil outlet channel of the filter head through the inner cavity of the hollow column and the oil outlet. Through the arrangement of this structure, the lubricating oil can be effectively filtered to ensure the quality of the lubricating oil.

Preferably, it also includes a one-way valve, which is installed at the oil outlet. The arrangement of this structure can ensure that the lubricating oil is discharged smoothly and avoid the backflow of the filtered lubricating oil.

Furthermore, the one-way valve includes a valve seat, a one-way valve core, a screw and a mounting spring. The upper end of the valve seat is provided with an opening connected to the inner cavity of the hollow cylinder, and the lower end opening is connected to the oil outlet channel. The valve seat is threadedly connected to the corresponding oil outlet of the filter head; the one-way valve core is arranged at the bottom end of the valve seat and its side wall is linearly sealed with the inner wall of the valve seat; the screw is vertically threadedly connected to the upper end of the one-way valve core; the mounting spring is sleeved on the outside of the screw and its upper end abuts against the screw head, and its lower end abuts against the upper end surface of the valve seat; when the lubricating oil enters the inner cavity of the hollow cylinder, the lubricating oil pressure acts on the upper side of the valve core, the valve core moves downward and a connecting channel is formed between the valve seat and the valve seat, the lubricating oil enters the oil outlet channel through the connecting channel, and when not working, the one-way valve core returns to its original position under the action of the mounting spring.

Furthermore, an assembly hole for mounting and cooperating with the valve seat is provided at the lower end of the inner wall of the hollow cylinder.

Preferably, a differential pressure transmitter is also included, which is fixed at the bottom of the filter head and its high-pressure end is connected to the oil inlet channel of the filter head, and its low-pressure end is connected to the oil outlet channel of the filter head. As more and more pollutants are blocked by the magnetic components and filter elements in the tank body, the inlet and outlet pressure difference becomes larger and larger. When the filter inlet and outlet pressure difference reaches the alarm value, the differential pressure transmitter alarms, and the filter tank is switched at this time.

Preferably, the top of the tank body of the first filter tank and the top of the tank body of the second filter tank are both provided with a venting screw plug.

Preferably, two oil drain plugs are installed at the bottom of the filter head and are both connected to the oil inlet channel.

It can be seen from the above technical solutions that, compared with the prior art, the utility model discloses a lubricating oil duplex filter. Compared with the prior art, the utility model at least includes the following technical effects:

1) By rotating the switching handle to drive the valve body to rotate, the oil inlet of the first filter tank and the oil inlet of the second filter tank can be blocked and switched, thereby switching the first filter tank and the second filter tank can be switched, which has a simple structure and is easy to use;

2) By installing the balancing valve core inside the valve body of the switching valve, when the filter tank needs to be switched, the switching handle is swung downward, and the lower part of the switching end surface of the switching handle moves upward accordingly and pushes the balancing valve core to move, thereby opening the oil through port, and the lubricating oil in the oil inlet channel enters the filter tank correspondingly blocked by the valve body through the oil through port, and the switching handle is released, the balancing valve core returns to its original position and blocks the oil through port. The arrangement of this structure can reduce the pressure difference between the two filter tanks when the first filter tank and the second filter tank are switched, reduce the switching torque, reduce the difficulty of operation, and make the switching easy and reliable;

3) Composite filtration is achieved through magnetic components and filter elements, which can effectively intercept impurities in the lubricating oil, thereby effectively ensuring the quality of the lubricating oil;

4) It integrates the balancing valve core, switching valve, magnetic component, filter element and one-way valve in a very small space, with a simple and compact structure, which improves its impact and vibration resistance and reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

FIG1 is an axial view of a lubricating oil duplex filter of the utility model.

FIG2 is a cross-sectional view of a lubricating oil duplex filter of the present invention;

FIG3 is a cross-sectional view of the filter head provided by the utility model in the first direction;

FIG4 is a cross-sectional view of the filter head provided by the present invention in the second direction;

FIG5 is a schematic structural diagram of the connection between the switching valve and the balancing valve core provided by the utility model;

FIG6 is a cross-sectional view of the connection between the switching valve and the balancing valve core provided by the utility model;

FIG7 is a working principle diagram of a lubricating oil duplex filter of the utility model;

FIG8 is a cross-sectional view of a second filter tank provided by the present invention;

FIG9 is a cross-sectional view of a magnetic assembly provided by the present invention;

FIG10 is a cross-sectional view of a filter element provided by the present invention;

FIG11 is a schematic diagram of the structure of a one-way valve provided by the present utility model;

Among them, 1 is a filter head; 11 is an oil inlet channel; 12 is an oil outlet channel; 13 is a mounting ring plate; 131 is a first limiting groove; 132 is a second limiting groove;

2 is the first filter tank; 21 is the tank body; 211 is the oil inlet; 212 is the oil outlet; 22 is the magnetic component; 221 is the hollow cylinder; 2211 is the assembly hole; 222 is the magnetic rod; 223 is the assembly shaft; 23 is the filter element; 231 is the support frame; 232 is the filter material; 24 is the magnetic adsorption filter section; 25 is the solid impurity filter section;

3 is the second filter tank;

4 is a switching valve; 41 is a valve body; 411 is a valve cavity; 412 is an oil port; 413 is an annular stage; 414 is a blocking block; 42 is a switching handle; 43 is a limit block; 44 is a pin shaft; 45 is a pressure ring;

5 is a balancing valve core; 51 is a valve plug; 511 is a connecting hole; 52 is a return spring; 53 is a core body; 54 is an ejector pin;

6 is a one-way valve; 61 is a valve seat; 62 is a one-way valve core; 63 is a screw; 64 is a mounting spring;

7 is a pressure difference transmitter;

8 is the oil drain plug;

9 is the bleed screw plug.

DETAILED DESCRIPTION

The technical solutions in the embodiments of the utility model are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

1-11 , the embodiment of the utility model discloses a lubricating oil double filter, including: a filter head 1, a first filter tank 2, a second filter tank 3, a switching valve 4 and a balancing valve core 5;

The filter head 1 has an oil inlet channel 11 and an oil outlet channel 12; the first filter tank 2 and the second filter tank 3 are both installed at the upper end of the filter head 1 and both are provided with an oil inlet 211 communicating with the oil inlet channel 11 and an oil outlet 212 communicating with the oil outlet channel 12; the switching valve 4 includes a valve body 41 and a switching handle 42, the valve body 41 is rotatably connected in the oil inlet channel 11 and its side wall can correspond to the oil inlet 211 of the first filter tank 2 or the second filter tank 3; the lower part of the switching handle 42 is hinged to the outer wall of the valve body 41 through a pin 44;

A valve cavity 411 connected to the oil inlet channel 11 is defined in the valve body 41, and an oil port 412 is defined on the side wall of the valve body 41 and connects the valve cavity 411 with the oil inlet 211 of the first filter tank 2 or the oil inlet 211 of the second filter tank 3; one end of the balancing valve core 5 is elastically connected to the inner wall of the valve cavity 411 along the axial direction of the oil port 412; the switching end face of the switching handle 42 is an inclined surface arranged at an angle to the moving direction of the balancing valve core 5, and the other end of the balancing valve core 5 passes through the side wall of the valve body 41 and abuts against the switching end face of the switching handle 42 to push or release the balancing valve core 5 to open or block the oil port 412.

Specifically, the valve body 41 has a fan-shaped blocking block 414, and rotating the switching handle can drive the blocking block 414 to rotate to correspond to closing the oil inlet 211 of the first filter tank 2 or the second filter tank 3, thereby realizing the switching of the oil circuit.

Specifically, the top of the tank body 21 of the first filter tank 2 and the second filter tank 3 are both provided with a venting screw plug 9. The bottom of the filter head 1 is provided with two oil draining screw plugs 8 both connected to the oil inlet channel.

In some implementation examples, the balancing valve core 5 includes a valve plug 51, a return spring 52, a core body 53 and a ejector pin 54. The valve plug 51 is connected to the open end of the valve cavity 411 by a thread and has four connecting holes 511 circumferentially opened on its end face that are connected to the oil inlet channel 11; the return spring 52 is located inside the valve cavity 411 and one end of the return spring 52 is fixedly connected to the valve plug 51; the core body 53 is fixed to the other end of the return spring 52 and seals the oil passage 412; one end of the ejector pin 54 is fixed to the other end of the core body 53, and the other end of the ejector pin 54 passes through the side wall of the valve body 41 and abuts against the switching end face of the switching handle 42. The ejector pin 54 and the valve body 41 can be sealed by a sealing ring.

Specifically, an annular stage 413 is convexly formed inwardly at the position of the side wall of the valve body 41 corresponding to the core body 53, and the oil port 412 is opened on the annular stage 413. The core body 53 has a conical structure, and its end connected to the ejector pin 54 is a small head end and extends into the annular stage 413, and its end connected to the return spring 52 is a large head end and its diameter is smaller than the diameter of the valve cavity 411. The side wall of the core body 53 abuts against the inner hole of the annular stage 413 to prevent lubricating oil from entering it.

In other implementation examples, a mounting hole is provided on the side wall of the filter head 1 and a mounting ring plate 13 is formed on its outer wall corresponding to the edge of the mounting hole. The mounting ring plate 13 is fixed on the outer wall of the filter head 1. The valve body 41 is rotatably connected to the mounting ring plate 13 and one end of the valve body 41 extends into the oil inlet channel 11 through the mounting hole to rotate and correspondingly block the oil inlet 211 of the first filter tank 2 or the second filter tank 3. A pressure ring 45 is filled between its outer wall and the inner wall of the mounting ring plate 13, and sealing rings are provided between the pressure ring 45 and the valve body 41 and between the pressure ring 45 and the mounting ring plate 13.

Specifically, a first limiting groove 131 corresponding to the first filter tank 2 and a second limiting groove 132 corresponding to the second filter tank 3 are opened on the mounting ring plate 13, and a limiting block 43 adapted to the first limiting groove 131 and the second limiting groove 132 is fixed on the switching handle 42 to limit the switching handle 42.

In other implementation examples, the first filter tank 2 and the second filter tank 3 both include a tank body 21, a magnetic component 22 and a filter element 23; the tank body 21 is fixed at the upper end of the filter head 1 and can be sealed by a sealing ring; the oil inlet 211 and the oil outlet 212 are both opened on the tank body 21; the magnetic component 22 and the filter element 23 are fixed in sequence from bottom to top inside the tank body 21 and correspondingly formed inside thereof are a connected magnetic adsorption filter section 24 and a solid impurity filter section 25; the inlet of the magnetic adsorption filter section 24 is connected to the oil inlet 211, and the outlet of the solid impurity filter section 25 is connected to the oil outlet 212.

In other implementation examples, the magnetic component 22 includes a hollow cylinder 221 and a magnetic rod 222. The hollow cylinder 221 is fixed at the bottom end of the tank body 21 and a magnetic adsorption filter section 24 is provided between its outer wall and the inner wall of the tank body 21. An assembly shaft 223 is provided at the upper end of the hollow cylinder 221; the magnetic rod 222 is located in the magnetic adsorption filter section 24 and is fixed to the outer wall of the hollow cylinder 221.

In other implementation examples, the filter element 23 includes a support frame 231 and a filter material 232, and the support frame 231 is fixed on the assembly shaft 223; the filter material 232 is wrapped around the side surface of the support frame 231, and the outer side surface thereof and the inner wall of the tank body 21 are the inlet of the solid impurity filter section 25 and are connected to the outlet of the magnetic adsorption filter section 24, the inner cavity of the support frame 231 is the outlet of the solid impurity filter section 25 and its lower end is connected to the inner cavity of the hollow cylinder 221, and the oil outlet 212 is opened at the bottom end of the tank body 21 and is connected to the inner cavity of the hollow cylinder 221.

In some other implementation examples, a one-way valve 6 installed at the oil outlet 212 is also included.

Specifically, the one-way valve 6 includes a valve seat 61, a one-way valve core 62, a screw 63 and a mounting spring 64. The upper end of the valve seat 61 is provided with an opening connected to the inner cavity of the hollow cylinder 221, and the lower end opening is connected to the oil outlet channel 12. The valve seat 61 is threadedly connected to the corresponding oil outlet 212 of the filter head 1; the one-way valve core 62 is arranged at the bottom end of the valve seat 61 and its side wall is sealed with the inner wall line of the valve seat 61; the screw 63 is vertically threadedly connected to the upper end of the one-way valve core 62; the mounting spring 64 is sleeved on the outside of the screw 63 and its upper end is abutted against the end face of the head of the screw 63, and the lower end is abutted against the upper end face of the valve seat 61.

Specifically, the lower end of the inner wall of the hollow cylinder 221 is provided with an assembly hole 2211 for mounting and cooperating with the valve seat 61 .

In some other implementation examples, a pressure differential transmitter 7 is further included. The pressure differential transmitter 7 is fixed at the bottom end of the filter head 1 and its high-pressure end is connected to the oil inlet channel 11 of the filter head 1, and its low-pressure end is connected to the oil outlet channel 12 of the filter head 1.

The lubricating oil duplex filter designed according to the utility model has at least the following technical effects:

1) By rotating the switching handle to drive the valve body to rotate, the oil inlet of the first filter tank and the oil inlet of the second filter tank can be blocked and switched, thereby switching the first filter tank and the second filter tank can be switched, which has a simple structure and is easy to use;

2) By installing the balancing valve core inside the valve body of the switching valve, when the filter tank needs to be switched, the switching handle is swung downward, and the lower part of the switching end surface of the switching handle moves upward accordingly and pushes the balancing valve core to move, thereby opening the oil through port, and the lubricating oil in the oil inlet channel enters the filter tank correspondingly blocked by the valve body through the oil through port, and the switching handle is released, the balancing valve core returns to its original position and blocks the oil through port. The arrangement of this structure can reduce the pressure difference between the two filter tanks when the first filter tank and the second filter tank are switched, reduce the switching torque, reduce the difficulty of operation, and make the switching easy and reliable;

3) Composite filtration is achieved through magnetic components and filter elements, which can effectively intercept impurities in the lubricating oil, thereby effectively ensuring the quality of the lubricating oil;

4) It integrates the balancing valve core, switching valve, magnetic component, filter element and one-way valve in a very small space, with a simple and compact structure, which improves its impact and vibration resistance and reliability.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A lubricating oil duplex filter, characterized in that it comprises: a filter head (1), a first filter tank (2), a second filter tank (3), a switching valve (4) and a balancing valve core (5); The filter head (1) has an oil inlet passage (11) and an oil outlet passage (12); the first filter tank (2) and the second filter tank (3) are both mounted on the upper end of the filter head (1) and are both provided with an oil inlet (211) communicating with the oil inlet passage (11) and an oil outlet (212) communicating with the oil outlet passage (12); the switching valve (4) comprises a valve body (41) and a switching handle (42); the valve body (41) is rotatably connected in the oil inlet passage (11) and its side wall can correspondingly close the oil inlet (211) of the first filter tank (2) or the second filter tank (3); the lower part of the switching handle (42) is hinged to the outer wall of the valve body (41) via a pin shaft (44); The valve body (41) is provided with a valve cavity (411) in communication with the oil inlet passage (11); the side wall of the valve body (41) is provided with an oil passage (412) in communication with the valve cavity (411) and the oil inlet (211) of the first filter tank (2) or the oil inlet (211) of the second filter tank (3); one end of the balancing valve core (5) is elastically connected to the inner wall of the valve cavity (411) along the axial direction of the oil passage (412); the switching end face of the switching handle (42) is an inclined surface arranged at an angle to the moving direction of the balancing valve core (5); the other end of the balancing valve core (5) passes through the side wall of the valve body (41) and abuts against the switching end face of the switching handle (42) to push or release the balancing valve core (5) to open or block the oil passage (412). 2. A lubricating oil duplex filter according to claim 1, characterized in that the balancing valve core (5) comprises a valve plug (51), a return spring (52), a core body (53) and a push pin (54); the valve plug (51) is connected to the open end of the valve cavity (411) by a thread and a connecting hole (511) connected to the oil inlet channel (11) is provided on its end face; the return spring (52) is located inside the valve cavity (411) and one end thereof is fixedly connected to the valve plug (51); the core body (53) is fixed to the other end of the return spring (52) and seals the oil passage (412); one end of the push pin (54) is fixed to the other end of the core body (53), and the other end thereof passes through the side wall of the valve body (41) and abuts against the switching end face of the switching handle (42). 3. A lubricating oil duplex filter according to claim 2, characterized in that an annular stage (413) is convexly formed inwardly at the position of the side wall of the valve body (41) corresponding to the core body (53), the oil port (412) is opened on the annular stage (413), the core body (53) is a conical structure, the end thereof connected to the ejector pin (54) is a small head end and extends into the annular stage (413), the end thereof connected to the return spring (52) is a large head end and its diameter is smaller than the diameter of the valve cavity (411), and the side wall of the core body (53) abuts against the inner hole of the annular stage (413) to prevent lubricating oil from entering therein. 4. A lubricating oil duplex filter according to claim 1, characterized in that a mounting hole is provided on the side wall of the filter head (1) and a mounting ring plate (13) is formed on its outer wall corresponding to the edge of the mounting hole, the valve body (41) is rotatably connected to the mounting ring plate (13) and one end thereof passes through the mounting hole and extends into the oil inlet channel (11) to rotate and correspondingly block the oil inlet (211) of the first filter tank (2) or the second filter tank (3), and the outer wall thereof is sealedly connected to the inner wall of the mounting ring plate (13) by a pressure ring (45). 5. A lubricating oil duplex filter according to claim 4, characterized in that a first limiting groove (131) corresponding to the first filter tank (2) and a second limiting groove (132) corresponding to the second filter tank (3) are provided on the mounting ring plate (13), and a limiting block (43) adapted to the first limiting groove (131) and the second limiting groove (132) is fixed on the switching handle (42) to limit the switching handle (42). 6. A lubricating oil duplex filter according to claim 1, characterized in that the first filter tank (2) and the second filter tank (3) both include a tank body (21), a magnetic component (22) and a filter element (23), the tank body (21) is fixed to the upper end of the filter head (1); the oil inlet (211) and the oil outlet (212) are both opened on the tank body (21); the magnetic component (22) and the filter element (23) are fixed in sequence from bottom to top inside the tank body (21) and a magnetic adsorption filter section (24) and a solid impurity filter section (25) are correspondingly formed therein, the inlet of the magnetic adsorption filter section (24) is connected to the oil inlet (211), and the outlet of the solid impurity filter section (25) is connected to the oil outlet (212). 7. A lubricating oil duplex filter according to claim 6, characterized in that the magnetic component (22) includes a hollow cylinder (221) and a magnetic rod (222), the hollow cylinder (221) is fixed at the bottom end of the tank body (21) and the magnetic adsorption filter section (24) is between its outer wall and the inner wall of the tank body (21); the magnetic rod (222) is located in the magnetic adsorption filter section (24) and is fixed to the outer wall of the hollow cylinder (221). 8. A lubricating oil duplex filter according to claim 7, characterized in that the filter element (23) includes a support frame (231) and a filter material (232), the support frame (231) is fixed to the upper end of the hollow cylinder (221); the filter material (232) is wrapped around the side surface of the support frame (231), and the area between its outer side and the inner wall of the tank body (21) is the inlet of the solid impurity filter section (25) and is connected to the outlet of the magnetic adsorption filter section (24); the inner cavity of the support frame (231) is the outlet of the solid impurity filter section (25) and its lower end is connected to the inner cavity of the hollow cylinder (221); the oil outlet (212) is opened at the bottom end of the tank body (21) and is connected to the inner cavity of the hollow cylinder (221). 9. A lubricating oil duplex filter according to claim 8, characterized in that it also comprises a one-way valve (6) installed at the oil outlet (212). 10. A lubricating oil duplex filter according to claim 1, characterized in that it also includes a differential pressure transmitter (7), wherein the differential pressure transmitter (7) is fixed at the bottom end of the filter head (1) and its high-pressure end is connected to the oil inlet channel (11) of the filter head (1), and its low-pressure end is connected to the oil outlet channel (12) of the filter head (1).