CN116044978A

CN116044978A - Gearbox and car with initiative lubricating system

Info

Publication number: CN116044978A
Application number: CN202211729377.1A
Authority: CN
Inventors: 张莉香; 曹辞; 张馨月; 向盼; 郑万生; 杜春鹏; 李剑平; 周万勇; 周珂; 刘薇
Original assignee: Dongfeng Trucks Co ltd
Current assignee: Dongfeng Trucks Co ltd
Priority date: 2022-12-30
Filing date: 2022-12-30
Publication date: 2023-05-02

Abstract

The invention discloses a gearbox with an active lubrication system and an automobile, and relates to the technical field of automobile gearboxes, wherein the gearbox comprises a gearbox shell, an oil pump and a drain valve assembly; wherein, the gearbox shell is provided with an oil duct, the interior of the gearbox shell is provided with a middle shaft assembly, at least two gears are arranged on the intermediate shaft assembly; the oil pump is communicated with the oil duct and can supply oil into the gearbox shell through the oil duct; the drain valve assembly comprises a valve body and a second spray lubrication unit, wherein the valve body is communicated or cut off with the oil duct, one part of the second spray lubrication unit is communicated with the oil duct through the valve body, the other part of the second spray lubrication unit stretches into the gearbox shell, and an oil injection hole of the second spray lubrication unit corresponds to the meshing point position of the gear pair with smaller diameter in the intermediate shaft gear pair. According to the invention, the spraying unit is integrally arranged at the position of the leakage valve, so that the lubricating system can reuse lubricating oil in the oil duct, which is leaked due to overlarge pressure, to lubricate the gear with smaller diameter.

Description

Gearbox and car with initiative lubricating system

Technical Field

The invention relates to the technical field of automobile gearboxes, in particular to a gearbox with an active lubrication system and an automobile.

Background

With the development of the automobile industry, automobiles have long become a main tool for people to travel. In order to improve the power performance and economy of the whole vehicle, the transmission efficiency of the transmission system needs to be improved. Among other things, gearbox efficiency is particularly important for the overall transmission system.

In the related art, the transmission lubricating system of the medium and heavy commercial vehicles mostly adopts an active lubricating system. When the gearbox runs, the height of the oil surface in the shell is lower, the gear with larger diameter on the intermediate shaft is immersed in lubricating oil below the axis of the intermediate shaft, the lubricating requirement of a gear engagement pair can be met by means of gear stirring, the gear with smaller diameter on the intermediate shaft cannot be lubricated by means of gear stirring due to the fact that the tooth top is higher than the height of the oil surface of the lubricating oil, the height of the oil surface is improved, the lubricating requirement of large and small gears can be met, but the transmission efficiency of the gearbox is seriously affected due to the fact that the gear stirring is excessive. For gearboxes adopting active lubrication, a combined mode of spray lubrication and oil immersion lubrication is often adopted to lubricate and dissipate heat of friction pairs such as gears, bearings and the like of a gearbox assembly. When the gearbox is operated, the lubrication system probably leads to the oil delivery oil circuit oil pressure to be too high because of the oil circuit jam, influences the reliability of gearbox work, and the designer often sets up the relief valve on the oil pump play oil passageway and lets out oil in order to reduce the oil pressure. However, once the safety valve is opened, the lubricating oil flows back to the shell from the oil drain port of the safety valve, the oil quantity in the spray oil pipe is greatly reduced, and the gear which is smaller in diameter and is not immersed in the lubricating oil on the intermediate shaft is difficult to meet the gear lubrication and heat dissipation requirements only by means of the oil quantity of spray lubrication. Especially, when the whole vehicle is at a low temperature Leng Qishi, the oil pressure of the gearbox is increased due to the excessive viscosity of the lubricating oil, so that the safety valve is opened. However, in practice, the oil pumping amount in the oil pump is insufficient, and after the safety valve is opened to drain oil, the lubricating oil in the spray pipe is extremely easy to be starved, so that the gear with smaller diameter on the intermediate shaft cannot be fully lubricated.

Disclosure of Invention

To gearbox initiative lubricating system among the prior art, because of the too big oil drainage of pressure, lead to lubricating oil to spray the effect poor, and then lead to gear lubrication, the poor problem of heat dissipation, this application provides a gearbox with initiative lubricating system, it includes: a transmission housing, an oil pump, and a drain valve assembly; wherein,,

the gearbox comprises a gearbox shell, wherein an oil duct is formed in the gearbox shell, an intermediate shaft assembly is arranged in the gearbox shell, and at least two gears are arranged on the intermediate shaft assembly;

an oil pump that communicates with the oil passage, and through which the oil pump can supply oil into the transmission case;

the leakage valve assembly comprises a valve body and a second spraying lubrication unit, wherein the valve body is used for being communicated with or cut off from the oil duct, one part of the second spraying lubrication unit is communicated with the oil duct through the valve body, the other part of the second spraying lubrication unit stretches into the gearbox shell, and an oil spraying hole of the second spraying lubrication unit corresponds to the gear position with the smallest diameter in the two gears.

In some embodiments, the valve body comprises:

one end of the drainage channel is communicated with the oil duct, and the other end of the drainage channel is communicated with the second spray lubrication unit;

and the movable contact is arranged in the drain passage and is used for sliding in the drain passage to stop or communicate with the drain passage.

In some embodiments, the moving contact comprises: a main body part, one end of which close to the oil duct is spherical, and the other end is provided with an elastic piece; wherein,,

when the pressure in the oil duct is lower than a preset threshold value, the elastic piece drives the main body part to move so as to stop the drainage channel, and when the pressure in the oil duct is not lower than the preset threshold value, the main body part moves in a direction away from the oil duct so as to enable the drainage channel to enter a circulation state.

In some embodiments, the second spray lubrication unit comprises: and one end of the spray oil pipe is communicated with the drainage channel, the other end of the spray oil pipe stretches into the gearbox shell, at least one oil spray hole is formed in one end of the spray oil pipe, which is positioned in the gearbox shell, and the equivalent cross-sectional area of the oil spray hole is larger than that of the drainage channel.

In some embodiments, six oil spray holes are formed in the spray oil pipe, and the total equivalent cross-sectional area of the six oil spray holes is larger than the equivalent cross-sectional area of the drainage channel.

In some embodiments, further comprising:

the oil baffle unit is arranged in the gearbox shell, the oil baffle unit is enveloped on the outer side of the gear to divide the gearbox shell into an upper oil cavity and a lower oil cavity, the oil baffle unit is positioned on one side of the upper oil cavity and is provided with a lubricating oil pool, and the lubricating oil pool is used for bearing lubricating oil sprayed by the second spraying lubricating unit.

In some embodiments, the oil baffle unit includes: the arc-shaped shell is fixedly connected with the first inner wall of the gearbox shell in a sealing manner along the first edge extending in the axial direction of the intermediate shaft assembly, the arc-shaped shell is arranged at intervals between the second edge extending in the axial direction of the intermediate shaft assembly and the second inner wall of the gearbox shell, the arc-shaped shell is provided with a lubricating oil pool, and the edge of the lubricating oil pool is flush with the second edge. And as the gear 13 rotates, lubricating oil in the shell is thrown from an upper oil cavity to a lower oil cavity of the oil baffle plate, and the oil immersion depth of the oil stirring gear is at most flush with the second edge of the oil baffle plate.

In some embodiments, the height of the second edge is equal to the height of the root circle of the gear with the largest diameter among the gears.

In some embodiments, an oil absorbing device is arranged at the bottom of the gearbox shell, a filter screen is arranged on the oil absorbing device, and the oil duct is communicated with the oil pump through the oil absorbing device.

In another aspect, the present application provides an automobile comprising: a gearbox according to any preceding claim.

According to the invention, the spraying unit is arranged at the drain valve, so that the lubricating system can reuse the lubricating oil drained from the drain valve due to overlarge pressure in the oil duct to lubricate and dissipate heat, and particularly, even if the condition that the oil quantity in the first spraying lubricating unit is too low to spray normally due to the oil drainage of the drain valve occurs, the lubricating oil can lubricate the gear with smaller diameter through the drain valve assembly.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a cross-sectional view of a drain valve assembly according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view of a first view of a lubrication system according to an embodiment of the present invention;

fig. 3 is a cross-sectional view of a second perspective of a lubrication system according to an embodiment of the present invention.

In the figure: 1. a gearbox housing; 11. an intermediate shaft assembly; 12. an oil passage; 13. a gear; 3. a first spray lubrication unit; 4. a drain valve assembly; 41. a valve body; 411. a drain passage; 412. a moving contact; 413. a main body portion; 414. an elastic member; 42. a second spray lubrication unit; 421. spraying an oil pipe; 422. an oil injection hole; 5. an oil baffle unit; 51. an arc-shaped housing; 511. a first edge; 512. a second edge; 6. an oil suction device.

Detailed Description

For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.

Embodiments of the present invention are described in further detail below with reference to the accompanying drawings. In the related art, the lubrication system may cause too high oil pressure of the oil delivery oil path due to the blockage of the oil pump oil path, so as to influence the transmission efficiency of the gearbox. To address such problems, practitioners need to drain oil at the oil pump outlet and set a relief valve to reduce oil pressure. However, once the safety valve is opened, the oil quantity in the spraying oil pipe is greatly reduced after the lubricating oil flows back to the shell from the oil drain port of the safety valve. This results in the fact that the amount of sprayed lubricating oil on the gears with smaller diameters on the intermediate shaft is difficult to meet the heat dissipation requirements. In particular, the whole vehicle is at a low temperature Leng Qishi, the oil pressure of the gearbox is increased due to the excessive viscosity of the lubricating oil, and then the safety valve is opened. However, in practice, the oil quantity in the oil pump is insufficient, and after the safety valve is opened to drain oil, the lubricating oil in the spray pipe is extremely easy to have the oil-free condition, so that the gear cannot obtain the spraying of the lubricating oil, and the heat dissipation effect is poor. In view of the above problems, as shown in two cross-sectional views of fig. 2 and 3, the present application provides a transmission provided with a lubrication system, comprising: a transmission housing 1, an oil pump and a drain valve assembly 4; wherein,,

the transmission comprises a transmission housing 1, wherein an oil duct 12 is formed in the transmission housing 1, a middle shaft assembly 11 is arranged in the transmission housing 1, and at least two gears 13 with different diameters are arranged on the middle shaft assembly 11; an oil pump which is communicated with the oil passage 12 and can supply oil into the transmission housing 1 through the oil passage 12; the drain valve assembly 4 comprises a valve body 41 and a second spray lubrication unit 42, wherein the valve body 41 is used for being communicated with or cut off from the oil duct 12, one part of the second spray lubrication unit 42 is communicated with the oil duct 12 through the valve body 41, the other part of the second spray lubrication unit 42 extends into the gearbox housing 1, and an oil spray hole 422 of the second spray lubrication unit 42 corresponds to the position of the gear 13 with the smallest diameter of the two gears 13.

It should be noted that the above gearbox further includes a first spray lubrication unit 3, which is disposed in the gearbox housing 1, and the first spray lubrication unit 3 is communicated with the oil duct 12.

When the gearbox is in normal use (i.e. the pressure of the oil passage 12 is not too high), the valve body 41 of the drain valve assembly 4 is in a cut-off state, i.e. the lubricating oil in the oil passage 12 cannot drain into the second spraying lubrication unit 42, and the gear 13 is sprayed. Instead, the lubricant oil in the oil passage 12 enters the first spray lubrication unit 3 to spray the lubricant oil conventionally on the gears, as shown in fig. 3. And once the conditions such as the cold start of the whole vehicle occur, the pressure rise is caused, that is, the valve body 41 is triggered to be separated from the cut-off state, and at the moment, the lubrication oil entering the first spray lubrication unit 3 is reduced or the oil-free condition occurs. The lubricating oil flows through the valve body 41 to the second spray lubrication unit 42, and is sprayed through the second spray lubrication unit 42 to the gear 13 which cannot be infiltrated into the deposited lubricating oil due to the too small diameter, (it is understood that a part of the gear 13 with a larger diameter is infiltrated into the lubricating oil deposited in the gearbox housing 1, and the lubricating oil is stirred by rotation so as to obtain the lubricating oil heat dissipation efficiency.) in this way, even if the pressure is too high, the release valve assembly 4 is triggered, the heat dissipation effect is not deteriorated.

Specifically, as shown in fig. 1, the valve body 41 includes: a drain channel 411 and a moving contact 412; wherein,,

one end of the drain passage 411 is communicated with the oil passage 12, and the other end is communicated with the second spray lubrication unit 42; a moving contact 412 is provided in the drain passage 411, and the moving contact 412 is configured to slide in the drain passage 411 to close or communicate with the drain passage 411.

In some preferred embodiments, to better enable leakage flow, the moving contact 412 includes: a main body 413, wherein one end of the main body 413, which is close to the oil duct 12, is spherical, and the other end is provided with an elastic member 414; wherein,,

when the pressure in the oil passage 12 is lower than a preset threshold value, the elastic piece 414 drives the main body 413 to move to stop the drain passage 411, and when the pressure in the oil passage 12 is not lower than the preset threshold value, the main body 413 moves away from the oil passage 12 to bring the drain passage 411 into a circulation state.

It should be noted that, because the reasonable deformation distance of the elastic member 414 is limited, the flow rate of the lubricating oil provided by the moving contact 412 is limited, and two sides of the valve body 41 on the other side of fig. 1 of the present application are flattened, so that the lubricating oil can pass through after the moving contact 412 moves away from the oil duct 12.

Further, the second spray lubrication unit 42 includes: and one end of the spray oil pipe 421 is communicated with the drain channel 411, the other end of the spray oil pipe 421 extends into the gearbox housing 1, and at least one oil injection hole 422 is formed in one end of the spray oil pipe 421 in the gearbox housing 1. In order to prevent the valve body from being opened normally due to excessive pressure in the drain passage 411 caused by too small equivalent cross-sectional area of the oil jet 422, the equivalent cross-sectional area of the oil jet 422 is larger than that of the drain passage 411.

Preferably, as shown in fig. 1, six oil spray holes 422 are provided on the spray oil pipe 421, and the total equivalent cross-sectional area of the six oil spray holes 422 is greater than the equivalent cross-sectional area of the drain passage 411.

In some alternative embodiments, the drain valve assembly 4 includes a valve body 41, a sealing pintle, a first spring, a pressure pintle, and a second spring.

Be provided with oil return pipe, oil feed pipe and pressure release hole on the valve body 41, the one end and the lateral wall intercommunication of oil duct 12 of pressure release hole still are provided with the valve opening on the valve body 41, valve opening and pressure release hole other end intercommunication, sealing pin and pressure pin are joined in marriage and are adorned in the valve opening, and sealing pin is arranged in controlling the switching of pressure release hole, and first spring is located between sealing pin and the pressure pin, and the second spring is located the other end of pressure pin, and the elasticity of first spring is less than the elasticity of second spring, and the other end of second spring is provided with the end cap, and the end cap seals the oral area of valve opening.

It should be noted that, in the above embodiment, the valve body 41 is provided with an oil inlet pipe and a valve hole, the valve hole is communicated with the oil duct 12 through a pressure release valve, a sealing pin and a pressure pin are arranged in the valve hole, two springs with different elasticity are arranged at two sides of the pressure pin, one spring is used for controlling the sealing pin to seal the pressure release hole, and the other spring is used for adjusting the pressure, so that the pressure regulation control precision is improved, and the pressure is kept within a reasonable pressure limit value; meanwhile, the pressure release valve is sealed through the pin, and the line contact sealing is improved to be the surface contact sealing, so that the sealing effect is improved.

Further, the pressure relief hole and the valve hole are coaxially arranged and form a stepped hole, the sealing pin is cylindrical, and the end part of the sealing pin is used for being abutted against a shoulder of the stepped hole.

In some optional embodiments, the shoulder surface of the step hole is a conical surface, and a chamfer inclined surface is arranged at the end part of the sealing pin, and the conical surface is matched with the conical surface of the step hole to realize sealing of the pressure relief hole.

Preferably, the sealing pin is connected with the pressure pin through a guiding mechanism, and the guiding mechanism is used for controlling the stretching direction of the sealing pin. Specifically, guiding mechanism includes pipe and guide pillar, and the pipe sets up with sealing pin is coaxial to with sealing pin's end connection, and the one end of guide pillar joins in marriage and installs in the pipe, and the other end is coaxial rigid coupling with the tip of pressure pin, and when sealing pin pressurized moved, the pipe moved along the guide pillar, played the effect of direction and support to sealing pin, avoided the skew, just avoided sealing pin card to die in the valve opening yet.

In some preferred embodiments, the gearbox further comprises: the oil baffle unit 5 is arranged in the gearbox housing 1, the outer side of the gear 13 is enveloped by the oil baffle unit 5 to divide the gearbox housing 1 into an upper oil cavity and a lower oil cavity, a lubricating oil pool is arranged on one side of the upper oil cavity of the oil baffle unit 5 and used for bearing lubricating oil sprayed by the first spraying lubricating unit 3 and the second spraying lubricating unit 42.

It will be appreciated that the oil deflector unit 5 is generally provided in the middle of the gearbox housing 1 in a horizontal direction and carries lubricating oil by means of a lubricating oil sump thereon, which lubricating oil does not have to be deposited from the bottom of the gearbox housing 1. Therefore, the gear can be soaked without spraying excessive lubricating oil.

Specifically, as shown in fig. 2 and 3, the oil baffle unit 5 includes: the arc-shaped shell 51 is fixedly connected with the first inner wall of the gearbox shell 1 in a sealing manner along the first edge 511 extending in the axial direction of the intermediate shaft assembly 11, the arc-shaped shell 51 is arranged at intervals between the second edge 512 extending in the axial direction of the intermediate shaft assembly 11 and the second inner wall of the gearbox shell 1, the arc-shaped shell 51 is provided with the lubricating oil pool, and the edge of the lubricating oil pool is flush with the second edge 512. Along with the rotation of the gear, lubricating oil in the shell is thrown from an upper oil cavity to a lower oil cavity of the oil baffle plate, and the oil immersion depth of the oil stirring gear is the largest and is flush with the second edge of the oil baffle plate.

It should be noted that the lubricating oil pool is surrounded by the arc-shaped housing 51 as described above. I.e. the second edge 512 of the arcuate housing 51 is the direction of the opening of the sump, whereas the height of the second edge 512 directly influences the maximum height of the sump deposited lubrication oil. Excess lubrication will flow from the upper oil pocket to the lower oil pocket through the gap between the second edge 512 and the second inner wall. In this way, the height of the second edge 512 determines the infiltration volume of the gear 13 in the lubricating oil pool, if the infiltration is excessive, the rotation efficiency of the gear 13 is greatly affected, and if the infiltration is insufficient, the heat dissipation effect is insufficient.

Preferably, the second edge 512 in this application is the same height as the root circle of the largest diameter gear 13 on the countershaft assembly 11.

In this way, through the structural combination of the drain valve assembly 4 integrated with the spray oil pipe and the oil baffle plate unit 5, even if the oil way of the lubrication system is blocked, the lower oil level can be used, the lubrication requirements of the large and small gears on the intermediate shaft are met through the secondary utilization of the lubricating oil discharged from the drain valve assembly 4, a large amount of lubricating oil is not required to be added in the shell, and the large and small gears of the intermediate shaft are all immersed in the lubricating oil to meet the lubrication requirements.

Preferably, as shown in fig. 3, for convenience of understanding, the arrow in fig. 3 indicates the direction in which the lubricating oil flows in the oil passage 12 and the first spray lubrication unit 3 and the second spray lubrication unit 42, the bottom of the transmission housing 1 is provided with an oil suction device 6, the oil suction device 6 is provided with a filter screen, and the oil passage 12 communicates with the oil pump through the oil suction device 6.

In another aspect, the present application provides an automobile comprising a gearbox provided with a lubrication system, the gearbox comprising: a transmission housing 1, an oil pump and a drain valve assembly 4; wherein,,

the gearbox comprises a gearbox housing 1, wherein an oil duct 12 is formed in the gearbox housing 1, a middle shaft assembly 11 is arranged in the gearbox housing 1, and at least two gears 13 are arranged on the middle shaft assembly 11; an oil pump which is communicated with the oil passage 12 and can supply oil into the transmission housing 1 through the oil passage 12; the drain valve assembly 4 comprises a valve body 41 and a second spray lubrication unit 42, wherein the valve body 41 is used for being communicated with or cut off from the oil duct 12, one part of the second spray lubrication unit 42 is communicated with the oil duct 12 through the valve body 41, the other part of the second spray lubrication unit 42 extends into the gearbox housing 1, and an oil spray hole 422 of the second spray lubrication unit 42 corresponds to the position of the gear 13 with the smallest diameter of the two gears 13.

In summary, the spraying unit is disposed at the drain valve in the present invention, so that the lubrication system can reuse the lubricating oil drained from the drain valve due to the excessive pressure in the oil duct to perform heat dissipation, specifically, even if the oil draining of the drain valve causes the too low oil amount in the first spraying lubrication unit to fail to spray normally, the lubricating oil can perform heat dissipation on the gear with smaller diameter through the drain valve assembly. Further, through the structural combination of the drain valve assembly 4 integrated with the spray oil pipe and the oil baffle unit 5, even if the oil way of the lubrication system is blocked, the lower oil level can be used, the lubrication requirements of the large and small gears on the intermediate shaft are met through the secondary utilization of the lubricating oil discharged from the drain valve assembly 4, a large amount of lubricating oil is not required to be added into the shell, and the large and small gears of the intermediate shaft are all immersed in the lubricating oil to meet the lubrication requirements.

In the description of the present application, it should be noted that the azimuth or positional relationship indicated by the terms "upper", "lower", etc. are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of description of the present application and simplification of the description, and are not indicative or implying that the apparatus or element in question must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present application. Unless specifically stated or limited otherwise, the terms "mounted," "connected," and "coupled" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.

It should be noted that in this application, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The foregoing is merely a specific embodiment of the application to enable one skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gearbox provided with an active lubrication system, comprising:

the gearbox comprises a gearbox shell (1), wherein an oil duct (12) is formed in the gearbox shell (1), a middle shaft assembly (11) is arranged in the gearbox shell (1), and at least two gears (13) with different diameters are arranged on the middle shaft assembly (11);

an oil pump which communicates with the oil passage (12) and which can supply oil into the transmission case (1) through the oil passage (12);

the bleeder valve subassembly (4), it includes valve body (41) and second spray lubrication unit (42), valve body (41) be used for with oil duct (12) intercommunication or stop, second spray lubrication unit (42) partly pass through valve body (41) with oil duct (12) intercommunication, another part stretches into in gearbox housing (1), second spray lubrication unit (42) are equipped with oil spray hole (422), just oil spray hole (422) with the diameter is less in gear (13) position corresponds.

2. Gearbox according to claim 1, wherein the valve body (41) comprises:

a drain passage (411) having one end communicating with the oil passage (12) and the other end communicating with the second spray lubrication unit (42);

and a movable contact (412) disposed in the drain passage (411), the movable contact (412) being configured to slide in the drain passage (411) to close or communicate with the drain passage (411).

3. The gearbox of claim 2, wherein the moving contact (412) comprises: a main body part (413) having a spherical shape at one end thereof adjacent to the oil passage (12) and an elastic member (414) at the other end thereof; wherein,,

when the pressure in the oil passage (12) is lower than a preset threshold value, the elastic piece (414) drives the main body part (413) to move so as to stop the drainage passage (411), and when the pressure in the oil passage (12) is not lower than the preset threshold value, the main body part (413) moves in a direction away from the oil passage (12) so as to enable the drainage passage (411) to enter a circulation state.

4. Gearbox according to claim 2, characterized in that the second spray lubrication unit (42) comprises: and one end of the spray oil pipe (421) is communicated with the drainage channel (411), the other end of the spray oil pipe extends into the gearbox housing (1), at least one oil spray hole (422) is formed in one end of the spray oil pipe (421) positioned in the gearbox housing (1), and the equivalent cross-sectional area of the oil spray hole (422) is larger than that of the drainage channel (411).

5. The gearbox of claim 4, wherein six oil spray holes (422) are arranged on the spray oil pipe (421), and the total equivalent cross-sectional area of the six oil spray holes (422) is larger than the equivalent cross-sectional area of the drain passage (411).

6. The transmission of claim 1, further comprising:

the oil baffle unit (5) is arranged in the gearbox housing (1), the oil baffle unit (5) is enveloped on the outer side of the gear (13) so as to divide the gearbox housing (1) into an upper oil cavity and a lower oil cavity, the oil baffle unit (5) is positioned on one side of the upper oil cavity and is provided with a lubricating oil pool, and the lubricating oil pool is used for bearing lubricating oil sprayed by the second spraying lubricating unit (42).

7. Gearbox according to claim 6, wherein the oil deflector unit (5) comprises: the gear box comprises an arc-shaped shell (51), wherein the arc-shaped shell (51) is fixedly connected with a first inner wall of a gear box shell (1) in a sealing mode along a first edge (511) extending in the axial direction of an intermediate shaft assembly (11), the arc-shaped shell (51) is arranged along a second edge (512) extending in the axial direction of the intermediate shaft assembly (11) and a second inner wall of the gear box shell (1) at intervals, a lubricating oil pool is arranged on the arc-shaped shell (51), and the edge of the lubricating oil pool is flush with the second edge (512).

8. Gearbox according to claim 7, characterised in that the height of the second edge (512) is equal to the height of the root circle of the gear (13) of the largest diameter of the gears (13).

9. Gearbox according to claim 6, characterized in that the bottom of the gearbox housing (1) is provided with an oil suction device (6), the oil suction device (6) is provided with a filter screen, and the oil duct (12) is communicated with the oil pump through the oil suction device (6).

10. An automobile, comprising: a gearbox according to any of claims 1-9.