Jack

Abstract

The utility model belongs to the technical field of jacks, and particularly relates to a jack which comprises a base and an oil tank, an oil storage cavity used for storing hydraulic oil is arranged in the oil tank, a hydraulic telescopic rod and a driving device are connected to the base, the driving device comprises an oil pump and a driving motor driving the oil pump to move, and the oil pump is arranged in the oil tank. An oil inlet hole connected with an oil pump is formed in the base, the oil inlet hole is connected with the hydraulic telescopic rod and can drive the hydraulic telescopic rod to extend or retract, an air cavity is formed above the oil storage cavity, and air in the oil storage cavity is stored in the air cavity under the action of buoyancy; an oil injection hole is formed in the bottom of the oil storage cavity or the lower portion of the side face of the oil storage cavity, and a sealing plug is detachably arranged in the oil injection hole.

Description

Technical Field

[0001] The utility model belongs to the technical field of jacks, in particular to a jack. Background Art

[0002] A jack is a lifting device commonly used in automobile production and maintenance. In order to make the jack have a larger lifting force, common jacks are driven by a rack structure, a spiral structure or a hydraulic device.

[0003] Most of the jacks on the market are driven by hydraulic devices, and in order to facilitate the use of users, some jacks are driven by oil pumps, such as an electric oil pump jack disclosed in Chinese utility model patent CN201811154686.4, which includes a fuselage body, a splint and a top plate; a fuselage body is fixedly arranged on the top of the base; a power module is fixedly arranged on one side of the top of the fuselage body; the power module is fixedly connected to the controller through a wire; the other side of the controller is fixedly connected to the car cigarette lighter through a wire. The setting of the splint is conducive to the safety of use. When in use, the top plate is driven upward by the electric oil pump to push the top column. When the top of the top plate contacts the bottom of the weight, the electric oil pump is stopped, and then the splint adjustment rocker on both sides of the top plate is rotated to drive the splint to move until the splint fits the bottom two sides of the weight, and then the controller is continued to control the operation of the electric oil pump until the weight is pushed to a suitable height and the electric oil pump is stopped. The splint will firmly lock the bottom side of the weight, which can effectively prevent the weight from sliding sideways when it is tilted, and improve the safety of use.

[0004] In the above-mentioned jack, the electric oil pump and the oil tank are independently arranged, and the electric oil pump is connected to the large hydraulic cylinder and the oil tank respectively through oil pipes, which is inconvenient to assemble and produce. After long-term use, the oil pipes are prone to corrosion or loosening, affecting the service life of the jack, and air will remain when hydraulic oil is added to the oil tank. When the hydraulic oil is too little or the oil pipe is loose, air is easy to enter the large hydraulic cylinder, thereby affecting the normal use of the jack. Summary of the invention

[0005] In order to overcome the defects in the prior art, the purpose of the utility model is to provide a jack which is convenient for users to use and has a long service life.

[0006] The purpose of the utility model is achieved in this way:

[0007] A jack comprises a base and an oil tank, wherein the oil tank is provided with an oil storage chamber for storing hydraulic oil, a hydraulic telescopic rod and a driving device are connected to the base, the driving device comprises an oil pump and a driving motor for driving the oil pump to move, the oil pump is arranged in the oil tank, an oil inlet hole connected to the oil pump is arranged in the base, the oil inlet hole is connected to the hydraulic telescopic rod and can drive the hydraulic telescopic rod to extend or shorten, an air chamber is arranged above the oil storage chamber, and the air in the oil storage chamber is stored in the air chamber under the action of buoyancy; an oil filling hole is arranged at the bottom of the oil storage chamber or at the lower part of the side of the oil storage chamber, and a sealing plug is detachably arranged in the oil filling hole.

[0008] The utility model is further configured as follows: the oil tank is a rubber oil tank, and during the extension and retraction of the hydraulic telescopic rod, the oil tank expands or contracts, and a protrusion is provided at the upper end of the oil tank, and an air cavity is provided in the protrusion to prevent the top of the air cavity from contracting into the oil storage cavity during the contraction of the oil tank.

[0009] The utility model is further configured as follows: the oil filling hole is arranged on the side of the oil storage cavity and is communicated with the bottom surface of the oil storage cavity.

[0010] The utility model is further configured as follows: one end of the oil filling hole away from the oil storage chamber extends toward the periphery and forms an annular step portion, an annular sealing gasket is provided on one side of the step portion, the sealing plug is threadedly connected to the oil filling hole, the sealing plug is tightly pressed against the sealing gasket and seals the oil filling hole.

[0011] The utility model is further configured as follows: the oil pump comprises a pump body and two sets of meshing gears, the pump body is provided with an installation cavity for installing the meshing gears, the installation cavity is connected with a first channel and a second channel, the first channel and the second channel are respectively connected with the oil tank and the oil inlet, and a second one-way valve is provided in the second channel; the meshing gears drive the hydraulic oil in the oil tank to enter the second channel through the first channel, and the hydraulic oil drives the second one-way valve to open and allows the hydraulic oil to flow into the base, thereby driving the hydraulic telescopic rod to extend;

[0012] A first one-way valve is arranged in the first channel, and the first one-way valve limits the oil in the second channel from entering the oil tank through the first channel, and a piston chamber and a reflux hole are arranged in the pump body, and the piston chamber is connected to the second channel, and a piston rod is slidably arranged in the piston chamber, and the piston rod can control the connection and sealing of the second channel and the reflux hole; the meshing gear drives the hydraulic oil in the base to enter the piston chamber through the second channel and the first channel, and the hydraulic oil drives the piston rod in the piston chamber to move and drives the second one-way valve to open, and at this time the hydraulic oil in the base can flow into the oil tank through the reflux hole, thereby driving the hydraulic telescopic rod to retract.

[0013] The utility model is further configured as follows: the pump body includes a left shell and a right shell that are detachably connected, the right shell is detachably connected to the base, the installation cavity and the first channel are both arranged on the left shell, and the piston cavity, the reflux hole and the second channel are all arranged on the right shell.

[0014] The utility model is further configured as follows: an articulated rod is provided on the meshing gear, and articulated holes adapted to the articulated rod are provided on the left shell and the right shell, the articulated hole is connected to the oil tank, and a through hole is provided on the articulated rod, and the reflux hole is connected to the oil tank via the through hole or the articulated hole.

[0015] The utility model is further configured as follows: a fixing plate is provided on the base, the drive motor and the oil tank are detachably arranged on both sides of the fixing plate, and a mounting hole is provided on the fixing plate, a sealed bearing is provided in the mounting hole, and the output shaft of the drive motor passes through the sealed bearing and is connected to the hinge rod.

[0016] The utility model is further configured as follows: a connecting hole is provided on the fixing plate, the second channel is connected with the oil inlet hole through the connecting hole, and a sealing groove is provided at the end of the second channel, a sealing gasket is provided in the sealing groove, and the hydraulic oil flows into the connecting hole through the sealing gasket.

[0017] The utility model is further configured as follows: a pressure relief hole is connected to the second channel or the side where the installation cavity is connected to the second channel, and a pressure relief valve is arranged on the pressure relief hole;

[0018] The piston rod is provided with an annular sealing ring, which is tightly matched with the piston cavity; the sealing ring is controlled to pass over the end of the reflux hole, so that the second channel and the reflux hole are connected or sealed.

[0019] Compared with the prior art, the utility model has the following advantages:

[0020] 1. In the utility model, the oil pump is directly arranged in the oil tank, and the oil pump is connected with the hydraulic telescopic rod through the oil inlet hole in the base. There is no need to connect through oil pipes during the assembly and production process, and there will be no situation where the oil pipe is corroded or loosened to cause damage to the jack, which is beneficial to extending the service life of the jack. The structure can also reduce the occurrence of hydraulic oil leakage. In the structure, air is stored in the air cavity above the oil storage cavity to prevent air from entering the oil pump or even the hydraulic telescopic rod during use, making it convenient for users to use the jack.

[0021] 2. The rubber oil tank in the utility model is convenient for reducing the pressure change in the oil tank during use, reducing the resistance of the oil pump during use, thereby reducing the energy consumption of the drive motor during use, and is beneficial to increasing the horizontal plane of the hydraulic oil in the oil tank, reducing or even avoiding the contact between air and the oil pump, and avoiding air from entering the oil pump or even the hydraulic telescopic rod. The provision of the raised portion avoids the top of the air cavity from shrinking into the oil storage cavity, reducing or even avoiding the contact between air and the oil pump during use, and can further avoid air from entering the oil pump or even the hydraulic telescopic rod.

[0022] 3. The oil filling hole arranged on the side of the oil storage chamber and connected with the bottom of the oil storage chamber in the utility model is convenient for the manufacturer to add more hydraulic oil to the liquid storage chamber, and is convenient for the hydraulic oil to flow out from the oil filling hole during the replacement of the hydraulic oil, which is convenient for the production and maintenance of the jack; the setting of the step portion not only facilitates the hydraulic oil to flow out of the oil filling hole, but also facilitates the installation of the sealing gasket and facilitates the sealing of the oil filling hole by the sealing plug.

[0023] 4. In the utility model, the second channel and the reflux hole are connected and sealed by the piston rod, and the second one-way valve is driven to open by the piston rod, thereby simplifying the oil circuit structure of the oil pump, which is beneficial to reducing the volume and weight of the oil pump, facilitating the production and processing of the jack, and facilitating the carrying and transportation of the jack; the piston chamber, the reflux hole and the second channel arranged on the right shell body are convenient for the connection and coordination between the piston rod and the reflux hole and the second one-way valve, and reducing the large friction of the piston rod caused by the installation error; the installation chamber and the first channel arranged on the left shell body are beneficial to simplifying the structure of the right shell body, and facilitating the production and processing of the left shell body and the right shell body; the reflux hole is connected with the oil tank through the hinge hole or the through hole, which is beneficial to the rapid reflux of the hydraulic oil, and makes the connection surface between the right shell body and the base smoother, so that the right shell body and the base are more tightly connected.

[0024] 5. In the utility model, the oil pump is arranged in the oil tank, and the driving motor is isolated from the oil tank by a fixing plate and a sealing bearing to avoid leakage of hydraulic oil, which is beneficial to keeping the jack clean and sanitary and convenient for heat dissipation of the driving motor; the oil pump is connected with the oil inlet hole through the connecting hole on the fixing plate, which is beneficial to reduce leakage of hydraulic oil caused by production errors and installation errors and is beneficial to prolonging the service life of the jack.

[0025] 6. The setting of the pressure relief hole and the pressure relief valve in the utility model avoids excessive pressure in the oil pump and the base, and prevents the oil pump from continuing to work and causing damage to the jack when the jack is raised to the limit position, which is beneficial to avoiding accidental damage to the jack; the setting structure of the annular sealing ring is simple, and it is convenient to control the connection or sealing of the second channel and the reflux hole through the piston rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a cross-sectional view of the utility model;

[0027] Figure 2 It is a structural schematic diagram of the utility model;

[0028] Figure 3 It is a cross-sectional view of the installation structure of the drive motor, the oil pump and the oil tank on the fixed plate in the utility model;

[0029] Figure 4 yes Figure 3 A partial enlarged view of the middle A;

[0030] Figure 5 It is a cross-sectional view of the installation structure of the drive motor and the oil pump on the fixed plate in the utility model;

[0031] Figure 6 It is a cross-sectional view of the oil pump in the utility model;

[0032] Figure 7 It is an explosion diagram of the oil pump in the utility model;

[0033] Figure 8 It is a cross-sectional view of the base in the utility model;

[0034] Fig. 9 It is a cross-sectional view of the oil tank in the utility model;

[0035] Fig.10 It is one of the structural schematic diagrams of the right housing in the utility model;

[0036] Fig.11 This is the second structural schematic diagram of the right housing in the utility model;

[0037] Fig.12 It is a cross-sectional view of the right housing in the utility model;

[0038] Fig.13 It is a structural schematic diagram of the left housing in the utility model;

[0039] Fig.14 It is a cross-sectional view of the meshing gears in the utility model.

[0040] Meanings of the numbers in the figure: 1-base; 11-fixed plate; 12-oil filling hole; 13-oil inlet hole; 111-mounting hole; 112-sealed bearing; 113-connecting hole; 121-step portion; 2-hydraulic telescopic rod; 3-driving motor; 31-output shaft; 32-first transmission hole; 4-oil tank; 41-oil storage chamber; 42-protrusion; 43-air chamber; 5-oil pump; 51-right housing; 52-left housing; 53-piston rod; 54-second one-way valve; 55-first one-way valve; 56-meshing gear; 57-transmission rod; 511-second channel; 512-piston chamber; 513-reflux hole;

[0041] 514-plug; 515-sealing groove; 516-sealing gasket; 517-hinge hole; 521-first channel;

[0042] 522-installation cavity; 523-pressure relief hole; 531-sealing ring; 561-through hole; 562-second transmission hole;

[0043] 563-hinged rod; 6-pressure relief valve; 7-sealing plug; 71-tightening inclined surface; 72-sealing gasket. DETAILED DESCRIPTION

[0044] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments:

[0045] See also Figures 1 to 14 As shown, a jack includes a base 1 and an oil tank 4, wherein the oil tank 4 is provided with an oil storage chamber 41 for storing hydraulic oil, a hydraulic telescopic rod 2 and a driving device are connected to the base 1, wherein the driving device includes an oil pump 5 and a driving motor 3 for driving the oil pump 5 to move, the oil pump 5 is arranged in the oil tank 4, and an oil inlet hole 13 connected to the oil pump 5 is provided in the base 1, the oil inlet hole 13 is connected to the hydraulic telescopic rod 2 and can drive the hydraulic telescopic rod 2 to extend or shorten, in this structure, the oil pump 5 is directly arranged in the oil tank 4, and the oil pump 5 is connected to the hydraulic telescopic rod 2 through the oil inlet hole 13 in the base 1, and no oil pipe connection is required during the assembly production process, and the oil pipe corrosion or loosening will not cause damage to the jack, which is beneficial to extending the service life of the jack, and this structure can reduce the occurrence of hydraulic oil leakage.

[0046] An air cavity 43 is provided above the oil storage cavity 41. The air in the oil storage cavity 41 is stored in the air cavity 43 under the action of buoyancy. In this structure, air is stored in the air cavity 43 above the oil storage cavity 41 to prevent air from entering the oil pump 5 or even the hydraulic telescopic rod 2 during use, making it convenient for users to use the jack.

[0047] The oil tank 4 described in the utility model is a rubber oil tank 4. During the extension and retraction process of the hydraulic telescopic rod 2, the oil tank 4 expands or contracts. The rubber oil tank 4 is convenient for reducing the pressure change in the oil tank 4 during use, reducing the resistance of the oil pump 5 during use, thereby reducing the energy consumption of the drive motor 3 during use, and is beneficial to increasing the horizontal surface of the hydraulic oil in the oil tank 4, reducing or even avoiding the contact between air and the oil pump 5, and avoiding air from entering the oil pump 5 or even the hydraulic telescopic rod 2.

[0048] Preferably, a protrusion 42 is provided at the upper end of the oil tank 4, and an air cavity 43 is provided in the protrusion 42 to prevent the top of the air cavity 43 from shrinking into the oil storage cavity 41 during the contraction of the oil tank 4. The provision of the protrusion 42 prevents the top of the air cavity 43 from shrinking into the oil storage cavity 41, thereby reducing or even preventing the contact between air and the oil pump 5 during use, and can further prevent air from entering the oil pump 5 or even the hydraulic telescopic rod 2.

[0049] An oil filling hole 12 is provided at the bottom of the oil storage chamber 41 or at the lower part of the side of the oil storage chamber 41, and a sealing plug 7 is detachably provided in the oil filling hole 12. The setting of the oil filling hole 12 is convenient for adding and replacing the hydraulic oil in the liquid storage chamber, and is convenient for users to use. In the utility model, the oil filling hole 12 is preferably arranged on the side of the oil storage chamber 41 and connected with the bottom of the oil storage chamber 41. The oil filling hole 12 arranged on the side of the oil storage chamber 41 and connected with the bottom of the oil storage chamber 41 is convenient for the manufacturer to add more hydraulic oil to the liquid storage chamber, and is convenient for the hydraulic oil to flow out of the oil filling hole 12 during the replacement of the hydraulic oil, which is convenient for the production and maintenance of the jack.

[0050] In this embodiment, the oil filling hole 12 described in one embodiment extends toward the periphery at one end away from the oil storage chamber 41 and forms an annular step portion 121. An annular sealing gasket 72 is arranged on one side of the step portion 121. The sealing plug 7 is threadedly connected to the oil filling hole 12. The sealing plug 7 is pressed against the sealing gasket 72 and seals the oil filling hole 12. The setting of the step portion 121 not only facilitates the outflow of hydraulic oil from the oil filling hole 12, but also facilitates the installation of the sealing gasket 72 and facilitates the sealing of the oil filling hole 12 by the sealing plug 7. Preferably, a conical pressing slope 71 is arranged at one end of the sealing plug 7 close to the step portion 121. The pressing slope 71 is penetrated in the sealing gasket 72 and presses the sealing gasket 72 against the adjusting plate 121.

[0051] The oil pump 5 includes a pump body and two sets of meshing gears 56. The pump body is provided with an installation cavity 522 for installing the meshing gears 56. The installation cavity 522 is connected with a first channel 521 and a second channel 511. The first channel 521 and the second channel 511 are respectively connected to the oil tank 4 and the oil inlet hole 13, and a second one-way valve 54 is provided in the second channel 511. The meshing gears 56 drive the hydraulic oil in the oil tank 4 to enter the second channel 511 through the first channel 521, and the hydraulic oil drives the second one-way valve 54 to open and allow the hydraulic oil to flow into the base 1, thereby driving the hydraulic telescopic rod 2 to extend.

[0052] A first one-way valve 55 is provided in the first channel 521, and the first one-way valve 55 limits the oil in the second channel 511 from entering the oil tank 4 through the first channel 521, and a piston chamber 512 and a reflux hole 513 are provided in the pump body, which are connected to each other. The piston chamber 512 is connected to the second channel 511, and a piston rod 53 is slidably provided in the piston chamber 512, and the piston rod 53 can control the connection and sealing between the second channel 511 and the reflux hole 513; the meshing gear 56 drives the hydraulic oil in the base 1 to enter the piston chamber 512 through the second channel 511 and the first channel 521, and the hydraulic oil drives the piston rod 53 in the piston chamber 512 to move and drives the second one-way valve 54 to open, at which time the hydraulic oil in the base 1 can flow into the oil tank 4 through the reflux hole 513, thereby driving the hydraulic telescopic rod 2 to retract.

[0053] In the above structure, the second channel 511 and the reflux hole 513 are connected and sealed by the piston rod 53, and the second one-way valve 54 is driven to open by the piston rod 53, thereby simplifying the oil circuit structure of the oil pump 5, which is beneficial to reducing the volume and weight of the oil pump 5, facilitating the production and processing of the jack, and facilitating the carrying and transportation of the jack. Moreover, since the oil pump 5 is arranged in the oil tank 4, it is beneficial to simplify the oil circuit structure of the jack and avoid leakage of hydraulic oil.

[0054] In this embodiment, a plug 514 is provided at one end of the piston chamber 512, and the piston rod 53 is installed in the piston chamber 512 through the plug 514. A plug 514 is detachably provided on one side of the second channel 511, and the plug 514 presses the second one-way valve 54 tightly in the second channel 511.

[0055] A pressure relief hole 523 is connected to the side where the second channel 511 or the installation cavity 522 is connected to the second channel 511, and a pressure relief valve 6 is arranged on the pressure relief hole 523. The arrangement of the pressure relief hole 523 and the pressure relief valve 6 prevents excessive pressure in the oil pump 5 and the base 1, and prevents the oil pump 5 from continuing to work and causing damage to the jack when the jack is raised to the limit position, which is beneficial to avoiding accidental damage to the jack.

[0056] The piston rod 53 is provided with an annular sealing ring 531, which is tightly matched with the piston chamber 512; the sealing ring 531 is controlled to pass over the end of the reflux hole 513, so that the second channel 511 and the reflux hole 513 are connected or sealed. The annular sealing ring 531 has a simple structure and is convenient for controlling the second channel 511 and the reflux hole 513 to be connected or sealed through the piston rod 53.

[0057] The pump body described in the utility model includes a left shell body 52 and a right shell body 51 which are detachably connected. The right shell body 51 is detachably connected to the base 1. The installation cavity 522 and the first channel 521 are both arranged on the left shell body 52. ​​The piston cavity 512, the reflux hole 513 and the second channel 511 are all arranged on the right shell body 51. The piston cavity 512, the reflux hole 513 and the second channel 511 arranged on the right shell body 51 facilitate the connection and cooperation between the piston rod 53 and the reflux hole 513 and the second one-way valve 54, and reduce the large friction force of the piston rod 53 caused by the installation error. The installation cavity 522 and the first channel 521 arranged on the left shell body 52 are conducive to simplifying the structure of the right shell body 51, and convenient for the production and processing of the left shell body 52 and the right shell body 51.

[0058] In this embodiment, the meshing gear 56 is provided with an articulated rod 563, and the left shell 52 and the right shell 51 are both provided with an articulated hole 517 adapted to the articulated rod 563. The articulated hole 517 is connected to the oil tank 4, and a through hole 561 is provided on the articulated rod 563. The reflux hole 513 is connected to the oil tank 4 through the through hole 561 or the articulated hole 517. The reflux hole 513 is connected to the oil tank 4 through the articulated hole 517 or the through hole 561, which is beneficial to the rapid reflux of the hydraulic oil and makes the connecting surface between the right shell 51 and the base 1 smoother, so that the right shell 51 and the base 1 are more tightly connected.

[0059] A fixing plate 11 is provided on the base 1, and the drive motor 3 and the oil tank 4 are detachably arranged on both sides of the fixing plate 11, and a mounting hole 111 is provided on the fixing plate 11, and a sealed bearing 112 is provided in the mounting hole 111. The output shaft 31 of the drive motor 3 passes through the sealed bearing 112 and is connected to the hinge rod 563. In this structure, since the oil pump 5 is arranged in the oil tank 4, and the drive motor 3 is isolated from the oil tank 4 by the fixing plate 11 and the sealed bearing 112, leakage of hydraulic oil is avoided, which is conducive to keeping the jack clean and sanitary, and convenient for heat dissipation of the drive motor 3.

[0060] In the utility model, a connecting hole 113 is provided on the fixing plate 11, and the second channel 511 is communicated with the oil inlet hole 13 through the connecting hole 113, and a sealing groove 515 is provided at the end of the second channel 511, and a sealing gasket 516 is provided in the sealing groove 515. The hydraulic oil flows into the connecting hole 113 through the sealing gasket 516, and the oil pump 5 is connected with the oil inlet hole 13 through the connecting hole 113 on the fixing plate 11, which is beneficial to reduce the leakage of hydraulic oil caused by production errors and installation errors, and is beneficial to prolonging the service life of the jack.

[0061] Preferably, a first transmission hole 32 is provided on the output shaft 31 of the driving motor 3, a second transmission hole 562 is provided on the meshing gear 56, and a transmission rod 57 is provided between the driving motor 3 and the meshing gear 56, and both ends of the transmission rod 57 are respectively connected to the first transmission hole 32 and the second transmission hole 562, and the driving motor 3 drives the meshing gear 56 to rotate through the transmission rod 57. In this embodiment, the cross-sections of the transmission rod 57, the first transmission hole 32 and the second transmission hole 562 are all regular hexagons, and the second transmission hole 562 is connected to the through hole 561.

[0062] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A jack, comprising a base (1) and an oil tank (4), wherein the oil tank (4) is provided with an oil storage chamber (41) for storing hydraulic oil, and the base (1) is connected with a hydraulic telescopic rod (2) and a driving device, characterized in that: The driving device comprises an oil pump (5) and a driving motor (3) for driving the oil pump (5) to move. The oil pump (5) is arranged in an oil tank (4). An oil inlet hole (13) connected to the oil pump (5) is arranged in the base (1). The oil inlet hole (13) is connected to the hydraulic telescopic rod (2) and can drive the hydraulic telescopic rod (2) to extend or shorten. An air cavity (43) is arranged above the oil storage cavity (41). The air in the oil storage cavity (41) is stored in the air cavity (43) under the action of buoyancy. An oil injection hole (12) is arranged at the bottom of the oil storage cavity (41) or at the lower part of the side of the oil storage cavity (41), and a sealing plug (7) is detachably arranged in the oil injection hole (12).

2. A jack according to claim 1, characterized in that: The oil tank (4) is a rubber oil tank (4). During the extension and retraction of the hydraulic telescopic rod (2), the oil tank (4) expands or contracts. A protrusion (42) is provided at the upper end of the oil tank (4). The air cavity (43) is provided in the protrusion (42) to prevent the top of the air cavity (43) from contracting into the oil storage cavity (41) during the contraction of the oil tank (4).

3. A jack according to claim 1, characterized in that: The oil filling hole (12) is arranged on the side of the oil storage cavity (41) and is communicated with the bottom surface of the oil storage cavity (41).

4. A jack according to claim 3, characterized in that: One end of the oil filling hole (12) away from the oil storage chamber (41) extends toward the periphery and forms an annular step portion (121), one side of the step portion is provided with an annular sealing gasket (72), the sealing plug (7) is threadedly connected to the oil filling hole (12), the sealing plug (7) is tightly pressed against the sealing gasket (72) and seals the oil filling hole (12).

5. A jack according to claim 1, characterized in that: The oil pump (5) comprises a pump body and two sets of meshing gears (56); a mounting cavity (522) for mounting the meshing gears (56) is provided in the pump body; a first channel (521) and a second channel (511) are connected to the mounting cavity (522); the first channel (521) and the second channel (511) are connected to the oil tank (4) and the oil inlet hole (13) respectively; and a second one-way valve (54) is provided in the second channel (511); the meshing gears (56) drive the hydraulic oil in the oil tank (4) to enter the second channel (511) through the first channel (521), and the hydraulic oil drives the second one-way valve (54) to open and allows the hydraulic oil to flow into the base (1), thereby driving the hydraulic telescopic rod (2) to extend; The first channel (521) is provided with a first one-way valve (55), the first one-way valve (55) restricting the oil in the second channel (511) from entering the oil tank (4) through the first channel (521), and the pump body is provided with a piston chamber (512) and a reflux hole (513) connected to each other, the piston chamber (512) is connected to the second channel (511), a piston rod (53) is slidably provided in the piston chamber (512), and the piston rod (53) can control the second channel ( The meshing gear (56) drives the hydraulic oil in the base (1) to enter the piston chamber (512) through the second channel (511) and the first channel (521), and the hydraulic oil drives the piston rod (53) in the piston chamber (512) to move and drives the second one-way valve (54) to open. At this time, the hydraulic oil in the base (1) can flow into the oil tank (4) through the reflux hole (513), thereby driving the hydraulic telescopic rod (2) to retract.

6. A jack according to claim 5, characterized in that: The pump body comprises a left shell (52) and a right shell (51) which are detachably connected, the right shell (51) is detachably connected to the base (1), the installation cavity (522) and the first channel (521) are both arranged on the left shell (52), and the piston cavity (512), the reflux hole (513) and the second channel (511) are all arranged on the right shell (51).

7. A jack according to claim 6, characterized in that: The meshing gear (56) is provided with an articulated rod (563), and the left housing (52) and the right housing (51) are both provided with an articulated hole (517) adapted to the articulated rod (563), the articulated hole (517) is connected to the oil tank (4), and the articulated rod (563) is provided with a through hole (561) penetrating therethrough, and the return hole (513) is connected to the oil tank (4) through the through hole (561) or the articulated hole (517).

8. A jack according to claim 5, 6 or 7, characterized in that: The base (1) is provided with a fixing plate (11), the driving motor (3) and the oil tank (4) are detachably arranged on both sides of the fixing plate (11), and the fixing plate (11) is provided with a mounting hole (111), a sealing bearing (112) is arranged in the mounting hole (111), and the output shaft (31) of the driving motor (3) passes through the sealing bearing (112) and is connected to the hinge rod (563).

9. A jack according to claim 8, characterized in that: The fixing plate (11) is provided with a connecting hole (113), the second channel (511) is connected to the oil inlet hole (13) through the connecting hole (113), and a sealing groove (515) is provided at the end of the second channel (511), a sealing gasket (516) is provided in the sealing groove (515), and the hydraulic oil flows into the connecting hole (113) through the sealing gasket (516).

10. A jack according to claim 5, characterized in that: A pressure relief hole (523) is connected to one side of the second channel (511) or the installation cavity (522) connected to the second channel (511), and a pressure relief valve (6) is provided on the pressure relief hole (523); The piston rod (53) is provided with an annular sealing ring (531), which is tightly matched with the piston chamber (512); the sealing ring (531) is controlled to pass over the end of the reflux hole (513), so that the second channel (511) and the reflux hole (513) are connected or sealed.

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