CN217421675U

CN217421675U - Hydraulic transmission system and LPG tank car

Info

Publication number: CN217421675U
Application number: CN202221209905.6U
Authority: CN
Inventors: 王金成; 刘斌; 施伟佳
Original assignee: China International Marine Containers Group Co Ltd; CIMC Enric Investment Holdings Shenzhen Co Ltd; Jingmen Hongtu Special Aircraft Manufacturing Co Ltd
Current assignee: China International Marine Containers Group Co Ltd; CIMC Enric Investment Holdings Shenzhen Co Ltd; Jingmen Hongtu Special Aircraft Manufacturing Co Ltd
Priority date: 2022-05-19
Filing date: 2022-05-19
Publication date: 2022-09-13
Anticipated expiration: 2032-05-19

Abstract

The present disclosure relates to a hydraulic transmission system and an LPG tanker. The hydraulic transmission system includes: a hydraulic actuator; an oil tank; the outlet of the oil inlet pipeline is connected with the oil inlet of the hydraulic actuating element, and the inlet of the oil inlet pipeline is connected with the oil tank; an inlet of the oil return pipeline is connected with an oil outlet of the hydraulic actuating element, and an outlet of the oil return pipeline is connected with the oil tank; the hydraulic pump is arranged on the oil inlet pipeline; a cooling unit including a throttle valve, a hydraulic motor, and a fan connected to an output shaft of the hydraulic motor; an oil inlet of the throttle valve is connected with the oil inlet pipeline, the connection position of the throttle valve is positioned at the downstream of the hydraulic pump, and an oil outlet of the throttle valve is connected with the hydraulic motor; the fan is arranged opposite to the oil return pipeline so as to blow air to cool the oil return pipeline. The fan is driven by the energy of the hydraulic oil to actively dissipate heat, so that the heat dissipation efficiency is higher, and the influence on the hydraulic loop is small.

Description

Hydraulic transmission system and LPG tank car

Technical Field

The disclosure belongs to the technical field of hydraulic pressure, and particularly relates to a hydraulic transmission system and an LPG tank truck.

Background

In a hydraulic transmission system, hydraulic power elements, hydraulic control elements, hydraulic actuators and the like need to be connected in series by using hydraulic oil, and therefore the hydraulic oil is the core of energy transmission thereof. When the hydraulic oil transfers mechanical energy, the energy of friction loss of mechanical parts of each component is converted into heat energy which is absorbed by the hydraulic oil. The long-time work of hydraulic transmission system will make the hydraulic oil temperature rise gradually in the return circuit, and the hydraulic oil temperature rise will make the viscosity and the lubricating property of hydraulic oil reduce, causes the abnormal wearing and tearing of hydraulic pressure components and parts, influences the components and parts life-span, and the rise of aggravation hydraulic oil temperature forms vicious circle simultaneously, directly leads to the reduction of transmission efficiency.

At present, the temperature of hydraulic oil is reduced passively by increasing the volume of an oil tank and improving the natural heat dissipation efficiency, but the above method cannot carry out active heat dissipation and has poor heat dissipation and cooling effects.

SUMMERY OF THE UTILITY MODEL

The purpose of the present disclosure is to provide a hydraulic transmission system, which can cool hydraulic oil through power provided by itself, and is actively controllable, and the heat dissipation and cooling effects are good.

A first aspect of the present disclosure provides a hydraulic transmission system, comprising: a hydraulic actuator; an oil tank;

the outlet of the oil inlet pipeline is connected with the oil inlet of the hydraulic actuating element, and the inlet of the oil inlet pipeline is connected with the oil tank; an inlet of the oil return pipeline is connected with an oil outlet of the hydraulic actuating element, and an outlet of the oil return pipeline is connected with the oil tank; the hydraulic pump is arranged on the oil inlet pipeline; a cooling unit including a throttle valve, a hydraulic motor, and a fan connected to an output shaft of the hydraulic motor; an oil inlet of the throttle valve is connected with the oil inlet pipeline, the connection position of the throttle valve is positioned at the downstream of the hydraulic pump, and an oil outlet of the throttle valve is connected with the hydraulic motor; the fan is arranged opposite to the oil return pipeline to blow air to cool the oil return pipeline.

In an exemplary embodiment of the disclosure, the oil return line includes a connection pipe section and a heat dissipation pipe section that are connected in series, an inlet of the connection pipe section is connected to an oil outlet of the hydraulic actuator, an outlet of the connection pipe section is connected to an inlet of the heat dissipation pipe section, an outlet of the heat dissipation pipe section is connected to the oil tank, and the fan is disposed opposite to the heat dissipation pipe section.

In an exemplary embodiment of the present disclosure, the heat radiating pipe section is integrally formed in a coil shape, or the outer wall of the heat radiating pipe section is provided with heat radiating fins.

In an exemplary embodiment of the present disclosure, the hydraulic transmission system further includes a temperature sensor disposed at the heat dissipation pipe section, the temperature sensor being electrically connected with the throttle valve.

In an exemplary embodiment of the present disclosure, the hydraulic transmission system further includes a directional valve and a first connecting line; the oil inlet pipeline comprises a first oil inlet pipeline and a second oil inlet pipeline; the inlet of the first oil inlet pipeline is connected with the oil tank, and the outlet of the first oil inlet pipeline is connected with the oil inlet of the reversing valve; an outlet of the second oil inlet pipeline is connected with an oil inlet of the hydraulic actuating element, and an inlet of the second oil inlet pipeline is connected with a first oil outlet of the reversing valve; a second oil outlet of the reversing valve is connected with an inlet of the first connecting pipeline, and an outlet of the first connecting pipeline is connected with the oil return pipeline; the oil inlet of the throttling valve is connected with the first oil inlet pipeline, and the hydraulic pump is arranged on the first oil inlet pipeline.

In an exemplary embodiment of the present disclosure, the hydraulic transmission system further includes a relief valve and a second connecting line; the overflow valve is arranged on the second connecting pipeline, the inlet of the second connecting pipeline is connected with the outlet of the first oil inlet pipeline, and the outlet of the second connecting pipeline is connected with the outlet of the first connecting pipeline.

In an exemplary embodiment of the present disclosure, the relief valve is disposed directly above the oil tank.

In an exemplary embodiment of the disclosure, the hydraulic transmission system further includes a check valve disposed on the oil return line between the hydraulic actuator and the first connecting line outlet connection.

In an exemplary embodiment of the present disclosure, oil filters are disposed between the oil inlet pipeline and the oil tank and between the oil return pipeline and the oil tank.

The second aspect of the disclosure provides an LPG tank truck, which comprises a unloading pump and the hydraulic transmission system, wherein the hydraulic actuating element is in driving connection with the unloading pump.

The scheme disclosed by the invention has the following beneficial effects:

this disclose under the condition that does not have the access of outside driving system, through setting up the choke valve, hydraulic motor and fan, the hydraulic oil that has hydraulic energy that obtains through choke valve department drives hydraulic motor action, thereby the drive fan is to returning oil pipe way cooling of blowing, reentrant oil tank next circulation after the hydraulic oil cooling that makes, compare at present through the volume that increases the oil tank and the mode that improves natural cooling efficiency, the scheme of this application utilizes the energy of hydraulic oil self to drive the fan and initiatively dispels the heat, the radiating efficiency is higher, the influence that produces hydraulic circuit is also very little.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows, or in part will be obvious from the description, or may be learned by practice of the disclosure.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure. It is to be understood that the drawings in the following description are merely exemplary of the disclosure, and that other drawings may be derived from those drawings by one of ordinary skill in the art without the exercise of inventive faculty.

Fig. 1 shows a schematic connection diagram of a hydraulic transmission system according to a first embodiment of the disclosure.

Description of reference numerals:

1. a hydraulic actuator; 2. an oil tank; 3. an oil inlet pipeline; 31. a first oil inlet pipeline; 32. a second oil inlet pipeline; 4. an oil return line; 41. connecting the pipe sections; 42. a heat dissipation pipe section; 5. a hydraulic pump; 6. a throttle valve; 7. a hydraulic motor; 8. a fan; 9. a diverter valve; 10. a first connecting line; 11. an overflow valve; 12. a second connecting line; 13. a one-way valve; 14. an oil filter; 15. a ball valve.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art.

In the present disclosure, the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present disclosure, "a plurality" means two or more unless specifically limited otherwise.

In the present disclosure, unless expressly stated or limited otherwise, the terms "mounted," "connected," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral connections; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or may be connected through the use of two elements or the interaction of two elements. The specific meaning of the above terms in the present disclosure can be understood as a specific case by a person of ordinary skill in the art.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the disclosure. One skilled in the relevant art will recognize, however, that the subject matter of the present disclosure can be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known methods, devices, implementations, or operations have not been shown or described in detail to avoid obscuring aspects of the disclosure.

Example one

Referring to fig. 1, the disclosed embodiment discloses a hydraulic transmission system, which includes a hydraulic actuator 1, an oil tank 2, an oil inlet pipeline 3, an oil return pipeline 4, a hydraulic pump 5, a cooling unit, a reversing valve 9, a first connecting pipeline 10, an overflow valve 11, a second connecting pipeline 12, a check valve 13, a temperature sensor, an oil filter 14, and a ball valve 15.

The oil tank 2 is a box-type structure, is mainly used for storing hydraulic oil, and is usually a rectangular box body, and the size of the oil tank 2 can be determined according to actual conditions.

The hydraulic actuator 1 is an output device in the whole hydraulic transmission system, can convert hydraulic pressure energy into mechanical energy and output the mechanical energy outwards, and can be a hydraulic motor or a hydraulic cylinder. Correspondingly, the hydraulic actuator 1 has an oil inlet and an oil outlet, wherein the oil inlet of the hydraulic actuator 1 is filled with high-pressure hydraulic oil, and the oil outlet of the hydraulic actuator 1 discharges low-pressure hydraulic oil. Therefore, the oil inlet of the hydraulic actuator 1 is connected with the outlet of the oil inlet pipeline 3, the oil outlet of the hydraulic actuator 1 is connected with the inlet of the oil return pipeline 4, the inlet of the oil inlet pipeline 3 is connected with the oil tank 2, and the outlet of the oil return pipeline 4 is also connected with the oil tank 2, so that a circulation loop is formed, and in order to enable hydraulic oil introduced into the oil inlet of the hydraulic actuator 1 to have certain pressure, the oil inlet pipeline 3 is further provided with the hydraulic pump 5.

The hydraulic pump 5 is a hydraulic power element in a hydraulic transmission system, and is used for pressurizing and transmitting hydraulic oil to the hydraulic actuator 1, the hydraulic pump 5 itself can be driven by an engine or a motor, and the hydraulic pump sucks the hydraulic oil in the oil tank 2 into the hydraulic pump 5 and pressurizes the hydraulic oil to form high-pressure hydraulic oil, and then the high-pressure hydraulic oil is input into the hydraulic actuator 1 through the oil inlet pipeline 3. The hydraulic pump 5 may be one of a gear pump, a plunger pump, a vane pump and a screw pump, and in this embodiment, the hydraulic pump 5 is a gear pump.

In the hydraulic transmission system, a hydraulic pump 5 sucks hydraulic oil in an oil tank 2 and transmits the hydraulic oil to a hydraulic actuator 1 in a pressurized manner, and the hydraulic actuator 1 discharges low-pressure hydraulic oil after acting and returns the low-pressure hydraulic oil to the oil tank 2 through an oil return pipeline 4, so that oil circuit circulation is formed. The part of the hydraulic oil generating heat is mainly concentrated at the hydraulic actuator 1, and the temperature of the hydraulic oil in the oil return pipeline 4 from the hydraulic actuator 1 to the oil tank 2 is higher, so in order to more effectively and pertinently reduce the temperature of the hydraulic oil, the cooling unit in the embodiment of the disclosure comprises a throttle valve 6, a hydraulic motor 7 and a fan 8 connected to an output shaft of the hydraulic motor 7, and the cooling unit cools the oil return pipeline 4.

Specifically, an oil inlet of the throttle valve 6 is connected with the oil inlet pipeline 3, the connection position is located at the downstream of the hydraulic pump 5, an oil outlet of the throttle valve 6 is connected with the hydraulic motor 7, high-pressure hydraulic oil output by the hydraulic pump 5 enters the hydraulic motor 7 through a small part of the throttle valve 6 to drive the hydraulic motor 7 to act so as to drive the fan 8 to rotate and generate wind power, and therefore the opposite oil return pipeline 4 is cooled by blowing air. The throttle valve 6 is a valve for controlling the flow of fluid by changing the throttle section or the throttle length, and can control the flow of fluid flowing through by controlling the opening of the valve core, thereby realizing the controllability of the cooling effect, actively adjusting the rotating speed of the fan 8, and further having better cooling effect. And because the hydraulic motor 7 drives the fan 8 to rotate and does not need excessive energy, the hydraulic oil with hydraulic energy obtained from the throttle valve 6 occupies a very small proportion and can be almost ignored, the influence of the hydraulic oil on a hydraulic loop is very small, and the good effect of driving the fan 8 to dissipate heat and cool the hydraulic oil by only depending on the energy of the hydraulic oil without accessing external power can be realized.

Further, the oil return pipeline 4 comprises a connecting pipe section 41 and a radiating pipe section 42 which are connected in series, an inlet of the connecting pipe section 41 is connected with an oil outlet of the hydraulic actuating element 1, an outlet of the connecting pipe section 41 is connected with an inlet of the radiating pipe section 42, and an outlet of the radiating pipe section 42 is connected with the oil tank 2. The oil return pipeline 4 is cooled by arranging the special cooling pipe section 42, and the fan 8 is arranged relative to the cooling pipe section 42, so that the temperature of the cooling pipe section 42 can be further reduced by the fan 8, and the cooling efficiency is improved.

In some embodiments, the heat dissipating tube 42 is generally coiled, such as a spiral coil or a U-shaped coil, etc., along its axial direction, so as to increase the routing length of the heat dissipating tube 42 in the same axial length, so that the path of the hydraulic oil flowing through the heat dissipating tube 42 is longer, and the hydraulic oil dissipates more heat and cools more quickly.

In other embodiments, the outer wall of the radiating pipe section 42 is provided with radiating fins distributed at intervals along the axial direction of the radiating pipe section 42, and the contact area between the radiating pipe section 42 and the air is enlarged by adding the radiating fins, so that the heat exchange efficiency between the radiating pipe section 42 and the air is improved, and the radiating and cooling efficiency of the radiating pipe section 42 is improved.

Of course, the radiating pipe section can also be in a coil shape, and the outer wall of the radiating pipe section is provided with radiating fins, so that the radiating and cooling efficiency can be further improved.

Furthermore, in order to facilitate automatic control of the opening of the throttle valve 6 to adjust the rotation speed of the fan 8, a temperature sensor may be disposed at the heat dissipation pipe section 42 for detecting the temperature at the heat dissipation pipe section 42 and feeding back the temperature information to the control module, the control module is electrically connected to the throttle valve 6, that is, the temperature sensor is electrically connected to the throttle valve, the throttle valve 6 adjusts the opening thereof according to the detection value of the temperature sensor, and then controls the rotation speed of the fan, thereby achieving active and controllable cooling. If the detected temperature is high, the opening of the throttle valve 6 is increased, the rotating speed of the fan 8 is increased, and the air circulation quantity at the radiating pipe section 42 is enhanced, and if the detected temperature is low, the opening of the throttle valve 6 is reduced, the rotating speed of the fan 8 is reduced, and the influence on the high-pressure hydraulic oil of the hydraulic actuator 1 is reduced.

The directional control valve 9 is a directional control valve having two or more flow forms and two or more oil ports, and is a valve capable of realizing communication, cutting-off and reversing of hydraulic oil flow, pressure unloading and sequential operation control, and is a directional control valve depending on the relative movement of a valve element and a valve body. The valve core is divided into two positions, three positions and the like according to the number of the working positions of the valve core staying in the valve body, and is divided into two-way, three-way, four-way, circulation and the like according to the number of oil ways connected with the valve body. In the embodiment of the present disclosure, the reversing valve 9 is a two-position three-way valve, and has two working positions and three oil ports, which are respectively an oil inlet and a first oil outlet and a second oil outlet, and the two working positions are respectively working and stopping.

Illustratively, the oil inlet pipeline 3 comprises a first oil inlet pipeline 31 and a second oil inlet pipeline 32, an inlet of the first oil inlet pipeline 31 is connected with the oil tank 2, an outlet of the first oil inlet pipeline 31 is connected with an oil inlet of the reversing valve 9, an outlet of the second oil inlet pipeline 32 is connected with an oil inlet of the hydraulic actuator 1, and an inlet of the second oil inlet pipeline 32 is connected with a first oil outlet of the reversing valve 9; a second oil outlet of the reversing valve 9 is connected with an inlet of a first connecting pipeline 10, and an outlet of the first connecting pipeline 10 is connected with the oil return pipeline 4; correspondingly, the oil inlet of the throttle valve 6 is connected with the first oil inlet pipeline 31, and the hydraulic pump 5 is arranged on the first oil inlet pipeline 31.

It can be understood that, when the reversing valve 9 is in the working position, the valve core of the reversing valve 9 acts, so that the oil inlet of the reversing valve 9 is communicated with the first oil outlet thereof, at this time, the first oil inlet pipeline 31 is communicated with the second oil inlet pipeline 32 through the reversing valve 9, the high-pressure hydraulic oil flows into the hydraulic actuator 1 from the reversing valve 9, and the hydraulic actuator 1 works normally; when the reversing valve 9 is at the stop position, the valve core of the reversing valve 9 acts to communicate the oil inlet of the reversing valve 9 with the second oil outlet thereof, at this time, the first oil inlet pipeline 31 is communicated with the first connecting pipeline 10 through the reversing valve 9, the high-pressure hydraulic oil directly flows into the oil return pipeline 4 through the reversing valve 9, does not enter the hydraulic actuator 1, and the hydraulic actuator 1 loses hydraulic oil drive and stops working. By switching the position of the selector valve 9, different operating modes of the hydraulic actuator 1 can be assigned.

Further, the overflow valve 11 is a hydraulic pressure control valve, and plays roles of constant pressure overflow, pressure stabilization, system unloading and safety protection in a hydraulic circuit. In the embodiment of the present disclosure, in order to ensure that the outlet pressure of the hydraulic pump 5 is constant and avoid an excessive pressure, the overflow valve 11 is disposed on the second connecting pipeline 12, an inlet of the second connecting pipeline 12 is connected to an outlet of the first oil inlet pipeline 31, and an outlet of the second connecting pipeline 12 is connected to an outlet of the first connecting pipeline 10. In this way, if the outlet pressure of the hydraulic pump 5 becomes larger than the allowable value, part of the hydraulic oil overflows through the relief valve 11, thereby reducing the circuit pressure and ensuring the stability of the system. Further, the overflow valve 11 is disposed right above the oil tank 2, so that the overflowed hydraulic oil can directly flow into the oil tank 2, and leakage is avoided.

The non-return valve 13 is exemplified as a valve body in which fluid can only flow along the inlet and the outlet medium cannot flow back. In the embodiment disclosed, in order to prevent the hydraulic oil from flowing back to the hydraulic actuator 1 through the return line 4 when the directional control valve 9 is in the rest position, a check valve 13 is disposed on the return line 4 between the hydraulic actuator 1 and the outlet connection of the first connecting line 10. It is conceivable that the inlet of the non-return valve 13 is connected to the outlet of the hydraulic actuator 1 and that the outlet of the non-return valve 13 is connected to the tank 2.

For example, an oil filter 14 may be disposed between the oil inlet pipeline 3 and the oil tank 2 and between the oil return pipeline 4 and the oil tank 2, and the oil filter 14 is configured to filter impurities in the hydraulic oil, so as to prevent the impurities from damaging the hydraulic pump 5 and the hydraulic actuator 1.

Illustratively, the oil inlet pipeline 3 is also provided with a ball valve 15, and the ball valve 15 is positioned at the upstream of the hydraulic pump 5. Can control the intercommunication of advancing oil pipe way 3 through ball valve 15 and turn off, avoid revealing of hydraulic oil in the return circuit, when hydraulic transmission system normally worked, ball valve 15 opened, and when hydraulic transmission system stopped working, ball valve 15 closed, cut off the circulation of hydraulic oil in the return circuit.

To sum up, this disclosed embodiment is under the condition that does not have the access of external power system, through setting up choke valve 6, hydraulic motor 7 and fan 8, hydraulic oil with hydraulic energy that obtains through choke valve 6 department drives hydraulic motor 7 action, thereby drive fan 8 is to returning oil pipe way 4 cooling of blowing, reentrant oil tank next circulation after the hydraulic oil cooling of messenger, compare present answer mode, can control the rotational speed of fan through the aperture of control choke valve 6, realize the initiative controllable cooling, the heat dissipation cooling effect is better, the influence that produces hydraulic circuit is also very little.

Example two

The embodiment of the disclosure provides an LPG (Liquefied natural Gas) tank truck for transporting Liquefied natural Gas, which comprises a truck body, a tank body, an unloading pump and a hydraulic transmission system as in the first embodiment, wherein the truck body comprises a chassis, the tank body and the unloading pump are arranged on the chassis, the unloading pump is communicated with the tank body, and a hydraulic actuating element 1 in the hydraulic transmission system is in driving connection with the unloading pump and used for driving the unloading pump to pump liquid in the tank body. Since the LPG tank truck of this embodiment has the hydraulic transmission system of the first embodiment, all the advantages of the hydraulic drive system are provided, and are not described herein again.

It should be noted that the hydraulic transmission system of the first embodiment is not limited to be applied to the LPG tanker of the second embodiment, and may be applied to other engineering vehicles such as a mixer truck and an excavator.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," and the like are to be construed broadly and include, for example, fixed connections, removable connections, or integral connections; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In the description herein, references to the description of the terms "some embodiments," "exemplary," etc. mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or exemplary is included in at least one embodiment or exemplary of the application. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present application have been shown and described, it is understood that the above embodiments are illustrative and should not be construed as limiting the present application and that various changes, modifications, substitutions and alterations can be made therein by those skilled in the art within the scope of the present application, and therefore all changes and modifications that come within the meaning of the claims and the description of the invention are to be embraced therein.

Claims

1. A hydraulic transmission system, comprising:

a hydraulic actuator;

an oil tank;

the outlet of the oil inlet pipeline is connected with the oil inlet of the hydraulic actuating element, and the inlet of the oil inlet pipeline is connected with the oil tank;

an inlet of the oil return pipeline is connected with an oil outlet of the hydraulic actuating element, and an outlet of the oil return pipeline is connected with the oil tank;

the hydraulic pump is arranged on the oil inlet pipeline;

a cooling unit including a throttle valve, a hydraulic motor, and a fan connected to an output shaft of the hydraulic motor; an oil inlet of the throttle valve is connected with the oil inlet pipeline, the connection position of the throttle valve is positioned at the downstream of the hydraulic pump, and an oil outlet of the throttle valve is connected with the hydraulic motor; the fan is arranged opposite to the oil return pipeline so as to blow air to cool the oil return pipeline.

2. The hydraulic transmission system according to claim 1, wherein the oil return line includes a connecting pipe section and a heat dissipating pipe section connected in series, an inlet of the connecting pipe section is connected to an oil outlet of the hydraulic actuator, an outlet of the connecting pipe section is connected to an inlet of the heat dissipating pipe section, an outlet of the heat dissipating pipe section is connected to the oil tank, and the fan is disposed opposite to the heat dissipating pipe section.

3. The hydraulic transmission system according to claim 2, wherein the heat radiating pipe section is integrally formed in a coil shape, or the outer wall of the heat radiating pipe section is provided with heat radiating fins.

4. The hydraulic transmission system according to claim 2, further comprising a temperature sensor disposed at the heat dissipation pipe section, the temperature sensor being electrically connected to the throttle valve.

5. The hydraulic transmission system according to any one of claims 1 to 4, further comprising a directional valve and a first connecting line;

the oil inlet pipeline comprises a first oil inlet pipeline and a second oil inlet pipeline;

an inlet of the first oil inlet pipeline is connected with the oil tank, and an outlet of the first oil inlet pipeline is connected with an oil inlet of the reversing valve;

an outlet of the second oil inlet pipeline is connected with an oil inlet of the hydraulic actuating element, and an inlet of the second oil inlet pipeline is connected with a first oil outlet of the reversing valve;

a second oil outlet of the reversing valve is connected with an inlet of the first connecting pipeline, and an outlet of the first connecting pipeline is connected with the oil return pipeline;

the oil inlet of the throttling valve is connected with the first oil inlet pipeline, and the hydraulic pump is arranged on the first oil inlet pipeline.

6. The hydraulic transmission system according to claim 5, further comprising a relief valve and a second connecting line;

the overflow valve is arranged on the second connecting pipeline, the inlet of the second connecting pipeline is connected with the outlet of the first oil inlet pipeline, and the outlet of the second connecting pipeline is connected with the outlet of the first connecting pipeline.

7. The hydraulic drive system of claim 6, wherein the relief valve is disposed directly above the oil tank.

8. The hydraulic drive system of claim 7, further comprising a check valve disposed on the return line between the hydraulic actuator and the first connecting line outlet connection.

9. The hydraulic transmission system according to claim 1, wherein an oil filter is provided between said oil inlet line and said oil tank and between said oil return line and said oil tank.

10. An LPG tanker truck, comprising a dump pump and a hydraulic transmission system as claimed in any one of claims 1 to 9, the hydraulic actuator being drivingly connected to the dump pump.