Hydraulic oil return system and loader

Abstract

The invention relates to the technical field of hydraulic oil return control, and discloses a hydraulic oil return system and a loader, the system comprises a pressure control unit, a proportional control unit, a hydraulic oil radiator, a controller and a temperature sensor; a first end of the pressure control unit is connected with a hydraulic oil return input port, a second end is connected with the hydraulic oil tank, and the pressure control unit is opened or closed under the pressure action of hydraulic oil; the first end of the proportional control unit is connected with a hydraulic oil return input port, and the second end is connected with the hydraulic oil radiator. The first end of the hydraulic oil radiator is connected with the proportional control unit, and the second end is connected with the hydraulic oil tank; the controller is used for obtaining the hydraulic oil temperature of the hydraulic oil from the temperature sensor and controlling the communication state of the proportional control unit according to the hydraulic oil temperature. Therefore, the oil return path of the hydraulic oil is controlled based on the hydraulic oil temperature and the oil return pressure, it is guaranteed that the hydraulic oil can rapidly enter the normal working state under the cold working condition, and the lower heat balance temperature is effectively achieved after the temperature of the hydraulic oil rises.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic oil return control, in particular to a hydraulic oil return system and a loader. Background Art

[0002] Generally, the hydraulic oil return of the loader is divided into two parts. One part does not pass through the hydraulic oil radiator and directly returns to the hydraulic oil tank. The other part needs to be cooled by the hydraulic oil radiator before returning to the hydraulic oil tank. This effectively prevents the hydraulic oil from overheating and ensures the service life of the hydraulic oil and related components. The specific implementation method can be referred to Figure 1 and Figure 2 The schematic diagram of the hydraulic oil return mode in the related art shown in FIG. Figure 1 As shown in FIG. 1 , a throttle valve 101 is installed on the return line of the hydraulic oil, or as shown in FIG. Figure 2 As shown, a one-way valve 201 is installed on the hydraulic oil return line to generate back pressure in the hydraulic line, so that a part of the hydraulic return oil enters the hydraulic oil radiator 102 for heat dissipation and then flows back to the return oil filter 103 and further flows into the hydraulic oil tank 104, while the other part of the hydraulic return oil directly flows back to the return oil filter 103 and further flows into the hydraulic oil tank 104.

[0003] The above-mentioned simple method of controlling the heat dissipation of the hydraulic oil by the throttle valve 101 or the one-way valve 201 is simple to implement and has a low production cost, but this method has some problems. For example, when the loader boom descends rapidly, a large oil return shock is generated, causing damage to the hydraulic oil radiator. And Figure 1 and Figure 2 In the scheme shown, a portion of the hydraulic oil always needs to pass through the hydraulic oil radiator before entering the oil tank. After the loader is started in cold areas, it is not conducive to the loader quickly entering the normal working state. Therefore, how to reasonably control the return of hydraulic oil has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] In view of this, the present invention provides a hydraulic oil return system and a loader to solve the problem that how to reasonably control the hydraulic oil return has become a technical problem that needs to be solved urgently.

[0005] In a first aspect, the present invention provides a hydraulic oil return system, the system comprising a pressure control unit, a proportional control unit, a hydraulic oil radiator, a controller and a temperature sensor;

[0006] The first end of the pressure control unit is connected to the return oil input port of the hydraulic oil, and the second end is connected to the hydraulic oil tank. The pressure control unit is opened or closed under the pressure of the hydraulic oil;

[0007] A first end of the proportional control unit is connected to the return oil input port of the hydraulic oil, and a second end is connected to the hydraulic oil radiator;

[0008] A first end of the hydraulic oil radiator is connected to the proportional control unit, and a second end is connected to the hydraulic oil tank;

[0009] The controller is used to obtain the hydraulic oil temperature of the hydraulic oil from the temperature sensor and control the connection state of the proportional control unit according to the hydraulic oil temperature;

[0010] Among them, when the connectivity state of the proportional control unit is the first connectivity state, the proportional control unit cuts off the passage for the hydraulic oil to flow back to the hydraulic oil tank through the hydraulic oil radiator. When the connectivity state of the proportional control unit is the second connectivity state, the hydraulic oil flows back to the hydraulic oil tank through the proportional control unit and the hydraulic oil radiator.

[0011] The hydraulic oil return system of the present invention realizes control of the hydraulic oil return passage based on the pressure control unit and the proportional control unit at the same time, and the controller controls the proportional control unit based on the temperature collected by the temperature sensor. In this way, when the hydraulic oil temperature is low, the controller can control the connectivity of the proportional control unit to be in the first connectivity state based on the hydraulic oil temperature, cut off the path for the hydraulic oil to flow back to the hydraulic oil tank through the hydraulic oil radiator, and the hydraulic oil directly enters the hydraulic oil tank for circulation, avoiding passing through the hydraulic oil radiator to avoid heat dissipation of the hydraulic oil, thereby achieving the purpose of rapid temperature rise. After the hydraulic oil temperature rises to the set temperature, the controller can control the connectivity of the proportional control unit to be in the second connectivity state based on the hydraulic oil temperature, and the hydraulic oil flows back to the hydraulic oil tank through the proportional control unit and the hydraulic oil radiator, and control more low-pressure hydraulic oil to enter the hydraulic oil radiator for heat dissipation by limiting the pressure through the pressure control unit, thereby achieving a lower thermal equilibrium temperature.

[0012] In an optional embodiment, the pressure control unit includes a throttle valve.

[0013] In an optional embodiment, the pressure control unit further includes a first one-way valve, and the first one-way valve is connected in parallel with the throttle valve.

[0014] The hydraulic oil return system of the present invention is equipped with a first one-way valve connected in parallel with the throttle valve. When the hydraulic oil pressure is relatively high, part of the hydraulic oil impact pressure is absorbed by the first one-way valve, thereby effectively preventing the hydraulic oil from impacting the hydraulic oil radiator, thereby significantly reducing the risk of damage to the hydraulic oil radiator caused by this.

[0015] In an optional embodiment, the pressure control unit includes a second one-way valve.

[0016] In an optional embodiment, the hydraulic oil radiator includes a heat dissipation body and a bypass valve, and the heat dissipation body and the bypass valve are connected in parallel.

[0017] In an optional embodiment, the pressure control unit includes a second one-way valve and a third one-way valve, the second one-way valve and the third one-way valve are connected in parallel, and a conduction pressure threshold of the second one-way valve is less than a conduction pressure threshold of the third one-way valve;

[0018] The hydraulic oil radiator comprises a heat dissipation body.

[0019] The hydraulic oil return system of the present invention is equipped with a third one-way valve whose conduction pressure threshold is greater than that of the second one-way valve. When a large impact pressure appears in the hydraulic oil, the third one-way valve can quickly disperse and absorb the impact pressure of the hydraulic oil, effectively reduce the impact of the hydraulic oil on the hydraulic oil radiator, and provide timely and sufficient protection for the hydraulic oil radiator. In this case, for situations where the hydraulic oil pressure is large and the flow rate is large, the two one-way valves can timely and fully disperse the impact pressure of the hydraulic oil, thereby fundamentally avoiding the problem of being unable to effectively protect the heat dissipation body of the hydraulic oil radiator due to reasons such as the delay in opening the valve core of the radiator bypass valve. Furthermore, in this case, the bypass valve of the hydraulic oil radiator can be directly cancelled, which effectively improves the protection effect of the hydraulic oil radiator while effectively reducing the cost of the hydraulic oil radiator.

[0020] In an optional embodiment, the proportional control unit includes a solenoid valve;

[0021] When the connected state of the proportional control unit is the first connected state, the solenoid valve is powered off, and the solenoid valve cuts off the hydraulic oil from flowing back to the hydraulic oil radiator;

[0022] When the connected state of the proportional control unit is the second connected state, the solenoid valve is energized, and the hydraulic oil flows back to the hydraulic oil tank through the solenoid valve and the hydraulic oil radiator.

[0023] In an optional embodiment, the proportional control unit includes a pilot relief valve;

[0024] The pilot relief valve comprises: an electromagnetic reversing valve and a pilot relief valve;

[0025] When the connected state of the proportional control unit is the first connected state, the electromagnetic reversing valve is powered off, the pilot relief valve is closed, and the pilot relief valve cuts off the hydraulic oil from flowing back to the hydraulic oil radiator;

[0026] When the connected state of the proportional control unit is the second connected state, the electromagnetic reversing valve is energized, the pilot relief valve is opened, and the hydraulic oil flows back to the hydraulic oil tank through the pilot relief valve and the hydraulic oil radiator.

[0027] The hydraulic oil return system of the present invention controls whether the hydraulic oil flows through the hydraulic oil radiator by cooperating with the electromagnetic reversing valve and the relief valve pilot relief valve. When the electromagnetic reversing valve is energized, the relief valve is turned on, and the hydraulic oil first passes through the pilot relief valve. Compared with the solution without the relief valve, a relatively small flow electromagnetic reversing valve can be selected here, which effectively reduces the equipment cost of the hydraulic oil return system while ensuring the heat balance control effect of the hydraulic oil.

[0028] In an optional embodiment, when the hydraulic oil temperature is lower than a set temperature, the controller controls the proportional control unit to be in a first connected state; when the hydraulic oil temperature reaches the set temperature, the controller controls the proportional control unit to be in a second connected state.

[0029] In the hydraulic oil return system of the present invention, the controller controls the proportional control unit to be in the first connection state when the hydraulic oil temperature is lower than the set temperature, and controls the proportional control unit to be in the second connection state when the hydraulic oil temperature reaches the set temperature. The heat loss of the hydraulic oil in the cold environment, after the vehicle is started and before it reaches the normal working state, etc. is fully considered, so that the hydraulic oil can be quickly heated up at low temperature to enter the best working state.

[0030] In a second aspect, the present invention provides a loader having a hydraulic oil return system according to the first aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 This is a schematic diagram of the implementation principle of the hydraulic oil return system in the related technology Figure 1 ;

[0033] Figure 2 This is a schematic diagram of the implementation principle of the hydraulic oil return system in the related technology Figure 2 ;

[0034] Figure 3 The schematic diagram of the implementation principle of the hydraulic oil return system according to the embodiment of the present invention is as follows: Figure 1 ;

[0035] Figure 4 The schematic diagram of the implementation principle of the hydraulic oil return system according to the embodiment of the present invention is as follows: Figure 2 ;

[0036] Figure 5The schematic diagram of the implementation principle of the hydraulic oil return system according to the embodiment of the present invention is as follows: Figure 3 ;

[0037] Figure 6 The schematic diagram of the implementation principle of the hydraulic oil return system according to the embodiment of the present invention is as follows: Figure 4 ;

[0038] Figure 7 is a schematic flow chart of a hydraulic oil reflux method according to an embodiment of the present invention;

[0039] Figure 8 It is a schematic structural diagram of a loader according to an embodiment of the present invention.

[0040] Description of Reference Numerals

[0041] 101 throttle valve; 102 hydraulic oil radiator;

[0042] 103 oil return filter element; 104 hydraulic oil tank;

[0043] 201 one-way valve; 301 pressure control unit;

[0044] 302 proportional control unit; 303 controller;

[0045] 304 temperature sensor; T return oil input port;

[0046] 1021 heat dissipation body; 1022 bypass valve;

[0047] 305 first electromagnetic reversing valve; 401 first one-way valve;

[0048] 402 solenoid valve; 501 second one-way valve;

[0049] 502 third one-way valve; 503 pilot relief valve;

[0050] 504 second electromagnetic reversing valve; 505 overflow valve. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0052] Reference again Figure 1 and Figure 2 It can be seen that Figure 1 and Figure 2The hydraulic oil radiator 102 in the related technical solution shown is equipped with a bypass valve 1022 to reduce the pressure impact of the hydraulic return oil on the heat dissipation body 1021. However, the bypass valve 1022 is mostly a spring-controlled valve block, which has the problem of delayed opening. During the period before the bypass valve 1022 opens, the heat dissipation body 1021 is still susceptible to pressure shocks exceeding its rated working pressure, resulting in damage to the heat dissipation body 1021. In addition, under low temperature conditions, the viscosity of the hydraulic oil is high, and the hydraulic oil needs to be quickly heated to a suitable working temperature so that the loader can enter a normal working state. The above Figure 1 and Figure 2 In the oil return method shown, a portion of the hydraulic oil always needs to be cooled through the hydraulic oil radiator 102, which is not conducive to the rapid heating of the hydraulic oil in cold weather.

[0053] In this regard, an embodiment of the present invention provides a hydraulic oil return system and a loader to solve the problem of how to reasonably control the hydraulic oil return, which has become a technical problem to be solved urgently.

[0054] According to an embodiment of the present invention, a hydraulic oil return system embodiment is provided. Figure 3 Schematic diagram of the hydraulic oil return method according to an embodiment of the present invention Figure 1 .

[0055] like Figure 3 As shown, the hydraulic oil return system provided by the present invention may include a pressure control unit 301 , a proportional control unit 302 , a hydraulic oil radiator 102 , a controller 303 and a temperature sensor 304 .

[0056] The first end of the pressure control unit 301 is connected to the return oil input port T of the hydraulic oil, and the second end of the pressure control unit 301 is connected to the hydraulic oil tank 104. The pressure control unit 301 is opened or closed under the pressure of the hydraulic oil. The first end of the proportional control unit 302 is connected to the return oil input port T of the hydraulic oil, and the second end is connected to the hydraulic oil radiator 102. The first end of the hydraulic oil radiator 102 is connected to the proportional control unit 302, and the second end is connected to the hydraulic oil tank 104. The controller 303 is used to obtain the hydraulic oil temperature of the hydraulic oil from the temperature sensor 304, and control the connection state of the proportional control unit 302 according to the hydraulic oil temperature.

[0057] Among them, when the connectivity state of the proportional control unit 302 is the first connectivity state, the proportional control unit 302 cuts off the passage for the hydraulic oil to flow back to the hydraulic oil tank 104 through the hydraulic oil radiator 102. When the connectivity state of the proportional control unit 302 is the second connectivity state, the hydraulic oil flows back to the hydraulic oil tank 104 through the proportional control unit 302 and the hydraulic oil radiator 102.

[0058] In an optional embodiment, the proportional control unit 302 may include a solenoid valve. Figure 3 , a first electromagnetic reversing valve 305 with a reversing function is used. When the communication state of the proportional control unit 302 is the first communication state, the first electromagnetic reversing valve 305 is de-energized, and the first electromagnetic reversing valve 305 cuts off the hydraulic oil from flowing back to the hydraulic oil radiator 102. When the communication state of the proportional control unit 302 is the second communication state, the first electromagnetic reversing valve 305 is energized, and the hydraulic oil flows back to the hydraulic oil tank 104 through the first electromagnetic reversing valve 305 and the hydraulic oil radiator 102.

[0059] Specifically, if the hydraulic oil temperature of the hydraulic oil is lower than the set temperature T0, the controller 303 can control the connection state of the proportional control unit 302 to be the first connection state, at which time the proportional control unit 302 cuts off the passage of the hydraulic oil backflowing to the hydraulic oil tank 104 through the hydraulic oil radiator 102. If the hydraulic oil temperature of the hydraulic oil reaches the set temperature T0, the connection state of the proportional control unit 302 can be controlled to be the second connection state, at which time the hydraulic oil flows back to the hydraulic oil tank 104 through the proportional control unit 302 and the hydraulic oil radiator 102.

[0060] In an optional embodiment, the system further includes an oil return filter 103 , a first end of the oil return filter 103 is connected to a second end of the pressure control unit 301 and a second end of the hydraulic oil radiator 102 , and a second end of the oil return filter 103 is connected to the hydraulic oil tank 104 .

[0061] It should be noted that Figure 3 In the embodiment shown, the pressure control unit 301 is shown as a throttle valve 101, and the proportional control unit 302 is shown as a first electromagnetic reversing valve 305 with a reversing function. Figure 3 In the illustrated embodiment, the pressure control unit 301 may also be a one-way valve 201, and the solenoid valve may also be a straight-through solenoid valve or other applicable solenoid valves.

[0062] The hydraulic oil return system of the present invention controls the hydraulic oil return passage based on the pressure control unit and the proportional control unit at the same time, and the controller controls the proportional control unit based on the temperature collected by the temperature sensor. In this way, when the hydraulic oil temperature is low, the controller can control the connectivity of the proportional control unit to be in the first connectivity state based on the hydraulic oil temperature, cut off the path for the hydraulic oil to flow back to the hydraulic oil tank through the hydraulic oil radiator, and the hydraulic oil directly enters the hydraulic oil tank to heat up quickly. After the hydraulic oil temperature rises to a certain temperature, the controller can control the connectivity of the proportional control unit to be in the second connectivity state based on the hydraulic oil temperature, and the hydraulic oil flows back to the hydraulic oil tank through the proportional control unit and the hydraulic oil radiator. The pressure control unit is used to limit the pressure to control more low-pressure hydraulic oil to enter the hydraulic oil radiator for heat dissipation, thereby achieving a lower thermal equilibrium temperature.

[0063] like Figure 3 The embodiment shown overcomes the problem that "when the loader is started in a cold environment, the hydraulic oil temperature is low. If the hydraulic oil passes through the radiator again, it cannot be quickly heated up to enter a normal working state." It achieves rapid heating of the hydraulic oil under cold working conditions, thereby enabling the loader to quickly and stably enter a normal working state.

[0064] However, when the return volume of hydraulic oil is large or the pressure is high, the valve core of the bypass valve 1022 of the hydraulic oil radiator 102 has a problem of delayed opening, and the pressure impact of the hydraulic oil on the heat dissipation body 1021 cannot be dispersed in time, which easily causes problems such as damage to the heat dissipation body 1021. Therefore, in order to overcome this problem, the embodiment of the present invention provides the following Figure 4 The embodiment shown.

[0065] Figure 4 Schematic diagram of the hydraulic oil return method according to an embodiment of the present invention Figure 2 ,like Figure 4 As shown, the pressure control unit 301 further includes a first one-way valve 401, which is connected in parallel with the throttle valve 101. When the return oil volume of the hydraulic oil is large or the pressure is high, as long as the return oil pressure of the hydraulic oil reaches the conduction pressure threshold value P1 of the first one-way valve 401, the first one-way valve 401 is opened, and part of the hydraulic oil flows back directly to the hydraulic oil tank 104 through the first one-way valve 401.

[0066] Therefore, the hydraulic oil return system of the present invention is configured with a first one-way valve 401 connected in parallel with the throttle valve 101. When the hydraulic oil pressure is relatively high, part of the hydraulic oil impact pressure is absorbed by the first one-way valve 401, thereby effectively preventing the hydraulic oil from impacting the hydraulic oil radiator 102. The pressure impact of the hydraulic oil on the heat dissipation body 1021 is effectively alleviated at the front end of the hydraulic oil radiator 102, thereby significantly reducing the risk of damage to the hydraulic oil radiator 102.

[0067] refer to Figure 4 , the proportional control unit 302 adopts a straight-through solenoid valve 402. When the communication state of the proportional control unit 302 is the first communication state, the solenoid valve 402 is de-energized, and the solenoid valve 402 cuts off the hydraulic oil from flowing back to the hydraulic oil radiator 102. When the communication state of the proportional control unit 302 is the second communication state, the solenoid valve 402 is energized, and the hydraulic oil flows back to the hydraulic oil tank 104 through the solenoid valve 402 and the hydraulic oil radiator 102.

[0068] It should be noted that Figure 3 The first electromagnetic reversing valve 305 and the throttle valve 101 used in Figure 4 The models and specifications of the components such as the solenoid valve 402 and the first one-way valve 401 used in the invention can be designed according to actual needs.

[0069] Further, such as Figure 3 and Figure 4 In the embodiment shown, whether the pressure control unit 301 adopts the throttle valve 101 or the check valve 201, the check valve 201 adopted by the proportional control unit 302 needs to adopt a solenoid valve or solenoid reversing valve with a larger flow rate to cooperate with it to implement the above technical solution, so as to achieve the purpose of rapid heating of the hydraulic oil under cold working conditions and to enable the loader to quickly and stably enter a normal working state. The cost of a solenoid reversing valve with a larger flow rate is relatively high, so the solution is further optimized here.

[0070] Figure 5 Schematic diagram of the hydraulic oil return method according to an embodiment of the present invention Figure 3 ,like Figure 5 As shown, the hydraulic oil return system provided by the present invention may include a pressure control unit 301 , a proportional control unit 302 , a hydraulic oil radiator 102 , a controller 303 and a temperature sensor 304 .

[0071] The first end of the pressure control unit 301 is connected to the return oil input port T of the hydraulic oil, and the second end of the pressure control unit 301 is connected to the hydraulic oil tank 104. The pressure control unit 301 is opened or closed under the pressure of the hydraulic oil. The first end of the proportional control unit 302 is connected to the return oil input port T of the hydraulic oil, and the second end is connected to the hydraulic oil radiator 102. The first end of the hydraulic oil radiator 102 is connected to the proportional control unit 302, and the second end is connected to the hydraulic oil tank 104. The controller 303 is used to obtain the hydraulic oil temperature of the hydraulic oil from the temperature sensor 304, and control the connection state of the proportional control unit 302 according to the hydraulic oil temperature.

[0072] The pressure control unit 301 includes a second one-way valve 501 and a third one-way valve 502 , and the second one-way valve 501 and the third one-way valve 502 are connected in parallel.

[0073] The proportional control unit 302 includes a pilot relief valve 503, and the pilot relief valve 503 includes a second electromagnetic reversing valve 504 and a relief valve 505. When the communication state of the proportional control unit 302 is the first communication state, the second electromagnetic reversing valve 504 is powered off, the relief valve 505 is closed, and the relief valve 505 cuts off the hydraulic oil from flowing back to the hydraulic oil radiator 102. When the communication state of the proportional control unit 302 is the second communication state, the second electromagnetic reversing valve 504 is powered on, the relief valve 505 is opened, and the hydraulic oil flows back to the hydraulic oil tank 104 through the relief valve 505 and the hydraulic oil radiator 102.

[0074] It should be noted that Figure 5 In the illustrated embodiment, it is a more preferred solution that the pressure control unit 301 includes the second one-way valve 501 and the third one-way valve 502 . Here, the pressure control unit 301 may also include only the second one-way valve 501 or the third one-way valve 502 .

[0075] also, Figure 5 and below Figure 6 In the embodiment shown, the flow rate of the second electromagnetic reversing valve 504 can be less than Figure 3 The flow rate of the first electromagnetic reversing valve 305 and Figure 4 The flow rate of the solenoid valve 402 is shown. In practical applications, the model specifications and flow rates of the first solenoid reversing valve 305, the solenoid valve 402 and the second solenoid reversing valve 504 can be determined according to actual needs, and the present invention does not make any specific limitations on this.

[0076] In some optional embodiments of the present invention, the conduction pressure threshold P1 of the second one-way valve 501 may be 3 bar. The conduction pressure threshold P2 of the third one-way valve 502 may be 6 bar. The controller 303 controls the proportional control unit 302 to change the hydraulic oil temperature of the connected state to the set temperature T0. If the hydraulic oil temperature of the hydraulic oil is lower than the set temperature T0, the controller 303 may control the connected state of the proportional control unit 302 to the first connected state. At this time, the proportional control unit 302 ( Figure 5 The pilot relief valve 503 is shown in the figure to cut off the passage of the hydraulic oil returning to the hydraulic oil tank 104 through the hydraulic oil radiator 102. If the hydraulic oil temperature of the hydraulic oil reaches the set temperature T0, the connection state of the proportional control unit 302 can be controlled to be the second connection state. At this time, the hydraulic oil returns to the hydraulic oil tank 104 through the proportional control unit 302 and the hydraulic oil radiator 102.

[0077] First, the case where the pressure control unit 301 of the hydraulic oil return system only has the second one-way valve 501 is described:

[0078] If the hydraulic oil temperature of the hydraulic oil is less than T0, the controller 303 can control the second electromagnetic reversing valve 504 to be powered off, and then control the pilot relief valve 503 to be closed. As the hydraulic system continues to return oil, when the pressure rises to the conduction pressure threshold value P1 of the second one-way valve 501, the hydraulic oil flows directly back to the hydraulic oil tank 104 through the second one-way valve 501. This situation is mainly used for cold start of loaders, such as when starting loaders and other vehicles in areas with low temperatures in winter. When the hydraulic oil temperature of the hydraulic oil is less than T0, the hydraulic oil is effectively controlled to flow back directly to the hydraulic oil tank 104 to avoid heat loss caused by the hydraulic oil radiator 102. Thereby, the hydraulic oil meets the requirements of the hydraulic oil of loaders and other vehicles to quickly heat up and enter the optimal working state.

[0079] If the hydraulic oil temperature of the hydraulic oil reaches T0, the controller 303 can control the second electromagnetic reversing valve 504 to be turned on, and then control the pilot relief valve 503 to be opened. Further, if the actual return oil pressure of the hydraulic oil is less than P1, the second check valve 501 is closed, and the hydraulic oil all passes through the relief valve 505 into the hydraulic oil radiator 102. Therefore, when the actual return oil pressure is relatively low, the hydraulic oil all passes through the hydraulic oil radiator 102, so that the hydraulic oil achieves a better thermal balance temperature.

[0080] Furthermore, if the actual return oil pressure of the hydraulic oil reaches P1, the second one-way valve 501 is opened, and a part of the hydraulic oil enters the hydraulic oil radiator 102 through the overflow valve 505, and the other part of the hydraulic oil directly flows back to the hydraulic oil tank 104. Most of the hydraulic oil is controlled to pass through the hydraulic oil radiator 102 to achieve a better thermal balance temperature, and the pressure impact of the return oil pressure of the hydraulic oil on the hydraulic oil radiator 102 is effectively dispersed.

[0081] The hydraulic oil return system of the present invention controls whether the hydraulic oil flows through the hydraulic oil radiator 102 by means of a pilot overflow valve 503 including a second electromagnetic reversing valve 504 and an overflow valve 505. When the second electromagnetic reversing valve 504 is energized, the overflow valve 505 is turned on, and the hydraulic oil first passes through the pilot overflow valve 503. Compared with the solution without the overflow valve 505, a relatively small flow electromagnetic valve can be selected here, which effectively reduces the equipment cost of the hydraulic oil return system while ensuring the heat balance control effect of the hydraulic oil.

[0082] Next, the following describes the situation in which the pressure control unit 301 of the hydraulic oil return system has two front check valves 201, namely, the second check valve 501 and the third check valve 502:

[0083] In order to further disperse the pressure impact of the hydraulic oil return pressure on the hydraulic oil radiator 102, two parallel-connected second check valves 501 and third check valves 502 are configured in the hydraulic oil return system, wherein the conduction pressure threshold value P2 of the third check valve 502 may be greater than the conduction pressure threshold value P1 of the second check valve 501. Thus, when the actual return pressure of the hydraulic oil reaches P2, the third check valve 502 is also conducted, and compared with the solution of a single front check valve 201, the pressure impact of the hydraulic oil return pressure on the hydraulic oil radiator 102 is further dispersed.

[0084] In the embodiment where the hydraulic oil return system has two front one-way valves 201, namely, the second one-way valve 501 and the third one-way valve 502, the pressure impact of the return pressure of the hydraulic oil on the hydraulic oil radiator 102 can be effectively dispersed by the two front one-way valves 201, thereby fully protecting the hydraulic oil radiator 102. Here, the structure of the hydraulic oil radiator 102 can be simplified, and the bypass valve 1022 is no longer provided for the hydraulic oil radiator 102. For details, please refer to Figure 6 The schematic diagram of the implementation principle of the hydraulic oil return system provided by the embodiment of the present invention is shown in FIG. Figure 4 .

[0085] The hydraulic oil return system of the present invention is equipped with a third one-way valve 502 whose conduction pressure threshold is greater than that of the second one-way valve 501. When the hydraulic oil has a large impact pressure, the impact pressure of the hydraulic oil is quickly dispersed and absorbed, effectively reducing the impact of the hydraulic oil on the hydraulic oil radiator 102, and providing timely and sufficient protection for the hydraulic oil radiator 102. In this case, for situations such as a large pressure and a large flow of the hydraulic oil, the two one-way valves 201 can timely and fully disperse the impact pressure of the hydraulic oil, thereby fundamentally avoiding the problem of being unable to effectively protect the heat dissipation body 1021 of the hydraulic oil radiator 102 due to the delay in opening the valve core of the radiator bypass valve 1022. Further, in this case, the bypass valve 1022 of the hydraulic oil radiator 102 can be directly cancelled, effectively improving the protection effect of the hydraulic oil radiator 102 while effectively reducing the cost of the hydraulic oil radiator 102.

[0086] based on Figure 3-Figure 6 The hydraulic oil return system shown in the figure, the embodiment of the present invention also provides a hydraulic oil return control method, Figure 7 is a flow chart of a hydraulic oil reflux method according to an embodiment of the present invention, such as Figure 7 As shown, the hydraulic oil reflux control method provided in the embodiment of the present invention may include the following process:

[0087] Step S701, the controller obtains the hydraulic oil temperature from the temperature sensor;

[0088] Step S702: The controller determines whether the hydraulic oil temperature is greater than a set temperature T0.

[0089] If the hydraulic oil temperature is greater than the set temperature T0, step S703 is executed.

[0090] In an optional embodiment, the controller controls the proportional control unit to be in a first connected state when the hydraulic oil temperature is lower than a set temperature, and controls the proportional control unit to be in a second connected state when the hydraulic oil temperature reaches the set temperature.

[0091] In the hydraulic oil return system of the present invention, the controller controls the proportional control unit to be in the first connection state when the hydraulic oil temperature is lower than the set temperature, and controls the proportional control unit to be in the second connection state when the hydraulic oil temperature reaches the set temperature. The heat loss of the hydraulic oil before the vehicle reaches the normal working state after starting in a cold environment is fully considered, so that the hydraulic oil can be quickly heated up at low temperature to enter the best working state.

[0092] Specifically, if the hydraulic oil temperature is not set to temperature T0, it is mostly a state in which a vehicle such as a loader has not reached a normal working state after starting in a cold environment. At this time, the pressure control unit is in the first connection state by default, and the controller returns to execute step S702 again without sending a control signal to the solenoid valve or solenoid reversing valve of the pressure control unit.

[0093] In practical applications, the connection state of the pressure control unit can also be controlled according to actual needs to keep the pressure control unit in the first connection state, and return to execute step S702 again.

[0094] Step S703: the controller controls the pressure control unit to be in a second connected state.

[0095] For example, here the controller is usually required to send a control signal for switching to the electromagnetic reversing valve of the pressure control unit to control the reversing of the electromagnetic reversing valve, thereby switching the connection state of the pressure control unit to the second connection state. In practical applications, the control signal and control method of the controller for controlling the pressure control unit can also be configured according to actual needs.

[0096] In this embodiment, a loader is also provided. Figure 8 As shown, the loader has the above Figure 3-Figure 6 A hydraulic oil return system according to any one of the embodiments.

[0097] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A hydraulic oil return system, characterized in that: The system includes a pressure control unit, a proportional control unit, a hydraulic oil radiator, a controller and a temperature sensor; The first end of the pressure control unit is connected to the return oil input port of the hydraulic oil, and the second end is connected to the hydraulic oil tank. The pressure control unit is opened or closed under the pressure of the hydraulic oil; The first end of the proportional control unit is connected to the return oil input port of the hydraulic oil, and the second end is connected to the hydraulic oil radiator; The first end of the hydraulic oil radiator is connected to the proportional control unit, and the second end is connected to the hydraulic oil tank; The controller is used to obtain the hydraulic oil temperature of the hydraulic oil from the temperature sensor, and control the connection state of the proportional control unit according to the hydraulic oil temperature; Among them, when the connectivity state of the proportional control unit is the first connectivity state, the proportional control unit cuts off the passage for the hydraulic oil to flow back to the hydraulic oil tank through the hydraulic oil radiator. When the connectivity state of the proportional control unit is the second connectivity state, the hydraulic oil flows back to the hydraulic oil tank through the proportional control unit and the hydraulic oil radiator.

2. The system according to claim 1, characterized in that The pressure control unit includes a throttle valve.

3. The system according to claim 2, characterized in that The pressure control unit further includes a first one-way valve connected in parallel with the throttle valve.

4. The system according to claim 1, characterized in that The pressure control unit includes a second one-way valve.

5. The system according to any one of claims 2 to 4, characterized in that: The hydraulic oil radiator comprises a radiator body and a bypass valve, and the radiator body and the bypass valve are connected in parallel.

6. The system according to claim 1, characterized in that The pressure control unit comprises a second one-way valve and a third one-way valve, the second one-way valve and the third one-way valve are connected in parallel, and a conduction pressure threshold of the second one-way valve is smaller than a conduction pressure threshold of the third one-way valve; The hydraulic oil radiator comprises a heat dissipation body.

7. The system according to claim 1, characterized in that The proportional control unit includes a solenoid valve; When the connected state of the proportional control unit is the first connected state, the solenoid valve is powered off, and the solenoid valve cuts off the hydraulic oil from flowing back to the hydraulic oil radiator; When the communication state of the proportional control unit is the second communication state, the solenoid valve is energized, and the hydraulic oil flows back to the hydraulic oil tank through the solenoid valve and the hydraulic oil radiator.

8. The system according to claim 1, characterized in that The proportional control unit includes a solenoid valve and a pilot relief valve; When the connected state of the proportional control unit is the first connected state, the solenoid valve is powered off, the pilot relief valve is closed, and the pilot relief valve cuts off the hydraulic oil from flowing back to the hydraulic oil radiator; When the connected state of the proportional control unit is the second connected state, the solenoid valve is energized, the pilot relief valve is opened, and the hydraulic oil flows back to the hydraulic oil tank through the pilot relief valve and the hydraulic oil radiator.

9. The system according to claim 1, characterized in that When the hydraulic oil temperature is lower than a set temperature, the controller controls the proportional control unit to be in a first connected state; when the hydraulic oil temperature reaches a set temperature, the controller controls the proportional control unit to be in a second connected state.

10. A loader, characterized in that: The loader has the hydraulic oil return system according to any one of claims 1-9.

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