Oil temperature control method, oil temperature control system, and working machine

Abstract

The present application belongs to the technical field of engineering machinery and provides an oil temperature control method, an oil temperature control system and a working machine. The oil temperature control method comprises obtaining the oil temperature of hydraulic oil; when the oil temperature of the hydraulic oil is not in a preset temperature interval, adjusting the target displacement of a cooling pump according to the control relationship between the oil temperature and the displacement in a preset mapping table, and simultaneously closing a throttling element, so that the cooling pump pumps the hydraulic oil to the motor at the target displacement to drive the fan to rotate; in the case where the cooling pump works at the target displacement for a preset length of time, adjusting the opening of the throttling element according to the dependent relationship between the oil temperature of the hydraulic oil and the preset temperature interval to adjust the oil temperature of the hydraulic oil. The method can effectively reduce the waste of system pressure and can realize dynamic regulation and control of the oil temperature.

Description

Technical Field

[0001] This invention belongs to the field of engineering machinery technology, specifically relating to an oil temperature control method, an oil temperature control system, and operating machinery. Background Technology

[0002] Some large engineering equipment (such as excavators exceeding 40 tons and super-large cranes) require independent oil temperature control methods for their hydraulic systems. Existing oil temperature control methods mainly include cooling pumps, coolers, motors, and fans. The motor drives the fan to blow air onto the cooler, thereby rapidly cooling the hydraulic oil flowing through the cooler.

[0003] Existing oil temperature control methods generally achieve motor and fan displacement regulation by connecting a throttle valve in series between the cooling pump and the motor. However, when such systems are running, the cooling pump always outputs at maximum displacement. The flow rate output by the cooling pump is throttled by the throttle valve before being sent to the motor, which causes a very large pressure loss and leads to severe system overheating. At the same time, this flow regulation method cannot achieve precise adjustment of fan displacement. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies, the present invention provides an oil temperature control method, an oil temperature control system and a working machine, aiming to solve the technical problems of high energy consumption, serious heat generation and inability to accurately adjust fan speed in existing oil temperature control methods.

[0005] To achieve the above objectives, the present invention provides an oil temperature control method. The method is applied to an oil temperature control system. The system includes a controller, a cooling pump, a motor, a fan, and a throttling element. The controller is communicatively connected to the cooling pump and the throttling element. The motor is used to drive the fan to rotate. The cooling pump and the motor constitute a fan drive circuit. The opening degree of the throttling element is adjustable and is connected in parallel with the motor between the oil inlet and oil return lines of the fan drive circuit.

[0006] Oil temperature control methods include:

[0007] S100: Obtain the temperature of the hydraulic oil;

[0008] S200: When the hydraulic oil temperature is not within the preset temperature range, adjust the target displacement of the cooling pump according to the correspondence between oil temperature and displacement in the preset mapping table, and at the same time close the throttling element so that the cooling pump pumps hydraulic oil to the motor according to the target displacement to drive the fan to rotate.

[0009] S300: When the cooling pump operates at the target displacement for a preset time, the opening of the throttling element is adjusted according to the subordinate relationship between the hydraulic oil temperature and the preset temperature range to adjust the hydraulic oil temperature.

[0010] In an embodiment of the present invention, step S300, adjusting the opening of the throttling element according to the subordinate relationship between the hydraulic oil temperature and a preset temperature range to adjust the hydraulic oil temperature, specifically includes:

[0011] S300a: If the hydraulic oil temperature is within the preset temperature range, the throttling element is kept closed and the cooling pump is controlled to run at the current displacement to keep the hydraulic oil at the current temperature.

[0012] S300b: If the hydraulic oil temperature is not within the preset temperature range, adjust at least one of the cooling pump displacement and the throttling element opening to raise or lower the oil temperature accordingly.

[0013] In an embodiment of the present invention, step S300b: if the hydraulic oil temperature is not within the preset temperature range, then at least one of the cooling pump displacement and the opening of the throttling element is adjusted to correspondingly raise or lower the oil temperature, specifically including:

[0014] S300b-1: If the hydraulic oil temperature is higher than the first preset temperature, the target displacement of the cooling pump will be readjusted according to the increased oil temperature, while keeping the throttling element closed, so that the cooling pump pumps hydraulic oil to the motor at the readjusted target displacement, driving the fan to increase the speed to reduce the oil temperature.

[0015] S300b-2: If the hydraulic oil temperature is lower than the second preset temperature, the cooling pump is controlled to maintain the current displacement, and the throttling element is controlled to change its opening to drive the fan to reduce its speed and increase the oil temperature until the hydraulic oil temperature stabilizes in the preset temperature range, at which point the current opening of the throttling element is maintained.

[0016] The first preset temperature and the second preset temperature are the upper and lower limits of the preset temperature range, respectively.

[0017] In an embodiment of the present invention, step S200: when the hydraulic oil temperature is not within the preset temperature range, the target displacement of the cooling pump is adjusted according to the correspondence between oil temperature and displacement in the preset mapping table, and the throttling element is closed at the same time, so that the cooling pump pumps hydraulic oil to the motor at the target displacement to drive the fan to rotate, specifically including:

[0018] S201: If the hydraulic oil temperature is lower than the third preset temperature, control the cooling pump to output at the minimum displacement, and at the same time close the throttling element so that the cooling pump pumps hydraulic oil to the motor at the minimum displacement to drive the fan to rotate.

[0019] The third preset temperature is lower than the lower limit of the preset temperature range.

[0020] In an embodiment of the present invention, step S300: when the cooling pump operates at the target displacement for a preset time, adjusting the opening of the throttling element according to the subordinate relationship between the hydraulic oil temperature and the preset temperature range to adjust the hydraulic oil temperature includes:

[0021] S301: If the hydraulic oil temperature is lower than the lower limit of the preset temperature range when the cooling pump operates at the minimum displacement for a preset time, the cooling pump will be controlled to maintain the current displacement, and the throttling element will be controlled to change the opening to adjust the hydraulic oil temperature until the motor stops completely.

[0022] To achieve the above objectives, the present invention also provides an oil temperature control system, wherein the oil temperature control system includes a fan drive circuit, a fan, a throttling element, and a controller. The fan drive circuit includes an oil inlet circuit, an oil return circuit, a cooling pump as a power input, and a motor as an actuator. The fan is drivenly connected to the motor. The throttling element is connected between the oil inlet circuit and the oil return circuit and is arranged in parallel with the motor. The controller is electrically connected to the cooling pump and the throttling element respectively. The controller is used to execute the oil temperature control method described above.

[0023] In an embodiment of the present invention, the oil temperature control system further includes a one-way oil replenishment circuit, which is connected in parallel with the cooling motor and between the oil inlet circuit and the oil return circuit. A one-way valve is provided on the one-way oil replenishment circuit, which is configured to open when hydraulic oil flows from the oil return circuit to the oil inlet circuit and close in the reverse direction.

[0024] In an embodiment of the present invention, a reversing valve is further provided between the cooling pump and the motor. The reversing valve is used to select one of the forward and reverse oil inlets of the motor to which the hydraulic oil in the oil inlet is directed, and to connect the other of the forward and reverse oil inlets to the return oil circuit.

[0025] In an embodiment of the present invention, the oil temperature control system further includes a temperature sensor, which is communicatively connected to the controller and used to detect the oil temperature of the hydraulic oil.

[0026] To achieve the above objectives, the present invention also provides a working machine, wherein the working machine includes an oil temperature control system according to the above description.

[0027] Through the above technical solution, the oil temperature control method provided by the embodiments of the present invention has the following beneficial effects:

[0028] This method first adjusts the cooling pump's displacement according to the hydraulic oil temperature, thereby adjusting the fan's displacement to closely match the actual cooling rate required by the hydraulic oil. Furthermore, when needed, by changing the opening of the throttling element, a portion of the flow from the variable pump to the motor can be redirected back to the return oil circuit, achieving further fine-tuning of the motor displacement (fan speed). After the cooling pump operates at the target speed corresponding to the oil temperature, because the fan speed (cooling pump displacement) is close to the actual cooling rate required by the hydraulic oil, only a very small portion of the hydraulic oil is throttled through the throttling element after adjustment, effectively reducing system pressure waste. Moreover, this method can adjust the cooling pump's displacement and the throttling element's opening based on changes in hydraulic oil temperature, achieving dynamic oil temperature control of the system.

[0029] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0030] The accompanying drawings are provided to illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0031] Figure 1 This is a general flowchart of the oil temperature control method according to an embodiment of the present invention;

[0032] Figure 2 This is a detailed step diagram of step S300 according to an embodiment of the present invention;

[0033] Figure 3 This is a detailed step diagram of step S300b according to an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the hydraulic connection principle of the oil temperature control system according to an embodiment of the present invention;

[0035] Figure 5 This is a control principle diagram of the oil temperature control system according to an embodiment of the present invention.

[0036] Explanation of reference numerals in the attached figures

[0037] 11. Oil inlet circuit; 12. Oil return circuit; 13. Cooling pump; 14. Motor; 2. Fan; 3. Throttling element; 4. One-way oil replenishment circuit; 5. Safety overflow circuit; 6. Reversing valve. Detailed Implementation

[0038] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0039] The oil temperature control method and oil temperature control system of the present invention are described below with reference to the accompanying drawings.

[0040] like Figure 4 and Figure 5 As shown, the present invention provides an oil temperature control system, which is mainly used for cooling hydraulic oil in the hydraulic system of certain large-scale machinery. The oil temperature control system includes a fan drive circuit, a fan 2, and a throttling element 3.

[0041] The fan drive circuit includes an oil inlet circuit 11, an oil return circuit 12, a cooling pump 13 as the power input, and a motor 14 as the actuator. When the cooling pump 13 is working, the output hydraulic oil enters the oil inlet of the motor 14 through the oil inlet circuit 11, and then flows out from the oil outlet of the motor 14, and flows back to the oil tank or the suction port of the cooling pump 13 through the oil return circuit 12.

[0042] Fan 2 is connected to motor 14 via a drive system.

[0043] Throttling element 3 is connected between oil inlet circuit 11 and oil return circuit 12 and is arranged in parallel with motor 14. The opening degree of throttling element 3 can be adjusted between 0-100%. When the opening degree of throttling element 3 is 0%, throttling element 3 is in the cut-off state. When the opening degree of throttling element 3 is 100%, throttling element 3 is in the maximum opening state. The flow rate of throttling element 3 at its maximum opening can be greater than the maximum displacement of cooling pump 13. When throttling element 3 completely bypasses motor 14, the throttling element can be in a non-maximum opening state.

[0044] The controller is electrically connected to the cooling pump 13 and the throttling element 3 respectively. The controller is used to adjust the displacement of the cooling pump 13 and the opening of the throttling element 3 according to the different oil temperatures of the hydraulic oil.

[0045] The greater the displacement of the cooling pump 13 to the motor 14, the higher the speed of the fan 2. By adjusting the displacement of the cooling pump 13, the speed of the fan 2 can be quickly adjusted. By changing the opening of the throttling element 3, a portion of the flow rate from the variable pump to the motor 14 can be returned to the return oil circuit 12 through the throttling element 3, thereby achieving further fine adjustment of the displacement of the motor 14. Through the cooperation of the variable pump and the throttling element 3, dead-zone-free adjustment and precise speed control of the motor 14 and fan 2 can be achieved.

[0046] Furthermore, such as Figure 1 As shown, the present invention also provides an oil temperature control method, which is applied to the oil temperature control system described above. The oil temperature control method includes:

[0047] S100: Obtain the temperature of the hydraulic oil;

[0048] S200: When the hydraulic oil temperature is not within the preset temperature range, adjust the target displacement of the cooling pump according to the correspondence between oil temperature and displacement in the preset mapping table, and at the same time close the throttling element so that the cooling pump pumps hydraulic oil to the motor according to the target displacement to drive the fan to rotate.

[0049] S300: When the cooling pump operates at the target displacement for a preset time, the opening of the throttling element is adjusted according to the subordinate relationship between the hydraulic oil temperature and the preset temperature range to adjust the hydraulic oil temperature.

[0050] This method first adjusts the displacement of the cooling pump 13 according to the hydraulic oil temperature, thereby adjusting the displacement of the fan 2 to be close to the actual required heat dissipation rate of the hydraulic oil. Furthermore, when needed, by changing the opening of the throttling element 3, a portion of the flow from the variable pump to the motor 14 can flow back to the return oil circuit 12 through the throttling element 3, thus achieving further fine adjustment of the motor 14 displacement (fan 2 speed). After the cooling pump 13 operates at the target speed corresponding to the oil temperature, since the fan 2 speed (cooling pump 13 displacement) is close to the actual required heat dissipation rate of the hydraulic oil, after the throttling element 3 is adjusted, at most only a very small portion of the hydraulic oil is throttled through the throttling element 3, effectively reducing the waste of system pressure. Moreover, this method can adjust the displacement of the cooling pump 13 and the opening of the throttling element 3 based on changes in the hydraulic oil temperature, achieving dynamic oil temperature control of the system.

[0051] Understandably, in some cases, if adjusting the displacement of the cooling pump 13 can match the cooling requirements of the hydraulic oil, then the throttling element 3 may not need to operate.

[0052] like Figure 2 As shown, in an embodiment of the present invention, before adjusting the displacement of the cooling pump 13 according to the correspondence between oil temperature and target displacement in a preset mapping table, or during the process of adjusting the cooling pump, it is also necessary to control the throttling element 3 to be fully closed.

[0053] Since the cooling pump 13 has a higher control priority than the throttling element 3, this method requires ensuring that the throttling element 3 is reset to the closed state before adjusting the displacement of the cooling pump 13 according to the hydraulic oil temperature each time. This is to avoid the throttling element 3 interfering with the adjustment of the cooling pump 13.

[0054] like Figure 2 As shown, in an embodiment of the present invention, step S300 involves adjusting the opening of the throttling element according to the subordinate relationship between the hydraulic oil temperature and a preset temperature range, thereby adjusting the hydraulic oil temperature. Specifically, this includes:

[0055] S300a: If the hydraulic oil temperature is within the preset temperature range, the throttling element is kept closed and the cooling pump is controlled to run at the current displacement to keep the hydraulic oil at the current temperature.

[0056] S300b: If the hydraulic oil temperature is not within the preset temperature range, adjust at least one of the cooling pump displacement and the throttling element opening to raise or lower the oil temperature accordingly.

[0057] Specifically, such as Figure 3 As shown, in an embodiment of the present invention, step S300b: if the hydraulic oil temperature is not within the preset temperature range, then at least one of the cooling pump displacement and the opening of the throttling element is adjusted to correspondingly raise or lower the oil temperature, specifically including:

[0058] S300b-1: If the hydraulic oil temperature is higher than the first preset temperature, the target displacement of the cooling pump will be readjusted according to the increased oil temperature, while keeping the throttling element closed, so that the cooling pump pumps hydraulic oil to the motor at the readjusted target displacement, driving the fan to increase the speed to reduce the oil temperature.

[0059] S300b-2: If the hydraulic oil temperature is lower than the second preset temperature, the cooling pump is controlled to maintain the current displacement, and the throttling element is controlled to change its opening to drive the fan to reduce its speed and increase the oil temperature until the hydraulic oil temperature stabilizes in the preset temperature range, at which point the current opening of the throttling element is maintained.

[0060] The first preset temperature and the second preset temperature are the upper and lower limits of the preset temperature range, respectively.

[0061] The correlation between oil temperature and target displacement in the preset mapping table refers to the comparison data obtained when the equipment is operating at laboratory ambient temperature. By testing hydraulic oil at different oil temperatures, the cooling pump 13 needs to supply oil to the motor 14 at different displacements to ensure that the oil temperature is maintained within the preset temperature range.

[0062] Due to changes in the actual ambient temperature, when the hydraulic pump operates at the target displacement corresponding to the oil temperature, there may be excessive heat dissipation or insufficient heat dissipation rate. For example, when the equipment operates in an environment of minus ten degrees Celsius, this temperature is significantly different from the laboratory ambient temperature. Although the oil temperature can be raised to twenty degrees Celsius by the hydraulic oil heater, if the cooling pump 13 operates at the target displacement corresponding to the twenty-degree oil temperature, it is easy to cause the system oil temperature to be too low.

[0063] Therefore, this method ensures that the speed of fan 2 matches the actual required cooling rate of hydraulic oil by selecting the intervention of the throttling element 3 at the appropriate time.

[0064] When adjusting the displacement of the cooling pump 13 alone is sufficient to match the fan 2 speed with the actual required cooling rate of the hydraulic oil, the throttling element 3 can be in the off state and not participate in operation. When it is difficult to adjust the fan 2 speed to match the actual required cooling rate of the hydraulic oil by adjusting the displacement of the cooling pump 13, the opening of the throttling element 3 can be further adjusted to fine-tune the displacement of the motor 14, thereby achieving a match between the two.

[0065] Taking the initial oil temperature of cooling pump 13 being higher than the preset temperature range as an example.

[0066] After the cooling pump 13 operates at the target displacement corresponding to the oil temperature for a preset time, if the oil temperature of the hydraulic oil drops and remains within the preset temperature range, the cooling pump 13 is controlled to continue operating at the current displacement, and the throttling element 3 is not operated.

[0067] After the cooling pump 13 operates at the target displacement corresponding to the oil temperature for a preset time, if the oil temperature of the hydraulic oil still exceeds the first preset temperature, the displacement of the cooling pump 13 will be changed again according to the increased oil temperature.

[0068] After the cooling pump 13 operates at the target displacement corresponding to the oil temperature for a preset time, if the oil temperature of the hydraulic oil is lower than the second preset temperature, the throttling element 3 is controlled to increase its opening.

[0069] During the adjustment of the displacement of the cooling pump 13, there may be instances where increasing the displacement of the cooling pump 13 slightly will cause the hydraulic oil temperature to rise continuously until it exceeds the preset temperature range, and decreasing the displacement of the cooling pump 13 slightly will cause the hydraulic oil temperature to drop continuously until it falls below the preset temperature range. In such cases, the flow rate from the cooling pump 13 to the motor 14 can be finely adjusted by adjusting the opening of the throttling element 3.

[0070] like Figure 1 As shown, in an embodiment of the present invention, step S200: when the hydraulic oil temperature is not within the preset temperature range, the target displacement of the cooling pump is adjusted according to the correspondence between oil temperature and displacement in the preset mapping table, and the throttling element is closed at the same time, so that the cooling pump pumps hydraulic oil to the motor at the target displacement to drive the fan to rotate. Specifically, this includes:

[0071] S201: If the hydraulic oil temperature is lower than the third preset temperature, control the cooling pump to output at the minimum displacement, and at the same time close the throttling element so that the cooling pump pumps hydraulic oil to the motor at the minimum displacement to drive the fan to rotate.

[0072] The third preset temperature is lower than the lower limit of the preset temperature range.

[0073] The third preset temperature is the threshold for determining a cold environment. When the oil temperature is lower than the third preset temperature, it means that the system is in a cold environment.

[0074] This regulatory process mainly occurs in cold environments.

[0075] In cold environments, when the equipment starts, the cooling pump 13 begins operation. When it is confirmed that the machinery is in a cold environment, i.e., the hydraulic oil temperature is below the third preset temperature, this method first controls the throttling element 3 to remain closed, then adjusts the displacement of the cooling pump 13 to the minimum, so that the cooling pump 13 outputs at its minimum displacement. A preset waiting time is then observed, during which the oil temperature is monitored. If the oil temperature rises and then remains within the preset temperature range, the cooling pump 13 continues to operate in its current state. If the oil temperature rises and exceeds the preset temperature range, the displacement of the cooling pump 13 is increased according to the different hydraulic oil temperatures.

[0076] For operational machinery, the required cooling rate of hydraulic oil varies depending on the region and season. Especially when equipment operates in northern winters, the initial temperature of the hydraulic oil can be as low as -10°C or even -20°C. Even if the cooling pump 13 operates at its lowest displacement, the airflow from the fan 2 can still cause the hydraulic oil temperature to drop too low. Conversely, if the fan 2 is completely stopped, the oil temperature may rise rapidly. Therefore, adjusting the displacement of the motor 14 by changing the displacement of the cooling pump 13 has a speed control blind spot.

[0077] Therefore, such as Figure 1 As shown, in an embodiment of the present invention, step S300: when the cooling pump operates at the target displacement for a preset time, adjusting the opening of the throttling element according to the subordinate relationship between the hydraulic oil temperature and the preset temperature range to adjust the hydraulic oil temperature includes:

[0078] S301: If the hydraulic oil temperature is lower than the lower limit of the preset temperature range when the cooling pump operates at the minimum displacement for a preset time, the cooling pump will be controlled to maintain the current displacement, and the throttling element will be controlled to change the opening to adjust the hydraulic oil temperature until the motor stops completely.

[0079] If the oil temperature rises only slightly or even drops after the cooling pump 13 is controlled to output at the minimum displacement, it indicates that even if the cooling pump 13 outputs at the minimum displacement, the current heat dissipation rate is still too fast for the hydraulic oil. In this case, the throttling element 3 can be controlled to increase its opening.

[0080] Furthermore, step S301 can be used for oil temperature control in extremely cold environments. In extremely cold environments, this method can further reduce the heat dissipation rate of hydraulic oil by adjusting the opening of the throttling element 3, thereby ensuring the normal operation of the equipment in extremely cold environments.

[0081] It is understandable that when adjusting the opening of the throttling element 3 in extremely cold environments, the throttling element 3 is allowed to completely bypass the motor 14, that is, in extremely cold environments, the fan 2 is allowed to completely stop.

[0082] like Figure 4 As shown, in an embodiment of the present invention, the oil temperature control system further includes a one-way oil replenishment circuit 4. The one-way oil replenishment circuit 4 is arranged in parallel with the cooling motor 14 and connected between the oil inlet circuit 11 and the oil return circuit 12. A one-way valve is provided on the one-way oil replenishment circuit 4. The one-way valve is configured to open when the hydraulic oil flows from the oil return circuit 12 to the oil inlet circuit 11 and close in the reverse direction.

[0083] When the cooling pump 13 stops, the fan 2, due to inertia, will drive the motor 14 to continue rotating. The continued operation of the motor 14 will cause one of its oil ports to draw oil from the oil inlet 11, and the other oil port to pump oil to the return oil channel 12. To achieve the function of slow stopping of the fan 2, a one-way oil replenishment channel 4 can be set between the oil inlet 11 and the return oil channel 12. Thus, when the cooling pump 13 stops, an independent loop is formed between the oil inlet 11, the return oil channel 12, the motor 14, and the one-way oil replenishment channel 4, ensuring that the motor 14 can float.

[0084] like Figure 4 As shown in the embodiment of the present invention, a reversing valve 6 is further provided between the cooling pump 13 and the motor 14 in the oil temperature control system. The reversing valve 6 is used to guide the hydraulic oil in the oil inlet 11 to one of the forward and reverse oil inlets of the motor 14, and to connect the other of the forward and reverse oil inlets to the return oil circuit 12. When the hydraulic oil in the oil inlet 11 enters from the forward oil inlet, the reverse oil inlet is connected to the return oil circuit 12, and the motor 14 rotates forward. When the hydraulic oil in the oil inlet 11 enters from the reverse oil inlet, the forward oil inlet is connected to the return oil circuit 12, and the motor 14 rotates in reverse.

[0085] like Figure 4 As shown, in an embodiment of the present invention, the reversing valve 6 is further provided with a stop valve position, which is configured to shut off the two oil ports of the motor 14, and to connect the oil inlet circuit 11 and the oil return circuit 12.

[0086] like Figure 4 As shown, in an embodiment of the present invention, the oil temperature control method further includes a safety overflow path 5, which is connected in parallel with the motor 14 between the oil inlet path 11 and the oil return path 12. By setting the safety overflow path 5, the maximum operating pressure of the oil temperature control system can be set.

[0087] like Figure 4 and Figure 5 As shown, in an embodiment of the present invention, the oil temperature control system further includes a temperature sensor, which is communicatively connected to the controller and used to detect the oil temperature of the hydraulic oil.

[0088] In an embodiment of the present invention, a heating rod can be installed in the oil tank of the working machine. When the working machine is started under cold conditions, the heating rod can be controlled to run for a period of time before the operation begins.

[0089] In embodiments of the present invention, starting refers to starting the engine in the working machinery, and working refers to the action of the actuator in the machinery.

[0090] To achieve the above objectives, the present invention also provides a working machine, wherein the working machine includes an oil temperature control system according to the above description. The working machine can be an excavator, a truck-mounted crane, etc. Since the working machine adopts all the technical solutions of the above embodiments, it at least has the beneficial effects brought by the above embodiments, and will not be repeated here.

[0091] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0092] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0093] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0094] Although embodiments of the present invention have been described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An oil temperature control method characterized by, The method is applied to an oil temperature control system, the system comprising a controller, a cooling pump (13), a motor (14), a fan (2) and a throttling element (3), the controller being communicatively connected with the cooling pump (13) and the throttling element (3) respectively, the motor (14) being used to drive the fan (2) to rotate, the cooling pump (13) and the motor (14) constituting a fan driving circuit, the throttling element (3) being adjustable in opening degree and being arranged in parallel with the motor (14) between an oil inlet path (11) and an oil return path (12) of the fan (2) driving circuit; The oil temperature control method comprises: obtaining an oil temperature of hydraulic oil; when the oil temperature of the hydraulic oil is not in a preset temperature interval, adjusting a target displacement of the cooling pump (13) according to a correspondence between oil temperature and displacement in a preset mapping table, and simultaneously closing the throttling element, so that the cooling pump (13) pumps hydraulic oil to the motor at the target displacement to drive the fan to rotate; when the cooling pump (13) works at the target displacement for a preset time length, adjusting an opening degree of the throttling element (3) according to a dependent relationship between the oil temperature of the hydraulic oil and the preset temperature interval, so as to adjust the oil temperature of the hydraulic oil.

2. The oil temperature control method according to claim 1, characterized by, Adjusting the opening degree of the throttling element (3) according to the dependent relationship between the oil temperature of the hydraulic oil and the preset temperature interval, so as to adjust the oil temperature of the hydraulic oil, specifically comprises: if the oil temperature of the hydraulic oil is in the preset temperature interval, controlling the throttling element (3) to remain closed, and controlling the cooling pump to operate at a current displacement, so as to keep the hydraulic oil at a current temperature; if the oil temperature of the hydraulic oil is not in the preset temperature interval, adjusting at least one of the displacement of the cooling pump and the opening degree of the throttling element, so as to correspondingly increase or decrease the oil temperature.

3. The oil temperature control method according to claim 2, characterized by, If the oil temperature of the hydraulic oil is not in the preset temperature interval, adjusting at least one of the displacement of the cooling pump and the opening degree of the throttling element, so as to correspondingly increase or decrease the oil temperature, specifically comprises: if the oil temperature of the hydraulic oil is higher than a first preset temperature, re-adjusting the target displacement of the cooling pump (13) according to the increased oil temperature, while keeping the throttling element closed, so that the cooling pump (13) pumps hydraulic oil to the motor at the re-adjusted target displacement to drive the fan to increase the rotational speed to reduce the oil temperature; if the oil temperature of the hydraulic oil is lower than a second preset temperature, controlling the cooling pump to keep operating at the current displacement, and controlling the throttling element (3) to change the opening degree, so as to drive the fan to reduce the rotational speed to increase the oil temperature, until the oil temperature of the hydraulic oil is stabilized at the preset temperature interval, the current opening degree of the throttling element (3) is kept; wherein the first preset temperature and the second preset temperature are respectively an upper limit value and a lower limit value of the preset temperature interval.

4. The oil temperature control method according to claim 1, characterized by, If the oil temperature of the hydraulic oil is not in the preset temperature range, the target displacement of the cooling pump (13) is adjusted according to the preset mapping table of the oil temperature and the displacement, and the throttle element is closed, so that the cooling pump (13) pumps the hydraulic oil to the motor at the target displacement to drive the fan to rotate, specifically comprising: If the oil temperature of the hydraulic oil is lower than the third preset temperature, the cooling pump (13) is controlled to output at the minimum displacement, and the throttle element is closed, so that the cooling pump (13) pumps the hydraulic oil to the motor at the minimum displacement to drive the fan to rotate; The third preset temperature is lower than the lower limit value of the preset temperature range.

5. The oil temperature control method according to claim 4, characterized by In the case that the cooling pump (13) works at the target displacement for a preset time length, the opening degree of the throttle element (3) is adjusted according to the dependent relationship between the oil temperature of the hydraulic oil and the preset temperature range to adjust the oil temperature of the hydraulic oil, comprising: In the case that the cooling pump (13) works at the minimum displacement for a preset time length, if the oil temperature of the hydraulic oil is lower than the lower limit value of the preset temperature range, the cooling pump is controlled to keep the current displacement and the throttle element (3) is controlled to change the opening degree to adjust the oil temperature of the hydraulic oil until the motor (14) completely stops.

6. An oil temperature control system characterized by, The oil temperature control system comprises: A fan driving circuit comprising an oil inlet path (11), an oil return path (12), a cooling pump (13) as a power input, and a motor (14) as an execution element; A fan (2) in driving connection with the motor (14); A throttle element (3) connected between the oil inlet path (11) and the oil return path (12) and arranged in parallel with the motor (14); A controller electrically connected with the cooling pump (13) and the throttle element (3), respectively, and configured to execute the oil temperature control method according to any one of claims 1 to 5.

7. The oil temperature control system of claim 6, wherein The oil temperature control system further comprises a one-way oil supplement path (4) arranged in parallel with the motor (14) and connected between the oil inlet path (11) and the oil return path (12), and a one-way valve is arranged on the one-way oil supplement path (4) and configured to be conductive when the hydraulic oil flows from the oil return path (12) to the oil inlet path (11) and to be reverse cut-off.

8. The oil temperature control system of claim 6, wherein A reversing valve (6) is further arranged between the cooling pump (13) and the motor (14), and the reversing valve (6) is configured to selectively guide the hydraulic oil of the oil inlet path (11) to one of the forward rotation oil inlet port and the reverse rotation oil inlet port of the motor (14) and to conduct the other of the forward rotation oil inlet port and the reverse rotation oil inlet port to the oil return path (12).

9. The oil temperature control system of claim 6, wherein The oil temperature control system further comprises a temperature sensor in communication connection with the controller and configured to detect the oil temperature of the hydraulic oil.

10. A work machine characterized by comprising: The oil temperature control system according to any one of claims 6 to 9. The oil temperature control system according to any one of claims 6 to 9.

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