Hydraulic system regenerative cooling and heat pump preheating combined device

Abstract

The utility model relates to the technical field of hydraulic systems, in particular to a regenerative cooling and heat pump preheating integrated device of a hydraulic system. Comprising a hydraulic oil tank, a thermodynamic cycle subsystem and an air supply subsystem. The thermodynamic cycle subsystem comprises a plate heat exchanger, an expansion and compression all-in-one machine, an electric power generation all-in-one machine, a tube fin type heat exchanger and a spiral tube heat exchanger; the air supply subsystem comprises a fan thermodynamic circulation subsystem which is a working medium circulation loop and is switched between a heat pump preheating mode and a regenerative cooling mode, and preheating and cooling of hydraulic oil are achieved. According to the system, the overall energy utilization rate of the system is comprehensively improved, switching between a regenerative cooling mode and a heat pump preheating mode is achieved by monitoring the oil temperature, and the cooling effect and the energy efficiency of regenerative cooling are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of hydraulic systems, and relates to a combined device for regenerative cooling and heat pump preheating of a hydraulic system. Background Technique

[0002] Due to the low energy efficiency of the hydraulic system, a large amount of heat energy is generated by the energy loss of the system, causing the oil temperature to rise rapidly. High temperature will have an adverse impact on the safety and reliability of the hydraulic system. Therefore, a cooling system needs to be equipped to control the oil temperature within a reasonable range. In mobile hydraulic drive equipment, due to limited installation space, traditional cooling systems consume more additional energy, increase the installed power of the system, and reduce the overall energy efficiency of the equipment. When starting the hydraulic system in a cold environment, the low temperature causes the oil viscosity to be high, and the system is difficult to work properly. Usually, an electric heater is added to increase the oil temperature, which will cause the local oil temperature to be too high and accelerate the deterioration of the oil. Content of the Utility Model

[0003] The utility model overcomes the deficiencies of the prior art and provides a combined device for regenerative cooling and heat pump preheating of a hydraulic system.

[0004] In order to achieve the above object, the utility model is realized by the following technical solutions.

[0005] A combined device for regenerative cooling and heat pump preheating of a hydraulic system includes a hydraulic oil tank, a thermal cycle subsystem and a air supply subsystem; the thermal cycle subsystem includes a plate heat exchanger, a scroll compressor-expansion machine, an electric generator-motor, a finned tube heat exchanger and a spiral tube heat exchanger; the air supply subsystem includes a fan.

[0006] The hydraulic oil tank is connected to the hot-phase inlet of the plate heat exchanger through a variable hydraulic pump, and the cold-phase outlet of the plate heat exchanger is connected to the hydraulic oil tank; the hot-phase outlet of the plate heat exchanger is connected to the scroll compressor-expansion machine; the scroll compressor-expansion machine is connected to the finned tube heat exchanger; the finned tube heat exchanger is connected to the cold-phase inlet of the plate heat exchanger; the scroll compressor-expansion machine is connected to the electric generator-motor.

[0007] A spiral tube heat exchanger is arranged in the hydraulic oil tank, one end of the spiral tube heat exchanger is connected to the scroll compressor-expansion machine, and the other end of the spiral tube heat exchanger is connected to the finned tube heat exchanger; the fan is arranged in the air pipeline of the finned tube heat exchanger to continuously supply ambient air to the finned tube heat exchanger.

[0008] The thermal cycle subsystem is a working medium circulation loop, which switches between two modes of heat pump preheating mode and regenerative cooling mode to realize the preheating and cooling of hydraulic oil.

[0009] Further, it also includes a first three-way solenoid valve and a second three-way solenoid valve; one end of the spiral tube heat exchanger is connected to the first three-way solenoid valve through a pipeline; the other two passages of the first three-way solenoid valve are respectively connected to the hot-phase outlet of the plate heat exchanger and the expansion-compression unit; the other end of the spiral tube heat exchanger is connected to the second three-way solenoid valve through a pipeline, and the other two passages of the second three-way solenoid valve are respectively connected to the cold-phase inlet of the plate heat exchanger and the tube-fin heat exchanger.

[0010] Further, it also includes a control system, and the control system includes a controller, a tank temperature sensor, an evaporation temperature sensor, an evaporation pressure sensor, and an ambient temperature sensor; the tank temperature sensor is arranged inside the hydraulic tank to detect the temperature of the hydraulic oil inside the hydraulic tank; both the evaporation temperature sensor and the evaporation pressure sensor are arranged on the pipeline connecting the first three-way solenoid valve and the expansion-compression unit; the ambient temperature sensor is arranged in the environment where the hydraulic system is located.

[0011] Furthermore, an expansion valve is arranged on the pipeline connecting the spiral tube heat exchanger and the second three-way solenoid valve, and a working fluid pump is arranged on the pipeline connecting the second three-way solenoid valve and the cold-phase inlet of the plate heat exchanger; the working fluid pump is connected with a working fluid pump motor.

[0012] Furthermore, the controller is respectively connected to the first three-way solenoid valve, the second three-way solenoid valve, the variable hydraulic pump, the expansion valve, the working fluid pump motor, the tank temperature sensor, the evaporation temperature sensor, the evaporation pressure sensor, and the ambient temperature sensor; the controller controls the entire system to switch between two modes, namely the heat pump preheating mode and the regenerative cooling mode, according to the temperature feedback, so as to realize the preheating and cooling of the hydraulic oil.

[0013] Further, the variable hydraulic pump is connected to a hydraulic pump motor.

[0014] Further, the fan is connected to a fan motor.

[0015] The beneficial effects of the present utility model compared with the prior art are as follows:

[0016] The present utility model takes into account that both the high-temperature hydraulic oil and the surrounding ambient air contain a certain amount of energy, and combines the organic Rankine cycle with the heat pump system to form a combined system for cooling and preheating of the hydraulic system. It replaces the traditional oil cooler with the organic Rankine cycle mode and replaces the electric heater with the heat pump mode, comprehensively improving the overall energy utilization rate of the system and achieving energy conservation and emission reduction. In terms of system control, the switching between the regenerative cooling mode and the heat pump preheating mode is realized by monitoring the oil temperature. At the same time, in the regenerative cooling mode, a model optimization control method is adopted to improve the cooling effect and energy efficiency of the regenerative cooling. Description of the Drawings

[0017] Figure 1Structural schematic diagram of the combined device for regenerative cooling and heat pump preheating provided by the present utility model;

[0018] Figure 2 Flow chart for switching the working mode of the combined device for regenerative cooling and heat pump preheating;

[0019] Figure 3 Control schematic diagram of the combined device for regenerative cooling and heat pump preheating;

[0020] Reference numerals in the figure:

[0021] 1 - hydraulic oil tank, 2 - variable hydraulic pump, 3 - overflow valve, 4 - plate heat exchanger, 5 - first three-way solenoid valve, 6 - integrated expansion compressor, 7 - integrated motor - generator, 8 - fan, 9 - fin - tube heat exchanger, 10 - second three-way solenoid valve, 11 - working fluid pump, 12 - expansion valve, 13 - spiral tube heat exchanger, 14 - oil tank temperature sensor, 15 - evaporation temperature sensor, 16 - evaporation pressure sensor, 17 - ambient temperature sensor, 18 - fan motor, 19 - working fluid pump motor, 20 - hydraulic pump motor, 21 - controller. Detailed implementation manners

[0022] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present utility model clearer and more understandable, the present utility model will be further described in detail in combination with embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model. The technical solutions of the present utility model will be described in detail below in combination with embodiments and the accompanying drawings, but the protection scope is not limited hereby.

[0023] Please refer to Figures 1 to 3 , this embodiment proposes a combined device and control method for regenerative cooling and heat pump preheating of a hydraulic system. The combined device mainly includes a hydraulic subsystem, a thermal cycle subsystem, a air supply subsystem and a control system.

[0024] The hydraulic subsystem includes a variable hydraulic oil tank 1, a variable hydraulic pump 2 and a safety valve 3;

[0025] The thermal cycle subsystem includes a plate heat exchanger 4, an integrated expansion compressor 6, an integrated motor - generator 7, a fin - tube heat exchanger 9 and a spiral tube heat exchanger 13;

[0026] The air supply subsystem includes a fan motor 18 and a fan 8;

[0027] The control system includes a controller 21, an oil tank temperature sensor 14, an evaporation temperature sensor 15, an evaporation pressure sensor 16, and an ambient temperature sensor 17;

[0028] The hydraulic oil tank 1 is connected to the hot-phase inlet of the plate heat exchanger 4 through a variable hydraulic pump 2, and the cold-phase outlet of the plate heat exchanger 4 is connected to the hydraulic oil tank 1; a safety valve 3 is connected between the hot-phase inlet and the cold-phase outlet of the plate heat exchanger 4.

[0029] A spiral tube heat exchanger 13 is arranged in the hydraulic oil tank 1, and one end of the spiral tube heat exchanger 13 is connected to a first three-way solenoid valve 5 through a pipeline; the other two passages of the first three-way solenoid valve 5 are respectively connected to the hot-phase outlet of the plate heat exchanger 4 and an expansion-compression integrated machine 6; the other end of the spiral tube heat exchanger 13 is connected to a second three-way solenoid valve 10 through a pipeline, and the other two passages of the second three-way solenoid valve 10 are respectively connected to the cold-phase inlet of the plate heat exchanger 4 and a tube-fin heat exchanger 9; the tube-fin heat exchanger 9 is connected to the expansion-compression integrated machine 6; the expansion-compression integrated machine 6 is connected to an electric power generation integrated machine 7. The thermal cycle subsystem is a working medium circulation loop, which can control the first three-way solenoid valve 5 and the second three-way solenoid valve 10 according to the hydraulic oil temperature, and switch between two modes, namely the heat pump preheating mode and the regenerative cooling mode, to realize the preheating and cooling of the hydraulic oil. The mode switching process is as Figure 2 shown. The electric power generation integrated machine 7 is directly connected to the expansion-compression integrated machine 6. In the regenerative cooling mode, the electric power generation integrated machine 7 is used as a generator, and the expansion-compression integrated machine 6 is used as an expander; while in the heat pump preheating mode, the electric power generation integrated machine 7 is used as a motor, and the expansion-compression integrated machine 6 is used as a compressor.

[0030] The fan motor 18 of the air supply subsystem is connected to the fan 8, and the fan 8 is arranged in the air pipeline of the tube-fin heat exchanger 9 to continuously supply ambient air to the tube-fin heat exchanger 9. In the regenerative cooling mode, the air supply subsystem serves as a cold source to condense the working medium; in the heat pump preheating mode, the air supply subsystem serves as a heat source to evaporate the working medium.

[0031] A tank temperature sensor 14 is arranged in the hydraulic oil tank 1 to detect the temperature of the hydraulic oil in the hydraulic oil tank 1; an evaporation temperature sensor 15 and an evaporation pressure sensor 16 are both arranged on the pipeline connecting the first three-way solenoid valve 5 and the expansion-compression integrated machine 6; an ambient temperature sensor 17 is arranged in the environment where the hydraulic system is located;

[0032] An expansion valve 12 is arranged on the pipeline connecting the spiral tube heat exchanger 13 and the second three-way solenoid valve 10, and a working medium pump 11 is arranged on the pipeline connecting the second three-way solenoid valve 10 and the cold-phase inlet of the plate heat exchanger 4; the working medium pump 11 is connected to a working medium pump motor 19; the variable hydraulic pump 2 is connected to a hydraulic pump motor 20.

[0033] The controller 21 is respectively connected to the first three-way solenoid valve 5, the second three-way solenoid valve 10, the variable hydraulic pump 2, the expansion valve 12, the working fluid pump motor 19, the oil tank temperature sensor 14, the evaporation temperature sensor 15, the evaporation pressure sensor 16, and the ambient temperature sensor 17; the controller 21 controls the conversion of the entire system between two modes, namely the heat pump preheating mode and the regenerative cooling mode, according to the temperature feedback, so as to realize the preheating and cooling of the hydraulic oil.

[0034] The combined control method for regenerative cooling and heat pump preheating of the hydraulic system is realized based on the above combined device:

[0035] In the existing equipment, the hydraulic transmission system is the driving and transmission part of the mobile equipment. When working, it sucks oil from the oil tank, and through energy conversion, it meets the working requirements of the equipment. The energy lost during the working process causes the temperature of the hydraulic oil to rise, and finally the heated hydraulic oil flows back to the main oil tank. Due to the large change in the flow rate of the hydraulic oil when it flows back to the oil tank in the hydraulic system, in order to make the flow rate of the hydraulic oil entering the evaporator stable and adjustable, an independent variable hydraulic pump 2 is used to supply oil.

[0036] When the temperature of the hydraulic oil is higher than 55 °C, the thermodynamic cycle subsystem adopts the regenerative cooling mode to cool the oil in the hydraulic oil tank 1. At this time, all three subsystems work. The plate heat exchanger 4 serves as the evaporator, the finned tube heat exchanger 9 serves as the condenser, the expansion-compression integrated machine 6 is used as the expander, and the motor-generator integrated machine 7 works in the generator state. When working, the variable hydraulic pump 2 sends the hot hydraulic oil in the oil tank 1 into the plate heat exchanger 4. The high-temperature hydraulic oil entering the plate heat exchanger 4 heats the working fluid from a liquid to a superheated vapor, and at the same time, the cooled hydraulic oil flows back to the hydraulic oil tank 1. The high-temperature and high-pressure working fluid vapor does work externally through the expansion-compression integrated machine 6 and becomes a low-temperature and low-pressure vapor. The generated mechanical energy can be converted into electrical energy by the motor-generator integrated machine 7. The fan 8 continuously provides cooling air for the finned tube heat exchanger 9 to cool the working fluid from a low-temperature vapor to a saturated liquid. The saturated working fluid is pressurized by the working fluid pump 11 and supplied to the plate heat exchanger 4 to start a new cycle.

[0037] When the temperature of the hydraulic oil is lower than 10 °C, the thermal cycle subsystem switches to the heat pump preheating mode to heat the oil in the hydraulic oil tank 1. At this time, the hydraulic subsystem does not work. The finned tube heat exchanger 9 acts as an evaporator, the expansion-compression integrated machine 6 acts as a compressor, and the motor-generator integrated machine 7 works in the motor state. The fan 8 provides ambient air for the finned tube heat exchanger 9. After the working medium absorbs the heat energy in the environment, it is converted from a liquid state to a vapor state. The motor-generator integrated machine 7 drives the expansion-compression integrated machine 6 to work, compressing the working medium vapor into a high-temperature and high-pressure vapor. The high-temperature steam passes through the spiral tube heat exchanger 13, transferring heat to the oil in the hydraulic oil tank 1, increasing the temperature of the hydraulic oil, and the working medium is cooled into a saturated liquid. The saturated liquid becomes a low-temperature and low-pressure unsaturated liquid after passing through the expansion valve 12, and the working medium enters the finned tube heat exchanger 9 again for evaporation, starting the next cycle. When the temperature of the oil in the hydraulic oil tank 1 reaches the set temperature (30 °C), the heat pump preheating subsystem stops working. Among them, the spiral tube heat exchanger 13 is arranged at the bottom of the hydraulic oil tank 1, relying on the natural convection heat transfer of the hydraulic oil.

[0038] Figure 2 The figure shows the flowchart of the working mode switching of the thermal cycle subsystem, mainly based on the measurement of the oil temperature by the oil tank temperature sensor 14 as the judgment basis. When it is detected that the oil temperature is lower than 10 °C, the heat pump preheating mode is started. At this time, the first three-way solenoid valve 5 and the second three-way solenoid valve 10 act, the fan motor 18 drives the fan 8 to rotate, the motor-generator integrated machine 7 works as a motor, and the expansion-compression integrated machine 6 works as a compressor. When it is detected that the value measured by the oil tank temperature sensor 14 is greater than 30 °C, the heat pump preheating system gradually stops working. When it is detected that the oil temperature is higher than 55 °C, the regenerative cooling mode is started. At this time, the first three-way solenoid valve 5 and the second three-way solenoid valve 10 do not act, the fan motor 18 drives the fan 8 to rotate, the variable hydraulic pump 2 works under the drive of the hydraulic pump motor 20, the motor-generator integrated machine 7 works as a generator, and the expansion-compression integrated machine 6 works as an expander. When it is detected that the value measured by the oil tank temperature sensor 14 is less than 45 °C, the regenerative cooling system gradually stops working. When it is detected that the oil temperature is between 10 °C and 55 °C, the combined device does not work.

[0039] Because the working time of the regenerative cooling mode is much longer than that of the heat pump preheating mode, the two first three-way solenoid valves 5 and the second three-way solenoid valve 10 are in the normal state, making the pipeline connection of the thermal cycle subsystem in the regenerative cooling mode. The switching temperature points in the thermal cycle subsystem can be set according to the hydraulic oil used and the local ambient temperature.

[0040] To enable the power generation power of the motor-generator integrated machine 7 and the cooling efficiency of the plate heat exchanger 4 to reach the best effect during the operation of the regenerative cooling mode, the regenerative cooling system is optimized and controlled by a model. The working principle of the control system is as Figure 3 shown.Figure 1 The dashed lines in it indicate the signal transmission between each monitoring and control component and the controller. Based on the geometric structure and characteristic parameters of the components actually used in the regenerative cooling system, a dynamic simulation model is established. Through the optimized operation of the model, the optimal working parameter maps of the system under different oil temperatures and ambient temperatures are obtained, and this data is used as the database of the actual control system. In actual control, according to the data obtained by the oil tank temperature sensor 14 and the ambient temperature sensor 17, and by referring to the model optimization database, the optimal evaporation pressure and the corresponding oil flow rate of the regenerative cooling system under the current working conditions are obtained. Calculate the displacement of the variable hydraulic pump 2 according to the oil flow rate, and output a control signal to control the swash plate swing angle of the variable hydraulic pump 2. According to the difference between the optimal evaporation pressure and the actual evaporation pressure, input it into the PID control algorithm to obtain the rotational speed of the working medium pump, and use this as a basis to control the working medium pump motor 19 to realize the regulation of the working medium state in the entire regenerative cooling system, and then monitor the system evaporation pressure through the evaporation pressure sensor 16 and compare it with the theoretical optimal evaporation pressure.

[0041] According to the Carnot cycle efficiency, when the oil temperature at the inlet of the heat exchanger Toil is 85 °C and the ambient temperature Tair is 30 °C, the maximum efficiency in the cooling mode is

[0042] ;

[0043] Generally, the thermal efficiency of ORC is about 5%, and for the air-cooled radiator used for cooling the hydraulic oil of mobile equipment, the cooling energy consumption is about 5% - 10% of the heat dissipation power. Here, the median value of 7.5% is taken. According to the above two efficiencies, taking a hydraulic system with an average power of 100 kW during operation as an example, calculate the energy efficiency of the new cooling method and the traditional cooling method. Assume that the average energy efficiency of the hydraulic system is 30%, that is, a heat generation power of 70 kW is generated.

[0044] If the traditional cooling method is adopted, the power to be consumed is

[0045] ;

[0046] If the new cooling method is adopted, no energy is consumed during the cooling process. Instead, energy can be generated through waste heat recovery and thermomechanical conversion, which can be used to charge the battery or directly drive mechanical components such as fans. The power generated is

[0047] ;

[0048] Therefore, compared with the traditional cooling method, the energy-saving effect produced by the new cooling method is

[0049] ;

[0050] During preheating, assuming the heating power is 10 kW, traditional preheating methods generally use electric heating or overflow heating. Even if other energy losses are ignored, the power consumption is still 10 kW. When using a heat pump for preheating, due to the utilization of the thermal energy of the air, the power consumed by the heat pump is much less than the heating power. Its coefficient of performance (the ratio of heat production power to power consumption) is generally 2 - 4. Assuming the average coefficient of performance is 3, that is, to generate a preheating power of 10 kW, only 3.33 kW of power needs to be consumed, and the energy-saving ratio is 67%.

[0051] The above content is a further detailed description of the present utility model in combination with specific preferred embodiments. It cannot be determined that the specific embodiments of the present utility model are limited thereto. For those of ordinary skill in the technical field to which the present utility model belongs, without departing from the premise of the present utility model, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the scope of patent protection determined by the claims submitted for the present utility model.

Claims

1. A combined device for hydraulic system regenerative cooling and heat pump preheating, characterized in that: It comprises a hydraulic oil tank (1), a thermal circulation subsystem and an air supply subsystem; the thermal circulation subsystem comprises a plate heat exchanger (4), an expansion-compression integrated machine (6), an electric power generation integrated machine (7), a tube-fin heat exchanger (9) and a spiral tube heat exchanger (13); the air supply subsystem comprises a fan (8); The hydraulic oil tank (1) is connected to the hot phase inlet of the plate heat exchanger (4) through a variable hydraulic pump (2); the cold phase outlet of the plate heat exchanger (4) is connected to the hydraulic oil tank (1); the hot phase outlet of the plate heat exchanger (4) is connected to the expansion-compression integrated machine (6); the expansion-compression integrated machine (6) is connected to the tube-fin heat exchanger (9); the tube-fin heat exchanger (9) is connected to the cold phase inlet of the plate heat exchanger (4); the expansion-compression integrated machine (6) is connected to the electric generator integrated machine (7); A spiral tube heat exchanger (13) is arranged in the hydraulic oil tank (1); one end of the spiral tube heat exchanger (13) is connected to the expansion-compression integrated machine (6), and the other end of the spiral tube heat exchanger (13) is connected to the tube-fin heat exchanger (9); a fan (8) is arranged in the air pipeline of the tube-fin heat exchanger (9) to continuously provide ambient air to the tube-fin heat exchanger (9).

2. A hydraulic system regenerative cooling and heat pump preheating combined device according to claim 1, characterized in that: The device further comprises a first three-way solenoid valve (5) and a second three-way solenoid valve (10); one end of the spiral tube heat exchanger (13) is connected to the first three-way solenoid valve (5) via a pipeline; the other two passages of the first three-way solenoid valve (5) are respectively connected to the hot phase outlet of the plate heat exchanger (4) and the expansion-compression integrated machine (6); the other end of the spiral tube heat exchanger (13) is connected to the second three-way solenoid valve (10) via a pipeline, and the other two passages of the second three-way solenoid valve (10) are respectively connected to the cold phase inlet of the plate heat exchanger (4) and the tube-fin heat exchanger (9).

3. A hydraulic system regenerative cooling and heat pump preheating combined device according to claim 2, characterized in that: The system also includes a control system, the control system including a controller (21), an oil tank temperature sensor (14), an evaporation temperature sensor (15), an evaporation pressure sensor (16), and an ambient temperature sensor (17); the oil tank temperature sensor (14) is arranged in the hydraulic oil tank (1) to detect the temperature of the hydraulic oil in the hydraulic oil tank (1); the evaporation temperature sensor (15) and the evaporation pressure sensor (16) are both arranged on a pipeline connecting the first three-way solenoid valve (5) and the expansion-compression integrated machine (6); and the ambient temperature sensor (17) is arranged in the environment where the hydraulic system is located.

4. A hydraulic system regenerative cooling and heat pump preheating combined device according to claim 3, characterized in that: An expansion valve (12) is provided on the pipeline connecting the spiral tube heat exchanger (13) and the second three-way solenoid valve (10), and a working fluid pump (11) is provided on the pipeline connecting the second three-way solenoid valve (10) and the cold phase inlet of the plate heat exchanger (4); the working fluid pump (11) is connected to a working fluid pump motor (19).

5. A hydraulic system regenerative cooling and heat pump preheating combined device according to claim 4, characterized in that: The controller (21) is respectively connected to the first three-way solenoid valve (5), the second three-way solenoid valve (10), the variable hydraulic pump (2), the expansion valve (12), the working fluid pump motor (19), the oil tank temperature sensor (14), the evaporation temperature sensor (15), the evaporation pressure sensor (16) and the ambient temperature sensor (17); the controller (21) controls the entire system to switch between the heat pump preheating mode and the regeneration cooling mode according to temperature feedback, thereby realizing preheating and cooling of the hydraulic oil.

6. A hydraulic system regenerative cooling and heat pump preheating combined device according to claim 1, characterized in that: The variable hydraulic pump (2) is connected to a hydraulic pump motor (20).

7. A hydraulic system regenerative cooling and heat pump preheating combined device according to claim 1, characterized in that: The fan (8) is connected to the fan motor (18).

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