Tractor multipath hydraulic output power tester with temperature correction function

Abstract

The invention discloses a tractor multi-path hydraulic output power tester with a temperature correction function. The tractor multi-path hydraulic output power tester comprises a control display unit, a measuring unit and a box body. The control display unit is fixed on the upper portion of the box body, and the measuring unit is installed on the lower portion of the box body and connected with the box body through a communication line. The control display unit comprises an industrial control display all-in-one machine, a communication line, a printer and a PLC. The measuring unit comprises large, medium and small flow tractor hydraulic output power measuring units. Each measuring unit is composed of a quick-change connector, an oil inlet hose, a high-pressure oil pipe, a pressure sensor, a temperature sensor, a filter, a flow meter, a proportional flow valve, an overflow valve, a one-way valve and an oil return hose. Hydraulic oil passes through the oil inlet hose, all parts of the measuring unit and the oil return hose to form a hydraulic output power testing loop. The flow of a pipeline is adjusted by controlling the opening degree of a hydraulic output test oil way proportional flow valve, and the hydraulic output power is calculated according to the change relation between the hydraulic output power and the flow and the change relation between the hydraulic output power and the pressure. And based on a heat balance theory, analyzing a hot pressure loss rule of the hydraulic system, calculating a hydraulic output power correction coefficient, and finally obtaining effective hydraulic output power. According to the invention, the test precision and test efficiency of multi-path hydraulic output power of tractors with different horsepower and flow rates are improved.

Description

Technical Field

[0001] The invention relates to the field of tractor multi-channel hydraulic output power detection equipment, in particular to a tractor multi-channel hydraulic output power tester with temperature correction. Technical Background

[0002] The hydraulic output system is a key component of the tractor, and the performance detection of the hydraulic output system is an important part of tractor research. At present, the existing hydraulic test equipment has good test stability, can realize the monitoring of the test process and the production of test records, and can basically meet the test requirements of single-channel or two-channel hydraulic output devices. Multi-channel testing is more difficult, and the test function is single, which cannot meet the needs of information-based test identification. Due to the low level of research and development attention of domestic enterprises and the small market for tractor testing and inspection, there has been no major technical update of related testing equipment so far. However, with the development of high-horsepower tractors, tractors with more than 300 horsepower are generally equipped with 3 or more hydraulic output devices. Traditional testing equipment can no longer meet the needs of multi-channel output device performance testing, nor can it meet the research and development test requirements of tractor hydraulic output systems, which is far behind foreign advanced technologies. Overall, there is not much research on tractor hydraulic output power test systems, and the existing equipment technology is relatively backward, and it is in urgent need of updating and optimization.

[0003] The tractor hydraulic output tester has a power loss caused by the temperature rise during the working process of the test equipment, which causes a large error between the test result and the actual value. In order to solve this problem, a new hydraulic output power calculation method is introduced. At present, it is urgent to improve the test accuracy. Summary of the invention

[0004] The object of the present invention is to provide a tractor multi-channel hydraulic output power tester with temperature correction to solve the problems raised in the above background technology.

[0005] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions: A tractor multi-channel hydraulic output power tester with temperature correction, comprising a control display unit, a measuring unit, and a box. The control display unit is fixed on the upper part of the box and connected to the measuring unit through a communication line; the measuring unit is installed below the control display unit and connected to the control display unit through a communication line. The control display unit: mainly includes an industrial control display all-in-one machine, a communication line, a printer, and a PLC controller; the industrial control display all-in-one machine is installed on the upper outer surface of the box; the printer is installed inside the upper right end of the box; the box includes a boss and a tool box. The boss is a part of the box, and the test instructions are operated by the placed manipulator; the tool box is placed on the right end of the boss. The large, medium and small flow tractor hydraulic output power measuring units in the measuring unit, whose oil inlet hose and oil return hose are used as links to connect the hydraulic oil circuit of the tractor and the measuring unit, and the quick-change joint is installed on the outside of the box and fixed by nuts inside; the pressure sensor is installed in the box at the end closest to the oil inlet and outlet; the temperature sensor is installed next to the pressure sensor inside the box; the filter is installed in the hydraulic main circuit; the flow meter is installed inside the box and connected to the filter and the one-way valve branch; the overflow valve is installed inside the box and the proportional flow valve is next to it; the entire proportional flow valve includes an actuator and a ball valve, the ball valve is in the main oil circuit, and the actuator is on its upper side; the industrial control display integrated machine is installed on the upper outer surface of the box; the one-way valve is installed between the branch and the main circuit inside the box; the high-pressure oil pipe is located inside the box, and the diameter of each layer of high-pressure oil pipe is related to the flow rate under different tractor horsepower sections; the external oil cooler is installed on the outside of the tester, between the equipment under test and the tester.

[0006] The peak pressure performance test oil circuit is located in the third part of the measuring unit. The hydraulic oil is connected to the pressure sensor through the quick-change joint from the oil inlet hose. The oil inlet hose and the oil return hose are used to connect the tractor and the tester. The hydraulic oil is connected to the hydraulic cylinder through the high-pressure oil pipe. The hydraulic oil is then connected through the pressure sensor, quick-change joint and oil return hose in the oil outlet; the hydraulic cylinder is installed between the two pressure sensors.

[0007] Test method: The first part of the measuring unit tests the oil circuit, which can test high-power tractors with a flow rate of 25-250L / min; the second part of the measuring unit can test medium power with a flow rate of 16-166L / min; the third part of the measuring unit can test low power with a flow rate of 10-100L / min. Single tests can be performed according to large, medium and small flow rates (power).

[0008] Test method: The tester can simultaneously test the performance of tractors within the range of large, medium and small flow rates; the tester can simultaneously test the power of three low-power tractors; the tester can simultaneously test two medium-power and one low-power tractors. That is, the first and second parts test medium-power, and the third layer tests low-power tractors; the tester can also test one high-power tractor and two low-power tractors at the same time. The first layer of the tester tests high power, and the second and third layers test low-power tractors. The first layer (flow rate ≤ 250L / min) can test large, medium and low-power tractors separately; the second layer (flow rate ≤ 166L / min) can test medium and low-power tractors separately; the third layer (flow rate ≤ 100L / min) can test low-power tractors separately.

[0009] The pressure sensor in the measuring unit is placed inside the tester, which can effectively prevent damage to the pressure sensor and reduce subsequent economic investment.

[0010] The measurement data measured by the flow meter in the measurement unit is directly uploaded to the computer and directly displayed through the industrial control display all-in-one machine, which is more convenient to operate.

[0011] The tractor hydraulic output power measuring units in parts 1 to 3 of the measuring unit all use two one-way valves. The main one-way valve is used to prevent back suction due to inertia when the test is stopped, which affects the accuracy of the power test; the branch one-way valve prevents the inlet and outlet oil circuits from being connected in opposition to each other and causing damage to the entire test system.

[0012] The measuring units in the tester are all equipped with overflow valves. When the overflow valve exceeds the set pressure, the overflowed hydraulic oil directly returns to the hydraulic oil circuit. This design greatly improves the utilization rate of the hydraulic oil and improves the power test accuracy.

[0013] The tester box body is added with an operating cabinet boss part, and the height of the boss is tailored to the operating habits of the operator; it can meet the needs of touch screen operation and manual operation control, and can be selected according to the needs of the tester, which greatly improves the test efficiency.

[0014] A tool box is added to the tester box, and this design makes the placement of tools more regular, which is convenient for operators to use in repair and maintenance.

[0015] The peak pressure performance and small flow hydraulic output power tests are both located in the third part of the measurement unit. Compared with the original tester placed separately, this design improves space utilization.

[0016] The measuring part of the tester adopts a ball valve for its proportional flow valve, which has the characteristics of small fluid resistance, tight and reliable, easy operation, and only needs to be rotated 90° from fully open to fully closed, which improves the test accuracy.

[0017] The measuring unit of the tester is equipped with an external oil cooler to cool the hydraulic oil and avoid excessive test errors and damage to test components caused by excessive temperature.

[0018] The oil inlet and outlet positions of the tester measuring unit are designed with multiple outlet joints, which can replace traditional quick-change joints and facilitate power performance testing under different horsepower and flow ranges.

[0019] Design of the louver heat dissipation holes in the tester box: As the test progresses, the sensors, valve blocks and oil circuits in the measuring unit convert part of the power into heat, causing the internal temperature of the tester to rise. At this time, the louver plays a role in heat dissipation.

[0020] The measuring unit of the tester establishes a heat balance calculation model for thermal pressure loss of a multi-channel hydraulic system based on the heat balance theory, and finally calculates the effective hydraulic output power coefficient η of the tester in combination with simulation experiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Control and display unit structure diagram;

[0022] Figure 2 Testing principle of tractor multi-channel hydraulic output power tester;

[0023] Figure 3 Measurement units 1 to 3 Parts 1 to 3 Structure and schematic diagram of the tractor hydraulic output power measurement unit;

[0024] Figure 4 Measuring unit 1 to 3 parts of the tractor hydraulic output power measuring unit oil circuit diagram;

[0025] Figure 5 Various views of the tractor multi-channel hydraulic output power tester device frame. DETAILED DESCRIPTION

[0026] The following will be combined with the accompanying drawings in the examples of the present invention to clearly and completely describe the technical solutions in the examples of the present invention. Obviously, the examples described are only part of the examples of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Figure 1 As shown, a tractor multi-channel hydraulic output power tester with temperature correction is characterized in that it includes 3 parts (such as Figure 3 a): a control display unit (01), a measuring unit (02) and a box (03); the measuring unit (02) comprises a large flow tractor hydraulic output power measuring unit (021), a medium flow tractor hydraulic output power measuring unit (022) and a small flow tractor hydraulic output power measuring unit (023).

[0027] The present invention will be further described below in conjunction with the accompanying drawings. Figure 3 The control display unit (01) shown in a includes Industrial control display integrated machine (011), communication cable (012), printer (013), PLC controller (014). The industrial control display integrated machine (011) is installed on the outer side of the upper end of the box body (03) to display test data and operation interface, and plays the role of data transmission and power supply; the communication cable (012) is used to connect the control display unit (01) and the measurement unit (02); the printer (013) is placed inside the upper end of the box body (03), and the test raw data and test report can be printed in the required format by clicking "Print Raw Data" and "Print Report", and has the function of querying and printing.

[0028] The box body (03) includes a boss (031) and a toolbox (032). The boss (031) is the box body part, and the test instructions of the tester are controlled by the placed controller; the toolbox (032) is convenient for placing tools. The function of the box body is to install sensors, valve blocks, hydraulic cylinders (311) of different specifications in the measurement unit (02) and the control display unit (01) inside it.

[0029] The present invention will be further described below with reference to the accompanying drawings. As Figure 3As shown in the measuring unit (02) in c, each includes an oil inlet hose (101A, 201A, 301A), a quick-change connector (102A, 102B, 202A, 202B, 302A and 302B), a pressure sensor (103A, 103B, 203A, 203B, 303A and 303B), a temperature sensor (104A, 104B, 204A, 204B, 304A and 304B), a filter (105, 205 and 305), a flow meter (106, 207, 307), proportional flow valve (107, 207, 307), relief valve (108, 208, 308), one-way valve (109A, 209A, and 309A), one-way valve (109B, 209B, and 309B), oil return hose (101B, 201B, 301B) and high-pressure oil pipe (110, 210 and 310. It is characterized in that the oil inlet hose (101A, 201A, 301A) and the oil return hose (101B , 201B, 301B) are used as a link to connect the oil circuit of the tractor and the tester measuring unit. The quick-change connectors (102A, 102B, 202A, 202B, 302A and 302B) are installed on the outside of the tester, which can quickly and conveniently disassemble and replace pipeline equipment to improve work efficiency. The pressure sensors (103A, 203A and 303A) are installed inside the box (03) at the closest point to the oil inlet and outlet ends to test the oil pressure of the oil inlet in real time. The temperature sensor (104A, 204A, 304A) are installed inside the measuring unit of the tester near the side of the pressure sensor (103A, 203A, 303A) to test the real-time temperature of the oil inlet during the entire test process. The filter (105, 205 and 305) is installed in the main circuit of the measuring unit and is connected to the one-way valve (109B, 209B, and 309B) in the branch to filter various impurities in the hydraulic system. The function of the one-way valve is to prevent the inlet and outlet from being connected in reverse, which will affect the tester.The flow meter (106, 207, 307) is installed between the filter (105, 205 and 305) and the proportional flow valve (107, 207, 307) in the hydraulic oil circuit to test the flow of the hydraulic oil circuit in real time. The overflow valve (108, 208, 308) is installed in the main hydraulic oil circuit to form a parallel relationship with the proportional flow valve (107, 207, 307) and the check valve (109A, 209A, and 309A) to avoid excessive system oil pressure and play an overflow and pressure stabilization role. The overflowed hydraulic oil returns to the hydraulic system, which improves the utilization rate of the hydraulic oil. The entire proportional flow valve (107, 207, 307) includes an actuator and a ball valve. The ball valve is in the main oil circuit, and the actuator is at its upper end. The opening of the ball valve is controlled by controlling the rotation angle of the actuator, thereby realizing real-time control of the flow. The one-way valve (109A, 209A, and 309A) mainly prevents hydraulic oil from being sucked back, thereby improving the stability of the flow measured by the flow meter (106, 207, 307) and the accuracy of power. The greater the pressure difference measured by the oil outlet pressure sensor (103B, 203B, and 303B) and the oil inlet pressure sensor (103A, 203A, and 303A), the greater the resistance to be overcome, and the greater the hydraulic output power. The temperature sensor is installed beside the pressure sensor (103B, 203B, and 303B). The temperature measured by the temperature sensor is different from the temperature measured by the oil inlet temperature sensor, which will generate heat in the form of power loss, that is, the greater the temperature difference, the greater the corresponding hydraulic output power loss. The external oil cooler (12) is installed outside the tester and between the tested equipment and the tester, with the purpose of cooling the hydraulic oil circuit system, reducing hydraulic power loss, and improving the effective hydraulic output power value. The diameter of the high-pressure oil pipe (110, 210, 310 and 312) is related to the flow rate under different tractor horsepower sections. It is installed in the (021-023) test oil circuit of the measuring unit, and its function is to connect the valves, sensors and other equipment in the (021-023) test oil circuit to form a loop.

[0030] The present invention will be further described below in conjunction with the accompanying drawings. Figure 3 c The third part of the measuring unit (02) is a small flow tractor hydraulic output power measuring unit (023), a tractor multi-channel hydraulic output power tester with temperature correction, characterized in that: the hydraulic cylinder (311) is installed in the third part of the measuring unit for peak pressure performance testing.

[0031] When testing the multi-channel hydraulic output power of a tractor, the hydraulic power output part of the tractor is used as the oil inlet port of the tester through a quick-change joint, and the effective hydraulic output power of the tractor is obtained by measuring the product of the pressure difference of the inlet and outlet pressure sensors (103, 203, 303) and the flow measured by the flow meter (106, 206, 306).

[0032] The present invention will be further described below in conjunction with the accompanying drawings. Figure 3 As shown in the third part of the measuring unit (02) in c, the entire peak pressure test oil circuit includes: an oil inlet hose (301C), a quick-change joint (302C), a pressure sensor (303C), a high-pressure oil pipe (312), a hydraulic cylinder (311), a pressure sensor (303D) in the return oil, and an oil return hose (301D) to form a peak pressure test circuit. During the peak pressure performance test, the hydraulic output port of the tractor is connected to the hydraulic cylinder (311) in the peak pressure test oil circuit through the quick-change joint (302C, 302D) for testing (the principle is: when the piston in the hydraulic cylinder is pushed to either end of the two sides, the oil pump is still continuously pressurizing until the overflow valve on the tractor opens, and the measured pressure is the peak pressure). When testing the peak pressure test under different horsepower ranges, it is only necessary to change the specifications of the quick-change joint (302C). According to the attached drawings, it can be seen that the entire peak pressure test oil circuit is symmetrically distributed on both sides with the hydraulic cylinder (311) as the center, and the two sides are respectively high-pressure oil pipes (312) and pressure sensors (303C, 303D). The oil inlet pressure sensor (303C) can test the maximum pressure value when the hydraulic cylinder is contracted, and the oil outlet pressure sensor (303D) tests the maximum pressure value of the hydraulic cylinder. Its purpose is to evaluate the performance and stability of the system under peak workload.

[0033] like Figure 4As shown, in the measuring unit (02), the oil inlet hose, the oil return hose, the quick-change joints at both ends of the hydraulic oil circuit, the pressure sensor, the temperature sensor, the filter, the flow meter, the proportional flow valve, the overflow valve, the check valve, the high-pressure oil pipe, the external oil cooler and the hydraulic cylinder are connected in series to form a tractor hydraulic output power measuring unit. The measuring unit (02) includes the tractor hydraulic output power measuring unit of parts 021 to 023. Among them, the function of the filter (105, 205, 305) is to filter impurities in the hydraulic oil to prevent the oil circuit from getting stuck; the function of the external oil cooler (12) is to cool the hydraulic oil to avoid excessive test errors and component damage caused by excessive temperature; the function of the one-way valve (109, 209, 309) is to prevent the oil circuit from being connected in reverse and damaging the components in the oil circuit: during the test, the proportional flow valve (107, 207, 307) is adjusted to adjust the pressure and flow to determine the maximum output power of the tractor; the flow meter (106, 206, 306) is used to measure the flow of the entire hydraulic circuit; the pressure sensor (103A, 103B, 203A, 203B, 303A, 303 The tester is equipped with a tester and a temperature sensor (104A, 104B, 204A, 204B, 304A, 304B) for measuring the pressure of the hydraulic oil circuit and the temperature of the hydraulic oil respectively; the quick-change connector (102A, 102B, 202A, 202B, 302A, 302B, 302C and 302D) is directly connected to the hydraulic output port of the tractor; the oil inlet hose (101A, 201A, 301A, 301C) and the oil return hose (101B, 201B, 301B, 301D) are the links between the tester and the tractor; the overflow valve (108, 208, 308) is used to prevent damage to components caused by excessive pressure in the hydraulic oil circuit and to play an overflow and pressure stabilization role.

[0034] In a specific embodiment of the present invention: the control and display unit (01) of the tester has a structure as follows Figure 1As shown, it includes an information collection system, a hydraulic system, a control system, etc. The information collection system is mainly composed of pressure sensors (103A, 103B, 203A, 203B, 303A, 303B, 303C and 303D), flow meters (106, 206, 306), temperature sensors (104A, 104B, 204A, 204B, 304A, 304B) and PLC, etc., mainly to realize the collection of pressure, flow and temperature and real-time processing of data and transmit them to the control system. The hydraulic system is mainly composed of relief valves (108, 208, 308), proportional flow valves (107, 207, 307), high-pressure oil pipes of different diameters (110, 210, 310 and 312) and an external oil cooler (12). The hydraulic system mainly realizes automatic control of the test status of the multi-channel hydraulic output power tester and the opening of the proportional flow valve (107, 207, 307). The (1-3) hydraulic oil circuits in the hydraulic output test oil circuit (02) of the tester are equipped with a group of proportional flow valves (107, 207, 307), and the flow rate can be adjusted by controlling the opening of the ball valve. When the oil pressure exceeds the set value, the valve port of the overflow valve (108, 208, 308) opens to play the role of overflow pressure stabilization, and the hydraulic oil flows to the oil tank through the hydraulic circuit; the function of the external oil cooler (12) is to realize the cooling and heat dissipation of the hydraulic oil. The control system is a host computer with a built-in control program. The program is based on Labview virtual technology, which can realize the curve display of key data such as effective hydraulic output power, hydraulic oil pressure, temperature and flow, and generate test records at the same time.

[0035] like Figure 2 As shown in the test steps, when the tester is working, Figure 3 Select a large, medium or small flow tractor hydraulic output power measurement unit (021-023) in the measurement unit (02) in c, open all the valves under this flow section, click the start button, and the valve opening changes from maximum to minimum (time setting 100s); the host computer sends a command signal to the PLC, and the current signal output by the PLC is converted into the working current required by the actuator through the power amplifier, and the valve opening is adjusted by the actuator to achieve flow regulation; at this time, the pressure, temperature and flow sensors collect data in real time and transmit it to the PLC, the PLC can realize the data collection function and process the data in real time and transmit it to the control system, the control system outputs control instructions to the hydraulic system according to the built-in running program or manual input parameters, and controls the hydraulic output flow of the tractor by controlling the opening of the proportional flow valve (107, 207, 307), and the control system records and displays key data in real time until the entire test procedure is completed. The traditional effective hydraulic output power calculation formula is formula (1). Based on the temperature correction method: This tester will have pressure loss during the test, that is, the oil uses some energy to overcome the viscous friction resistance during the flow process, and the lost energy is converted into heat and enters the hydraulic system, thereby increasing the oil temperature and causing the system to work less efficiently. According to the principles of thermodynamics, as long as heat is generated in the system, heat will be dissipated, and the hydraulic pipelines, hydraulic valves, sensors, etc. in the hydraulic system will play a role in heat dissipation.

[0036] Based on the heat balance theory, a universal heat balance calculation model for thermal pressure loss of a multi-channel hydraulic system is established. Based on the existing Amesim simulation, a simulation sub-model of common hydraulic components is established from the perspective of heat balance based on the AMESim thermal fluid simulation module. On this basis, a heat balance simulation model of a multi-channel hydraulic system is built, and the effective hydraulic output power of the tractor is calculated theoretically. Tester power loss ΔP = pipeline energy loss (pressure loss along the way + local pressure loss of oil at the elbow) + hydraulic valve power loss + hydraulic system heat dissipation analysis [heat conduction + heat convection (pipelines + valves) + radiation heat exchange (pipelines + valves)]. (1) Pipeline energy loss When hydraulic oil flows in the pipeline, two types of energy loss usually occur, one is the pressure loss along the way, and the other is the local pressure loss. The pressure loss along the way of the oil in the hydraulic pipeline is: Where: ρ-oil density, Kg / m 3 ; λ- resistance coefficient along the way, which is related to the flow state, relative roughness of the pipe wall and the shape of the pipe; ι-length of hydraulic pipeline, m; d-diameter of hydraulic pipeline, m; v-average velocity of the liquid in the tube, m / s. The local pressure loss of oil at the elbow of the hydraulic pipeline is: Where: ρ-hydraulic oil density, Kg / m 3 ; v-average velocity of the liquid in the tube, m / s; ζ-local resistance coefficient; The total pressure loss of the hydraulic pipeline is: Δp h =∑Δp λ +∑Δp ξ Where: Δp h -Total pressure loss in the pipeline, Pa; Δp λ -Pressure loss along the way, Pa; Δpζ -Local pressure loss, Pa. (2) Loss of electro-hydraulic proportional flow valve For the electro-hydraulic proportional flow valve, when the oil passes through the hydraulic valve, the flow rate of the oil will change suddenly when the cross-sectional area of ​​the proportional flow valve is different, which will cause energy loss and cause the oil temperature to rise. The power loss of the proportional flow valve is: P v =Δp v q v (3) Where: P v -Power loss of hydraulic valve, W; Δp v -Hydraulic valve pressure loss, MPa; q v -Flow through the hydraulic valve, m 3 / s; (3) Heat transfer loss In hydraulic systems, pressure loss often occurs, that is, the oil uses some energy to overcome viscous friction resistance during the flow process. The lost energy is converted into heat and enters the system, thereby increasing the oil temperature and causing the system's working efficiency to decrease. According to the knowledge of thermodynamics, as long as there is an increase in heat in the system, there will be heat dissipation. The hydraulic hoses, high-pressure oil pipes, proportional flow valves, sensors, etc. in the hydraulic system will play a role in heat dissipation. There are three basic ways of heat transfer, namely heat conduction, heat radiation and heat convection. The actual heat transfer process can be a single transfer method, but most heat is transferred in two or more of these ways. ① Heat conduction: In the hydraulic system, heat transfer between each hydraulic component and each part of each hydraulic component is carried out in the form of heat conduction. In heat transfer, the heat flux of heat conduction is inversely proportional to the length of the object, and is proportional to the cross-sectional area acting in the heat conduction direction and the temperature difference at both ends of the object conducting heat. It is also affected by the material of the object. Heat flux is the amount of heat transferred per unit time during heat conduction. Where: Ф 1 -Heat flow during heat conduction, W; A 1 - cross-sectional area perpendicular to the direction of heat conduction, m; L-thermal conduction length, m; T 1 , T 2 -The temperature at both ends of the heat transfer, K; λ- thermal conductivity of the material, W / (m 2 ·K). ② Thermal convection: The medium of thermal convection is gas or liquid. In these two states, when the temperatures of different parts are different, the phenomenon of transferring heat from one place to another due to relative macroscopic movement is thermal convection. Ф 2 =δA 2 (T 1 -T 2 ) (5) Where: Ф 2 Heat flux of thermal convection, W; A 2 -Effective heat exchange area, m 2 ; T 1 - solid wall temperature, K; T 2 - temperature of the fluid, K; δ-Convection heat transfer coefficient, W / (m 2 ·K) ③ Thermal radiation: Thermal radiation is the phenomenon that an object radiates electromagnetic waves when it has temperature. It is a basic form of heat transfer that does not rely on any medium. In the tractor multi-way hydraulic oil system, heat is transferred between hydraulic components, hydraulic pipelines, etc. and the external environment in the form of thermal radiation. Ф 3 =γA 3 σ(T 1 4 -T 2 4 ) (6) Where: Ф 3 -Heat transfer by thermal radiation, W; T 1 -Thermodynamic temperature of a solid high temperature object, K; T 2 -Thermodynamic temperature of a low temperature object, K; γ- equivalent radiation coefficient of the object surface; A 3 -Heat exchange area, m 2 ; σ-blackbody radiation coefficient, σ=5.67x10W / (m 2 ·K 4 ) P——effective hydraulic power through a pair of hydraulic joints, in kilowatts (kW) P 1 ——The pressure of the pressure sensor (103A, 203A and 303A) near the quick-change connector (102A, 202A and 302A) where the hydraulic oil is output from the tractor, in megapascals (MPa). P 2 - the pressure of the pressure sensor (103B, 203B and 303B) near the quick-change connector (102B, 202B and 302B) where the hydraulic oil re-enters the tractor, in megapascals (MPa); Q——Flow rate measured by flow meter (106, 207, 307), unit is liter per minute (L / min). This coefficient (η) is obtained by multiplying equation (7) and (8) to obtain equation (9), and the effective hydraulic output power is calculated and substituted into the test program. Since the materials of the sensors, valves, pipes, etc. inside the tester remain unchanged, the power loss calculation is mainly related to the flow rate of the tractor, and finally the corrected effective hydraulic output power is obtained. After the test, the control system can generate test records according to the test standard requirements and can be retrieved and called, generate inspection reports according to the test basis and transmit them to the information test identification system through the information upload module. It can display multiple key parameters and test results, and can control the test system through a virtual interface; based on the electro-hydraulic proportional control valve, it can achieve precise control of hydraulic flow to ensure the accuracy of the test results; it has an information test result output interface, which is compatible with the agricultural machinery test and inspection information platform, and realizes automatic upload and storage of inspection reports; it realizes real-time data collection and storage, and designs data analysis functions, which can realize a comprehensive analysis of the performance of the tractor hydraulic output system based on test data.

[0037] Selection of model specifications: according to Figure 3 c. The (021-023) part of the measuring unit (02), the pressure sensors (103A, 103B, 203A, 203B, 303A, 303B, 303C and 303D) and temperature sensors (104A, 104B, 204A, 204B, 304A and 304B) used in each part of the test oil circuit have model specifications of (MC20AS. 0-35Mpa, MCT80S. 0-160°C) respectively; the tractors with different horsepower and flow ranges all use an external oil cooler (12) with model WHO-50B, which is installed between the tester and the tractor; the model specifications of the oil inlet hose (101A, 201A, 301A) and the oil return hose (101B, 201B, 301B) are related to the tractors with different flow ranges, and their pipe diameters increase accordingly as the flow specifications of the tractor increase. The component models and specifications of the (021~023) parts in other measurement units (02) are different, as shown in the following table. according to Figure 3 c. The first part (or 021) of the measuring unit (02) and its sensors, valves, etc. are of the following models: the filter (105) is of DFB-H240X10C; the flow meter (106) is of NS-LWGY-32NFW05T3Z (35 MPa) S1N; the proportional flow valve (107) comprises an electric actuator and a ball valve, of which the electric actuator of NT-10 and the ball valve of YJZQ-J32B are selected to meet the flow rate of 25-250 L / min and the pressure of 0-35 MPa; the overflow valve (108) is of DBDH20P10 / 40; the check valve (109A, 109B) is of RVP30-2-L2X; the specification of the high-pressure oil pipe (110) is Ф=32 cm. according to Figure 3 c. The second part (or 022) of the measuring unit (02) includes sensors, valves, etc., of which the models are as follows: the filter (205) is DFB-H160X10C; the flow meter (206) is NS-LWGY-25NFW05T3Z (35Mpa) S1N; the proportional flow valve (207) includes an electric actuator and a ball valve, of which the electric actuator of the NT-10 model and the ball valve of the YJZQ-J25B model are selected to meet the flow rate of 25-250L / min and the pressure of 0-35Mpa; the overflow valve (208) is DBDH20P10 / 40; the check valve (209A, 209B) is RVP25-2-L2X; the specification of the high-pressure oil pipe (210) is Ф=25cm. according to Figure 3 c The third part (or 021) of the measuring unit (02) includes sensors, valves, etc. of the following types: filter (305) of DFB-H110X10C; flow meter (306) of NS-LWGY-15NFW05T3Z (35Mpa) S1N; proportional flow valve (307) includes an electric actuator and a ball valve, of which NT-5 electric actuator and YJZQ-J15B ball valve are selected to meet the requirements of 10-100L / min and pressure of 0-35Mp; overflow valve (308) of DBDH10P10 / 40; check valve (309A, 309B) of RVP15-2-L2X; high-pressure oil pipe (310) of Ф=15cm; and the hydraulic cylinder (311) of Ф80X200 is selected for the peak pressure performance test.

Claims

1. A tractor multi-channel hydraulic output power tester with temperature correction, Features: The invention comprises a control display unit (01), a measuring unit (02) and a box (03). The invention is characterized in that the control display unit (01) is fixed on the upper part of the box (03) and connected to the measuring unit (02) via a communication line (012); the measuring unit (02) is installed at the lower end of the box (03), and the two are connected via a communication line.

2. A tractor multi-channel hydraulic output power tester with temperature correction according to claim 1, Features: The control display unit (01) comprises an industrial control display all-in-one machine (011), a communication line (012), a printer (013), and a PLC controller (014). The industrial control display all-in-one machine (011) is installed on the upper outer surface of the box (03); and the printer (013) is installed on the inner side of the upper left end of the box (03).

3. A tractor multi-channel hydraulic output power tester with temperature correction according to claim 1, Features: The measuring unit (02) comprises three parts, the first part being a large flow tractor hydraulic output power measuring unit (021) located at the bottom of the box (03), the upper side of which is a second part being a medium flow tractor hydraulic output power measuring unit (022), and the third part at the top being a small flow tractor hydraulic output power measuring unit (023).

4. A tractor multi-channel hydraulic output power tester with temperature correction according to claim 4, Features: The tractor hydraulic output power measuring unit (021-023) in the measuring unit comprises: an oil inlet hose (101A, 201A, 301A) and an oil return hose (101B, 201B, 301B) as a link for connecting the tractor and the oil circuit of the measuring unit (02); a quick-change connector (102A, 102B, 202A, 202B, 302A and 302B) installed on the outside of the box and fixed by an internal nut; a pressure sensor (103A, 103B, 201A, 301A) and a pressure sensor (103B, 103A, 201B, 301B) as a link for connecting the tractor and the oil circuit of the measuring unit (02); and a quick-change connector (102A, 102B, 202A, 202B, 302A and 302B) installed on the outside of the box and fixed by an internal nut. 3A, 203B, 303A and 303B) are installed in the box (03) at the nearest position to the oil inlet and outlet ends; the temperature sensor (104A, 104B, 204A, 204B, 304A and 304B) are installed next to the pressure sensor (103A, 103B, 203A, 203B, 303A and 303B) in the box (03); the filter (105, 205 and 305) is installed in the hydraulic main circuit; the flow meter (106, 207, 307) is installed The proportional flow valve (107, 207, 307) is installed inside the box and connected to the filter (105, 205 and 305) and the one-way valve (109A, 109B, 209A, 209B, 309A and 309B) branch; the overflow valve (108, 208, 308) is installed inside the box and next to it is the proportional flow valve (107, 207, 307); the entire proportional flow valve (107, 207, 307) includes an actuator and a ball valve, the ball valve is in the main oil circuit, and the actuator is on its upper side; the industrial control display integrated machine (011) is installed in the box The one-way valves (109A, 109B, 209A, 209B, 309A, 309B) are installed between the branch and the main path inside the box (03); the high-pressure oil pipes (110, 210, 310 and 312) are located inside the box (03), and the diameter of each layer of the high-pressure oil pipes (110, 210, 310 and 312) is related to the flow rate under different tractor horsepower sections; the external oil cooler (12) is installed outside the tester and is between the tested equipment and the tester.

5. A tractor multi-channel hydraulic output power tester with temperature correction according to claim 1, Features: The box (03) comprises a boss (031) and a tool box (032). The boss (031) is a part of the box (03) and is used to operate the test instructions through a manipulator placed thereon; the tool box (032) is placed at the right end of the boss (031).

6. A tractor multi-channel hydraulic output power tester with temperature correction according to claim 7, Features: The peak pressure test oil circuit is located in the small flow tractor hydraulic output power measurement unit (023) in the third part. The hydraulic oil is connected to the pressure sensor (303C) through the quick-change joint (302C) from the oil inlet hose (301C), the hydraulic oil is connected to the hydraulic cylinder (311) through the high-pressure oil pipe (312), and the hydraulic oil is connected through the pressure sensor (303D) in the oil outlet, the quick-change joint (302D) and the oil return hose (301D); the hydraulic cylinder (311) is installed between the pressure sensor (303C) and the pressure sensor (303D).

7. A tractor multi-channel hydraulic output power tester with temperature correction as claimed in claim 1, Features: Based on the temperature correction method: the tester often has pressure loss, that is, the oil uses some energy to overcome the viscous friction resistance during the flow process, and the lost energy is converted into heat and enters the hydraulic system, thereby increasing the oil temperature and causing the system to work less efficiently. According to the principles of thermodynamics, as long as heat is generated in the system, heat will be dissipated. The hydraulic pipelines, hydraulic valves, sensors, etc. in the hydraulic system will play a role in heat dissipation. Maximum hydraulic output power of tractor: P——effective hydraulic power through a pair of hydraulic joints, in kilowatts (kW); P1 - the pressure near the hydraulic joint where the hydraulic oil is output from the tractor, in megapascals (MPa); P2 – the pressure near the hydraulic joint where the hydraulic oil re-enters the tractor, in megapascals (MPa); Q——Measured flow rate, in liters per minute (L / min). Based on the heat balance theory, a universal heat balance calculation model for thermal pressure loss of a multi-channel hydraulic system is established. Based on the existing Amesim simulation, a simulation sub-model of common hydraulic components is established from the perspective of heat balance based on the AMESim thermal fluid simulation module. On this basis, a heat balance simulation model of a multi-channel hydraulic system is built, and the effective hydraulic output power of the tractor is calculated theoretically. Tester power loss ΔP = pipeline energy loss (pressure loss along the way + local pressure loss of oil at the elbow) + hydraulic valve power loss + hydraulic system heat dissipation analysis [heat conduction + heat convection (pipelines + valves) + radiation heat exchange (pipelines + valves)]. This coefficient (η) is obtained by multiplying equation (1) and (2) to obtain equation (3), and is incorporated into the test program by calculating the effective hydraulic output power. Since the materials of the sensors, valves, and pipes inside the tester remain unchanged, the power loss calculation is mainly related to the flow rate of the tractor, and the corrected hydraulic output power is finally obtained.

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