Method for testing transient cooling flow of energy-consuming components by using working fluid overflow temperature difference

Abstract

The present invention relates to a method for testing the transient cooling flow of an energy-consuming element by using the temperature difference of the working fluid flowing through the liquid, and belongs to the technical field of performance testing of liquid-cooled energy-consuming elements. The method is aimed at a liquid-cooled energy-consuming element installed on a vehicle or a test bench, and by testing the real-time temperature of the working fluid inlet and outlet under the working state, and utilizing the energy conversion characteristic that the energy consumed by the energy-consuming element is substantially equal to the energy absorbed by the working fluid, the transient cooling flow is obtained through measurement. The method can realize the measurement of the real-time transient cooling flow of the energy-consuming element through a relatively simple test system. This method of calculating the flow by measuring temperature simplifies the complexity of the test system and reduces the requirements of the test instrument on the installation environment and the system cost.

Description

Technical Field

[0001] The invention belongs to the technical field of performance testing of liquid-cooled energy-consuming components, and in particular relates to a method for testing the transient cooling flow of an energy-consuming component through the overflow temperature difference of a working fluid. Background Art

[0002] Fluid flow rate is an important performance parameter of liquid-cooled energy-consuming components. Especially for hydraulic retarders, the flow rate is directly related to their output braking torque, heat transfer cooling design, hydraulic system design and control strategy.

[0003] At present, there are three situations that restrict the direct testing of coolant flow through flowmeters: First, high-precision flowmeters are expensive, and the installation and use environment requirements are harsh. There are no high-reliability flow test components and methods suitable for vehicle installation to realize real-time status detection and fault diagnosis of energy-consuming components. Second, the fluids in the liquid circuit of liquid-cooled high-energy-consuming components are mostly multiphase fluids. For example, the fluid in the hydraulic retarder is composed of mixed components such as oil, oil mist, and air, which interferes with the flowmeter measurement. The above reasons make it difficult to accurately measure the transient flow rate of liquid-cooled high-energy-consuming components at low cost by connecting flowmeters in series on the pipeline. Third, the installation of most flowmeters will cause major structural changes to the original system pipelines, affecting the realization of higher system control targets such as flow and pressure. In summary, there is an urgent need to form a test method that is simple in structure, reliable, and adaptable to multiphase fluid conditions and has little impact on pipeline flow, so as to meet the flow test needs under complex test conditions such as vehicle installation. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] The technical problem to be solved by the present invention is: how to propose a method for testing the transient cooling flow of energy-consuming components by means of a fast-response working fluid flow temperature difference in response to the requirements of liquid-cooled energy-consuming components for flow parameters.

[0006] (II) Technical solution

[0007] In order to solve the above technical problems, the present invention provides a method for testing the transient cooling flow of an energy-consuming component by using the flow temperature difference of a working fluid, comprising the following steps:

[0008] Step 1: Calculate the braking energy W1 consumed by the energy-consuming element within time t;

[0009] Step 2: Calculate the heat W2 absorbed by the working fluid after passing through the energy-consuming element;

[0010] Step 3: Based on the energy conversion characteristic that the braking energy consumed by the energy-consuming element can be converted into heat absorbed by the working fluid, calculate the flow rate of the working fluid.

[0011] Preferably, step 1 is as follows:

[0012] Case 1: For the hydraulic retarder and liquid-cooled friction brake, which are energy-consuming components undergoing bench testing, a torque meter is used to measure the braking torque and speed of the energy-consuming components under stable working conditions. The braking energy W1 consumed by the hydraulic retarder within time t is expressed as follows:

[0013] W1=Mωt

[0014] Where: M is the braking torque of the hydraulic retarder, ω is the angular velocity of the hydraulic retarder;

[0015] Case 2: For the hydraulic retarder and liquid-cooled friction brake installed on the vehicle, these energy-consuming components are used to calculate the consumed braking energy W1 and the instantaneous power P at time t using the vehicle speed, road conditions, and vehicle weight information according to the following formula: t :

[0016]

[0017] Where: m is the vehicle mass, I is the equivalent wheel inertia, r is the wheel rolling radius, v' is the vehicle acceleration, F W is the air resistance, F i is the slope resistance, F f is the rolling resistance, v is the vehicle speed;

[0018] Case 3: For the energy-consuming components such as hydraulic retarder, mechanical brake and brake resistor with known braking characteristics, the consumed braking energy W1=W(v,i) is obtained by using the information of vehicle speed v and working gear i; W() represents the energy function;

[0019] Preferably, in case 3 of step 1, for the hydraulic retarder, the braking torque formula of the hydraulic retarder is:

[0020] M=λρn 2 D 5

[0021] Where: λ is the braking torque coefficient of the hydraulic retarder, ρ is the working medium density of the hydraulic retarder, n is the rotor speed of the hydraulic retarder, and D is the circulation circle radius of the hydraulic retarder;

[0022] When the hydraulic retarder is working stably, its filling rate is a constant, that is, the inlet and outlet flow rates of the hydraulic retarder are consistent. The working gear of the hydraulic retarder determines the filling rate, and the vehicle speed determines the speed of the hydraulic retarder. That is, the consumed braking energy can be obtained by combining the working gear and vehicle speed information during the working process of the hydraulic retarder with its own braking torque coefficient and circulation circle radius.

[0023] Preferably, step 2 is specifically:

[0024] The working fluid flows through the energy-consuming element and exchanges heat with the energy-consuming element. Finally, W1 is converted into the heat energy W2 of the liquid. The inlet and outlet oil temperature sensors are installed on the working fluid pipelines entering and exiting the energy-consuming element, respectively, to measure the real-time temperatures T1 and T2 of the working fluid. The heat W2 absorbed by the working fluid after passing through the energy-consuming element is calculated by the following formula:

[0025]

[0026] Where: T2 is the temperature measured by the oil outlet temperature sensor, T1 is the temperature measured by the oil inlet temperature sensor, c is the specific heat capacity of the working fluid, m1 is the flow mass of the working fluid, and Q is the instantaneous flow rate of the working fluid.

[0027] Preferably, in step 3, according to the law of conservation of energy, the braking energy consumed by the energy-consuming element is converted into heat of the working fluid, as shown in the following formula:

[0028] kW1=W2

[0029] Where k is the energy correction coefficient, which indicates the ratio of the calculated consumed braking energy transferred to the liquid temperature rise, and is used to correct the braking energy consumed by the energy-consuming components to obtain the energy dissipated by convection heat dissipation;

[0030] Combining the equations of step 1 and step 2, we can obtain the flow rate Q of the working fluid.

[0031] Preferably, for the energy correction coefficient, the calibration method is: under ideal conditions, a flow meter is used to perform calibration measurements to determine a specific value of the energy correction coefficient k.

[0032] Preferably, the flow rate of the working fluid obtained by combining the equations of step 1 and step 2 is specifically:

[0033] For case 1, the calculation formula for the flow rate Q is:

[0034]

[0035] For case 2, the calculation formula for the flow rate Q is:

[0036]

[0037] For case 3, the calculation formula for the flow rate Q is:

[0038] P() stands for power function.

[0039] The invention also provides a testing system for implementing the method.

[0040] The present invention also provides a method for testing the performance of a liquid-cooled energy-consuming element using the method.

[0041] The present invention also provides an application of the system in a performance testing method for a liquid-cooled energy-consuming element.

[0042] (III) Beneficial effects

[0043] The present invention utilizes the energy conversion characteristic that the heat generation power of energy-consuming elements is approximately equal to the heat dissipation power, and tests the transient cooling flow of energy-consuming elements such as hydraulic retarders, friction brakes and brake resistors through a fast-responding working fluid overflow temperature difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the transient cooling flow rate test principle of the liquid-cooled energy-consuming element of the present invention.

[0045] Among them: 1 energy-consuming element, 2 liquid cooling device, 3 oil outlet temperature sensor, 4 oil inlet temperature sensor, 5 radiator, 6 oil return pipeline, 7 oil inlet pipeline, 8 oil tank.

[0046] Figure 2 It is a schematic diagram of transient cooling flow test of a hydraulic retarder according to an embodiment of the present invention.

[0047] Among them: 1' hydraulic retarder, 2' transmission shaft. DETAILED DESCRIPTION

[0048] In order to make the purpose, content, and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings and examples.

[0049] The present invention utilizes the energy conversion characteristic that the heat generation power of the energy-consuming element is approximately equal to the heat dissipation power, and tests the transient cooling flow of energy-consuming elements such as hydraulic retarders, friction brakes and brake resistors through the rapid response of the working fluid flow temperature difference. The method installs an oil inlet temperature sensor and an oil outlet temperature sensor on the working fluid pipelines entering and exiting the energy-consuming element, respectively, and measures the real-time temperatures T1 and T2 of the working fluid; according to the law of conservation of energy, the working fluid flow rate (instantaneous flow rate) Q is calculated, and the specific implementation steps are as follows:

[0050] Step 1: Calculate the braking energy W1 consumed by the energy-consuming element within time t.

[0051] Case 1: For energy-consuming components such as hydraulic retarders and liquid-cooled friction brakes that are undergoing bench testing, a torque meter can be used to measure the braking torque and speed of the energy-consuming components under stable working conditions. The braking energy W1 consumed by the hydraulic retarder within time t can be expressed as follows:

[0052] W1=Mωt

[0053] Where: M is the braking torque of the hydraulic retarder, ω is the angular velocity of the hydraulic retarder.

[0054] Case 2: For energy-consuming components such as hydraulic retarders and liquid-cooled friction brakes installed on vehicles, the consumed braking energy W1 and the instantaneous power P at time t can be calculated using information such as vehicle speed, road conditions, and vehicle weight according to the following formula: t :

[0055]

[0056] Where: m is the vehicle mass, I is the equivalent wheel inertia, r is the wheel rolling radius, v' is the vehicle acceleration, F W is the air resistance, F i is the slope resistance, F f is the rolling resistance and v is the vehicle speed.

[0057] Case 3: For energy-consuming components such as hydraulic retarders, mechanical brakes, brake resistors, etc. with known braking characteristics, the consumed braking energy W1=W(v,i) can be obtained using information such as vehicle speed v and working gear i, where W() represents the energy function.

[0058] For the hydraulic retarder, according to the braking torque formula of the hydraulic retarder:

[0059] M=λρn 2 D 5

[0060] Where: λ is the braking torque coefficient of the hydraulic retarder, ρ is the working medium density of the hydraulic retarder, n is the rotor speed of the hydraulic retarder, and D is the circulation circle radius of the hydraulic retarder.

[0061] When the hydraulic retarder is working stably, the braking torque remains basically unchanged, and its filling rate is a constant, that is, the inlet and outlet flow rates of the hydraulic retarder are consistent. The working gear of the hydraulic retarder determines the filling rate, and the vehicle speed determines the speed of the hydraulic retarder. That is, the consumed braking energy can be obtained by combining the working gear and vehicle speed information during the working process of the hydraulic retarder with its own braking torque coefficient and circulation circle radius.

[0062] Step 2: Calculate the heat W2 absorbed by the working fluid after passing through the energy-consuming element.

[0063] The working fluid flows through the energy-consuming element and exchanges heat with the energy-consuming element, and finally W1 is converted into the heat energy W2 of the liquid. The inlet and outlet oil temperature sensors are installed on the working fluid pipelines entering and exiting the energy-consuming element, respectively, to measure the real-time temperatures T1 and T2 of the working fluid. The heat W2 absorbed by the working fluid after passing through the energy-consuming element can be calculated by the following formula:

[0064]

[0065] Where: T2 is the temperature measured by the oil outlet temperature sensor, T1 is the temperature measured by the oil inlet temperature sensor, c is the specific heat capacity of the working fluid, m1 is the flow mass of the working fluid, and Q is the instantaneous flow rate of the working fluid.

[0066] Step 3: Calculate the flow rate of the working fluid based on the energy conversion characteristic that the braking energy consumed by the energy-consuming element is converted into heat absorbed by the working fluid.

[0067] According to the law of conservation of energy, the braking energy consumed by the energy-consuming element is converted into heat of the working fluid, as shown in the following formula:

[0068] kW1=W2

[0069] In the formula, k is the energy correction coefficient, which indicates the ratio of calculated consumed braking energy transferred to liquid temperature rise, and is used to correct the braking energy consumed by energy-consuming components and obtain the energy dissipated by convection heat dissipation. For example, in friction energy-consuming components, about 88% of the braking power is converted into the working fluid, and the rest of the energy is dissipated by heat conduction or thermal radiation. Calibration method: Under ideal conditions, high-precision flowmeters are used for calibration measurement to determine the specific value of the energy correction coefficient k; for situations with high measurement accuracy requirements or other dissipation methods affected by temperature changes, a parameter table that changes with temperature is further formed through the variable temperature environment parameter method, which is used to improve test accuracy under variable temperature environment conditions.

[0070] By combining the equations of step 1 and step 2, the flow rate (instantaneous flow rate) Q of the working fluid can be obtained.

[0071] For case 1, the calculation formula for the flow rate Q is:

[0072]

[0073] For case 2, the calculation formula for the flow rate Q is:

[0074]

[0075] For case 3, the calculation formula for the flow rate Q is:

[0076] P() stands for power function.

[0077] The following is an example of the implementation steps of a method for testing the transient cooling flow rate of a hydraulic retarder by using a fast-response working fluid overflow temperature difference provided by the present invention:

[0078] Step 1: Build the test bench (including mechanical connection and drive part) and test platform (i.e. test system, including sensors for testing temperature, torque and speed, data acquisition, analysis and storage system) as follows: Figure 2As shown, the transmission shaft 2' on the hydraulic retarder 1' is connected to the transmission shaft of the vehicle or the test bench to consume its kinetic energy. The braking torque of the hydraulic retarder 1' is M and the speed is ω; the oil tank 8 provides working fluid (i.e., oil) for the hydraulic retarder 1', and the oil enters the hydraulic retarder 1' from the pressure oil tank 8 through the oil inlet pipeline 7. The oil inlet temperature sensor 4 is installed on the oil inlet pipeline 7 to test the real-time temperature of the oil in the oil inlet pipeline 7; the oil undergoes eddy and circulatory motion in the hydraulic retarder 1', converting most of the kinetic energy of the transmission system into fluid thermal energy, and the high-temperature oil is discharged from the outlet of the hydraulic retarder 1'; the high-temperature oil discharged from the outlet of the hydraulic retarder 1' enters the radiator 5 through the return oil pipeline 6 for cooling, and finally flows back into the pressure oil tank 8; the return oil temperature sensor 3 is installed on the pipeline between the outlet of the hydraulic retarder 1' and the radiator 5 to measure the real-time temperature of the high-temperature oil in the return oil pipeline 6.

[0079] Step 2: When the hydraulic retarder 1' is working, the pressure oil tank 8 supplies oil to the hydraulic retarder 1', and the hydraulic retarder 1' works normally at this time; the real-time temperature data T1 of the oil inlet temperature sensor 4, the real-time temperature data T2 of the oil outlet temperature sensor 3, and the torque M and speed ω data of the hydraulic retarder 1' are transmitted to the industrial computer through the acquisition system for storage and processing.

[0080] Step 3: Perform data calculation and processing according to the following formula to obtain the real-time transient flow rate Q of the hydraulic retarder 1'.

[0081]

[0082] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for testing the transient cooling flow of an energy-consuming component by using the working fluid flow temperature difference, characterized in that: The following steps are involved: Step 1: Calculate the braking energy W1 consumed by the energy-consuming element within time t; Step 2: Calculate the heat W2 absorbed by the working fluid after passing through the energy-consuming element; Step 3: Calculate the flow rate of the working fluid based on the energy conversion characteristic that the braking energy consumed by the energy-consuming element can be converted into heat absorbed by the working fluid; Step 1 is as follows: Case 1: For the hydraulic retarder and liquid-cooled friction brake, which are energy-consuming components undergoing bench testing, a torque meter is used to measure the braking torque and speed of the energy-consuming components under stable working conditions. The braking energy W1 consumed by the hydraulic retarder within time t is expressed as follows: W1=Mωt Where: M is the braking torque of the hydraulic retarder, ω is the angular velocity of the hydraulic retarder; Case 2: For the hydraulic retarder and liquid-cooled friction brake installed on the vehicle, these energy-consuming components are used to calculate the consumed braking energy W1 and the instantaneous power P at time t using the vehicle speed, road conditions, and vehicle weight information according to the following formula: t : Where: m is the vehicle mass, I is the equivalent wheel inertia, r is the wheel rolling radius, v' is the vehicle acceleration, F W is the air resistance, F i is the slope resistance, F f is the rolling resistance, v is the vehicle speed; Case 3: For the energy-consuming components such as hydraulic retarder, mechanical brake and brake resistor with known braking characteristics, the consumed braking energy W1=W(v,i) is obtained by using the information of vehicle speed v and working gear i; W() represents the energy function; Step 2 is as follows: The working fluid flows through the energy-consuming element and exchanges heat with the energy-consuming element. Finally, W1 is converted into the heat energy W2 of the liquid. The inlet and outlet oil temperature sensors are installed on the working fluid pipelines entering and exiting the energy-consuming element, respectively, to measure the real-time temperatures T1 and T2 of the working fluid. The heat W2 absorbed by the working fluid after passing through the energy-consuming element is calculated by the following formula: Where: T2 is the temperature measured by the oil outlet temperature sensor, T1 is the temperature measured by the oil inlet temperature sensor, c is the specific heat capacity of the working fluid, m1 is the flow mass of the working fluid, and Q is the instantaneous flow rate of the working fluid; In step 3, according to the law of conservation of energy, the braking energy consumed by the energy-consuming element is converted into heat of the working fluid, as shown in the following formula: kW1=W2 Where k is the energy correction coefficient, which indicates the ratio of the calculated consumed braking energy transferred to the liquid temperature rise, and is used to correct the braking energy consumed by the energy-consuming components to obtain the energy dissipated by convection heat dissipation; Combining the equations of step 1 and step 2, we can obtain the flow rate Q of the working fluid.

2. The method according to claim 1, characterized in that In case 3 of step 1, for the hydraulic retarder, the braking torque formula of the hydraulic retarder is: M=λρn 2 D 5 Where: λ is the braking torque coefficient of the hydraulic retarder, ρ is the working medium density of the hydraulic retarder, n is the rotor speed of the hydraulic retarder, and D is the circulation circle radius of the hydraulic retarder; When the hydraulic retarder is working stably, its filling rate is a constant, that is, the inlet and outlet flow rates of the hydraulic retarder are consistent. The working gear of the hydraulic retarder determines the filling rate, and the vehicle speed determines the speed of the hydraulic retarder. That is, the consumed braking energy can be obtained by combining the working gear and vehicle speed information during the working process of the hydraulic retarder with its own braking torque coefficient and circulation circle radius.

3. The method according to claim 1, characterized in that For the energy correction factor, the calibration method is: under ideal conditions, the flow meter is used to perform calibration measurements to determine the specific value of the energy correction factor k.

4. The method according to claim 1, characterized in that Combining the equations of step 1 and step 2, the flow rate of the working fluid is obtained as follows: For case 1, the calculation formula for the flow rate Q is: For case 2, the calculation formula for the flow rate Q is: For case 3, the calculation formula for the flow rate Q is: P() stands for power function.

5. A test system for implementing the method according to any one of claims 1 to 4.

6. A method for testing the performance of a liquid-cooled energy-consuming component implemented by the method as claimed in any one of claims 1 to 4.

7. An application of the system as claimed in claim 5 in a method for testing the performance of a liquid-cooled energy-consuming component.

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