Experimental method and improvement of hydraulic pump for hydraulic system of hydraulic test bench

Hydraulic test bench hydraulic system hydraulic pump comprehensive mode and improvement at a glance. Hydraulic Yingcai network hydraulic Ligong share power steering hydraulic pump in the test process, the main parameters need to be measured in addition to the general hydraulic pump temperature, flow, pressure, speed, torque In addition to the characteristic parameters, due to the special layout and use requirements of the power steering hydraulic pump, it has its specific performance. Therefore, when developing the power steering hydraulic pump test bench, how can the measurement performance of the steering hydraulic pump be accurately and conveniently measured? This is the most critical issue.

Power steering hydraulic pump test method.

Steering hydraulic pump test scale "ZBT23002 automotive power steering hydraulic pump bench test method" was formulated in 1984, announced in 1987, has been used for more than ten years, at that time, the domestic automotive power steering hydraulic pump products are gear pumps, The car turned to tribute for no reason.

At the glance, the hydraulic consultant Ligong, a senior consultant of Hydraulic Yingcai.com, said that with the rapid growth of the automobile industry in recent years, the power steering hydraulic pump industry has also made great progress. The steering vane pump has almost replaced the gear pump, and the steering hydraulic pump has been widely used. The use of foreign technology, especially the introduction of foreign technology, the original test method has been relatively backward, can not be comprehensive, accurate detection of existing products, especially in the first quarter of 1997, Chongqing Automotive Research Institute in the National Technical Supervision Bureau In the task of quality inspection of automobile steering hydraulic pump, it was found that the original test method can not meet the testing requirements of existing products, and it is difficult to operate in the test process. It is difficult to make comprehensive, fair and accurate quality of the product. The evaluation is that in order to meet the development needs of China's automobile industry products, and effectively control the quality of the products, it is necessary to conduct in-depth discussion and research on the test methods.

0,85pmax pressure concept.

The original test method requires that during the performance test such as running-in and flow detection, the product is carried out under the condition of the maximum working pressure pmax. At this time, the steering hydraulic pump safety valve is fully opened, and the flow is zero. Test, and easy to burn the pump, in order to avoid the opening of the hydraulic pump safety valve during the test, the steering hydraulic pump safety valve must be locked before the experiment, this method is equivalent to the adjustment of the hydraulic pump, so this method is neither Science is also not suitable for loading conditions, and it is not comprehensive enough to accurately detect the product performance. It is based on the pressure concept of 0,85pmax, that is, the product is run at 0,85 times the highest pressure. Performance testing such as flow detection, at this time, the hydraulic test bench will not open to the hydraulic pump safety valve, so the detected performance accurately reflects the real situation of the steering hydraulic pump.

Air tightness test.

The original test method has no air tightness test requirements. Through a large number of test confession, the air tightness test can accurately and reliably reflect the sealing performance of the steering hydraulic pump seal and the assembly quality between the parts, and the test is simple and feasible. The cost is low and it is easy to promote and apply.

The oil temperature of the sex test is reliable.

The operating conditions of the steering hydraulic pump are much more complicated than the working conditions of the general engineering pump.

When used, the steering hydraulic pump is often in the speed and the pressure is changed. The oil temperature changes drastically and the range is large. In addition, the orifice of the small diameter hole is installed at the oil outlet of the steering hydraulic pump. Excess flow overflows and leaks directly back into the oil inlet chamber, forming a small circulation in the steering hydraulic pump, which makes the steering hydraulic pump heating phenomenon much more serious than the general pump. At the same time, due to the limitation of the layout, the steering hydraulic pump is in the whole The car is usually installed next to the engine. The temperature is very high, so the steering hydraulic pump has a more serious fever, and the oil in the power steering system is very small, usually 1~3L, and its heat is not easy to dissipate.

Therefore, in order to accurately check the performance and life of the steering hydraulic pump, the experimental oil temperature is preferably around 70 °C.

Breaking experiment.

In the original test method, the current test method was proposed with reference to the general pump test method, because the power steering gear assembly generally has a stroke unloading valve. When the limit position is turned to the limit position, the stroke unloading valve is opened, so that the steering hydraulic pump is unloaded. In the situation, even if there is no stroke unloading valve, there will be a certain amount of internal leakage due to the avoidance of the power steering gear assembly, so the steering hydraulic pump will not be in a state of interruption, especially the vane pump has almost no current interruption capability. Therefore, the flow test project should be eliminated, 2, 5, variable speed impact test.

As everyone knows, due to the special utilization conditions of the steering, the steering hydraulic pump can not be in continuous overload state during the driving process. On the contrary, the driving speed of the car is constantly changing while the driving process is in progress, and the steering system is always ensuring The car travels according to the inevitable trajectory. Because of the road surface, the steering wheel is inexhaustly impacted by the road surface. Therefore, the steering hydraulic pump is inexhaustibly subjected to the impact load during the running of the vehicle.

In order to make the experimental conditions consistent with the actual working conditions, so that the experimental data can be truly and accurately reflected the service life of the steering hydraulic pump, it is proposed to change the continuous overload test in the original test mode to the variable speed impact fitter training platform test. .

Introduction to the test bench layout.

The driving device adopts AC frequency conversion speed regulation, and the AC electromechanical directly drives the tested pump through the connecting sleeve and the slider. For the test pieces of different installation forms, only the connecting flange and the slider need to be replaced.

The fuel tank is installed on the work surface with a volume of about 150L. The fuel tank is equipped with a 3kW heater. The bottom of the fuel tank is about 200mm from the middle of the drive shaft. The suction port has a diameter of 30mm. The hydraulic pump can be used to ensure good oil absorption. The fuel tank panel is equipped with Vacuum gauges and pressure gauges to monitor the suction port vacuum and the port load pressure.

The suction and return ports adopt quick-change joints to make the installation simple and agile, while avoiding the oil out of the tank.

Hydraulic test bench hydraulic system.

The test bench is loaded by a proportional relief valve, and the proportional machine is controlled by an electric signal to control the proportional solenoid valve, and the proportional relief valve is finely adjusted by the pressure sensor feedback signal, and the loading is accurate, and the loading process is automated.

Due to the continuous replacement of the tested parts, it is bound to bring a large amount of pollutants to the whole system, and the proportional relief valve has higher requirements on the cleanliness of the oil. Therefore, in order to ensure the normal operation of all the systems, the design takes The 2-stage high-pressure filtration makes the filtration precision reach 5μm and uses a fully enclosed fuel tank.

The viscosity of the oil is greatly affected by the oil temperature. In order to ensure the accuracy of the flow test, the system uses a water cooler to strictly control the oil temperature so that the conversion range is within ±2 °C.

Bench test system.

The test parameters of the test bench have four parameters such as speed, flow, pressure and temperature.

The speed sensor is an inductive sensor. Its output is a sine wave signal. After the transistor is placed, it is shaped by the Schmidt circuit (4093 chip) and divided by the resistor and input to the inverter (4011). The input terminal is connected to the G2 terminal of the 7210 board of the calculator. Since the trigger level of the 4093 chip is above 6V, the voltage applied to the transistor and the 4093 is 12V, such as the 4093 shaping. The high level of the output is 12V, and the low level is 0V, and the input voltage of the computer is not higher than 5V. Therefore, after the voltage is divided by the resistor, the pulse signal of 5V is sent to the device after the reverse circuit. machine.

The output of the flow sensor itself is a 12V pulse signal, each pulse represents 0,1L. When counting the flow pulse, if the number of pulses is counted by time, the maximum number of pulses can be approximated, and the charting model is tested. The time is short, and the number of discarded pulses will be released, which will inevitably produce a large measurement error. Therefore, when counting the number of flow pulses, it is more accurate to measure the time by the pulse, in order to reduce interference, The signals of pressure and temperature adopt analog quantity of 4~20mA, and the signal is directly sent to the 5411 board for A/D conversion through the HK16 core plug.

The correct grounding of the test rig can avoid external interference signals. Because the inverter is used, if the grounding method is not correct, serious interference will occur to the computer system. After the grounding problem of the test system is explored, the final result is satisfactory. The problem of interference is solved. Regardless of whether the sheltering method is grounding protection or zero-connection protection, the direction of the line must be as follows: the zero (ground) line first enters the grounding end of the frequency converter, and then leads to the experimental bench, and then to the control cabinet. Connection (be careful not to use single core wire), since the inverter is hung on the control cabinet, it is necessary to insulate the inverter's outer casing from the cabinet when installing the variable transformer.

The test bench counts the machine system.

The control software is an advanced multi-task industrial control configuration software based on MS-DOS operating system. The software has full Chinese graphic reminder, the operation is simple and reliable, the interface is good, and it is proved to be a better industrial control configuration software. .

Hardware system.

The host is IPC486DX4/100, NA5411 and ACL7120 control templates, EPSON300K printer.

Software system.

The industrial control configuration software can graphically display working conditions, print reports online, and provide manual and automatic operation screens. It has a graphic reminder function in manual operation.

The industrial control configuration software consists of the following files:

CHZHI, EXE can fulfill software, SYS, DAT configuration data files, CQHI16J, 116 dot matrix fonts, CBTYPE, DAT model data files.

According to Li Gong, a senior consultant of Hydraulic Yingcai.com, he summed up the trial and analysis of the amount of the large amount of hydraulic pump test method. After more than one year of actual production, the test method is easy to operate and the test results can be true. Accurately react to the performance of the steering hydraulic pump. After using the certificate, the ZYBT-II type steering hydraulic pump test bench works safely and reliably, the performance is unchanged, the test process is fully automated, the operation is simple, the compliance is strong, and the test results are accurate and credible. And greatly improve the efficiency of the test, with the value of universal promotion.
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