A performance test system for the low-pressure fuel transfer pump of a common rail pump

Abstract

The invention discloses a performance test system for a low-pressure fuel transfer pump of a common rail pump, which is characterized by comprising: a pressure sensor, an inlet metering valve, a pneumatic three-way ball valve and a control system. When performing performance detection on the low-pressure fuel transfer pump of the common rail pump to be tested, the pressure sensor, the inlet metering valve and the pneumatic three-way ball valve are sequentially installed on the outlet pipeline of the low-pressure fuel transfer pump of the common rail pump. The inlet of the low-pressure fuel transfer pump of the common rail pump is communicated with a fuel tank. The pneumatic three-way ball valve has one inlet and two outlets, and the two outlets respectively return to the fuel tank through two pipelines, and a first flowmeter and a second flowmeter are respectively arranged on the two pipelines; the control system is respectively connected to the low-pressure fuel transfer pump of the common rail pump to be tested, the pressure sensor, the inlet metering valve and the pneumatic three-way ball valve to control the performance test of the low-pressure fuel transfer pump of the common rail pump.

Description

Technical Field

[0001] The present invention belongs to the field of fuel injection device testing, and particularly relates to a performance testing system for a common rail pump low-pressure transfer pump. Background Art

[0002] The common rail pump low-pressure transfer pump (Transfer Pump, abbreviated as TP in English), with the type of external gear pump, is driven by the diesel engine camshaft to transport fuel from the fuel tank to the inlet of the high-pressure pump of the common rail pump.

[0003] The performance of the common rail pump low-pressure transfer pump directly affects the rail pressure control and fuel injection quantity of the common rail pump and even the entire common rail fuel injection system. Currently, there is no publicly available technology that can test the performance of the common rail pump low-pressure transfer pump. Chinese Patent CN201922451138 discloses a performance testing device for a high-speed high-pressure transfer pump, in which the object to be measured requires an additional fuel supply pump to pump oil from the fuel tank, and the characteristics and control methods of the test medium and the proportional overflow valve are not described. Chinese Patent CN201620041618 discloses a reliability verification device for an electric fuel pump, in which the object to be measured is driven by electricity rather than the engine, and in addition, only a one-way valve is installed at the outlet of the object to be measured, that is, the outlet pressure cannot be adjusted.

[0004] Therefore, there is an urgent need for a device that can test the performance of the common rail pump low-pressure transfer pump. Summary of the Invention

[0005] The purpose of the present invention is to provide a performance testing system for a common rail pump low-pressure transfer pump in view of the defects of the prior art.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions: A performance testing system for a common rail pump low-pressure transfer pump, characterized by comprising: a pressure sensor, an inlet metering valve, a pneumatic three-way ball valve, and a control system. When detecting the performance of the common rail pump low-pressure transfer pump to be measured, the pressure sensor, the inlet metering valve, and the pneumatic three-way ball valve are sequentially installed on the outlet pipeline of the common rail pump low-pressure transfer pump. The inlet of the common rail pump low-pressure transfer pump is connected to the fuel tank. The pneumatic three-way ball valve has one inlet and two outlets, and the two outlets respectively return to the fuel tank through two pipelines. A first flow meter and a second flow meter are respectively arranged on the two pipelines; the control system is respectively connected to the common rail pump low-pressure transfer pump to be measured, the pressure sensor, the inlet metering valve, and the pneumatic three-way ball valve to control the performance test of the common rail pump low-pressure transfer pump.

[0007] Furthermore, the inlet metering valve is provided with an NI board card PCIe-6321 and a drive circuit for collecting the real-time drive current of the oil metering valve.

[0008] Further, the drive circuit includes a MOS transistor, a fuse, a current sensor, and a freewheeling diode. The analog voltage output channel AO0 of the NI board PCIe-6321 outputs a PWM voltage signal through programming and connects it to the G pole of the MOS transistor to control the on / off of the MOS transistor. The fuel inlet metering valve is connected between the positive power supply and the D pole of the MOS transistor, and a fuse and a current sensor are connected in series in its circuit, and a freewheeling diode is connected in parallel. The analog voltage input channel AI0 of the NI board PCIe-6321 continuously samples the output waveform of the current sensor and calculates the root mean square value of the current waveform once every 100 ms to obtain the current drive current of the fuel inlet metering valve.

[0009] Further, the pressure sensor and the fuel inlet metering valve are installed on a special tooling. During the test, the test oil first passes through the pressure sensor, then enters from the bottom surface of the fuel inlet metering valve, and finally outputs from the side surface of the fuel inlet metering valve.

[0010] Further, a metal filter screen is installed at the fuel inlet of the fuel inlet metering valve to filter large particle impurities.

[0011] Further, the performance tested by the test system for the low-pressure fuel pump of the common rail pump includes: a set test for detecting the working conditions of the tested low-pressure fuel pump of the common rail pump and detecting the performance data of the low-pressure fuel pump of the common rail pump.

[0012] Further, for the set test of the working conditions of the tested low-pressure fuel pump of the common rail pump by the test system, the following steps are adopted:

[0013] (1) Calibrate the maximum duty cycle of the PWM voltage signal of the fuel inlet metering valve;

[0014] (2) Set the rotational speed of the servo motor driving the low-pressure fuel pump. After the rotational speed is stable, open-loop adjust the duty cycle of the PWM voltage signal of the fuel inlet metering valve so that the outlet pressure of the low-pressure fuel pump is stable within the range of ±0.05 bar of the set value, and record the current drive current of the fuel inlet metering valve and the current outlet flow rate of the low-pressure fuel pump.

[0015] (3) According to the flow formula of the fuel inlet metering valve as shown in Equation 1,

[0016]

[0017] where: C DTo test the flow coefficient of the oil; S is the flow area of the inlet metering valve; ΔP is the pressure difference between the inlet and outlet of the inlet metering valve; ρ is the density of the test oil; when the outlet pressure of the inlet metering valve is approximately 0, the outlet flow rate of the low-pressure fuel transfer pump is the flow rate through the inlet metering valve. Then, according to the relationship diagram of current and flow rate under a 2-bar pressure difference of the inlet metering valve, verify whether the recorded drive current and outlet flow rate are correct. The duty cycle of the PWM signal measured under each test condition is denoted as Di, and Di ± 10 is used as the set range of the duty cycle of the PWM signal for closed-loop regulation of the outlet pressure under this test condition.

[0018] Further, the test system tests the performance data of the low-pressure fuel transfer pump of the common rail pump, including the following steps:

[0019] (1) Set the current of the inlet metering valve to 0, set the rotational speed of the servo motor driving the low-pressure fuel transfer pump, first determine whether the rotational speed is stable and then determine whether the flow rate is stable. When the flow rate is stable, it is considered that the exhaust is completed;

[0020] (2) After the exhaust is completed, close-loop regulate the duty cycle of the PWM voltage signal of the inlet metering valve so that the outlet pressure of the low-pressure fuel transfer pump is stable within the range of ±0.05 bar of the set value. At this time, the outlet flow rate value is the measured value under this test condition;

[0021] (4) Traverse all test conditions, the automatic test process ends, and the flow rates of the low-pressure fuel transfer pump of the common rail pump at different rotational speeds and different outlet pressures, that is, the performance data, are measured.

[0022] Further, it is determined that the rotational speed is stable when the rotational speed is stable within the range of ±5 r / min of the set value for 2 consecutive seconds.

[0023] Further, it is determined that the flow rate is stable when the flow rate fluctuates no more than ±2 L / h for 2 consecutive seconds.

[0024] The test system of the present invention creatively uses an inlet metering valve to regulate the outlet pressure of the low-pressure fuel transfer pump of the common rail pump, gives the steps of setting the test conditions for the test, and gives the judgment criteria for determining the end of exhaust before testing under each condition. Using the test system of this application to detect the low-pressure fuel transfer pump of the common rail pump, the test results are accurate, providing a test means for the development and mass production test of the low-pressure fuel transfer pump of the common rail pump. Description of the Drawings

[0025] Figure 1 It is a schematic structural diagram of the low-pressure fuel transfer pump of the common rail pump.

[0026] Figure 2 It is a schematic structural diagram of the performance test system of the low-pressure fuel transfer pump of the common rail pump in the embodiment.

[0027] Figure 3 It is an external view of the inlet metering valve in the embodiment

[0028] Figure 4 It is a graph showing the relationship between current and flow rate when the pressure difference between the inlet and outlet of the fuel inlet metering valve in the embodiment is constant.

[0029] Figure 5 It is a schematic structural diagram of the pressure sensor, fuel inlet metering valve and special tooling in the embodiment.

[0030] Figure 6 It is the drive circuit of the fuel inlet metering valve in the embodiment. Detailed implementation manners

[0031] In order to enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the protection scope of this application.

[0032] It should be noted that the terms "including" and "having" in the specification and claims of this application and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or devices.

[0033] As shown in the attached Figure 1 As shown, the low-pressure fuel pump of the common rail pump generally consists of a housing 1, a driving gear 2, a driven gear 3, a safety valve 4 and an exhaust valve 5. The driving gear 2 is driven by the driving shaft of the common rail pump, sucks oil from the upper end inlet into the cavity of the housing 1, and discharges it from the lower end outlet through gear rotation to complete the fuel pumping action. When the outlet pressure is too high, the safety valve 4 opens to let the oil return to the inlet. When air is inhaled at the inlet, the air is discharged through the exhaust valve 5 to prevent it from entering the cavity of the housing 1.

[0034] When testing the performance of the low-pressure fuel pump of the common rail pump, the test oil used is calibration pump oil that complies with the ISO 4113 standard. The main components of its test system are as shown in the attached Figure 2 As shown, the low-pressure fuel pump 8 (the pump to be tested) sucks oil from the fuel tank 6, and a primary filter 7 is installed between its inlet and the oil suction port. The low-pressure fuel pump is driven by a servo motor to ensure stable driving speed and short speed establishment time during working condition switching.

[0035] A pressure sensor 9 and a fuel inlet metering valve 10 are installed at the outlet of the low-pressure fuel pump 8. As shown in the attached Figure 3As shown, the inlet metering valve 10 is an electro-hydraulic proportional flow valve. The upper part is an electromagnet and the lower part is a valve body. It is an important component of the common rail pump. The flow characteristic of the inlet metering valve, that is, the relationship between current and flow rate when the pressure difference between the inlet and outlet is constant, is as shown in the appendix Figure 4 As shown, as the current increases, the flow rate gradually decreases until it closes.

[0036] As shown in the appendix Figure 5 As shown, the pressure sensor 9 and the inlet metering valve 10 are installed on a special tooling. From left to right, the test oil first passes through the pressure sensor 9, then enters from the bottom surface of the inlet metering valve 10, and finally exits from the side surface of the inlet metering valve 10. A metal filter screen is installed at the inlet of the inlet metering valve 10 to filter large particle impurities to avoid jamming of the inlet metering valve 10.

[0037] A pneumatic three-way ball valve 11 is installed at the outlet of the inlet metering valve 10. It has one inlet and two outlets. One outlet is connected to the flowmeter 12 and the other outlet is connected to the flowmeter 13. The outlets of the flowmeters 12 and 13 each return to the fuel tank 6.

[0038] The flowmeter 12 uses the volumetric flowmeter VCA0.1FER1 of KRACHT company, with a range of 4.8 - 600 L / h. The flowmeter 13 selects the volumetric flowmeter LSF40 of OVAL company, with a range of 1 - 50 L / h. By default, the pneumatic three-way ball valve 11 switches to the flowmeter 12 path. When the flow rate is less than 40 L / h, the pneumatic three-way ball valve 11 switches to the flowmeter 13 path. After the test is completed, the pneumatic three-way ball valve 11 switches to the flowmeter 12 path.

[0039] The drive current of the inlet metering valve 10 is jointly given by the NI board PCIe - 6321 and the drive circuit. As shown in the appendix Figure 6 As shown, the analog voltage output channel AO0 of the NI board PCIe - 6321 outputs a PWM voltage signal through programming and connects it to the G pole of the MOS transistor to control the on / off of the MOS transistor. The inlet metering valve 10 is connected between the positive power supply and the D pole of the MOS transistor. A fuse F1 and a current sensor I1 are connected in series in its circuit, and a freewheeling diode is connected in parallel.

[0040] The analog voltage input channel AI0 of the NI board PCIe - 6321 continuously samples the output waveform of the current sensor I1, and calculates the root mean square value of the current waveform once every 100 ms to obtain the current drive current of the inlet metering valve 10. The frequency of the PWM voltage signal of the inlet metering valve 10 remains constant, and the magnitude of its drive current is closed-loop controlled through the PID regulation of the duty cycle of the PWM voltage signal.

[0041] The performance test method of the low-pressure fuel transfer pump of the common rail pump by the test system described in the present invention is as follows:

[0042] First, calibrate the maximum duty cycle of the PWM voltage signal of the fuel inlet metering valve. The PWM voltage signal frequency of the fuel inlet metering valve 10 is 400 Hz, powered by 12 V, with a resistance of approximately 2.15 Ω and a maximum operating current of 2.5 A. Considering that the resistance of the fuel inlet metering valve increases due to temperature rise during the test, and correspondingly, the duty cycle of its PWM voltage signal also increases, the upper limit of the duty cycle of the PWM voltage signal is set to 75%.

[0043] Next, conduct the setting test for each test condition of the common rail pump low-pressure fuel transfer pump. First, set the rotational speed of the servo motor driving the low-pressure fuel transfer pump. When the rotational speed remains stable within the range of ±5 r / min of the set value for 2 consecutive seconds, it is considered that the rotational speed is stable. After the rotational speed is stable, open-loop adjust the duty cycle of the PWM voltage signal of the fuel inlet metering valve 10 to make the outlet pressure of the low-pressure fuel transfer pump stable within the range of ±0.05 bar of the set value, and record the current driving current of the fuel inlet metering valve and the current outlet flow rate of the low-pressure fuel transfer pump.

[0044] According to the flow formula of the fuel inlet metering valve:

[0045]

[0046] In the formula: C D is the flow coefficient of the test oil; S is the flow area of the fuel inlet metering valve; ΔP is the pressure difference between the inlet and outlet of the fuel inlet metering valve; ρ is the density of the test oil. It can be seen that the outlet pressure of the low-pressure fuel transfer pump is the inlet pressure of the fuel inlet metering valve, the outlet pressure of the fuel inlet metering valve is approximately 0, and the outlet flow rate of the low-pressure fuel transfer pump is the flow rate passing through the fuel inlet metering valve. Then, according to the appendix Figure 4 the relationship between the current and flow rate of the fuel inlet metering valve under a pressure difference of 2 bar can be used to verify whether the recorded driving current and outlet flow rate are correct. For example, when the outlet pressure is 11.86 bar, the driving current of the fuel inlet metering valve is 1.25 A, and the outlet flow rate is 191.86 L / h. The flow rate converted to a pressure difference of 2 bar according to the following formula is:

[0047]

[0048] Look up the appendix Figure 4 the flow rate of the fuel inlet metering valve at 1.25 A under a pressure difference of 2 bar is 81.7 L / h, which is consistent with the test value. Based on this, add 10 to the duty cycle of the PWM signal obtained under each test condition as the upper limit of the closed-loop regulation of the outlet pressure under this test condition, and subtract 10 as the lower limit of the closed-loop regulation of the outlet pressure under this test condition. For example, if the duty cycle of the PWM voltage signal of the fuel inlet metering valve obtained under a certain test condition is 35%, then the upper limit of the duty cycle for closed-loop regulating the outlet pressure of the low-pressure fuel transfer pump under this condition is 45%, and the lower limit is 25%.

[0049] Finally, continuous automatic tests are carried out for each test condition of the common rail pump low-pressure fuel transfer pump. The specific process is as follows: Set the current of the inlet metering valve to 0, set the rotational speed of the servo motor driving the low-pressure fuel transfer pump. When the rotational speed remains stable within the range of ±5 r / min of the set value for 2 consecutive seconds, it is considered that the rotational speed is stable; after the rotational speed is stable, judge whether the outlet flow rate is stable. When the flow rate fluctuates no more than ±2 L / h within 2 consecutive seconds, it is considered that the flow rate is stable, and the stable flow rate indicates that the exhaust is completed; after the exhaust is completed, close-loop regulate the duty ratio of the PWM voltage signal of the inlet metering valve 10 so that the outlet pressure of the low-pressure fuel transfer pump is stable within the range of ±0.05 bar of the set value. At this time, the outlet flow rate value is the measured value under this test condition; traverse all test conditions, and the automatic test process ends. The flow rates of the common rail pump low-pressure fuel transfer pump at different rotational speeds and different outlet pressures, that is, the performance data, are measured.

[0050] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A performance test system for a low-pressure fuel transfer pump of a common rail pump, characterized in that Including: A pressure sensor, an inlet metering valve, a pneumatic three-way ball valve, and a control system. When performing performance testing on the low-pressure fuel transfer pump of the common rail pump to be measured, the pressure sensor, the inlet metering valve, and the pneumatic three-way ball valve are sequentially installed on the outlet pipeline of the low-pressure fuel transfer pump of the common rail pump. The inlet of the low-pressure fuel transfer pump of the common rail pump is connected to the fuel tank. The pneumatic three-way ball valve has one inlet and two outlets, and the two outlets respectively return to the fuel tank through two pipelines. A first flowmeter and a second flowmeter are respectively arranged on the two pipelines; The control system is respectively connected to the low-pressure fuel transfer pump of the common rail pump to be measured, the pressure sensor, the inlet metering valve, and the pneumatic three-way ball valve to control the performance testing of the low-pressure fuel transfer pump of the common rail pump; The performance testing of the low-pressure fuel transfer pump of the common rail pump by the testing system includes: setting tests for detecting the operating conditions of the low-pressure fuel transfer pump of the common rail pump to be measured and detecting the performance data of the low-pressure fuel transfer pump of the common rail pump; The testing system conducts setting tests for the operating conditions of the low-pressure fuel transfer pump of the common rail pump to be measured, using the following steps: (1) Calibrate the maximum duty cycle of the PWM voltage signal of the inlet metering valve; (2) Set the rotational speed of the servo motor driving the low-pressure fuel transfer pump. After the rotational speed is stable, open-loop adjust the duty cycle of the PWM voltage signal of the inlet metering valve so that the outlet pressure of the low-pressure fuel transfer pump is stable within the range of ±0.05 bar of the set value, and record the current driving current of the inlet metering valve and the current outlet flow rate of the low-pressure fuel transfer pump; (3) According to the flow formula of the inlet metering valve as shown in Equation 1, （1） Wherein: C D is the flow coefficient of the test oil; S is the flow area of the inlet metering valve; is the pressure difference between the inlet and outlet of the inlet metering valve; ρ is the density of the test oil; when the outlet pressure of the inlet metering valve is approximately 0, the outlet flow rate of the low-pressure oil transfer pump is the flow rate passing through the inlet metering valve. Then, according to the relationship diagram of the current and flow rate under a 2-bar pressure difference of the inlet metering valve, verify whether the recorded drive current and outlet flow rate are correct. The duty cycle of the PWM signal measured under each test condition is denoted as Di, and Di ± 10 is used as the set range of the duty cycle of the PWM signal for closed-loop regulation of the outlet pressure under this test condition; The testing system tests the performance data of the low-pressure fuel transfer pump of the common rail pump, including the following steps: (1) Set the current of the inlet metering valve to 0, set the rotational speed of the servo motor driving the low-pressure fuel transfer pump, first determine whether the rotational speed is stable and then determine whether the flow rate is stable. When the flow rate is stable, it is considered that the exhaust is completed; (2) After the exhaust is completed, close-loop adjust the duty cycle of the PWM voltage signal of the inlet metering valve so that the outlet pressure of the low-pressure fuel transfer pump is stable within the range of ±0.05 bar of the set value. The outlet flow rate value at this time is the measured value under this test condition; (3) Traverse all test conditions, and when the automatic testing process ends, measure the flow rates of the low-pressure fuel transfer pump of the common rail pump at different rotational speeds and different outlet pressures, that is, the performance data.

2. The common rail pump low-pressure fuel transfer pump performance test system according to claim 1, characterized in that: The inlet metering valve is provided with an NI board PCIe-6321 and a driving circuit for collecting the real-time driving current of the inlet metering valve.

3. The common rail pump low-pressure fuel transfer pump performance test system according to claim 2, characterized in that: The driving circuit includes a MOS tube, a fuse, a current sensor, and a freewheeling diode. The analog voltage output channel AO0 of the NI board PCIe-6321 outputs a PWM voltage signal through programming and connects it to the G pole of the MOS tube to control the on-off of the MOS tube; the inlet metering valve is connected between the positive power supply and the D pole of the MOS tube, and a fuse and a current sensor are connected in series on its loop, and a freewheeling diode is connected in parallel; the analog voltage input channel AI0 of the NI board PCIe-6321 continuously samples the output waveform of the current sensor and calculates the root mean square value of the current waveform once every 100 ms to obtain the current driving current of the inlet metering valve.

4. The common rail pump low-pressure fuel transfer pump performance test system according to claim 1, characterized in that: The pressure sensor and the fuel inlet metering valve are installed on a special tooling. During testing, the test oil first passes through the pressure sensor, then enters from the bottom surface of the fuel inlet metering valve, and finally outputs from the side surface of the fuel inlet metering valve.

5. The common rail pump low-pressure fuel transfer pump performance test system according to claim 1, wherein: A metal filter screen is installed at the fuel inlet of the fuel inlet metering valve to filter large particle impurities.

6. The common rail pump low-pressure fuel transfer pump performance test system according to claim 1, characterized in that: The determination of stable speed is made when the speed is stable within the range of ±5 r / min of the set value for 2 consecutive seconds.

7. The common rail pump low-pressure fuel transfer pump performance testing system according to claim 1, characterized in that: The determination of stable flow rate is made when the flow rate fluctuates no more than ±2 L / h for 2 consecutive seconds.

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