JP4487893B2 - Fuel consumption measuring device - Google Patents

Description

  The present invention relates to a fuel consumption measuring device for measuring a fuel consumption characteristic of an internal combustion engine, and more specifically, enables accurate fuel consumption measurement without being affected by pulsation of return fuel from the internal combustion engine. It is related to measures.

  In general, a mass-burette fuel consumption measuring device is used to measure in detail the characteristics of fuel consumption according to the operating state of an internal combustion engine. The fuel consumption measuring device includes a fuel tank that stores fuel, a fuel outlet pipe that is connected to an outlet of the fuel tank and supplies fuel to the internal combustion engine, and communicates with the fuel tank. A sub-tank maintained at a reference pressure by the pressure sensor, and a differential pressure measuring means for measuring a specific gravity differential pressure between the fuel in the fuel tank and the fluid in the sub-tank, and the difference measured by the differential pressure measuring means The amount of fuel consumed in the fuel tank is measured based on the pressure.

In addition, it is also conventionally known that such a differential pressure measuring unit is applied to a liquid-tight inspection device that performs liquid-tight inspection of an inspection object such as a fuel injection valve or a flow control valve at the time of shipment (for example, Patent Document 1). In this product, the test liquid supplied to the test object is stored in a test liquid storage container, and the test liquid in the test liquid storage container is pressurized with a gas having the same pressure as the actual use, and the test at that time is performed. The amount of leakage from the object is obtained by measuring the pressure difference between the head (liquid level) of the test liquid in the test liquid storage container and the gas pressure.
JP 2004-270562 A

  By the way, in the electronically controlled fuel injection device, the fuel that has not been injected by the fuel injection device is returned as return fuel from the internal combustion engine, so that it is necessary to accurately measure the fuel consumption in the fuel tank. It is necessary to connect a return fuel return pipe for returning the return fuel from the internal combustion engine to the fuel outlet pipe of the fuel consumption measuring device.

  In that case, in the fuel consumption measuring device, there is no problem in the characteristics of the fuel consumption according to the operating state if the operating state of the internal combustion engine is high so that the fuel in the fuel tank is used up at once. If it is possible to measure, but the operating state of the internal combustion engine with a low engine speed (the operating state in the shaded area in FIG. 2), the fuel consumption characteristics according to the operating state indicate that the fuel in the fuel tank When the pulsation of the return fuel propagates to the fuel that gradually decreases in the fuel tank, the specific gravity between the fuel in the fuel tank and the fluid in the sub tank is measured by the differential pressure measurement means. May affect measurement of differential pressure. This is presumably because when the amount of fuel in the fuel tank decreases, the pulsation of the return fuel propagates to a small amount of fuel in the fuel tank and is less susceptible to the influence of the propagation.

  At this time, the pressure of the gas to be pressurized when the fuel in the fuel tank is reduced even if the test liquid in the test liquid storage container is pressurized with a gas having the same pressure as the pressure actually used, as in the above-described conventional one. Therefore, when the pulsation of the return fuel propagates to a small amount of fuel in the fuel tank, it is similarly susceptible to the influence of the propagation.

  From this point, when the fuel in the fuel tank decreases, the measurement value varies due to the influence of the pulsation of the return fuel, and it is impossible to measure the fuel consumption with high accuracy.

  The present invention has been made in view of such a point, and the object of the present invention is to perform highly accurate fuel consumption measurement even with a small amount of fuel in a fuel tank without being affected by the pulsation of return fuel. An object of the present invention is to provide a fuel consumption measuring device that can be used.

In order to achieve the above object, the present invention is a fuel consumption measuring device for measuring characteristics of fuel consumption, which is connected to a fuel tank for storing fuel and an outlet of the fuel tank, and is used for fuel to an internal combustion engine. A fuel outlet pipe for supplying the fuel, a return fuel return pipe for returning the return fuel from the internal combustion engine to the fuel outlet pipe, a sub tank connected to the fuel tank and held at a reference pressure by a predetermined fluid substance, When the fuel in the fuel tank is used in a plurality of times, the pressure applied to the fuel in the fuel tank is adjusted according to the amount of fuel used. Pressure maintaining means for constantly maintaining the pressure at a predetermined pressure, and differential pressure measuring means for measuring the specific gravity differential pressure between the fuel in the fuel tank and the fluid in the sub tank. It is to measure the consumption of fuel in the fuel tank based on the differential pressure.

Due to this specific matter, the pressure of the fuel in the fuel tank is always kept at a predetermined pressure by the application of pressure by the pressure holding means, so that the operating state of the internal combustion engine with a low engine speed (the region shown by the hatched area in FIG. 2) The fuel pressure in the fuel tank decreases even if the fuel in the fuel tank is used in several batches and gradually decreases when repeatedly measuring the characteristics of the fuel consumption according to the operating conditions) The pressure is maintained at a predetermined pressure. Therefore, even if the pulsation of the return fuel propagates to a small amount of fuel in the fuel tank, it is not easily affected by the propagation, and the specific gravity differential pressure between the fuel in the fuel tank and the fluid in the sub tank by the differential pressure measuring means is reduced. There is no variation in measured values, and it is possible to perform highly accurate fuel consumption measurement even with a small amount of fuel in the fuel tank.
Here, the fuel consumption measuring device can be used to measure the characteristics of the fuel consumption in the operating state where the rotational speed of the internal combustion engine is lower than a predetermined value. In addition, as the reference pressure, it is possible to employ a pressure that can suppress the measurement variation of the specific gravity differential pressure due to the pulsation of the return fuel from the internal combustion engine.

  In particular, the following configurations are listed as specifying the pressure holding means.

That is, the pressure holding means applies pressure corresponding to the amount of fuel used when the fuel in the fuel tank is used in a plurality of times to the fuel in the fuel tank, and the pressure Pressure leak means is provided for leaking the fuel pressure in the fuel tank when the pressure of the fuel in the fuel tank applied by the applying means exceeds a predetermined pressure.

  With this specific matter, the fuel pressure in the fuel tank can be quickly held at a predetermined pressure, and safety can be ensured when the fuel pressure in the fuel tank exceeds the predetermined pressure. It becomes.

  Further, in the case where the pressure is applied to the fluid in the sub tank by the pressure application means so as to keep the reference pressure, the fuel in the fuel tank and the fluid in the sub tank can be maintained by the single pressure application means. The pressure is applied to both of them, and the pressurizing means for holding the predetermined fluid in the sub tank at the reference pressure can be eliminated to simplify the apparatus and reduce the cost.

  In short, by keeping the fuel pressure in the fuel tank at a predetermined pressure at all times, the fuel pressure reduced in the fuel tank is maintained at a predetermined pressure without being reduced, and is affected by the pulsation of return fuel. This makes it difficult to measure the fuel consumption with high accuracy even with a small amount of fuel in the fuel tank.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a fuel consumption measuring device according to an embodiment of the present invention.

  As shown in FIG. 1, the fuel consumption measuring device 1 is connected to a burette 11 as a fuel tank for storing fuel G, and to the burette 11, and is connected to the engine E as an internal combustion engine via a fuel cooler 21. The fuel outlet pipe 12 for supplying the fuel G, the return fuel return pipe 13 connected to the fuel outlet pipe 12 for returning the return fuel from the engine E, and the burette 11 are communicated with each other as a predetermined fluid. Pressure maintaining the sub-tank 14 held at a reference pressure by the silicon oil S and the fuel G in the burette 11 so that the pressure of the fuel G in the buret 11 is always kept at a predetermined pressure. As a differential pressure measuring means for measuring the specific gravity differential pressure between the means 15 and the fuel G in the burette 11 and the silicon oil S in the sub tank 14 And a pressure sensor 16. In the fuel consumption measuring device 1, the consumption of the fuel G in the burette 11 is measured based on the differential pressure measured by the differential pressure sensor 16. In this case, the burette 11, the sub tank 14, and the differential pressure sensor 16 are accommodated in the main body casing 10 of the fuel consumption measuring device 1.

  Further, the fuel consumption measuring device 1 is connected to a fuel filling pipe 17 that fills the buret 11 with fuel G from the lower end thereof. The upstream end of the fuel filling pipe 17 is connected to a fuel storage source. An electromagnetic valve 17 a that opens and closes the pipe line is provided at the downstream end of the fuel filling pipe 17.

  Here, each component of the fuel consumption measuring device 1 will be described in detail.

  The burette 11 has a substantially cylindrical shape and is configured to store approximately 1000 ml of fuel G. The upper end surface of the burette 11 opens upward.

  The upstream end of the fuel outlet pipe 12 is connected to an outlet 11 a that opens to the lowermost end of the burette 11. The fuel G from the fuel outlet pipe 12 is supplied to the engine E after being cooled and regulated by the fuel cooler 21.

  The return fuel return pipe 13 is for returning the return fuel from the engine E that has not been injected by the fuel injection device of the engine E to the fuel outlet pipe 12, and its downstream end is located upstream of the fuel cooler 21. It is connected in the middle of the fuel outlet pipe 12 located.

  The sub tank 14 is made of a thin circular tube having a diameter of about 3 mm, and its upper end surface opens upward at the same height as the upper end surface of the burette 11. In this case, the silicon oil S is stored in the sub-tank 14, but any fluid may be used as long as it does not deteriorate and the quality is easily stabilized.

  The pressure holding means 15 is a back pressure space that communicates with the upper end surface of the buret 11 and the upper end surface of the sub tank 14 so as to apply back pressure to the fuel G in the buret 11 and the silicon oil S in the sub tank 14, respectively. 15a. The pressure holding means 15 includes a pressure applying means 15b for applying pressure to the fuel G in the burette 11, and the pressure of the fuel G in the burette 11 applied by the pressure applying means 15b is a predetermined pressure (for example, 20 KPa). ), The pressure leak means 15c for leaking the pressure of the fuel G in the burette 11 is provided.

  The pressure applying unit 15b includes a pressurized air supply pipe 15d that supplies the pressurized air A to the back pressure space 15a. The upstream end of the pressurized air supply pipe 15d is connected to a factory air supply source that provides pure air A containing no 99.999% impurities, while the downstream end is connected to the back pressure space 15a. . The pressurized air supply pipe 15d includes a regulator 15e that pressurizes pure air A from the factory air supply source to 20 KPa, and a first electromagnetic that adjusts the opening degree of the pressurized air supply pipe 15d on the downstream side of the regulator 15e. And a valve 15f. Then, pure air from the factory air supply source is pressurized to 20 KPa by the regulator 15e, and the fuel in the back pressure space 15a and the burette 11 is released by the first electromagnetic valve 15f that is opened as the fuel G in the burette 11 decreases. The space up to the oil level of G is always filled with pressurized air A of 20 KPa. In this case, the pressure applying means 15b applies back pressure to the fuel G in the burette 11 and the silicon oil S in the sub tank 14, respectively, so that the pressure of the fuel G in the buret 11 is always a predetermined pressure of 20 KPa. The pressure of the silicon oil S in the sub tank 14 is always kept at a reference pressure of 20 KPa.

  The pressure leak means 15c includes a pressurized air discharge pipe 15g that discharges the pressurized air A from the back pressure space 15a. The upstream end of the pressurized air discharge pipe 15g is connected to the back pressure space 15a. The pressurized air discharge pipe 15g includes a pressure sensor 15h that detects the back pressure of the pressurized air A in the back pressure space 15a in the pressurized air discharge pipe 15g, and a pressurized air discharge on the downstream side of the pressure sensor 15h. When the pressure (back pressure) of the pressurized air A in the pressurized air discharge pipe 15g on the downstream side of the second solenoid valve 15i for adjusting the opening of the pipe 15g and the second solenoid valve 15i exceeds 20 KPa And a check valve 15j to be opened. The detection value of the pressure sensor 15h is output to a control unit 18 composed of a CPU, and the control unit 18 controls the opening adjustment of the first electromagnetic valve 15f and the second electromagnetic valve 15i. When the fuel G in the burette 11 runs out and the fuel G is filled from the fuel filling pipe 17 into the burette 11, the fuel G in the burette 11 decreases as the fuel G decreases. When the pressure sensor 15h detects the back pressure of the pressurized air A that rises due to the fuel G being filled against the pressure of the pressurized air A that has been filled in, the first command is sent from the control unit 18 to the first While the opening degree of the electromagnetic valve 15 f is controlled to be fully closed, the opening degree of the second electromagnetic valve 15 i is controlled to be fully open, the check valve 15 j is opened, and the pressurized air A is passed through the canister 19. It is supposed to be discharged.

  The differential pressure sensor 16 is composed of a strain gauge, and is provided between the fuel pressure detection unit 11b at the lower end of the burette 11 and the silicon oil pressure detection unit 14a at the lower end of the sub tank 14 facing the fuel pressure detection unit 11b. . Then, the differential pressure difference between the fuel G in the burette 11 and the silicon oil S in the sub-tank 14 is measured by the differential pressure sensor 16 sandwiched between the fuel pressure detection unit 11b and the silicon oil pressure detection unit 14a facing each other. It has come to be.

  Therefore, in the above embodiment, the pressure of the fuel G in the burette 11 is applied by applying the back pressure of the back pressure space 15 a to the fuel G in the burette 11 by applying the pressure by the regulator 15 e of the pressure holding means 15. Is constantly maintained at a predetermined pressure of 20 KPa, so when repeatedly measuring the characteristics of the fuel consumption according to the operating state of the internal combustion engine having a low engine speed (the operating state in the shaded area in FIG. 2). Even if the fuel G in the burette 11 is used in a plurality of times and gradually decreases, the back pressure space 15a and the view are opened by the first electromagnetic valve 15f that opens as the fuel G in the burette 11 decreases. The space up to the oil level of the fuel G in the let 11 is quickly filled with the pressurized air A of 20 KPa, and the pressure of the fuel G in the buret 11 is not lowered. , So that the pressure of the fuel G regardless remaining amount of fuel G of in the burette 11 is constantly maintained to a predetermined pressure (20 KPa). Therefore, even if the pulsation of the return fuel returned from the return fuel return pipe 13 propagates to a small amount of fuel G in the burette 11, it becomes difficult to be affected by the propagation, and the fuel pressure detection unit 11b and the silicon oil pressure facing each other There is no variation in the measurement of the specific gravity differential pressure between the fuel G in the burette 11 and the silicon oil S in the sub tank 14 by the differential pressure sensor 16 sandwiched between the detectors 14a, and there is little fuel in the burette 11. Even with G, it is possible to perform highly accurate fuel consumption measurement.

  In addition, when the fuel G in the burette 11 runs out and the fuel G is filled from the fuel filling pipe 17 into the burette 11, the fuel G in the burette 11 decreases with the decrease in the oil level of the fuel G. When the pressure sensor 15h detects the back pressure of the pressurized air A that rises because the fuel G is filled against the pressure of the pressurized air A that has been filled, the first electromagnetic wave is generated by a command from the control unit 18. While the opening degree of the valve 15f is controlled to be fully closed, the opening degree of the second electromagnetic valve 15i is controlled to be fully opened, the check valve 15j is opened, and the pressurized air A is discharged. Therefore, it is possible to ensure the safety of the fuel consumption measuring device 1 when the pressure of the fuel G in the burette 11 exceeds a predetermined pressure (20 KPa).

  Further, by applying a back pressure to the fuel G in the burette 11 and the silicon oil S in the sub tank 14 by the pressure applying means 15b, the pressure of the fuel G in the buret 11 is always kept at a predetermined pressure of 20 KPa. Since the pressure of the silicon oil S in the tank 14 is always kept at a reference pressure of 20 KPa, both the fuel G in the burette 11 and the silicon oil S in the sub tank 14 are applied to the single pressure application means 15b. It is not necessary to provide pressurizing means for applying pressure and holding the silicon oil S in the sub tank 14 at the reference pressure, and the fuel consumption measuring device 1 can be simplified and the cost can be reduced.

It is a schematic block diagram of the fuel consumption measuring device which concerns on embodiment of this invention. FIG. 6 is a characteristic diagram showing a region in which variation at the time of measurement with return fuel in the fuel injection amount characteristic with respect to the engine speed is likely to occur.

Explanation of symbols

1 Fuel consumption measuring device 11 Viewlet (fuel tank)
11a Outlet 12 Fuel outlet pipe 13 Return fuel return pipe 14 Sub tank 15 Pressure holding means 15b Pressure applying means 15c Pressure leak means 16 Differential pressure sensor (differential pressure measuring means)
E engine (internal combustion engine)
G Fuel S Silicon oil (predetermined fluid)

Claims (5)

A fuel consumption measuring device for measuring characteristics of fuel consumption,
A fuel tank for storing fuel;
A fuel outlet pipe connected to the outlet of the fuel tank and supplying fuel to the internal combustion engine;
A return fuel return pipe for returning the return fuel from the internal combustion engine to the fuel outlet pipe;
A sub-tank communicating with the fuel tank and held at a reference pressure by a predetermined fluid;
The fuel pressure in the fuel tank is adjusted by adjusting the pressure applied to the fuel in the fuel tank according to the amount of fuel used when the fuel in the fuel tank is used in several times. Pressure holding means for constantly holding the pressure at a predetermined pressure;
A differential pressure measuring means for measuring a specific gravity differential pressure between the fuel in the fuel tank and the fluid in the sub-tank,
A fuel consumption measuring apparatus, characterized in that the fuel consumption in the fuel tank is measured based on the differential pressure measured by the differential pressure measuring means. The fuel consumption measuring device according to claim 1,
The fuel consumption measuring device, a fuel consumption measurement device according to claim Rukoto used to the speed of the internal combustion engine to measure the characteristics of the fuel consumption of a low operating state than a predetermined value. In the fuel consumption measuring device according to claim 1 or 2,
The reference pressure, fuel consumption measurement device according to claim pressure der Rukoto capable of suppressing measure variations in the specific gravity differential pressure by pulsation of the return fuel from the internal combustion engine. In the fuel consumption measuring device according to any one of claims 1 to 3,
The pressure holding means includes a pressure applying means for applying a pressure corresponding to the amount of fuel used when the fuel in the fuel tank is used in a plurality of times, and the pressure applying means. And a pressure leak means for leaking the pressure of the fuel in the fuel tank when the pressure of the fuel in the fuel tank applied by the pressure exceeds a predetermined pressure. In the fuel consumption measuring device according to claim 4,
The fuel consumption measuring device, wherein the pressure applying means applies pressure to the fluid in the sub-tank to maintain the reference pressure.

Images