JPH0647975B2 - Fuel injection rate measuring device - Google Patents

Description

The present invention relates to a fuel injection rate measuring device.

[Conventional technology]

A fuel chamber having a constant volume for measuring a fuel injection rate from a fuel injection valve used in an internal combustion engine, a fuel injection valve for injecting fuel into the fuel chamber, a pressure sensor for detecting a pressure in the fuel chamber, and a fuel in the fuel chamber. A fuel injection rate measuring device is known, which is provided with a fuel discharge device for discharging the fuel to the outside, and is capable of discharging the pressurized fuel to the outside after injecting the fuel into the fuel chamber filled with the fuel (MTZ No. 22). Volume 9 (1961
(See page 345). In this fuel injection rate measuring device, fuel is injected from a fuel injection valve into a fuel chamber filled with fuel, the pressure increase in the fuel chamber due to this fuel injection is detected by a pressure sensor, and then the fuel injection action from the fuel injection valve is detected. Upon completion, the pressurized fuel in the fuel chamber is discharged to the outside, then fuel injection from the fuel injection valve is performed again, and the pressure sensor detects the pressure increase in the fuel chamber. The fuel injection rate is calculated from the pressure change in the fuel chamber at the time of fuel injection.
That is, the bulk elastic modulus K of the fuel used is investigated or measured in advance, and the volume change of the fuel in the fuel chamber due to the fuel injection is calculated from this bulk elastic modulus K and the pressure change in the fuel chamber, and this volume change is calculated. The fuel injection rate is calculated from.

[Problems to be solved by the invention]

The calculation accuracy of the fuel injection rate depends on the measurement accuracy of the pressure change in the fuel chamber and the accuracy of the bulk modulus K. However, the bulk modulus K differs depending on the type of fuel and also greatly changes depending on the gas content in the fuel. Therefore, it is not possible to accurately calculate the fuel injection rate by using the bulk modulus K that has been previously investigated or measured as the bulk modulus K as described above.

[Means for solving problems]

In order to solve the above problems, according to the present invention, a fuel chamber having a constant volume, a fuel injection valve for injecting fuel into the fuel chamber, a pressure sensor for detecting the pressure in the combustion chamber, and a fuel in the fuel chamber to the outside are provided. It is provided with a fuel discharge device for discharging and a calibration device for measuring the bulk modulus of the fuel in the fuel chamber.

〔Example〕

With reference to FIGS. 1 to 3, a fuel injection rate measuring apparatus, which is generally denoted by reference numeral 1, is composed of a measuring apparatus main body 2, a fuel discharging apparatus 3, and a calibration apparatus 4. The measuring device main body 2 includes an upper housing 5, a lower housing 6, and an intermediate housing 7 located between the housings 5 and 6, and the intermediate housing 7 has a cylindrical inner peripheral wall surface 7a. On the other hand, the upper housing 5 has a conical inner wall surface 5a that widens downward, and the lower housing 6 has a flat inner wall surface 6a. Housing 5,
A fuel chamber 8 having a constant volume defined by the cylindrical inner peripheral wall surface 7a, the conical inner wall surface 5a, and the flat inner wall surface 6a is formed in each of the cylinders 6 and 7. An adapter receiving hole 9 is formed on the outer peripheral wall surface of the intermediate housing 7, and the adapter 10 is fitted into the adapter receiving hole 9. This adapter 10 is firmly held by an adapter holding plate 12 that is fastened to the intermediate housing 7 by bolts 11.
A fuel injection valve 13 is attached inside. As shown in FIG. 1, the fuel injection valve 13 is connected to a fuel injection pump 15 driven by an electric motor 14, and the fuel injection pump 1
An encoder 16 that rotates in synchronization with the fuel injection pump 15 is attached to 5. Fuel is injected from the fuel injection valve 13 into the fuel chamber 8 through an opening 17 formed in the intermediate housing 7. As will be described later, when the fuel injection rate is measured, the fuel chamber 8 is filled with high-pressure fuel, so that the fuel is injected into the high-pressure fuel. In the embodiment shown in FIG. 1, one fuel injection valve 13 is attached to the intermediate housing 7, but two or more fuel injection valves 13 can be attached to the intermediate housing 7.

A safety valve 18 that opens when the fuel pressure in the fuel chamber 8 exceeds a predetermined pressure is attached to the intermediate housing 7 on the side opposite to the fuel injection valve 13. A temperature sensor 19 for detecting the fuel temperature in 8 is arranged (FIG. 3). In the embodiment shown in FIG. 3, this temperature sensor 19 comprises a thermocouple. On the other hand, in the intermediate housing 7, a pair of pressure sensors 20 and 21 are arranged at an angular interval of approximately 90 degrees from the fuel injection valve 13. Pressure sensor 2
Reference numeral 0 is composed of a pressure-receiving diaphragm, a strain-generating body that generates strain according to the fuel pressure applied to the pressure-receiving diaphragm, and a strain gauge type pressure sensor including a strain gauge attached to the strain-generating body. On the other hand, the pressure sensor 21 is a piezo type pressure sensor using a piezoelectric element. When fuel is injected from the fuel injection valve 13, a pressure wave propagates toward the cylindrical inner peripheral wall surface 7a located on the opposite side of the fuel injection valve 13 as indicated by an arrow X in FIG. However, since the inner peripheral wall surface 7a of the intermediate housing 7 is formed in a cylindrical shape, the pressure waves reflected on the inner peripheral wall surface 7a collide with each other on the injection axis of the fuel injection valve 13 as indicated by an arrow Y, and as a result, Since the pressure wave loses energy, the pressure fluctuation in the fuel chamber 8 is suppressed. Further, a strong pressure wave does not propagate within the angle range of about 90 degrees from the fuel injection valve 13 and is not affected by the reflected wave. Therefore, as shown in FIGS. 1 and 3, by arranging the pressure sensors 20 and 21 at an angular interval of approximately 90 degrees with respect to the fuel injection valve 13, the pressure sensors 20 and 21 generate pressure waves. The pressure in the fuel chamber 8 can be detected without being affected. In order to accelerate the attenuation of the reflected wave by causing the reflected wave to interfere on the cylindrical inner peripheral wall surface 7a of the intermediate housing 7, a cushioning material may be attached on the cylindrical inner peripheral wall surface 7a, or an inner cylindrical shape may be used. The inner peripheral wall surface 7a can be formed in a corrugated cross-sectional shape.

When the fuel is injected from the fuel injection valve 13, the fuel chamber 8
The fuel pressure in the inside increases, but the degree of increase in the fuel pressure depends on the amount of fuel injected into the fuel chamber 8. That is, when the fuel injection amount is small, the rise in the fuel pressure in the fuel chamber 8 becomes too small, whereas when the fuel injection amount is large, the fuel pressure in the fuel chamber 8 rises too much. Therefore, no matter what kind of fuel injection valve 13 is used, in order to obtain a proper pressure increase, the fuel chamber 8 can be adjusted according to the fuel injection amount of the fuel injection valve 13.
It is preferred that the volume of can be varied. Therefore, several kinds of upper housings 5 as shown in FIG. 1 or FIG. 4 are prepared and these upper housings 5 are selectively used according to the fuel injection valve 13 or a block is provided in the fuel chamber 8. By inserting it, the fuel chamber 8 having an optimum volume can be formed.

Referring to FIG. 1, the fuel discharge device 3 includes an upper housing 5
It is fastened with bolts 30. This fuel discharge device 3
Is a fuel discharge hole 31 arranged at the top of the conical inner wall surface 5a of the upper housing 5, a needle 32 for controlling the opening and closing of the fuel discharge hole 31, a movable member 33 arranged in alignment with the needle 32, and a movable member. A compression spring 34 that presses 33 toward the needle 32 and a solenoid 35 that drives the movable member 33 are provided. A pressurizing chamber 36 is formed around the conical pressure receiving surface 32a of the needle 32.
6 is connected to the fuel discharge hole 31 on the one hand, and is connected to the pressure holding device 38 via the fuel discharge passage 37 on the other hand.
In the embodiment shown in FIG. 1, this pressure holding device 38 comprises a relief valve capable of adjusting the relief pressure. However, the pressure holding device 38 can also be formed of, for example, a nitrogen gas tank filled with a constant pressure of nitrogen gas. When the solenoid 35 is energized, the movable member 33 rises, so that the needle 32 rises. As a result, since the needle 32 opens the fuel discharge hole 31, the pressurized fuel in the fuel chamber 8 is discharged to the outside via the pressure holding device 38, for example, the relief valve. Next, when the pressure in the fuel chamber 8 reaches a constant pressure determined by the relief valve, the fuel discharge operation is stopped. Then, when the solenoid 35 is deenergized, the needle 32 closes the fuel discharge hole 31. Therefore, the fuel pressure in the fuel chamber 8 is maintained at a constant pressure determined by the relief valve.

Referring to FIGS. 1 to 3, the calibration device 4 is attached to the lower housing 6. The calibration device 4 is attached to a cam shaft 42 rotatably supported by a pair of bearings 40, 41, a drive motor 43 connected to one end of the cam shaft 42, and the other end of the cam shaft 42. An encoder 44, a plunger support sleeve 45 fitted and fixed to the lower housing 6,
In this sleeve 45, the linear ball bearing 4
6 and a plunger 47 slidably arranged in the axial direction via the plunger 6. The plunger 47 has a small diameter portion 47a that can project into the fuel chamber 8. As shown in FIG. 5, a circular cam 48 is integrally formed on the cam shaft 42, and the lower end portion of the plunger 47 is mounted on the circular cam 48.
The outer race 49a of 9 contacts. The center O ₂ of the circular cam 48 is eccentric with respect to the center O ₁ of the cam shaft 42. Therefore, when the cam shaft 42 rotates, the plunger 47 moves up and down. At this time, the lift amount of the plunger 47 changes like a sine curve with the passage of time. Various cam shapes can be used as the cam 48, and therefore the lift amount of the plunger 47 need not necessarily be changed in a sine curve shape over time.

The fuel volume V in the fuel chamber 8 and the fuel volume change ΔV,
The pressure change ΔP in the fuel chamber 8 due to this volume change ΔV,
The following relationship is established with the bulk modulus K of the fuel in the fuel chamber 8.

ΔV = (V / K) · ΔP Since the volume change ΔV of the fuel in the fuel chamber 8 is caused by the fuel injection from the fuel injection valve 13, the volume V of the fuel in the fuel chamber 8, the volume elastic modulus K and the pressure change ΔP are If it is known, the volume ΔV of the fuel injected from the fuel injection valve 13 can be known, and the fuel injection rate can be calculated from this volume ΔV.

Therefore, first, the measurement of the bulk modulus K using the calibration device 4 will be described. FIG. 6 shows a schematic diagram of a calculation circuit for the bulk modulus K. Referring to FIG. 6, the output voltage of the piezoelectric pressure sensor 21 is the amplifier 50.
Via the input to the high peak hold circuit 51 and the low peak hold circuit 52, the output voltage of the high peak hold circuit 51 and the output voltage of the low peak hold circuit 52 are input to the subtraction circuit 53, and the difference between these output voltages is calculated. Desired. The output voltage of the subtraction circuit 53 is input to the display device 55 via the analog switch 54. On the other hand, the output voltage of the strain gauge type pressure sensor 20 is input to the high peak hold circuit 57 and the low peak hold circuit 58 via the amplifier 56, and the output voltages of the high peak hold circuit 57 and the low peak hold circuit 58 correspond to each other. It is input to the display device 55 through the analog switches 59 and 60 which are turned on. The output voltage of the temperature sensor 19 is input to the display device 55 via the amplifier 61 and the analog switch 62. The encoder 44 of the calibration device 4 has a camshaft 42.
Generates a reference pulse for each rotation, and an angle pulse for each rotation of the camshaft 42, for example. The reference pulse generated by the encoder 44 is the analog switch 5
4, 59, 60, and 62, and when the reference pulse is generated, the output voltages of the subtraction circuit 53, the high peak hold circuit 57, the low peak hold circuit 58, and the amplifier 61 are input to the display device 55. Is displayed. Further, the reference pulse of the encode 44 is input to each peak hold circuit 51, 52, 57, 58 via the delay circuit 63, whereby each peak hold circuit 51, 52, 57, 58 is reset. The high peak hold circuits 51 and 57 hold the maximum value of the input voltage after being reset and then reset again, and the low peak hold circuits 52 and 58 are input after being reset and before being reset again. Holds the minimum voltage value.

FIG. 7 shows a time chart when the arithmetic circuit of FIG. 6 is used. Camshaft 4 of calibration device 4
When 2 is rotated by the drive motor 43, the plunger 47 moves up and down, whereby the amount of protrusion of the small diameter portion 47a of the plunger into the fuel chamber 8 changes periodically. As a result, the fuel pressure in the fuel chamber 8 changes as shown by the curve F in FIG. The curve E _{1 in} FIG. 7 shows the output voltage of the high peak hold circuits 51, 57 when the fuel pressure F changes in this way, and the curve E ₂ shows the low peak hold circuits 52, 58.
The output voltage of is shown. Further, R indicates a reference pulse, and R ′ indicates a reference pulse delayed by the delay circuit 63. On the display device 55, when the reference pulse R is generated, the voltage difference ΔE between the high peak value E _h and the low peak value E _l of the output voltage of the piezo type pressure sensor 21 and the high peak of the output voltage of the strain gauge type pressure sensor 20. Value E _h and low peak value E
_l and the fuel temperature T are displayed. The voltage difference ΔE between the high peak value E _h and the low peak value E _l of the output voltage of the piezo-type pressure sensor 21 corresponds to the fuel pressure change ΔP due to the projecting action of the small diameter portion 47 a of the plunger, while the fuel pressure in the fuel chamber 8 changes. Volume V
And the volume change ΔV of the fuel due to the movement of the small diameter portion 47a of the plunger is known in advance. The bulk modulus K is K =
It is represented by (V / ΔV) · ΔP. Therefore, the above-mentioned voltage difference ΔE represents the bulk modulus K, and therefore the display device 5
5, the bulk modulus K, the maximum pressure (E _h ) and the minimum pressure (E _l ) in the fuel chamber 8, and the fuel temperature T are displayed. Actually, the bulk elastic modulus K is obtained with the fuel pressure in the fuel chamber 8 maintained at about 20 atm, and the maximum fuel pressure at this time is from 30 atm to 40 atm. The bulk modulus K of the fuel in the fuel chamber 8 is determined from the bulk modulus K repeatedly obtained in this way. The maximum and minimum values of the fuel pressure and the fuel temperature T are used to correct the bulk elastic modulus K as needed.

FIG. 8A shows the relationship between the output voltage E of the piezo pressure sensor 21 and the fuel pressure P, and FIG. 8B shows the relationship between the output voltage E of the strain gauge pressure sensor 20 and the fuel pressure P. Indicates.
As can be seen from FIG. 8 (A), the piezoelectric pressure sensor 21
Has excellent linearity, but the output voltage E does not always become zero when the fuel pressure P is 0 gauge pressure. On the other hand, the eighth
As shown in FIG. 3B, the strain gauge type pressure sensor 20 has an output voltage of zero when the fuel pressure P is 0 gauge pressure, but its linearity is slightly inferior to that of the piezo type piezoelectric element 21. In particular, the linearity of the strain gauge type pressure sensor 20 using a diaphragm having a small size is deteriorated so that the volume in the fuel chamber 8 does not change due to the movement of the diaphragm. Therefore, as shown in FIG. 6, a piezo type pressure sensor 21 having excellent linearity is used to obtain the pressure difference ΔP, and a strain gauge type pressure sensor 20 is used to obtain the fuel pressure gauge pressure. The bulk modulus K can be obtained with high accuracy. Since the gauge pressure of the fuel pressure does not directly affect the bulk elastic modulus K, even if the linearity of the strain gauge type pressure sensor 20 is somewhat poor, no particular problem occurs.

Next, the fuel injection rate is calculated using the bulk modulus K thus obtained. In calculating the fuel injection rate, it is necessary that the volume V of the fuel before the start of fuel injection be a predetermined set value, and therefore the small plunger portion 47a is stopped at the most retracted position. . That is, the camshaft 42 is controlled by the output pulse of the comparator 44 so as to stop at the position where the plunger small diameter portion 47a is most retracted.

FIG. 9 shows a schematic diagram of an arithmetic circuit for obtaining the fuel injection rate. Referring to FIG. 9, a piezo type pressure sensor 2
The output voltage of 1 is input to the arithmetic circuit 71 via the amplifier 70. The arithmetic circuit 71 obtains the fuel volume change ΔV based on the equation ΔV = (V / K) · ΔP. This fuel volume change ΔV represents the volume Q of the fuel injected from the fuel injection valve 13, and therefore the arithmetic circuit 71 calculates the volume Q or mass M of the injected fuel. The arithmetic circuit 7
As the bulk modulus K used in No. 1, the value obtained by calibrating is introduced. On the one hand, the output voltage of the arithmetic circuit 71 is input to the display device 55, whereby the display device 55 displays the change in the fuel injection amount Q or M. Further, the output voltage of the arithmetic circuit 71 is input to the differentiating circuit 72 in the local area, and the fuel injection amount is differentiated with respect to time. The output voltage of the differentiating circuit 72 is then input to the display device 55, and thus the fuel injection rate dQ / dt or dM / dt.
Is displayed. On the other hand, when it is desired to obtain the change in the fuel injection amount for each crank angle, the encoder 16 of the fuel injection pump 15
The angle differentiation may be performed in the differentiating circuit 72 based on the output signal of. In this case, the display device 55 displays the fuel injection rate dQ /
dθ or dM / dθ will be displayed. The output voltage of the strain gauge type pressure sensor 20 is input to the display device 55 via the amplifier 73, and the output voltage of the temperature sensor 19 is input to the display device 55 via the amplifier 74. The fuel pressure in the fuel chamber 8 before the fuel injection is started is maintained at, for example, 20 atmospheric pressure, and whether the fuel pressure is maintained at 20 atmospheric pressure is checked from the display device 55 displaying the output of the strain gauge type pressure sensor 20. be able to.

Encoder 16 that rotates in synchronization with fuel injection pump 15
Generates a reference pulse at a constant rotation angle before the start of injection, and generates an angle pulse each time it rotates, for example. As shown in FIG. 9, the reference pulse and the angle pulse generated by the encoder 16 are input to the counter 75. The counter 75 starts the counter action when the reference pulse is generated, and is counted up each time the angle signal is generated. The output signal of the counter 75 is input to one input terminal of the comparator 77 via the DA converter 76 and is compared with a preset count value. When the count value exceeds the set count value, the counter 75 is reset and the drive signal is input to the drive circuit 78 at the same time. Drive circuit 7
8 has, for example, a built-in monostable multivibrator,
When the drive signal is input, a pulse having a constant width for activating the solenoid 35 is output.

FIG. 10 shows a time chart when the arithmetic circuit shown in FIG. 9 is used. In FIG. 10, Q is the fuel injection amount, d
Q / dt and dQ / dθ are the fuel injection rates, S is the reference pulse of the comparator 16, C is the count value of the counter 75, and C is
₀ indicates the set count value, and N indicates the drive pulse of the solenoid 35. The set count value C ₀ is set to a counter value C near the time when the fuel injection is completed. Therefore, when the fuel injection is completed, the drive pulse N of the solenoid 35 is generated. When the drive pulse N is generated, the solenoid 35 is energized, so that the needle 32 of the fuel discharge device 3 is energized.
Opens the fuel discharge hole 31, and the discharge operation of the fuel in the fuel chamber 8 is started. Next, when the fuel pressure in the fuel chamber 8 reaches the fuel pressure determined by the pressure holding device 38, for example, 20 atmospheric pressure, the needle 32 closes the fuel discharge hole 31, and the fuel injection from the fuel injection valve 13 is started again. In this way, the fuel injection amount Q and the fuel injection rates dQ / dt, dQ / dθ
Is continuously measured many times.

In the embodiment shown in FIG. 10, the fuel discharging operation is started when the count value C reaches the set count value C ₀ , that is, when the fuel injection pump 15 rotates by a certain angle. There are various ways to start. For example, the fuel discharge operation may be started after a certain time has elapsed since the encoder 16 of the fuel injection pump 15 generated the reference pulse. In this case, a timer that responds to the reference pulse is provided, and the solenoid 3 responds to the output signal of the timer after a fixed time has elapsed after the reference pulse is generated.
5 is activated. It is also possible to start the fuel discharging operation when the fuel pressure in the fuel chamber 8 exceeds a predetermined pressure. In this case, the energization of the solenoid 35 is started based on the output signal of the strain gauge type pressure sensor 20.

11 and 12 show the case where the fuel injection amount and the fuel injection rate are calculated using a digital computer in consideration of the change of the bulk modulus K based on the fluctuation of the fuel pressure and the fuel temperature. . Referring to FIG. 11, an electronic control unit 80 composed of a digital computer includes a ROM (Read Only Memory) 82, a RAM (Random Access Memory) 83, a CP interconnected by a bidirectional bus 81.
It has a U (microprocessor) 84, an input port 85 and an output port 86. The output signals of the strain gate type pressure sensor 20, the piezo type pressure sensor 21, and the temperature sensor 19 are input to the input port 85 via the corresponding AD converters 87, 88, 89, and further, of the encoder 16 of the fuel injection pump 15. The reference pulse and the angle pulse are input to the input port 85. Further, the output port 86 is connected to the display device 55.

FIG. 12 shows a calculation processing routine of the fuel injection amount and the fuel injection rate. This routine is executed at regular time intervals. Referring to FIG. 12, first, at step 90, the output signal of the strain gauge type pressure sensor 20 representing the gauge pressure P in the fuel chamber 8 is taken in, and then at step 91, the fuel temperature T in the fuel chamber 8 is represented. The output signal of the temperature sensor 19 is captured. Then step 92
Then, the bulk modulus K _nm is calculated based on the following equation.

K _nm = (K _nm / K _tp ) · K _tp Here, K _nm is a basic bulk modulus determined from the current fuel pressure P _m and the fuel temperature T _n , and K _tp is the fuel pressure P _p and the fuel temperature at the time of calibration. Basic bulk modulus determined from T _t ,
K _tp is the actual bulk modulus obtained by calibration. As shown in FIG. 13 (A), the basic bulk modulus k _n1 changes as the fuel temperature T changes, and as shown in FIG. 13 (B), the basic bulk modulus K _1m changes with the fuel pressure P.
Changes when changes. Therefore, the basic bulk modulus k _nm is a function of the fuel temperature T and the fuel pressure P, and the basic bulk modulus k
The relationship between _nm , the fuel temperature T, and the fuel pressure P is stored in advance in the ROM 82 in the form of a map as shown in FIG. Therefore, in step 92, k _nm is obtained from the relationship shown in FIG. On the other hand, k _tp is calculated from the fuel temperature T _t and the fuel pressure P _p during calibration using the map shown in FIG. 14, and the calculated k _tp is stored in the RAM 83 in advance. The actual bulk modulus K _tp obtained by the calibration is stored in the RAM 83 in advance.

Next, at step 93, the output signal of the piezo type pressure sensor 21 representing the fuel pressure p ₁ in the fuel chamber 8 is taken in. Next, at step 94, the fuel pressure p ₂ in the previous processing routine is subtracted from the current fuel pressure p ₁ and the subtraction result is Δp.
And Next, at step 95, the increase amount ΔV of the fuel volume in the fuel chamber 8 is calculated. This increase amount ΔV represents the increase amount of the fuel injected from the fuel injection valve 13 per time, that is, the fuel injection rate dQ / dt. Then step 9
At 6, ΔV is added to ΣΔV. This ΣΔV represents the fuel injection amount Q. Next, in step 97, p _{1 is set} to p _2, and then in step 98, the fuel injection rate dQ / d
ΔV representing t and ΣΔV representing the fuel injection amount Q are output to the output port 86 and displayed by the display device 55.

In addition, the arithmetic processing routine shown in FIG.
The fuel injection rate dQ / dθ can be obtained by executing the process every time the angle pulse is generated based on the angle pulse of No. 6.

〔The invention's effect〕

Since the bulk modulus of the fuel in the fuel chamber before and after the fuel injection can be measured, the fuel injection rate can be accurately measured.

[Brief description of drawings]

1 is a partial cross-sectional side view of the fuel injection rate measuring device, FIG. 2 is a partial cross-sectional side view of FIG. 1, and FIG. 3 is a plan view of FIG. 1 showing the upper housing removed. FIG. 4 is a partial sectional side view showing another embodiment, FIG. 5 is a side view of a cam, a bearing and a plunger, FIG. 6 is a block diagram for performing calibration calculation, and FIG. 7 is a calibration. Time chart of arithmetic processing, FIG. 8 is a diagram showing the output voltage of the pressure sensor, FIG. 9 is a block diagram for calculating the fuel injection amount and the fuel injection rate, and FIG. 10 is the fuel injection amount and the fuel injection. Time chart of rate calculation processing,
FIG. 11 is a diagram showing an electronic control unit, FIG. 12 is a flow chart for executing a calculation process of a fuel injection amount and a fuel injection rate, and FIG. 13 is a diagram showing a bulk elastic modulus.
FIG. 4 is a diagram showing a map storing the bulk modulus. 1 ... Fuel injection rate measuring device, 2 ... Measuring device main body, 3 ... Fuel discharging device, 4 ... Calibration device, 8 ... Fuel chamber, 13 ... Fuel injection valve, 19 ... Temperature sensor, 20 ...... Strain gauge type pressure sensor, 21 ...... Piezo type pressure sensor, 31 …… Fuel discharge hole, 38 …… Pressure holding device, 47 …… Plunger.

Claims (1)

[Claims] 1. A fuel chamber having a constant volume, a fuel injection valve for injecting fuel into the fuel chamber, a pressure sensor for detecting the pressure in the fuel chamber, and a fuel discharge device for discharging the fuel in the fuel chamber to the outside. And a calibration device for measuring the bulk modulus of the fuel in the fuel chamber.