JP2748673B2 - Injection nozzle characteristics measurement device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for measuring injection nozzle characteristics of a fuel injection valve or the like of an internal combustion engine.

[Prior Art] The characteristics of an injection nozzle such as a fuel injection valve of an internal combustion engine affect the injection amount control or the design of an actuator, a spring, or the like for driving the injection nozzle. Therefore, in realizing a predetermined fuel injection, it is important to know its characteristics. Of these, the relationship between the lift amount of the needle nozzle and the injection amount is particularly important.

For example, the actual injection port flow coefficient α exists as a value representing the pressure loss of the fuel injection nozzle. This α has the following relationship with each parameter.

Q = α · f (Δx) · (2g · P / γ) ^1/2 where Q: injection amount, Δx: needle lift amount, f (Δ
x): a function representing the opening area with Δx as a parameter, g:
Gravitational acceleration, P: pressure difference between fuel pressure and external pressure, γ: specific weight of fuel.

Of these, g, P, and γ are set conditions and set dimensions.
It is usually constant and can be determined relatively easily. However, the injection amount Q and the needle lift amount Δx are, under conditions close to actual conditions,
It cannot be determined unless fuel is actually injected and the relationship between the needle lift amount and the injection amount Q is measured.

Therefore, a measuring device that can determine this relationship is desired.

2. Description of the Related Art Conventionally, there has been known a device in which a biasing spring position of a needle nozzle is adjusted by screwing an adjusting screw so that a fuel injection amount becomes a predetermined injection amount while fuel is injected from a fuel injection nozzle. (JP-A-61-277869).

[Problem to be Solved by the Invention] This device certainly measures the fuel injection amount at the time of injection amount adjustment, but the adjustment is performed by adjusting the spring position. Fuel remains injected. However, in actual fuel injection, the spring position does not change and does not remain injected. Therefore, the actual fuel injection is measured in a method far apart from the actual fuel injection. Further, the injection amount according to the needle lift amount is not measured.

Further, since the lift amount of the needle nozzle is not measured, the lift amount cannot be determined. Moreover, the spring position adjusting means is connected to the needle nozzle via the biasing spring. For this reason, even if an attempt is made to determine the lift position from the adjustment amount of the spring position adjustment means, the position of the needle nozzle is indeterminate due to the expansion and contraction of the biasing spring, so it is not possible to determine the lift amount of the needle nozzle from the adjustment amount. Can not. Therefore, the relationship between the needle lift amount and the injection amount is not at all known from this device.

In addition, a fuel pressure gauge is provided to measure the valve opening pressure and observe the injection state (Japanese Patent Application Laid-Open No. 58-217761), and to measure the movement amount of a servo plunger to measure the fuel injection amount. (Japanese Utility Model Publication No. 60-23248),
In any case, the relationship between the lift amount and the injection amount of the needle nozzle cannot be measured.

The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an injection nozzle characteristic measuring device capable of measuring a relationship between a needle nozzle lift amount and an injection amount under injection conditions that are close to actual conditions. It is in.

Means for Solving the Problems In order to achieve the above object, according to the present invention, a liquid is supplied to an injection nozzle including a needle nozzle and a body nozzle, and the liquid is discharged from the injection nozzle to eject the liquid. An apparatus for measuring characteristics of a nozzle, a pressure setting means for maintaining a pressure of a liquid supplied to the injection nozzle at a set pressure during a measurement operation, and a desired lift of the needle nozzle with respect to the body nozzle. Needle moving means for relative movement by an amount, needle lift measuring means for measuring a lift amount of a needle nozzle by the needle moving means, and an injection flow rate which is an amount of liquid flowing through the injection nozzle can be continuously measured. Injection flow rate measuring means, the needle lift amount measured by the needle lift amount measuring means, and the injection flow rate measuring means Therefore, the gist of the present invention is an injection nozzle characteristic measuring apparatus including a measurement data recording unit for recording the measured injection flow rate and the temporal correlation between the two while clearly indicating the correlation.

[Operation] The pressure setting unit maintains the pressure of the liquid supplied to the ejection nozzle at the set pressure during the measurement operation of the nozzle characteristics. Thereby, the precondition for nozzle characteristic measurement that the supply pressure of the liquid is constant is set. As the needle moving means moves the needle nozzle relative to the body nozzle, the opening degree of the injection nozzle changes, and the amount of liquid flowing through the injection nozzle (that is, the injection flow rate) changes accordingly. At this time, the lift amount of the needle nozzle is measured by the needle lift amount measuring means, and the injection flow rate is continuously measured by the injection flow rate measuring means. The needle lift amount and the injection flow rate measured in this way are recorded by the measurement data recording means while clearly showing a temporal correlation between the two. Therefore, data on the correlation over time between the needle lift amount and the injection flow rate can be accurately obtained. In particular, since the needle nozzle is moved to a desired lift amount by the needle moving means, it is not only possible to grasp the relationship with the injection flow rate in a state where the needle nozzle is stopped at a specific lift amount, but in the process of moving the needle nozzle, It is possible to grasp a more realistic relationship between the needle lift amount and the injection flow rate.

First Embodiment Hereinafter, a first embodiment of the present invention will be described. The present invention is not limited to these, and includes various embodiments in a range not departing from the gist thereof.

1 to 3 show a fuel injection nozzle characteristic measuring apparatus according to the present embodiment. 1 is an overall schematic configuration diagram, FIG. 2 is a vertical sectional view in the front direction of the measuring unit, and FIG. 3 is a vertical sectional view in the right side direction of the measuring unit.

This characteristic measuring device includes a pressure setting unit 1, a measuring unit 3, and a calculating unit 5. In the pressure setting unit 1, a hydraulic pump 9 driven by a hydraulic pump motor 7 pumps up a hydraulic oil 13 in an oil tank 11, sets a predetermined pressure with a relief valve 15, and sets a predetermined pressure through a servo valve 17. The pressure is fed to the left chamber 19b or the right chamber 19c separated by the piston 19a of the servo cylinder 19. The rod 19d of the servo cylinder 19 is the pressure generating cylinder 2
One rod 21a is connected, and both 19d and 21a are integrated. A pressure gauge 22 is provided at the outlet of the hydraulic pump 9 so that the set hydraulic pressure can be observed.

In a fuel chamber 21c provided on the right side of the piston 21b of the pressure generating cylinder 21 in the drawing, fuel 29 pumped from a fuel tank 27 by a fuel pump 25 driven by a fuel pump motor 23 passes through a check valve 31. Supplied. The fuel 29 is also supplied to the reservoir tank 33 and the measuring section 3 side.

The reservoir tank 33 is provided with a pressure gauge 35 and a pressure converter 37, and the pressure of the fuel 29 in the reservoir tank 33 can be observed by the pressure gauge 35. Also a pressure transducer
The pressure data detected by 37 is output to the servo amplifier 41 as a voltage signal by the dynamic strain meter 39. Servo amplifier 41
Compares the voltage from the dynamic strain meter 39 with the voltage set in the control power supply 43, and, based on the result,
Is switched.

The servo valve 17 is a four-port three-position valve.
The center position 17a is set by 41. In the case of the center position 17a, the communication between the hydraulic pump 9 and the servo cylinder 19 is shut off, and the hydraulic pressure in the servo cylinder 19 is maintained.

When the voltage on the dynamic strain meter 39 side is lower, that is, when the fuel pressure in the reservoir tank 33 is lower than the set pressure, the servo valve 17 is set to the offset position 17b on the left side in the drawing.
At the left offset position 17b, the hydraulic oil 13 from the hydraulic pump 9 is supplied to the left chamber 19b of the servo cylinder 19 and the right chamber 1
9c is opened to the oil tank 11 and the differential pressure is
Is biased rightward in the figure. This pressure is applied to the piston 21b of the pressure generating cylinder 21 to increase the pressure of the fuel in the fuel chamber 21c. Therefore, the pressure of the fuel in the reservoir tank 33 communicating with the fuel chamber 21c and the pressure of the fuel supplied to the measuring section 3 also increase.

This state continues until the fuel pressure reaches the set pressure.When the fuel pressure reaches the set pressure, the voltages of the dynamic strain gauge 39 and the control power supply 43 become the same, the servo valve 17 returns to the center position 17a, and the servo cylinder 19 Is maintained.

Conversely, when the fuel pressure in the reservoir tank 33 exceeds the set pressure, the voltage output from the dynamic strain meter 39 increases. Therefore, the servo amplifier 41 moves the servo valve 17 to the offset position 17c on the right side of the figure so that the voltage of the dynamic strain gauge 39 and the voltage of the control power supply 43 become the same, that is, the fuel pressure in the reservoir tank 33 decreases. Switch. At the right offset position 17c, the hydraulic oil 13 from the hydraulic pump 9 is supplied to the right chamber 19c of the servo cylinder 19, the left chamber 19b is opened to the oil tank 11, and the differential pressure causes the piston 19a to move in the left direction in the figure. Energize. Therefore, the pressure inside the fuel chamber 21c of the pressure generating cylinder 21 is reduced. This state continues until the fuel pressure reaches the set pressure, and when the voltages of the dynamic strain gauge 39 and the control power supply 43 become the same, the servo valve 17 is returned to the center position, and the pressure state of the servo cylinder 19 is maintained. .

Thus, the pressure setting unit 1 controls the fuel pressure to the pressure set by the control power supply 43 and supplies the fuel pressure to the measuring unit 3 side.

As shown in FIGS. 2 and 3, the measuring section 3 includes an injection nozzle attaching section 1a, a needle lift measuring section 1b, and a needle thrust measuring section.
1c, a needle moving unit 1d, and a fuel flow measuring unit 1e. These are fixed to a vertical plate 45a of the base 45.

The injection nozzle mounting portion 1a includes a nozzle mounting base 47 and a nut nozzle retaining 49 screwed to an outer threaded surface of the cylindrical injection valve housing portion 47a, and the injection nozzle to be measured.
51 is fixed in a posture of jetting vertically upward with respect to the horizontal plane. This fixing is performed by inserting the spacer member 53 into the inner bottom portion of the injection valve housing portion 47a, then inserting the base side of the injection nozzle 51 and inserting the injection nozzle 51 into the through hole of the nut nozzle retaining 49.
The nut nozzle retaining 49 is screwed into the threaded outer peripheral surface of the injection valve housing part 47a by inserting the tip of the nut into the nozzle nozzle retaining 49. The injection nozzle 51 includes a body nozzle 51a and a needle nozzle 51b inside the body nozzle 51a, and an oil reservoir 51 is provided between the body nozzle 51a and the needle nozzle 51b.
c is provided. The oil sump portion 51c is provided with a port 47b provided in the nozzle mounting base 47 and three fuel passages 47.
It communicates with the reservoir tank 33 by c, 53a, 51d.
Therefore, the reservoir tank 33 is filled with the same pressure fuel.

The nozzle mounting base 47 is provided with a sliding hole 55 which is opened at the inner bottom of the injection valve housing 47a and penetrates on the opposite side. A pressure pin 57 is slidably inserted into the sliding hole 55. The distal end surface of the upper protruding end 57a of the pressure pin 57 has a spherical shape and is in point contact with the lower end plane of the needle nozzle 51b. A disc-shaped sensor plate 59 made of a ferromagnetic material is fitted and fixed to the lower protruding end 57b of the pressure pin 57. Therefore, the sensor plate 59 is a pressure pin
Moves with 57 moves.

The needle lift amount measuring unit 1b uses the sensor plate 59
And an adjacent stroke sensor 61. Since the stroke sensor 61 is fixed to the base 45 side, the movement of the pressure pin 57 changes the gap between the stroke sensor 61 and the sensor plate 59. The stroke sensor 61 detects the distance of the gap from a change in the magnetic field of the electric coil provided therein, and outputs an electric signal corresponding to the distance.

The needle thrust measuring section 1c includes a load cell 63, a leak fuel receiving section 65, a slide shaft 67, two slide bearings 69, and a housing 71 thereof. Load cell
The distal end of the pressure receiving portion 63a has a spherical shape and is in point contact with the planar end surface of the lower protruding end 57b of the pressure pin 57. The load cell 63 is fixed to the upper end 67a of the slide shaft 67 via a base 63b with bolts or the like. The leak fuel receiving portion 65 is fixed to the base 63b with bolts or the like, and its peripheral wall 65a surrounds the load cell 63. Since the slide shaft 67 is supported by the slide bearing 69, it can be moved to a desired vertical position while maintaining its axial position.

The nozzle mounting base 47 of the injection nozzle mounting portion 1a and the stroke sensor 61 of the needle lift measuring unit 1b are fixed to the housing 71 of the needle thrust measuring unit 1c.

The needle moving unit 1d includes a pressure shaft 73, a feed screw 75, a worm wheel 77, a worm 79, and a handle 80.
It has. These components are housed in a gear box 81. The pressure shaft 73 includes a sliding hole member 81a.
Is slidably inserted in a vertical direction into a slide hole 81b provided at the center of the. The sliding hole member 81a is integrated with the gear box 81 by bolts. The upper end of the pressure shaft 73 has a spherical shape and is in point contact with the lower end plane of the slide shaft 67.

On the other hand, a threaded portion 73a is formed in a screw shape on the outer peripheral surface on the lower end side having a smaller diameter than the upper end side, and the screw hole 7 at the center of the feed screw 75 is formed.
It is screwed with 5a. A sliding groove 73b is provided in the upper end side of the pressure shaft 73 in the axial direction, and a pin 81c protruding from the sliding hole member 81a is inserted. Therefore, the pressure shaft 73 can slide in the vertical direction, but its rotation is restricted.

The feed screw 75 is fixed to the worm wheel 77 with a bolt 75c via a spacer 75b. Worm wheel
77 is rotatably supported by a sliding hole member 81a via a bearing 77a. The worm 79 meshed with the worm wheel 77 is directly connected to the handle 80, and can be operated by the handle 80 so as to be rotatable left and right.

Therefore, the operator moves the handle 80 rightward (in the direction of arrow A).
The worm 79 rotates clockwise, which causes the worm wheel 77 to rotate counterclockwise when viewed from above.
At the same time, the feed screw 75 also rotates counterclockwise, but since the pressure shaft 73 screwed to the feed screw 75 cannot rotate due to the pin 81c, the screw between the screw hole 75a of the feed screw 75 and the threaded portion 73a of the pressure shaft 73 is formed. Sliding occurs at the mating surface, and the pressure shaft 73 moves downward.

The pressure shaft 73 is connected to the needle nozzle via the slide shaft 67, the load cell 63, and the pressure pin 57.
Since the needle nozzle 51b receives the downward force, the needle nozzle 51b moves by the same amount as the movement amount of the pressure shaft 73 because the needle nozzle 51b receives the downward force. Since the amount of movement of the pressure shaft 73 can be adjusted by the amount of rotation of the handle 80, the amount of lift can be arbitrarily adjusted with the handle 80.

The fuel flow measuring unit 1e includes a flow meter 83, a pressure gauge 85, and a variable throttle valve 87. Among them, the flow meter 83 is the injection nozzle 51
It outputs the flow rate of the fuel injected from the ECU as an electric signal. The variable throttle valve 87 reduces the back pressure during fuel injection by 1 k.
g / cm ² or more to reduce bubbles in the fuel
This is to eliminate the influence on the detected value.

The calculation unit 5 constituting the measurement data recording means includes a calculation circuit
89, a display device 91 and a plotter 93. Arithmetic circuit 89
Receives electric signals from the stroke sensor 61, the load cell 63, and the flow meter 83, performs predetermined calculations, and outputs the results to the display device 91 or the plotter 93 as characters or graphs. In this embodiment, a timing chart of distance data, thrust data, and flow rate data obtained from the electric signal is output to the plotter 93.

In addition to this, the characteristic measurement device
7 and filters 99 and 101.

Next, an example of measurement using the characteristic measuring device of this embodiment will be described. FIG. 4 shows a timing chart of each detection value during measurement.

First, adjust the control power supply 43 to reduce the fuel pressure to 200 kg / cm ²
Set to. When the fuel pressure is stabilized, the rotation of the handle 80 is started next. Initially, the needle nozzle 51b is seated on the seat portion of the body nozzle 51a, and pressure is applied from the handle 80 side.Before the control nozzle 51 opens, as the handle 80 rotates, the load cell 63 The needle thrust F detected at (1) temporarily decreases (t0 to t1). Then, as the pressure shaft 73 moves downward, the slide shaft 67, the load cell 63, and the pressure pin 57 also move downward while maintaining contact with each other due to the needle thrust (pressure) F.

At this time, due to the downward thrust by the fuel pressure of the oil sump portion 51c between the body nozzle 51a and the needle nozzle 51b, the lower end surface of the needle nozzle 51b moves to the upper projecting end 57a of the pressure pin 57 moving downward. Try to maintain the contact state. Therefore, the needle nozzle 51b moves downward together with the pressure pin 57. For this reason, the tip end surface of the needle nozzle 51b starts to separate from the body nozzle 51a (t1). When starting to separate, the high pressure fuel pressure also acts on the tip of the needle nozzle 51b that has been receiving the low pressure on the flow meter 83 side. Therefore, as shown in FIG. 4, the needle thrust F increases.

Thereafter, the needle nozzle 51b moves downward together with the pressure pin 57, so that the needle lift increases in proportion to the rotation of the handle 80. During the increase (t2)
If the lift becomes sufficiently large, the needle nozzle 51
b The fuel pressure at the tip becomes maximum, and as a result, the needle thrust F reaches the maximum value. Further, since the opening area becomes maximum before and after, the injection flow rate Q also reaches the maximum value. Therefore, the needle lift increases linearly until the rotation of the handle 80 is stopped, but the needle thrust F and the injection flow rate Q do not change. And when the rotation of the handle 80 stops,
The needle lift also stops increasing (t3).

Next, when the rotation of the handle 80 to the left is started (t4), the pressure pin 57 is pushed up, and the needle thrust F, the injection flow rate Q, and the needle lift return to the original pattern in the reverse pattern. When the needle nozzle 51b is seated on the seat portion of the body nozzle 51a (t5), the handle 8
Stop 0 rotation. However, after seating, a little pressure is applied from the handle 80 side due to friction or the like, so that the output value of the load cell 63 slightly increases.

According to the present embodiment, as described above, the needle nozzle 51
The relationship between the needle lift amount and the injection flow rate Q in the dynamic state as well as the static state in b is clarified. Further, since the load cell 63 measures the needle thrust F between the pressure pin 57 and the slide shaft 67, the relationship with the needle thrust F can be determined at the same time. Therefore, it is possible to obtain an accurate value of the actual injection port flow coefficient α and the like, and it is possible to provide useful data for designing an actuator of the fuel injection valve.

Further, the needle thrust F may vary depending on the frictional force when sliding between the body nozzle 51a and the needle nozzle 51b and between the nozzle mounting base 47 and the pressure pin 57. In other words, in FIG. 4, if L1 indicates a forward path and L2 indicates a return path, a step d occurs between the forward path L1 and the return path L2. If the frictional force between the nozzle mounting base 47 and the pressure pin 57 is set to be negligible, 1/1 / the step d is set.
2 represents the frictional force between the body nozzle 51a and the needle nozzle 51b, so that the frictional force can be measured. The actual needle thrust Fa when this friction force appears
Is a value (Fb + d / 2) obtained by adding d / 2 to the needle thrust Fb measured in the forward path L1.

Also, part of the fuel in the oil sump 51c is
The fuel leaks from the gap between the body nozzle 51a and the needle nozzle 51b, but this fuel passes through the spacer member 53 and the gap between the nozzle mounting base 47 and the pressure pin 57, and further flows on the upper surface of the sensor plate 59. It hangs down from the edge and accumulates in the leak fuel receiving portion 65. Since this leaked fuel is discharged from the discharge port 65b, if the flow rate is measured, the leak amount of the injection nozzle 51 can also be measured.

Further, in the above embodiment, measurement was performed by manually rotating the handle, but of course, by moving the needle nozzle 51b according to the set pattern under the control of the control device using various rotation driving devices, The measurement may be performed fully automatically.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a partial schematic configuration diagram of the pressure setting unit 1 and the measurement unit 3 in the injection nozzle characteristic measuring device, and FIG. 6 is a partially enlarged cross-sectional view of the injection nozzle attachment unit 1a.

In this embodiment, the mounting position of the flow meter 83 for measuring the flow rate of the fuel, and the shape of the spacer member 53 fitted into the inner bottom of the injection valve housing 47a are different from those of the first embodiment, The configuration is the same as in the first embodiment. Hereinafter, these differences will be described in comparison with the first embodiment.

In the first embodiment, as shown in FIG. 1, a flow meter 83 is mounted on the downstream side of the injection nozzle 51, and the flow rate of the injected fuel from the injection nozzle 51 is measured. This way,
When the fuel is injected from the injection nozzle 51, the pressure of the fuel rapidly drops from about 200 kg / cm ² , and as a result, the bubbles contained in the fuel expand and the measurement accuracy of the flow meter 83 increases. May be affected. For this reason, in the first embodiment, the back pressure at the time of fuel injection by the variable throttle valve 87 is 1 kg / cm
^It is set to ² or more (approximately 5 kg / cm ² ) to reduce the amount of bubbles in the fuel to address the above problem.

However, even if the back pressure is generated by the variable throttle valve 87, it is difficult to completely eliminate the influence of the expansion of the bubble on the measurement accuracy. This is for the following reasons.

FIG. 7 is a diagram showing the relationship between the needle lift amount and the back pressure P, and the relationship between the needle lift amount and the injection flow rate Q;
From this figure, the back pressure at the maximum injection flow rate (when the needle lift is large, the right side of the dashed line in the figure) is about 5 kg / cm ²
However, it can be seen that when the needle nozzle 51b starts to open (when the needle lift is small, the portion on the left side of the chain line in the figure), almost no back pressure is applied. for that reason,
At the start of fuel injection, the effect of the back pressure is hardly observed, and the measurement accuracy of the flow meter 83 is low.

Furthermore, even after the needle nozzle 51b has moved up to some extent, a back pressure of about 5 kg / cm ² is not enough to eliminate the expansion of bubbles, and this expansion may affect measurement accuracy. It is conceivable to increase the back pressure by strongly reducing the variable throttle valve 87, but this is not preferable because the back pressure affects the flow rate.

Therefore, in the second embodiment, as shown in FIG. 5, the flow meter 83 is interposed between the reservoir tank 33 and the injection nozzle 51 in a high-pressure (200 kg / cm ² ) line. By doing so, the difference between the fuel pressures before and after the flow meter 83 becomes almost zero, and it is possible to eliminate the expansion of the bubbles in the fuel due to the rapid pressure change. Therefore, according to this embodiment, the measurement accuracy of the flow meter 83 can be improved as compared with the first embodiment.

In the first embodiment, as shown in FIG. 1, the spacer member 53 has no function of restricting the downward movement of the needle nozzle 51b. Move to. Therefore, the amount of fuel leakage at each part, for example, the amount of leakage at the sliding portion of the needle nozzle 51b with respect to the body nozzle 51a, is
3 cannot be measured.

In contrast, in the second embodiment, as shown in FIG. 6, the upper protruding end 57a of the pressure pin 57 has a smaller diameter than the lower end of the needle nozzle 51b, and the spacer member 53 through which the upper protruding end 57a is inserted. The inner diameter of the through hole 53b is smaller than the lower end of the needle nozzle 51b.

For this reason, when the pressure pin 57 is moved down, the needle nozzle 51b moves down integrally with the pressure pin 57 until the lower end surface of the needle nozzle 51b comes into contact with the upper surface of the spacer member 53. Needle nozzle when touched
Further downward movement of 51b is regulated.

In this way, it is possible to measure the amount of fuel leakage based on the gap A between the outer peripheral surface at the lower end of the needle nozzle 51b and the inner peripheral surface at the lower end of the body nozzle 51a. In addition, when the lower end surface of the needle nozzle 51b contacts the upper surface of the spacer member 53, the amount of fuel leakage based on the gap B between the two can be measured. These will be described with reference to the timing chart shown in FIG. The vertical axis in FIG. 8 indicates the needle thrust F, the injection flow rate Q, and the needle lift amount, respectively.

When the right rotation of the handle 80 is started to lower the pressure pin 57 and the needle nozzle 51b (t0), the needle nozzle 51b is pushed up by the pressure pin 57, and the lower end surface of the needle nozzle 51b is a spacer. The space S is largely separated upward from the member 53, and a space S is formed between them (see the solid line in FIG. 6). Therefore, the fuel passage
The fuel supplied to the oil sump portion 51c through the cylinders 47c, 53a, and 51d passes through the gap A and then enters the space S. Further, the fuel flows into the gap C between the spacer member 53 and the nozzle mounting base 47 and the pressure pin 57.

Therefore, assuming that the amount of fuel leakage based on the gap A is e1, the tip of the needle nozzle 51b starts to separate from the body nozzle 51a (t1), the injection flow rate Q becomes maximum (t2), and the lower end surface of the needle nozzle 51b is Until the upper surface of the member 53 contacts (t3), the injection flow rate Q increases by the leak amount e1 as compared with the first embodiment.

Needle nozzle with lowering of pressure pin 57
When the lower end surface of 51b comes into contact with the upper surface of the spacer member 53, the downward movement of the pressure pin 57 continues, but the downward movement of the needle nozzle 51b is regulated by the spacer member 53, so that the needle thrust F sharply increases. descend.

At this time, if there is no gap B between the lower end surface of the needle nozzle 51b and the upper surface of the spacer member 53, the leak amount e1 based on the gap A becomes 0, and the injection flow rate Q becomes as shown by the broken line in FIG. , The leakage amount e1 decreases. However, if there is any gap B, the fuel passing through the gap A enters the gap C via the gap B.

Here, when the leak amount based on the gap B is represented by e2 and the actual leak amount is represented by e3, the latter leak e3 is not the same as the leak amount e1 based on the gap A, but is equal to the leak amount e2 based on the gap B. Only many. With this in mind,
Based on the timing chart of the injection flow rate Q obtained by the measuring device of the present embodiment, the gap B is obtained from the relational expression of e2 = e1−e3.
The fuel leak amount e2 can be obtained based on the following equation.

After the lower end surface of the needle nozzle 51b contacts the upper surface of the spacer member 53, when the rotation of the handle 80 is stopped, the increase in the needle lift is stopped (t4).

Next, when the left rotation of the handle 80 is started (t5), the pressure pin 57 comes into contact with the needle nozzle 51b and pushes up (t6), and the needle thrust F, the injection flow rate Q, and the needle lift amount are reversed. Go back in the pattern. Then, when the tip of the needle nozzle 51b is seated on the seat portion of the body nozzle 51a (t7), the rotation of the handle 80 is stopped.

In the timing chart of the needle thrust F shown in FIG. 8, the solid line L1 indicates the forward path, and the broken line L2 indicates the return path. A step d similar to that of the first embodiment is provided between the forward path L1 and the return path L2.
May occur. Therefore, based on the step d,
The friction force (d / 2) between the body nozzle 51a and the needle nozzle 51b can be measured.

FIG. 9 is a diagram showing the characteristics of the needle nozzle 51b obtained by the measuring device of the present embodiment. In the figure,
The horizontal axis is the needle lift, and the vertical axis is the needle thrust F
And the injection flow rate Q. From this figure, the needle nozzle 51
The relationship between the needle lift amount and the injection flow rate Q when b is moved and the relationship between the needle lift amount and the needle thrust F are also found. Further, a leak amount e1 based on the gap A and a leak amount e2 based on the gap B are also found.

Furthermore, according to the present embodiment, in addition to the above-described functions and effects, since the flow meter 83 is mounted between the reservoir tank 33 and the injection nozzle 51 in the high-pressure line, the injection flow rate of the flow meter 83 It is not necessary to set a back pressure at the time of measurement, so that the variable throttle valve 87 can be omitted. For this reason, not only the back pressure adjustment work using the variable throttle valve 87 in the first embodiment becomes unnecessary, but also the number of parts can be reduced by the variable throttle valve 87.

[Effects of the Invention] According to the injection nozzle characteristic measuring device of the present invention, the needle nozzle is moved while the supply pressure of the liquid to the injection nozzle is maintained at the set pressure, and the lift amount and the injection flow rate of the needle nozzle during that time Can be measured and recorded while revealing the correlation over time between the two.
For this reason, the relationship between the needle lift amount and the injection flow rate can be obtained in a state close to the situation where the injection nozzle is actually used, and thus, useful data for analyzing the characteristics of the injection nozzle can be obtained.

[Brief description of the drawings]

1 to 4 show a first embodiment embodying the present invention, FIG. 1 is an overall schematic configuration diagram of a fuel injection nozzle characteristic measuring device,
FIG. 2 is a vertical sectional view in the front direction of the measuring unit, FIG. 3 is a vertical sectional view in the right side direction, FIG. 4 is a timing chart of measured values, and FIGS. For example,
FIG. 5 is a schematic configuration diagram of a pressure setting unit and a measuring unit in the injection nozzle characteristic measuring device, FIG. 6 is a partially enlarged sectional view of the injection nozzle attachment unit, and FIG. FIG. 8 is a diagram showing the relationship between the pressure and the injection flow rate, FIG. 8 is a timing chart of the needle thrust, the injection flow rate and the needle lift amount, and FIG. 9 is a view showing the characteristics of the injection nozzle obtained by the measuring device. 1 ... Pressure setting section as pressure setting means, 1a ... Injection nozzle mounting section, 1b ... Needle lift amount measurement section as needle lift amount measurement means, 1c ... Needle thrust measurement section
1d ... Needle moving part as needle moving means, 1e ...
... Fuel flow rate measuring section as injection flow rate measuring means, 3 ... Measuring section, 5 ... Calculating section as measurement data recording means, 51 ...
... injection nozzle, 51a ... body nozzle, 51b ... needle nozzle, 61 ... stroke sensor, 83 ... flow meter.

Claims (1)

(57) [Claims] 1. An apparatus for supplying a liquid to an injection nozzle composed of a needle nozzle and a body nozzle and discharging the liquid from the injection nozzle to measure characteristics of the injection nozzle. Pressure setting means for maintaining the pressure of the liquid supplied to the ejection nozzle at a set pressure; needle movement means for relatively moving the needle nozzle by a desired lift amount with respect to the body nozzle; and the needle movement means Needle lift amount measuring means for measuring the lift amount of the needle nozzle due to the above, injection flow rate measuring means capable of continuously measuring the injection flow rate which is the amount of liquid flowing through the injection nozzle, and the needle lift amount measuring means The needle lift amount and the injection flow rate measured by the injection flow rate measurement means are compared with each other over time. Injection nozzle characteristic measurement apparatus comprising the measurement data recording means for recording with explicit relationships.