JPS5837485B2 - Injection amount measurement method and measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measuring method and a measuring device suitable for measuring the injection amount of an injection pump that injects fuel oil into an internal combustion engine, particularly a diesel engine. Used for pump adjustment and inspection.

Conventionally, in the method of measuring the injection amount of this type of injection pump, fuel oil is injected from the nozzle of the pump to be measured into the injection chamber for measurement, the injected fuel oil pushes and displaces the piston, and the displacement of the piston is measured. A displacement detector consisting of a differential transformer converts it into an electrical signal, and this electrical signal is further input to a computing unit, which uses the electrical output of the displacement detector before injection of the pump to be measured as a reference zero, and calculates the The electrical output of the displacement detector after injection from the measurement pump is converted into an injection amount and displayed.

However, according to the study conducted by the inventor of the present invention, it has been found that the above measurement method cannot measure the injection amount with high precision for the following reasons.

That is, in the above method, since there is a large pressure difference (for example, about 7 kg/cr!) between the injection chamber pressure before injection of the pump to be measured and the injection chamber pressure after injection, the volume increase due to injection in the injection chamber There is a problem in that the amount is reduced by the compression volume due to the pressure difference, and the injection amount is measured to be smaller than the actual injection amount by that amount.

In particular, not only fuel oil but also a small amount of gas is mixed in the injection chamber, and since the volume of gas is inversely proportional to pressure, the compressed volume increases due to the increase in pressure.

For example, when the injection chamber volume is 400 mm, the compressed volume of gas and compressed volume of fuel oil ranges from about 2 to 61 n♂,
The injection amount was measured to be smaller by this compression volume, making it impossible to measure the injection amount with high accuracy.

The present invention has been made in view of the above-mentioned fact, and the pressure in the injection chamber is raised to a predetermined pressure in advance before the injection of the measured injector, and then the measured injection is injected into the injection chamber where the pressure has increased. By injecting a liquid such as fuel oil from a container and displacing the displacement member due to the increase in volume of the injection chamber due to this injection, and measuring the injection amount from the displacement amount, It is an object of the present invention to provide a measuring method and a measuring device that can measure the injection amount for each injection with high precision while minimizing measurement errors.

The present invention will be described in detail below with reference to Examples.

FIG. 1 schematically shows the overall configuration of an apparatus for carrying out the method of the present invention, in which 1 is a prime mover consisting of a motor, which moves a measured injector 2, an ejector 3, and a pressure riser 4 in a predetermined manner. It is driven in the order of operation.

5 is an injection chamber for measurement, 6 is a displacement member that displaces according to the volume change of the injection chamber 5, I is a displacement detector that converts the amount of displacement of the displacement member 6 into an electric quantity, and 8 is a displacement detector 1 of this displacement detector 1. This is a calculation unit that calculates and displays the injection amount by calculating the electrical output.

FIG. 2 illustrates a specific configuration of the device shown in FIG.
It consists of 2,103,104.

The metered injector 2 includes a metered pump 200 used as a fuel injection pump for a diesel engine, and a discharge pipe 20.
1 and an injection nozzle 203 that injects fuel oil into the injection chamber 5.

The pump 200 to be measured is operated by a cam 200a that rotates together with the shafts 101 to 104.

The ejector 3 includes a cam 300 that rotates together with the shafts 101 to 104, a tappet 301 that slides on the cam 300, a spring 302 that presses the tappet 301, a valve 303, and an ejector that is opened and closed by the valve 303. It consists of an oil passage 304 and a valve seat 305 on which the valve 303 is seated, and the fuel oil in the injection chamber 5 is discharged to the outside through the oil drain passage 304.

The pressure riser 4 includes an injection pump 400 and a discharge pipe 40
1 and an injection nozzle 402 that injects fuel oil into the injection chamber 5, and the injection pump 400 has shafts 101 to 104.
It is operated by a cam 400a that rotates together with the cam 400a.

The displacement member 6 is a piston 6 having a stepped stopper portion 600.
01, this piston 601 has a spring 6
02, the stepped stopper portion 60 is pressed downward in the figure.
0 comes into contact with the end surface 603 of the piston fitting hole.

The displacement detector I is composed of a differential transformer that generates an electric signal (voltage) according to the position of the movable core 100, and the movable core 700 is connected to the piston 60 by a shaft 701.
1.

The arithmetic unit 8 includes an electric signal 102 from the displacement detector 7, that is, an electric signal 102 corresponding to the amount of displacement of the displacement member 6, and a rotary HALS that generates pulse signals 901 and 902 at predetermined rotational positions A and B of the shafts 101 to 104. Pulse signals 901 and 902 from the generator 9 are input, and by performing predetermined calculations, the injection amount is digitally measured and displayed.

Various known rotary pulse generators can be used as the rotary pulse generator 9. For example, a disc with slits that rotates integrally with the shafts 101 to 104 is used to generate a pulse signal by an optical method by intermittent light to a photoelectric element. It may be something that generates.

Reference numeral 10 denotes an oil supply section that supplies fuel oil to the injection pumps 200, 400.

Reference numeral 11 denotes a main body of the measuring device which houses the injection chamber 5 and holds each of the above-mentioned devices.

FIG. 3 illustrates the basic configuration of the arithmetic unit 8, including an amplifier 801, an analog-digital converter (hereinafter referred to as A/D converter 5) 802, memory circuits 803, 804, and arithmetic circuits 805, 1 to 9999. It consists of an average count setting circuit 806 that can manually set an arbitrary number up to 1, an arithmetic control circuit 801, an addition storage circuit 808, an average value calculation storage circuit 809, and a display circuit 810.

Next, the method of the present invention with the above structure will be explained in order of steps with reference to FIGS. 4 and 5.

A motor 100 of the prime mover 1 has shafts 101 to 104 and drives the cams 200a, 300, 400a and the rotational pulse generator 9 one rotation.

When the shaft rotation angle reaches θ, the cam 300 of the ejector 3 pushes up the tappet 301, and the spring 3
Since the valve 303 is raised via the valve 02, the valve 303 comes into close contact with the valve seat 305 and closes the oil drain passage 304.

Next, the rotation angle of the shafts 101 to 104 progresses to θ2
, the cam 400a of the pressure riser 4 is activated by the injection pump 4.
00, the nozzle 4 is discharged through the discharge pipe 401.
Fuel oil is injected into the injector 5 from 02.

Due to this injection, the pressure in the injection chamber is set to a predetermined pressure P which is slightly higher than the pressure P1 at which the piston 601 starts to displace (as shown in FIG. 5).
A and the piston 601 is displaced.

This is the measurement preparation process shown in FIG.

When the shaft rotation angle reaches θ3 in FIG. 4, the rotation pulse generator 9 generates a rotation pulse 901 and inputs it to the calculation control circuit 807K of the calculation unit 8.

Also, at this time, the piston 601 is displaced by the injection from the pressure riser 4, and the displacement detector 1 detects the output voltage V1.
, the arithmetic control circuit 801 uses the rotation pulse 901 to store a digital signal corresponding to the output voltage V1 of the displacement detector 7 in one of the storage circuits 803.

Next, when the shaft rotation angle slightly advances from θ3 and reaches θ4, the cam 200a operates the measured pump 200 to inject fuel oil into the injection chamber 5 from the nozzle 203.

Due to this injection from the measured pump 200, the pressure in the injection chamber rises to the pressure PB shown in FIGS. 4 and 5, and the pressure in the injection chamber 5 increases.
As the zero volume increases, the piston 601 is displaced and the displacement detector I generates an output voltage V2.

Then, when the shaft rotation angle reaches θ, the rotation pulse generator 9 generates a rotation pulse 902 and inputs it to the calculation control circuit 80t of the calculation unit 8, so this calculation control circuit 80γ
stores the digital signal corresponding to the output voltage v2 in the other storage circuit 804.

Then, the arithmetic circuit 805 calculates the difference V between V2 and V.

(V2 - V1 = vo) to find the injection amount per injection, and this V.

is added to the addition storage circuit 808. The steps up to this point are the measurement steps shown in FIG.

Next, when the shaft rotation angle reaches θ6, the lift of the cam 300 begins to descend, and the tappet 301 descends, so the force of the spring 302 that tries to push up the valve 303 decreases, and the pressure in the injection chamber decreases. Then, the valve 303 opens from the valve seat 305 to open the oil drain passage 304, so the fuel oil in the injection chamber 5 is discharged to the outside through the oil drain passage 304, and the pressure in the injection chamber is reduced to the oil drain passage shown in FIG. The pressure decreases to the latter.

This is the oil draining process shown in FIG.

Note that the pressure inside the injection chamber 5 after oil draining tends to decrease as the injection amount into the injection chamber 5 increases, as shown in FIG. 5, and the pressure after oil draining is P.

In this case, ΔP2 indicates the pressure increase due to the injection from the pressure riser 4, and ΔP indicates the pressure increase due to the injection from the measured injector 2.

The measurement preparation process, measurement process, and oil drain process described above are sequentially repeated as one cycle by the shaft 101 to 1040 rotations of the prime mover 1, and the addition memory circuit 80 of the calculator 8
8 is the output V of the arithmetic circuit 805.

is added by the number N set by the average number setting circuit 806.

The addition output ΣVo of the addition storage circuit 808 is added to the average value calculation storage circuit 809, where it is divided by the number of times N to calculate the average injection amount for the number of injections N, and the display circuit 810 displays the average injection amount. displayed digitally.

By the way, the method of the present invention has the most distinctive features in the measurement preparation process and the measurement process among the series of measurement processes described above.
To further describe this point, in the method of the present invention, before the injection of the pump 200 to be measured, that is, in the measurement preparation step,
By performing auxiliary injection by the pressure riser 4,
The injection chamber pressure is changed to the pressure after draining the oil (e.g. P.

= 10 kg/crA) to a predetermined pressure (e.g. P
A=15 kg/crA), the fuel oil, air bubbles, etc. in the injection chamber 5 are sufficiently compressed in volume at the time when the injection by the pressure riser 4 is completed.

In this way, after the fuel oil, air bubbles, etc. filling the injection chamber 5 have been sufficiently compressed in volume, the measured pump 2
00 injection is performed, when measuring the injection amount of the pump 200 to be measured, there is no influence of errors due to compressed volume of fuel oil, air bubbles, etc. that are filled in the injection chamber 5 in advance, and 1.
This allows the injection amount for each injection to be measured with high precision.

According to an experimental performance example of the method of the present invention, the size of the injection chamber 5 is 400m71L3, and the injection amount of the pressure riser 4 is 10
1n, and the injection amount of the pump 200 to be measured is 0 to i5.
When varied within the range of 0 myrt3, the measurement error per injection is ±0. It was possible to keep the injection amount within a range of 5 mm'', making it possible to measure the injection amount with extremely high accuracy.

FIG. 6 shows another embodiment of the device of the present invention, in which the valve 303 in the ejector 3 is driven by an electromagnetic solenoid, and the cam 300 and tappet 301 of the previous embodiment are eliminated.

306 is an excitation coil of an electromagnetic solenoid, and 30l is a plunger made of a magnetic material that is attracted by this excitation coil 306K, and is integrally connected to the valve 303.

The illustrated position of the plunger 30γ indicates the position where it is attracted by the excitation coil 306.

308 is a spring for returning the plunger 30r.

Further, the pressure increaser 4 is also driven by an electromagnetic solenoid, and the injection pump 400 and the like of the above-mentioned embodiments are eliminated.

403 is an excitation coil of an electromagnetic solenoid; 404 is a plunger made of a magnetic material that is attracted by the excitation coil 403; and is integrally coupled to a piston 405.

406 is a plunger return spring.

When the excitation coil 403 is energized, the plunger 404 is attracted against the spring 406, and the piston 405 moves forward, thereby increasing the pressure within the injection chamber.

In this example, as described above, the cam 300, tappet 301,
By replacing the injection pump 400 and the like with electromagnetic members, the only part of the measuring device of the present invention that is mechanically connected to the injector 2 to be measured is the injection chamber 5, and the shafts 101 to 104 as in the embodiment in FIG. need not be combined by
This has the advantage of increasing the degree of freedom in designing the measuring device.

Further, a bellows 602 is used as the displacement member 6, and one end 602a of the bellows 602 is fixed to the device main body 11, and the shaft r01 of the displacement detector γ is connected to the other free end 602b, so that the pressure inside the injection chamber is The bellows 602 is displaced against the spring force of the bellows 602 itself.

In the embodiment shown in FIG. 6, the shafts 101--
A control circuit 12 is provided to detect the rotation angle of the shaft 104, and the control circuit 12 energizes the excitation coils 306 and 403 at a predetermined shaft rotation angle.

As described above, the present invention can be implemented in various ways, and its application is not limited to measuring the injection amount of fuel injection pumps for diesel engines, but can of course be widely applied to measuring the injection amount of liquid in various fields. It is.

As detailed above, according to the present invention, the injection amount for each injection can be measured with high precision by minimizing measurement errors caused by the compressed volume of liquid, bubbles, etc. filling the injection chamber. It has a positive effect.

Furthermore, there is an effect that the injection amount can be measured immediately without causing a response delay, and the single injection amount can also be easily measured.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of the device of the present invention, FIG. 2 is a sectional view of a main part showing an embodiment of the device of the present invention, and FIG. 3 is a structure of the computing unit 8 shown in FIG. FIG. 4 is a waveform diagram of various parts for explaining the operation of the method of the present invention, and FIG. 5 is a graph for explaining the operation of the method of the present invention, showing changes in the pressure inside the injection chamber. FIG. 6 is a sectional view of a main part showing another embodiment of the device of the present invention. DESCRIPTION OF SYMBOLS 1... Prime mover, 2... Measured injector, 3... Ejector, 4... Pressure riser, 5... Injection chamber, 6... Displacement member, l... Displacement Detector, 8... Arithmetic unit, 11.
...Measuring device main body.

Claims (1)

[Claims] 1. Before the injection of the measured injector, the pressure in the measuring injection chamber is increased to a predetermined pressure, and then the liquid is injected from the measured injector into the injection chamber where the pressure has increased, An injection amount measuring method characterized by displacing a displacement member due to an increase in volume of an injection chamber accompanying this injection, and measuring an injection amount of an injector to be measured from the amount of displacement of this displacement member. 2. Injection amount measurement according to claim 1, characterized in that, before injection from the measured injector, the pressure in the measurement injection chamber is increased to a pressure at which the displacement member starts to change or a pressure slightly higher than that. Method. 3. A measuring injection chamber into which liquid is injected from the measured injector, a prime mover that drives the measured injector, and a prime mover that operates according to the shaft rotation angle of the prime mover, and that operates before injection of the measured injector. a pressure riser that increases the pressure in the injection chamber to a predetermined pressure; and a discharge device that operates according to the shaft rotation angle of the prime mover and discharges the liquid in the injection chamber to the outside after the measurement target injector finishes injection. a displacement member that is displaced according to a change in the volume of the injection chamber; a displacement detector that converts the amount of displacement of the displacement member into an electrical signal; and a displacement detector that calculates the electrical signal of the displacement detector to generate the measured injection. 1. An injection amount measuring device comprising: a computing unit that displays an injection amount of a container.