JPS5939966A - Apparatus for measuring fuel injection timing of engine - Google Patents

Abstract

PURPOSE:To provide accurate fuel injection timing and easy measurement of same even in an engine using a distribution type fuel injection pump by mounting a vibration detector on a spill tube. CONSTITUTION:A spill tube 13 communicates to respective injection nozzles 10A-10F to return surplus fuel to a fuel injection pump 11. The spill tube 13 is provided with a vibration detector 14. When the vibration detector 14 is mounted in the spill tube 13, and fuel is injected from the injection nozzles 10A-10F into cylinders with high pressure the vibration detector detects injection vibration produced in the injection nozzles through the spill tube 13 to thereby measure injection timing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring the fuel injection timing of diesel engines and other engines, and more particularly to a device that allows an inspector at a service factory or the like to easily measure the fuel injection timing.

As a conventional device for measuring the fuel injection timing of a diesel engine, there are nine examples, such as those shown in FIGS. 1 and 2 (Japanese Utility Model Application No. 52-42922).

FIG. 1 is an external view of the fuel injection pump. In FIG. 1, 1 is a fuel injection pump main body, 2 is a delivery pipe that sends fuel from the fuel injection pump main body 1 to the injection nozzle of each cylinder, and 3 is a delivery pipe holder for attaching the delivery pipe 2 to the fuel injection pump main body 1. , 4 is a detector that detects vibrations caused by pressure changes that occur in the delivery pipe when fuel is injected.

FIG. 2 is a block diagram of the circuit of the fuel injection timing measuring device.

In FIG. 2, 5 is an amplifier that increases the signal detected from the detector 4, 6 is a detection circuit that detects the opening timing of the injection nozzle, and 7 is a trigger signal that causes the discharge light emitter to emit light. The bird that generates is the generator.

Reference numeral 8 indicates a discharge light emitter that emits light by the output of the trigger generator 7.

Next, its operation will be explained. In a rotating diesel engine, a detector 4 having a unique resonance frequency is attached to the delivery pipe 2 or delivery pipe holder 3 for the first cylinder of the fuel injection pump 1. The detector 4 picks up vibrations caused by pressure changes that occur in the pipe when fuel is injected at high pressure. The output voltage of the detector 4 due to this vibration is increased by +1JL by the detector 5, and by the detection circuit 6,
A signal corresponding to the injection timing is detected. Tori is the generator 7.

In response to the output of the detection circuit 6, a trigger signal is generated to cause the discharge-light emitter 8 to emit light at the fuel injection timing. The discharge light emitting device 8, which is filled with rare earth inert gas such as neon or xenon, emits light in response to a signal. The measurer observes the mark in a stationary state by irradiating it with the flashing light of the discharge emitter 8 at the dead center mark of the first cylinder or the mark at the start of fuel injection, which is engraved on a rotating part such as the flywheel of the engine. Then, the appropriateness of the injection timing is determined based on the positional relationship with the alignment mark fixed on the engine block side.

However, with the conventional fuel injection timing measuring device as described above,
It is possible to measure this in the case of sub-type fuel injection pumps, which are normally used in truck engines, etc., but it is not possible to measure in the case of distribution-type fuel injection pumps, which are usually used in passenger car engines, etc. There is a problem.

That is, in the conventional apparatus shown in FIGS. 1 and 2,
Although it is supposed to detect pressure changes in the delivery pipe, it actually detects the mechanical vibrations that occur when the auxiliary fuel injection pump opens, through the delivery pipe. However, in the case of a distribution type fuel injection pump, there is no mechanism for generating mechanical vibration when the valve is opened, so it was impossible to measure it using the conventional device as described above.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a device that can accurately measure fuel injection timing regardless of the type of fuel injection pump.

In order to achieve the above object, the present invention has the following features.

In order to send excess fuel back to the fuel injection pump, a vibration detector is installed in the spill tube connected to the injection nozzle, and the vibration caused by injection when the injection nozzle is opened is detected, thereby measuring the fuel injection timing. It is composed of

The present invention will be described in detail below based on the drawings.

FIG. 3 is a diagram showing one embodiment of the present invention, and is a diagram showing a mounting location of a vibration detector.

In FIG. 3, 9 is the engine body, and 10A to IOF are injection nozzles provided in each cylinder.

11 is a fuel injection pump, 12 is a delivery pipe, 13 is a spill tube that communicates with each injection nozzle 10A to IOF in order to return excess fuel to the fuel injection pump 11, and 14 is a vibration detector attached to the spill tube 13. vessel, 1
5 is a lead wire for taking out the signal of the vibration detector J4 to the outside.

If the vibration detector 14 is attached to the spill tube 13 as shown in Section 2, when fuel is injected into the cylinder at high pressure from the injection nozzles IOA to IOF, the injection vibrations generated in the injection nozzle will be transmitted through the spill tube 13. Can be detected.

At the time of inspection, the vibration detector 14 can be attached to the spill tube 13 by screwing, clipping, or the like.

Figure 4 is a comparison diagram of vibration waveforms, when a 5-distribution fuel injection pump is used, (A) is when a vibration detector is attached to the spill tube as shown in Figure 3, and (B) is when a vibration detector is attached to the spill tube as shown in Figure 3. (3 in Figure 1), (C
) is the delivery pipe near the fuel injection pump (2 in Figure 1).
) shows the waveform when installed.

In addition, Sl is the cutoff frequency of the vibration detector signal, 9Q.
The waveform is passed through a kHz bypass filter.

SL detects the open state of the injection nozzle,
The rising time to of 2 indicates the valve opening timing of the injection nozzle, that is, the fuel injection timing.

As can be seen from Figure 4, when a vibration detector is attached to the spill tube in (A), the signal output start point of the vibration detector coincides with time to, so a 5-distribution fuel injection pump is used. The fuel injection timing can be detected accurately even in the case of

However, in the case of B) and (C), the signal of the vibration detector is detected before the 9th point Lo, and it is at that point Lo. No particular change was observed in the signal level. Therefore, it can be seen that when a distributed fuel injection pump is used, it is not possible to accurately detect the fuel injection timing by attaching a vibration detector to the delivery pipe or delivery pipe holder.

Next, FIG. 5 is a block diagram of an embodiment of the fuel injection timing measuring device of the present invention. Further, FIG. 6 is a signal waveform diagram of the apparatus shown in FIG. 5, and +83 to SIO indicate signal waveforms at the locations designated by the same reference numerals in FIG. 5, respectively.

In FIG. 5, the vibration detector 14 is connected to the spill tube 13.
For example, as shown in Figure 3.

Install near the injection nozzle IOA of the first cylinder.

4 A signal S5 having a level is output.

It outputs a signal S6 which remains at a high level while the value after passing through the filter 17 remains at a high level.

As mentioned above, since the vibration detector 14 is installed near the injection nozzle IOA of the first cylinder, the level of the signal S3 is higher when the first cylinder is injected than in other cases. By appropriately setting the comparison level of 20, the signal S6 can be sent only during the first cylinder injection.

This makes it possible to detect injection in the first cylinder.

Next, the counting circuit 21 counts the signal S5, and the count value is 6 (
(in the case of a 6-cylinder engine), a high level signal is output,
And it is reset at the falling edge of the signal S6.

Therefore, the rising edge of the signal S7 from the counting circuit 21 corresponds to the fuel injection timing of the first cylinder.

Next, the variable delay circuit 22 outputs a signal S8 obtained by delaying the signal S7 by a delay time τ1. This delay time τ1 can be changed by the inspector's operation.

The reason why the delay time τ1 is provided in this manner is to delay the light emission timing of the nine light emitters from the fuel injection timing in order to match the light emission timing with the compression top dead center of the first cylinder.

The light emitter 23 emits light in response to the above signal S8.

On the other hand, the delay time measuring circuit 24 measures the time +l+, that is, the delay time τ1, from the rising edge of the signal S7 to the rising edge of the signal S8, and outputs a corresponding signal ``FS9''.

Further, the period measuring circuit 25 measures the period of the signal S7, that is, the period τ2 of two revolutions of the crankshaft, and outputs a signal StO corresponding to the period τ2.

Next, the arithmetic circuit 26 receives the signals S9 and SIO.

By calculating θ-ELX720°, a signal indicating the delay amount, that is, the fuel τ2 injection timing is before the compression top dead center of the first cylinder is outputted, and the angle is displayed on the second display device 27.

Next, a method for measuring fuel injection timing using the above device will be explained.

The inspector first attaches the vibration detector 14 to the spill tube 13 near the injection nozzle of the first cylinder and starts the engine.

Then, by illuminating the top dead center mark of the first cylinder engraved on a rotating part such as the flywheel with flashing light from the light emitter 23, the top dead center mark can be observed in a stationary state, and the top dead center mark is on the side of the engine block. The delay time τ is set by operating the variable delay circuit 22 until the mark appears directly opposite the alignment mark fixed on the
Adjust 1.

The angle θ shown on the display device 27 when adjusted as described above becomes a value indicating the fuel injection timing as an angle before the first cylinder compression top dead center.

Note that the sensor and signal S7 detect the compression top dead center of the first cylinder.
From the rising point of the signal to the point when the signal of the sensor is output ("
A circuit for measuring the time τ0 (corresponding to the above-mentioned τl) up to the two-dimensional point), a means for detecting the engine rotation speed N (rpm), a circuit for calculating θ=' For example, the fuel injection timing can be detected immediately without performing mark alignment, etc., and as explained above by the inspector (according to the present invention, by attaching a vibration detector to the spill tube, it is possible to detect the fuel injection timing immediately). Even in the case of an engine using a distribution type fuel injection pump, which was not possible, the fuel injection timing can be accurately and easily measured.

[Brief explanation of the drawing]

Figure 1 is an external view of a fuel injection pump, Figure 2 is a block diagram of an example of a conventional measuring device, Figure 3 is a diagram of an undiscovered embodiment, and shows where the vibration detector is installed. 4 is a signal waveform diagram of the vibration detector, FIG. 5 is a block diagram of an embodiment of the measuring device of the present invention, and FIG. 6 is a signal waveform diagram of the device shown in FIG. Explanation of symbols 1...Fuel injection pump body 2...Delivery pipe 3...Delivery pipe holder 4...Detector 5...Additional 11" device 6...
Detection circuit 7...Trigger generator 8...Discharge light emitter 9...Engine main body 10A to IOF...
Injection nozzle 11... Fuel injection pump 12... Delivery pipe 13... Spill tube 14... Vibration detector 15
...Lead wire 16...Additional unit 17...
・Filter 18...Detector 19...Comparator 20...Comparator 21...Counting circuit
22... Variable delay circuit 23... Light emitter
24...Delay time measurement circuit 25...Period measurement circuit
26...Arithmetic circuit 27...Display device agent patent attorney Junnosuke Nakamura 1 Figure 1-2 Figure 5P3 Leap 9

Claims (1)

[Claims] 1. A vibration detector attached to a spill tube connected to the injection nozzle as a path for returning excess fuel to the fuel injection pump, and calculation of fuel injection timing from the signal of the vibration detector. and an arithmetic display means for displaying the information, the engine detects injection vibrations generated when fuel is injected from an injection nozzle into a cylinder via a spill tube, and thereby measures fuel injection timing. Fuel injection timing measuring device. 2. The calculation display means detects the time point at which the injection nozzle of a specific cylinder injects from the signal of the vibration detector, and outputs a first signal at each time point, and the first signal can be changed. means for outputting a second signal delayed by a delay time τl; means for emitting light every time the second signal is applied; and means for measuring the delay time τ; 1, a means for measuring the period τ2 of the signal θ−−EL−
Claim 1, comprising: τ2 means for measuring x72o°; and means for displaying the above θ, that is, the fuel injection timing of a specific cylinder expressed as an angle before compression top dead center. A fuel injection timing measuring device for the engine described above. 3. The second calculation display means is a means for detecting the point in time when the injection nozzle of the specific cylinder injects from the signal of the second vibration detector, and outputting the first signal at each time point. ” - means for outputting a third signal when the specified cylinder reaches compression top dead center; means for detecting a time interval τ0 between the first signal and the third signal; and a means for detecting the engine rotational speed N. The present invention is characterized by comprising means for detecting θ-ux36oxτ0, means for calculating θ−ux36oxτ0, and means for displaying the above θ, that is, the fuel injection timing of a specific cylinder expressed as an angle before compression top dead center. A fuel injection timing measuring device for an engine according to claim 1.