JPS5841318A - Detector for quantity of fuel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the delivery of pulses of injected fuel to an internal combustion engine, and more particularly to an apparatus for sensing and indicating the timing and amount of pulses of injected fuel while the engine is operating. Such information is useful in fuel injection systems, particularly in diesel engines, as a source of parameters for engine calibration and feedback control.

The prior art includes various apparatus and devices that provide signals indicating the timing of fuel injection during engine operation. These devices are generally based on the detection of pressure or shock pulses in the fuel injection path, or on the detection of certain characteristic noises or vibrations occurring in the injector or other parts of the fuel system. It is certain that these devices will work properly with diesel engines. Furthermore, a number of fuel injection quantity indicators or indicating systems have been shown in the prior art.

However, these devices are generally very complex, cumbersome to handle, and slow to operate during actual engine operation. Therefore, it is generally used for calibration and testing purposes.

SUMMARY OF THE INVENTION An object of the present invention is to provide a device for informing both the timing and amount of fuel injection for each stroke in a fuel injection system of an internal combustion engine.

A further object of the invention is to provide a device suitable for use during normal operation of a diesel engine mounted on a vehicle.

These objectives are achieved by the apparatus of the invention as described below. In the device of the invention, a body having a cylindrical cavity with an inlet and an outlet on axially opposite sides is inserted into the fuel passage.

A magnetic piston moves in the axial direction inside the cylindrical cavity, and the piston stops at a position where the piston blocks the entrance to the cylindrical cavity. The size of the piston is such that fuel can flow even while being cut through it.

There is a magnetic circuit that includes the piston and an actuation coil that moves the piston. A means of applying a direct current to the coil to move the piston to its stop F position before each injection event, applying an alternating current to the coil so that the voltage across the coil varies depending on the position of the piston. There is a means.

Furthermore, by means of detecting the voltage between both terminals of the coil,
A signal is generated indicating the start of injection when the voltage exceeds a first predetermined reference value.

Further, the detection means indicates the voltage at the moment when the rate of change of the voltage decreases below the second reference value while the detected voltage is higher than the first reference value as the voltage indicating the amount of fuel injected. Details and advantages of the invention will become apparent from the drawings and the following description of the examples.

Please refer to FIG. The diesel engine 10 has a fuel injection system consisting of a plurality of fuel injectors 11, one injector installed in each cylinder, and an injection claw pump 1.
4 and is supplied with fuel by a high pressure fuel pipe 12.

The injection pump 14 is connected to a low pressure pump 18 via a low pressure fuel pipe 16.
receives fuel from the fuel tank 15 and returns the fuel to the tank 15 via the bypass return pipe 19. A fuel filter 20 is included in the low pressure pipe 16 .

The injection system shown in FIG. 1 is standard and well known as described above. It has been used in diesel engines manufactured by Old Mobile Division, the assignee of the present invention, and is described in repair manuals and other publications. The fuel pump 14 is manufactured by Stanadyne (5tanadyne).
Corporation) and is described in the publication.

FIG. 2 shows a combination of the fuel injector 110 of FIG. 1 and the detector 30. Injector 11 includes a housing 22 and a spring-loaded, pressure-actuated mushroom valve 24. The mushroom valve 24 is normally closed, but the injection pump 14
It is opened by a high-pressure pulse of fuel applied via high-pressure pipe 12 from the engine, allowing a portion of the fuel to enter the engine cylinder for combustion.

For convenience of explanation, the injector 11 shown in FIG. 2 is drawn to some extent with an emphasis on its ideal and functional aspects. Also, since this portion of the figure relates to devices known in the prior art, this figure should not be considered as a preferred embodiment. Any suitable pressure-operated injector valve may be used in the present invention, such that the upstream end 26 has just enough force to receive the detector 30.

The detector 30 has a housing 31, and the housing 31
There is an inlet end 32 which serves as an inlet opening and is fitted to connect with one of the high pressure passages 12. The housing 31 further has an outlet end 35 with an outlet opening [
] 36 and is fitted to mate with the inlet end 26 of the injector 11. The inlet opening 33 and the outlet opening 36 are in communication on axially opposite sides of the cylindrical hollow member 3γ, and the connection between the artificial opening 33 and the hollow cavity is made through a passageway 38 of smaller diameter. be exposed. cylindrical piston 4
0 can move in the axial direction inside the hollow member 3γ, and its outer diameter is slightly smaller than the inner diameter of the hollow member 37 and larger (d) than the inner diameter of the passage 38. Therefore, in FIG. , when the piston 40 moves in its leftmost position, it hits the passageway 38 and blocks it, so that the sudden pulse of incoming high-pressure fuel pushes the piston to the right. and hollow member 37
The relationship between the inner diameter of the piston 40 and the inner diameter of the piston 40 is such that although the fuel can flow around the piston and pass toward the injector 11, it is blocked to some extent by the piston and has a tendency to pull the piston 40 along the same direction. be. Medium cavity member 37
A stopper 42 is provided at the outlet end of.

However, the design of the device is such that the piston 40 can reach the stop 42 during normal injection operations.

The housing 31 includes first and second pole pieces 43 and 4.
4 is included. One part 45 of the magnetic pole piece 43 and the hollow member 3
7 forms a winding frame of the coil 46, and the coil 46 is wound there. The piston 40 is made of a magnetic material, and a magnetic circuit is formed by the bowl-shaped magnetic pole piece 43, the disk-shaped magnetic pole piece 44, and the piston, and the roughtance of the magnetic circuit changes depending on the axial position of the piston 40. .

Since the inductance of the coil 46 is determined by this reluctance, the inductance also changes depending on the axial position of the piston. Terminals 47 and 48 are provided for connecting the ends of the coil 46.

The operation of the apparatus of FIG. 2 while the system of FIG. 1 is emitting injection pulses will be briefly described.

The system is initially assumed to have piston 40 blocking inlet passageway 38 and coil 46 being supplied with a suitable alternating current. When the injection pump 14 delivers a high pressure pulse of fuel through the high pressure line to the injector 11 of FIG. drag the piston,
The flow increases the pressure within the injector 11, thereby causing the valve 24 to open and inject fuel into the cylinders of the engine 10. The initial movement of the piston 40 causes the coil 4 to
6, which causes a change in the voltage between the crossed terminals 47 and 48. When this voltage passes through a first reference value, it can be detected by a suitable device as a signal indicating the start of injection by the injector itself.

At the end of the high pressure pulse, as the pressure begins to drop and the injector valve 24 begins to close, the rate of change of displacement of the piston, the voltage across the terminals 47, 48, falls below a second reference value. The voltage between the actual displacement terminals 47 and 48 of the piston 40 at this point is indicative of the actual flow of fuel through the hollow member 37 and into the cylinder through the injector valve 24. . The movement of the piston accurately indicates the amount of fuel moved by the piston and therefore the amount injected. This is because piston overtravel occurs when the fuel flow begins to slow, which compensates for the initial lag of the piston at the beginning of the fuel flow. Therefore, the second
In the device setup shown, terminal 47 is connected between each injection event.
．． Apply direct current between terminals 48 and 47.4.
By monitoring the voltage across these terminals and the rate of change of the voltage while applying an alternating current between the two terminals, it is possible to determine the actual onset of the injection pulse and the amount of fuel released during the injection pulse. can.

FIG. 3 shows an electrical device adapted for use with the device of FIG. 2 in the manner described above.

The device shown in FIG. 3 includes a DC power supply 50 (which may be thought of as an on-board battery) and an AC power supply 51. In this embodiment, the AC power supply 51 is a 100 kilohertz oscillator. Oscillator 5
1, of course, its power is derived from the battery 50. The coil 46 symbolizes the inductance of the coil 46 in FIG. 2, and a series circuit with a resistor 52 is connected to both ends of the oscillator 51. Diode 5 in parallel with coil 46
3 is not connected, the anode of diode 53, coil 4
6 and the junction 54 of the oscillator 51 are grounded. P
The collector of the NP transistor 55 is the diode 53
is connected to the junction of the coil 46 and the resistor 52. The emitter of the PNP transistor raster 55 is connected to the non-ground terminal of the battery 50. The output of the oscillator 51 is directly connected to the synchronization power 58a of the synchronization detector 58. On the other hand, the junction point 56 is connected to the detection force 58b of the synchronization detector 58 via a capacitor 59. Oscillator 5
The output of 1 is further connected to a reference generation circuit 60, which generates a first reference voltage A and a second reference voltage B by a method to be described later, and outputs them to comparators 61 and 62, respectively. to be applied. The output of the synchronization detector 58 is applied to a comparator 61 and also to another input of a comparator 62 via a differentiator 63. Comparators 61 and 6
The output of 2 is given to 1dAND gate 64, and its AND
The output of gate 64 is provided as a set input to sampling gate 65 and a trigger input to sampling timer 66. The output of the synchronization detector 58 is further applied to a sampling input of a sampling gate 65. The output of sampling timer 66 is provided to the reset input of sampling gate 65 and the trigger input of reset timer 67, the output of reset timer 67 being connected to the base of transistor 55. Sampling gate 65
The output of is connected to a hold amplifier 68 which maintains a signal voltage indicative of fuel per stroke. The start of the injection pulse is a sharp-edged signal obtained from the output of comparator 61.

Before describing the operation of the system of FIG. 3, some of the system's components will be described in a little more detail. Oscillator 51 may be any suitable device that can be used with a DC power source, such as a battery. Of course, due to this, adequate shielding must be performed to prevent 100 kilohertz electromagnetic interference from in-vehicle radios and electronic control equipment. The synchronous detector 58 need only be a synchronous detector or sensing circuit capable of providing a direct current similar to the alternating voltage across the coil 46. Sampling timer 66 and reset timer 61j: Any suitable one-shot circuit can be used as long as it can generate an output signal after a predetermined time from the trigger when a trigger is applied. The sampling gate 65 is a simple gate circuit that allows the input signal to pass through when it receives a set input, and blocks it from passing when it receives a reset input. Holding amplifier 68H is a device that maintains the signal applied to its input even after that signal has ceased, in the presence of other signals. The reference signal generator 60 is shown in detail in FIG. The detector 70 is synchronous and its output is connected to a filter 71, the output of which is applied to a pair of voltage dividing potentiometers 72 and 73.
Output voltages A and B are supplied from potentiometers 72 and 73, respectively. Detectors 70 and 71 provide a DC voltage similar to the voltage across the oscillator 51, and potentiometers 72 and 73 divide the DC voltage by a fixed ratio, respectively, to comparators 61 and 71 as reference voltages A and B. 62 each.

Now, let us explain the operation of the system shown in Figure 3.

Before the injection event begins, reset timer 67 turns on transistor 55, providing direct current to coil 46 and generating a magnetic force in coil 46. Thereby, the coil 46
pulls the piston 40 until it meets the pole piece 43 at the end of the inlet passageway 38. The current flowing through the transistor 55 is sufficiently larger than the 100 kHz signal of the oscillator 51, and the 100 kHz signal is merely a pulsating current. This pulsating flow has no effect on resetting the piston 40. However, if you wish to disconnect the DC pulse development oscillator, you can do so.

When the period of reset timer 67 expires, transistor 5
5 is turned off, and a 100 kHz AC signal is applied from the oscillator 51 to the series circuit of the coil 46 and resistor 52, the synchronization detector 58, and the reference signal generator 60, respectively.

The voltage between both terminals of the coil 46 is applied to the synchronous detector 58 via a DC blocking capacitor 59.
is generated in DC representation so that the output can be compared to comparator 610 reference A. Reference A is adjusted by potentiometer 72 so that its value is slightly greater than the output of synchronization detector 58 when the piston is in the initial position. At this time, the output of the differentiator 63 is zero, which is of course smaller than the reference B supplied from the potentiometer 73. At this time, the outputs from comparators 61 and 62 to AND gate 64 are a low output from comparator 61, or O, and a high output, or 1, from comparator 62.

When injection begins and the piston 40 begins to move to the right in FIG. let As the output of sync detector 58 rises, it then passes through base $A, causing comparator 61 to go high or 1 to AND gate 64.
0 input and outputs a signal to start the injection pulse.

This injection pulse start signal is a pulse edge signal and can be used for various purposes in other devices. All of the operations described so far have not included a combustion process in which both inputs to AND gate 64 are high or 1. However, when the injection pulse ends, the increase in the output voltage of the synchronous detector 58 begins to slow down, and
The output of the differentiator 63 rapidly falls below the reference value B. At this point, the output of comparator 62 switches to a high output, causing AND gate 64 to set sampling gate 65 while simultaneously triggering sampling tie 166.

The output of the synchronization detector 58 is passed through a sampling gate 65 to a holding amplifier 68, where it is held as a signal representing the amount of fuel per stroke. Almost immediately thereafter, sampling timer 66 resets sampling gate 65;
Reset timer 67 is triggered to reset the apparatus of FIG. 2 as described above.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the fuel injection system of a diesel engine. FIG. 2 is an axial cross-sectional view of an embodiment of the present invention inserted into one of the fuel injection passages of FIG. 1. FIG. 3 is a block diagram of an electrical control section that includes another part of the invention and can be used in conjunction with the part of FIG. FIG. 4 is a circuit diagram of a reference signal generator that can be used in the apparatus of FIG. [Explanation of symbols of main parts] Main body 30 cylindrical cavity in Fig. 2
37 Magnetic piston (or piston) 40 Means including a magnetic circuit 43 in Figure 2
．． 44.46 Operating coil (or coil)〃46 Resetting means 67.55.5° in Fig. 3 Parameter measuring means 51.52.58.60.6 in Fig. 3
1.62. 63.64.65. 66.68

Claims (1)

[Claims] 1. In a pulsed fuel injection system for an internal combustion engine, the amount of fuel per pulse in a fuel path with a fuel injector is electromagnetically monitored by movement of an element movable with the fuel. A sensing device for sensing by: a body inserted into a fuel passage defining a cylindrical cavity having an inlet and an outlet at each axial end; and a magnetic piston movable from the rest position, the outer diameter of the piston being between the inner diameter of the cylindrical cavity and the liquid flowing past the piston applying an axial force to the piston. means for forming a magnetic circuit with the piston, the actuation coil having an inductance that varies with the axial position of the piston over the range of movement of the piston due to the fuel injection pulse; , a reset means operative to apply a current to the coil to move the piston to the rest position before each injection event, together with an inductance of the coil at least when the piston is within a range of movement of the piston; A fuel quantity sensing device characterized in that it comprises means operative to measure a varying parameter and to determine from said parameter the distance traveled by said piston in response to a fuel injection pulse as a measure of the quantity of fuel injected. . 2. In the detection device according to claim 1, at least when the piston is within a movement range of the piston, a parameter that changes with the inductance of the coil is measured, and from the parameter, it is determined whether the piston is fuel or not. The means for determining the distance traveled in response to an injection pulse as a measure of the amount of fuel injected is also operative to determine the start time of the axial movement of said piston as a measure of the injection time. Fuel amount detection device. 3. The sensing device according to claim 1 or 2, wherein the resetting means applies a large current to the coil to move the piston to the stop position before each injection event, and The parameter measuring means applies the large current and a small alternating current to the coil to measure the voltage between both ends of the coil, and from the voltage and the rate of change of the voltage, the piston responds to the fuel injection pulse. A fuel quantity sensing device characterized in that it determines a substantial distance traveled in a direction. 4. The fuel amount detecting device according to any one of claims 1 to 3, wherein the magnetic piston closes the entrance of the cylindrical cavity at the stop position. 5. In the detection device according to any one of claims 1 to 4, the parameter measuring means determines whether or not to start injection when the voltage detected between both terminals of the coil exceeds a first predetermined standard. A fuel quantity sensing device characterized in that it generates a signal and then indicates the voltage sensed at the moment the rate of change of the voltage decreases by a second predetermined criterion.