JPS5918243A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To increase the accuracy in controlling the injection quantity of fuel, by providing an electrostatic capacity type potentiometer for detecting the operational position of a relief valve in a fuel injection pump of the type controlling the injection quantity of fuel by controlling the operational position of the relief valve. CONSTITUTION:A fuel injection pump shown in the drawing feeds fuel to an injection valve via passages 7-9, etc. after pressurizing fuel in a work space 6 by reciprocating a plunger 3 in the axial direction while causing rotation of the same by the rotation of a cam disk 2. Here, the injection quantity of fuel is controlled by controlling the operational position of a relief valve 29 for opening and closing a relief passage 11. The relief valve 29 consists of an annular permanent magnet 30 and electrode rings 32a, 32b made of a conductive material which are connected to the opposite ends of the permanent magnet 30 by the intermediary of magnetic pole pieces 31a, 31b, respectively. Further, operational position sensors 34a, 34b are attached to the opposite ends of an outside yoke 36 of an actuator 33 for displacing the relief valve 29, and the actuator 33 is feedback controlled in response to the outputs of the position sensors 34a, 34b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel pump in which the position of a relief valve for residual fuel provided in the fuel injection pump is detected using a capacitive potentiometer.

For example, a conventional fuel pump is shown in FIG. 1(a).

There are some as shown in (1)).

In the fuel injection pump 1 shown in FIG. 1(b), a plunger 3 rotates and moves back in the axial direction by the rotation of a cam disc 2 connected to a drive shaft (not shown) of a diesel engine. It is composed of two.

Then, in the suction stroke, when the plunger 1'-3 moves to the left in the figure, the suction vertical groove 4 coincides with the fuel flow passage 5, so that fuel is sucked into the operating space 6 of the plunger 3.

Next, in the discharge stroke, the plunger 3 starts moving to the right in the figure, the sucked fuel passes through the discharge vertical passage 7, and when the discharge vertical groove 8 coincides with the discharge passage 9, the check valve 10 is activated. The liquid is then discharged to an injection valve (not shown) in the cylinder.

At this time, the injection pump 1 finishes discharging the fuel by releasing the remaining fuel from the escape passage 11 formed in the plunger 3 to the outside of the injection pump 1 (space inside the pump housing). The gap is opened by a cylindrical relief valve 12 that is slidably fitted onto the outer periphery of the blank 3. Furthermore, by sliding the relief valve 12, the opening position of the relief passage 11 can be adjusted.

In other words, if the relief valve 12 is moved to the right side in the figure,
The closing period of the escape passage 11 is extended, and the time from the start to the end of ejection of the fuel H is lengthened by 41, and the amount of fuel injection increases. Conversely, if the relief valve 12 is moved to the left in the figure, the period from the start to the end of ejection of the fuel H will be shortened, and the fuel injection amount will be reduced.

-1 The mechanism for performing the sliding operation of the relief valve 12 includes the electromagnet 15, etc. 118 is a permanently rotating member rotatably supported by the housing 17 by the rotating shaft 16 within the space.

A fan-shaped piece 19 is eccentrically attached to the lower end of the rotating shaft 16 (C1-1), and a spherical engagement piece 2o fixed eccentrically with respect to the center axis of one of the fan-shaped pieces is attached to the relief valve 12. It fits into the hole 21, and is configured so that the C relief valve 12 slides as the rotation permanent b1 (3) rotates.

181! The driving current for the electromagnet 15, which determines the rotation angle of the rotary permanent 11<i; 18, is supplied from a control circuit 23 via an amplifier 22, as shown in FIG. 1(a).

The control circuit 23 includes an engine speed signal from the rotation sensor 25, an accelerator pedal position signal from the oscillator 26, and an intake pipe angular pressure (not shown).

Various engine operating parameter signals, such as signals related to engine temperature or ambient temperature, etc., are input, and the fuel output corresponding to the optimum fuel amount determined based on these operating parameters is input. The JJ'ri flow is outputted and supplied to the electromagnet 15.

Furthermore, a feedback control signal is supplied to the control circuit 23 from a differential transformer 27.

That is, the tip of the arm 27b connected to the movable iron core 27a of the differential transformer 27 is connected to the rotating permanent 1) stone 18.
The output of the differential transformer 27, which changes as the movable iron core 278 moves in accordance with the rotation angle of the rotating permanent magnet 18, is supplied to the control circuit 23, and the relief valve 12 is placed in a predetermined position. It is determined whether or not the positioning is accurate, and the rotation angle of the rotating permanent magnet 18 is corrected as appropriate: l? 4 has been completed.

In addition, the -1 rotation adjustment lever 25 is the engine drive switch) -G control (=J-digit toothed disc 24)
llll,! induction coil 2 wound around the magnet 25a
From 5b, the AC pressure proportional to the engine speed is
28 is an oscillator that supplies an alternating current for exciting the primary coil of the differential lance 27.

The above configuration (optimizes fuel efficiency and power performance)
The fuel suspension is controlled.

However, in the conventional fuel injection pump as described above, the operating position of the relief valve '12 is indirectly detected based on the rotation angle of the rotating permanent I11ε3. Errors between the rotating permanent magnet 1B and the rotating shaft 16, eccentricity)
Installation errors between the spherical engagement cap 21 and the like caused by abrasion caused the detection accuracy of the operating position of the relief valve 12 and, by extension, the fuel injection amount control precision. .

This invention was developed in view of the above-mentioned circumstances, and in the fuel If4 pump, which controls the fuel injection amount by adjusting the operating position of the relief valve, as in the conventional example described above,
By configuring the operating position of the relief valve to be directly detected by a capacitive potentiometer,
The purpose of the present invention is to provide a fuel injection pump that improves the detection accuracy of the relief valve operation (fx position) and improves the control accuracy of the fuel injection amount.

Hereinafter, embodiments of the present invention will be described in detail using the drawings from FIG. 2 onwards.

FIG. 2 shows an embodiment of the fuel injection pump according to the present invention.
FIG. 2 is a sectional view showing a first embodiment (hereinafter referred to as a first embodiment). In addition,
Components that are the same as those of the conventional example shown in FIGS.

The hidden fuel injection pump shown in the figure has the same cam disk 2. It has a plunger 3, and is configured so that operations from fuel suction to fuel discharge strokes are carried out in the same way as in the conventional example.

In this fuel 11 injection pump, the relief valve 29 for opening and closing the fuel relief passage 11 is a circular permanent 11 stone 30 that is slidably fitted into the outer periphery of the cylinder 3.
, ring-shaped magnetic pole pieces 31a, 311) made of silkworm material are joined to both ends of this permanent magnet 30, and these magnetic pole pieces 31
It is composed of ring-shaped electrode rings 32a and 3211 made of a conductive material such as aluminum attached to both ends of the permanent magnet 130 via a and 31b.

"M/e," - so as to cover the outer periphery of the recording/relief valve 29 without contacting it. A cutter 1 is provided, and this cutter is wound in an annular shape opposite to the outer periphery of the relief valve 29, and is arranged in parallel in the axial direction of the plunger 3. The two field coils 33a, 33b, 4] An annular magnetic body that covers and fixes the outer periphery of the field coils 33a, 331+. Operating position levers 34a, 3/
It is roughly composed of Ib, etc.

1. As shown in FIG. 4, the Pi1+operation position regulators 1 and 34a and 34b are made of an insulating material such as ceramic or synthetic resin, and have a medium-high annular shape with an annular convex portion 38 formed in the center. Two divided ring-shaped fixed electrodes 35a and 35b made of a good conductor such as copper are formed on two surfaces of the convex portion 38''.
, 35c, and 35d are formed by printing and baking. Furthermore, each of the fixed electrodes 35a, 35b, 35c
, 35d has a lead terminal 3 penetrating to the back surface of the convex portion 38.
7a, 37b, 37c.

37d are connected to each other.

The operating position sensor 34. As shown in FIG. 3, a and 3/Ib are fixed one poles 35a and 3°5b, respectively, fitted to both ends of the outer shaft yoke 36.

350.356 is the electrode ring 32 of the relief valve 29.

32b, and a small gap 1+.

H is distributed with a temperature of 2 degrees Celsius between them.

The sum of the above small gaps 1+ and lz (f+-1-I!, 2) is ~
This is the movement range of the relief valve 29.

Electrical control of the drive a3 of the actuator 1 and detection of the operating position of the relief valve 29 is performed by a control system as shown in FIG.

In the same figure, the deception circuit 40 receives the J signal shown in FIG. omitted) Intake pipe negative pressure.

Various T signals such as engine temperature or ambient temperature etc.
It inputs engine operating parameter signals, calculates the optimum fuel injection amount based on these operating parameters, and supplies the calculated injection fJJ HA data to the control circuit 41.

The control circuit 11 controls the excitation current of the field coils 33a and 33b supplied via the drive circuit 42, and controls the excitation current supplied from the arithmetic circuit 40. J111 T'
- data is compared with detection data of the operating position of the relief valve supplied from the sensor 1/no circuit 43, and the excitation current is controlled so that both are in an equilibrium state.

The drive circuit 42 varies the direction J3 and magnitude of the excitation current supplied to the field coils 33a, 33F) based on the excitation current control signal from the control circuit 41, and controls the relief valve 2.
By changing the magnetic field acting on the permanent magnet 30 of No. 9, the relief valve 29 is moved to a predetermined operating position and adjusted.

The sensor circuit 43 is the operating position sensor 34a.

Based on the capacitance data obtained from 34b, it outputs detection data of the operating position of the relief valve, and constitutes a type of capacitance type potentiometer.

In other words, fixed electrode 35a-electrode ring 32. 'l Variable capacitors C+ and C2 are formed between the fixed electrode 35b and between the fixed electrode 35C, the electrode ring 32b and the fixed electrode 35d, respectively. It is configured to be incorporated into an AC bridge 44 as shown in the figure, and to supply an output based on the level of the unbalanced voltage e to the control circuit 41 as the detection data.

The above unbalanced voltage e is calculated as follows: If the capacitances of the above ]ndenq CI, 02 are shifted from Ca and Cb, e = Vs (
Ca-Cb)/(Ca+Cb)...(1
) (where Vs is the applied voltage), and 1- capacitance Ca, C11 is the small gap 1!1. Since the length of ,l,2 is determined by [1, ecc(,gl-f2)/(f+ -112)...
The following relationship is established: ・<2)°L, and the operating position of the relief valve 29 can be found from this equation (2).

”-The unbalanced voltage e output from the alternating current norditch 44 is rectified by the full-wave rectifier 45, and then passed through the differential amplifier/I6...
After being amplified, it is converted to a DC voltage level via a peak hold circuit 47 and output as detection data.

1, in this combustion pump, the operating position of the relief valve is detected by the operating position lens 34a.
, 34b and J are directly detected, it is possible to greatly improve the detection rate.

J. In this embodiment, the relief valve is composed of an annular permanent magnet 30, and the field coil 33 of the actuator is
By adopting a configuration in which the movement and positioning of the relief valve is performed in a non-contact manner by controlling the excitation current supplied to a and 33b, the conventional J: mechanical aquacony
Compared to the case, the structure is simpler and the error can be reduced.

FIG. 7 is a sectional view showing another embodiment (hereinafter referred to as the first and second embodiment) of the present invention. In the drawings d3 and llil, only the relief valve d3 and the actuator 11 are shown, but the other components are the same as those in the first embodiment, so illustrations and explanations are omitted, and the second
Components that are the same as those shown in the figures are designated by the same reference numerals, and descriptions thereof will be omitted.

As shown in the figure, the relief valve 50 of the fuel injection pump is
Similar to the embodiment, ring-shaped electrode rings 518 and 51b made of a conductive material such as aluminum are attached to both ends of the annular permanent magnet 30 attached to the plunger 3 via 611 pole pieces 31a and 32b. () is being done.

The outer periphery of the electrode rings 51a and 51b is formed into a tapered shape that contracts toward the tip.

Further, as in the first embodiment, the actuator includes a field coil 33a surrounding the outer periphery of the relief valve 50 in a non-contact manner.
, 33b, the jacket yoke 36, and the jacket 3'S
Operating position hinge Q52a, 5 fitted between both ends of 6
2b.

”? d operating position 52a, 59bL, t, the first
Similarly to the embodiment, it is made of an insulating material such as ceramic or synthetic resin, and is formed in a medium convex annular shape with an annular convex portion provided in the center.

The central circular hole is provided with a voltage t4i of the relief valve 50.
The tapered surfaces of the rings 51a and 51fl are formed in a "tapered shape" corresponding to the outer peripheral shape of the rings 51a and 51fl so as to face each other with a small gap therebetween. Fixed electrode 53 in the form of a two-part tapered ring made of a good conductor
a, 53b, 53c, 53 (1) are formed.A3 Although not shown, each of the above fixed electrodes 53a, 53
Lead terminals are connected to terminals b, 53C, and 53d.

1 - A fuel injection pump configured as described below;
The detection operation of the operating position of the tl relief valve and the driving operation of the actuator 1 are carried out by the control system shown in FIGS. 5 and 6 (exactly in the same manner as in the first embodiment). Therefore, the explanation of the operation will be omitted.

Therefore, in the fuel injection pump of this second embodiment,
The relief valve 50 exhibits the same effect as the fuel injection pump of the first embodiment, and as described above, the opposing surfaces of the electrode rings 5ia, 5i11 and the operating position sensors 52a, 52b are tapered to enlarge the electrode area. The change in electrostatic capacitance due to the movement of the relief valve 50 increases, thereby making it possible to further improve the detection accuracy of the operating position of the relief valve 50.

FIG. 8 is a sectional view showing still another embodiment (hereinafter referred to as the third embodiment) of the present invention. Note that in the figure, like the second embodiment, only the relief valve and the acticoator are shown, but the other components are the same as the first embodiment, so illustrations and explanations are omitted. However, the same components are denoted by the same reference numerals, and the description thereof will be omitted.

The relief valve 60 of the fuel injection pump shown in the same figure has a permanent (4★I+30) fitted into the plunger 3 similar to the first embodiment, and a permanent 117:i30 with a number A'' on both end faces thereof. ) i31a, 31b,
Furthermore, an electrode yA64 made of a conductive material such as aluminum and formed in an annular shape with a constant width is provided on the outer circumference of the permanent 14ine 30.

In addition, the same field coils 33a and 33b as in the first embodiment and the jacket yoke 36 are formed around the outer periphery of the relief valve 60 in a non-contact manner, and the jacket yoke 36 are formed by fitting ring-shaped flat plates 61a and 6111 made of an insulator such as ceramic or synthetic resin into the openings at both ends of the field coils 338 and 331). , these field coils 33
An operating position sensor 9'62 is provided which is formed in an annular shape concentric with a and 3311.

As shown in FIG. 9, the one-slot sensor 62 in this operation has a minute gap (for example, several tens of
Fixed electrodes 62a, 6211 made of a good conductor such as copper are formed in an annular shape with a constant width and have inner circumferential surfaces facing each other with a distance of several hundred μm), and are fixed side by side at equal intervals with an insulating material 63. .

62C is formed.

And the three fixed electrodes 62a, 62b.

62G, the central fixed electrode 6211 is used as a common electrode, and the fixed electrode 628 - electrode ring 60 - fixed type...62b is the first
Corresponding to the capacitor vC+ in the example, the fixed electrode 6
2b-electrode ring 60-fixed electrode 62G is similarly configured to correspond to capacitor C2.

In the fuel injection pump configured as shown in FIG. This is carried out in the same manner as in the first embodiment. Therefore, a description of the operation will be omitted.

Therefore, the fuel injection bong of the third embodiment exhibits the same effects as the fuel injection pump of the first embodiment, and as described above, the electrode ring 64 is placed on the outer circumferential surface of the relief valve 60. The electrode ring 64 and the fixed electrodes 62a, 6 are formed by forming the sill 62 in a concentric ring shape such that its inner circumferential surface faces the electrode ring 64.
2b and 62c can be made narrower, thereby increasing the change in capacitance due to the movement of the relief valve 60, and increasing the operating position detection MIa of the relief valve 60. It can be made even more appealing.

In addition, in the "-Registered Example, operation 4 < y, the detection of the capacitance change of the capacitors CI and C2 constituted by each fixed electrode of It is also possible to use other means such as incorporating it into the capacitor and converting it into an oscillation frequency change and detecting it, or incorporating it into a UF extension circuit and converting it into a delay time change and detect it, and the same effect can be obtained. I can do that.

In the named embodiment, the relief valve is provided with an annular permanent magnet, and the movement and position of the relief valve is determined by controlling the excited Ti flow of the actuator. However, the present invention is not limited to this, and other configurations may also be used, and even in that case, the operating position of the relief valve can be directly adjusted by providing an operating position lock sensor as shown in each of the above embodiments. It is clear that it can be detected.

As explained in detail above, in the fuel injection side pump of the present invention, the operation (f/position) of the relief valve is directly detected and covered by a capacitive potentiometer. In addition to improving the detection leakage of the operating position of the relief valve, it is possible to avoid improving the control accuracy of the fuel injection parts, and it is possible to further improve fuel efficiency and ljj performance.

In addition, since the above-mentioned electrostatic potentiometer is not affected by external fields, it has the advantage that it can be integrated with an electromagnetic actuator that moves and positions the relief valve. ing.

[Brief explanation of drawings]

Fig. 1 (fl) and <b) are diagrams showing the configuration of a conventional fuel injection pump, Fig. 2 is a sectional view of J showing an embodiment of the fuel injection pump according to the present invention, and Fig. 3 is a sectional view of other main parts. FIG. 4 is a perspective view showing the external appearance of the operation engine 17 of the same embodiment, and FIG. 5 is a cross-sectional view showing the electrical control system of the same embodiment. 6 is a circuit configuration diagram showing an example of the Renley circuit in FIG. 5, FIG. 7 is a J-sectional view showing another embodiment of the present invention, and FIG. 8 is a circuit diagram showing another embodiment of the present invention. 29.50.60...Relief valves 32a, 321
1.51a, 51b, 64... Electric bridge ring 3/Ia, 3411.52a, 52b, 62...
・Operating position sensor /13... Sensor circuit 1JI revision Applicant: Nissan Motor Co., Ltd.

Claims (1)

[Claims] (1) Adjust the operating device of the relief valve to release residual fuel into a predetermined cavity (in a fuel injection pump that controls the fuel injection interval; a capacitance type device that detects the operating position of the relief valve) A fuel injection pump characterized by being equipped with a potentiometer.