JPS5949365A - Discharge amount adjusting device in fuel injection pump - Google Patents

Abstract

PURPOSE:To simplify the structure of a discharge adjusting device, by directly displacing a valve member by means of a permanent magnet and energizing current for electro-magnet coils so that, even when one of the electro-magnet coils fails, the other one thereof is energized to displace the valve member. CONSTITUTION:A sleeve valve 30 in which magnetic pole pieces 32a, 32b are secured to both end faces of a permanent magnet 31, is alidably fitted onto the outer periphery of a plunger 3 in the axial direction thereof. A cover yoke 35 which is secured to an outer casing 17 by means of screws, surrounds a pair of cylindrical electo-magnet coils 33, 34 arranged to face the outer periphery of the sleeve 30. A magnetic stay 36 secured to the pole piece 32a, is projected outward, radially of the plunger 3, and a magnetic position sensor 37 is attached to a bracket 17b in the position corresponding to the front end of part of the stay 36. A detection signal from the position sensor 36 is used as a feed-back signal. During the adjustment of discharge amount, if the wire of the electro- magnet coil 33 is broken in the energizing condition of the electro-magnet coils 33, 34, the sleeve valve 30 is successively displaced in the direction B since the electro-magnet coil 34 is energized with the same polarity as that of the coil 33.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge amount adjusting device for adjusting the fuel discharge amount of a fuel injection pump in a diesel engine or the like.

As a conventional fuel injection pump discharge amount adjusting device, there is one shown in FIGS. 1(a) and 1(b), as described in, for example, Japanese Patent Publication No. 55-31307.

That is, this fuel injection pump 1 has a plunger 3 that performs axial reciprocating movement and rotational movement by 20 rotations of a cam disk connected to the drive shaft of the engine. When the plunger 6 moves to the left and the suction vertical groove 4 coincides with the fuel inflow passage 5, fuel is sucked into the operating space 6 of the plunger 6.

Next, in the discharge stroke, the plunger 3 moves to the right to pressurize the inhaled fuel, and the pressurized fuel passes through the vertical passage 7, and when the discharge vertical groove 8 coincides with the discharge passage 9, the plunger 3 moves to the right side and pressurizes the sucked fuel. The fuel is discharged through the exhaust valve 10 to the injection valve (not shown) of the corresponding cylinder.

In this case, the discharge of the injection pump is completed by releasing the fuel in the operating space 6 of the pump to the space inside the pump outer casing via the fuel escape passage 11 provided in the plunger B. Open the cylindrical valve member (slidably fitted around the outer periphery of the plunger B).
The displacement of the sleeve valve 12 in the axial direction adjusts the amount of fuel discharged.

In this conventional example, the mechanism for operating the valve member 12 consists of an electromagnet having two coils 14 and 15 wound around an iron core 16 having a cylindrical gap, and an outer casing mounted by a rotating shaft 16 within the gap. A torque motor consisting of a rotating permanent magnet 18 rotatably supported by a magnet 17 is used.

A fan-shaped piece 19 is attached eccentrically to the lower end of the rotating shaft 16 of the torque motor, and a spherical retaining piece 20 fixed eccentrically from the central axis of the fan-shaped piece 19 is attached to the hole 20 of the valve member 12.
The rotary permanent magnet 18 is fitted into the valve member 12 so that the rotational movement of the rotating permanent magnet 18 is transmitted to the valve member 12 to cause the valve member 12 to be displaced in the axial direction.

The electromagnetic coil 14 , 15 is connected via an amplifier 22 to an output of a control device 26 . This control device 26
The operating parameters (operating conditions) of the internal combustion engine include, for example, an engine rotation speed signal from a rotation speed sensor 25, an accelerator pedal position signal from an oscillator 26, and other intake pipe negative pressure (not shown).

A signal relating to engine temperature or ambient temperature is given as an input, and a current corresponding to these operating parameters is supplied via an amplifier 22 to rotate the rotating permanent magnet 18 with a corresponding operating force.

The rotation sensor 25 is arranged facing a toothed disk 24 attached to the drive shaft of the engine, and generates a voltage proportional to the engine rotation speed from an induction coil 251) wound around a magnet 25a, and controls it. input to device 26;

Further, a position sensor 27 that generates a feedback signal for controlling the position of the valve member 12 controls the rotation of the rotating permanent magnet 18 from the cam plate 29 . The rod 27a and the spring 271) convert the linear displacement of the ferrite magnetic core 27C into two inductance coils 27d, which are supplied with power from the oscillator 28.
, 27e, the position of the valve member 12 is indirectly detected.

However, in such a conventional fuel injection pump discharge amount control device, a torque motor is used to displace the valve member 12, and the torque is applied to the rotation shaft 16. Since the signal is transmitted to the valve member 12 through members such as the eccentric fan-shaped piece 199 and the spherical retaining piece 20, the mechanism is complicated and mechanical errors occur between each member, making it difficult to perform highly accurate adjustment. could not.

Furthermore, if the torque motor fails, the valve member 12 cannot be displaced (therefore, the amount of fuel discharged remains high and there is a risk that the engine may run out of control).

This invention has been made in view of the above points, and an object of the present invention is to simplify the structure of the discharge amount adjusting device in the above-mentioned fuel injection pump, reduce costs, improve adjustment accuracy, and improve safety. With the goal.

Therefore, in the fuel injection pump discharge amount adjusting device according to the present invention, the above-mentioned cylindrical valve member (sleeve valve) for adjusting the discharge amount is constituted by a cylindrical permanent magnet or integrally with a cylindrical permanent magnet. A pair of electromagnetic coils are provided on the outer periphery of the valve member, facing each other at a distance, and the excitation current of the pair of electromagnetic coils is changed in relation to the operating parameters (operating conditions) of the internal combustion engine to transmit driving force to the valve member. In addition to directly displacing the valve member without using a mechanism, even if one of the pair of electromagnetic coils fails, the other electromagnetic coil can be energized to displace the valve member.

Embodiments of the present invention will be described below with reference to FIG. 2 and subsequent figures.

FIG. 2 is a longitudinal sectional view of a discharge amount adjusting device portion of a fuel injection pump showing an embodiment of the present invention, and parts corresponding to those in FIG. Their explanation will be omitted.

In this embodiment, the sleeve valve 60, which is a cylindrical valve member that opens and closes the fuel escape passage 11 provided in the plunger B, has a ring-shaped pole piece 32a made of a magnetic material on both end surfaces of a cylindrical permanent magnet 31. , 32b', and is fitted to the outer periphery of the plunger B so as to be slidable in the axial direction.

The permanent magnet 61 of this sleeve valve 60 is, for example, the left pole piece 32a'k N pole and the right pole piece 3 in the figure.
It is magnetized to make it 2bffiS pole.

On the other hand, in order to displace this sleeve valve 30 from side to side,
A pair of cylindrical electromagnetic coils 33 and 34 are provided on the outer periphery of this sleeve valve 60, facing each other with an interval, and the outer periphery is surrounded by an outer yoke 65 that serves as a magnetic path and protection for the coil. It is fixed to section 17 with screws.

The sleeve valve 30 made of the permanent magnet 61 and the pair of left and right electromagnetic coils 33 and 34 constitute the main part of the discharge amount adjusting device.

In addition, a magnetic stay 66 is fixed to the pole piece 328 of the sleeve valve 60 so as to protrude outward in the radial direction of the plunger B, and the displacement of the sleeve valve 60 is detected in a non-contact manner by facing the tip of the magnetic stay 66. A position sensor 67, which is a magnetic sensor, is attached to a bracket 17b that is integrated with the outer casing 17.

The detection signal from this position sensor 36 is then used as a feedback signal. Note that 68 is a plunger spring, and 39 is a spring receiving plate.

FIG. 3 is a block diagram showing a drive control circuit of this discharge amount adjusting device.

Reference numeral 41 denotes a high frequency generation circuit, which outputs a high frequency rectangular wave signal for operating the first drive circuit 50 and the second drive circuit 51.

42 is a triangular wave generation circuit that outputs a triangular wave signal, 46 is a command circuit that outputs a target value signal for the sleeve valve 60, and 44 is a position detection circuit including the position sensor 67 shown in FIG. 2, which detects the actual sleeve valve position. outputs the real value signal.

Reference numeral 45 denotes a deviation amplification circuit, which outputs a deviation signal corresponding to the deviation between the target value signal SO from the command circuit 46 and the actual value signal SF from the position detection circuit 44.

46 is a comparison circuit which compares the triangular wave signal of the triangular wave generating circuit 42 and the deviation signal of the deviation amplifying circuit 45, and converts the deviation signal into a pulse signal having a pulse width corresponding to the magnitude of the deviation at a predetermined period. It acts as a converting pulse width modulation circuit.

47 is an AND circuit, which performs an AND operation between the output of the comparator circuit 46 and the high frequency rectangular wave signal from the high frequency generation circuit 41, and outputs a driving signal.

48 is a comparison circuit that compares the magnitude of the target value signal So from the command circuit 46 and the actual value signal SF from the position detection circuit 44.

49 is a selection circuit which selects the drive signal A from the AND circuit 47 according to the output from the comparison circuit 48. selectively applied to the second drive circuit 50.51 and the electromagnetic coil 33.
The direction of the excitation current applied to 34 is controlled.

FIG. 4 shows this selection circuit 49 and the first . Second drive circuit 50
,51. 2 is a circuit diagram showing a specific example of a comparison circuit 48. FIG.

The comparison circuit 48 sets the output to a low level ``L'' when the target value SO is larger than the actual value SF, and sets the output to a high level ``H#'' when the target value So is smaller than the actual value 5 prp.

The selection circuit 49 is constituted by a changeover switch circuit consisting of a pair of analog switches whose ON and OFF states are reversely controlled, for example, by the output of the comparison circuit 48, and receives the driving signal A from the AND circuit 47 in FIG. -i output line B or C
Switch to output.

The first drive circuit 50 has transistors Trz and 2, and the second drive circuit 51 has transistors Tr3 and Tr4, which form a bridge circuit so that excitation current flows in the opposite direction to the electromagnetic coils 33 and 34 connected in parallel. .

Next, the operation of this embodiment will be explained with reference also to FIGS. 5 and 6.

Now, the command circuit 46 determines the position of the sleeve valve 60 that provides the optimum fuel discharge amount according to the operating parameters (operating conditions) of the engine, such as engine speed, accelerator pedal position, intake pipe negative pressure, engine power level, etc. When the target value is output, the sleeve valve 60 is initially at the left end position and the actual value signal SF from the position detection circuit 44 is 0, so the output of the deviation amplification circuit 45 becomes large and the comparison circuit The output of 48 is Q
It becomes L I+.

In this case, the selection circuit 49 outputs the drive signal A to the output line B, and the transistor Tr1 of the first drive circuit 50
．． When the Trz is turned on and actually turns on and off repeatedly due to high-frequency pulses), excitation current is applied to the electromagnetic coil 36°64 in the direction shown by the solid arrow in Fig. 4, and as shown in Fig. 5 (
As shown in b), S poles are generated in adjacent parts and N poles are generated at the outer ends.

Thereby, the sleeve valve 30 receives a force so as to be displaced in the direction of the arrow A, and moves to the right in the axial direction of the plunger B.

When the sleeve valve 30 reaches the target position, the actual value signal from the position detection circuit 44 matches the target value signal, so the output of the deviation amplification circuit 45 becomes 0.1. Since the drive signal A is no longer output, the selection circuit 49 selects the first. Second
No activation signal is output to the drive circuits 50, 51 (and no excitation current flows to the electromagnetic coils 63, 34).

On the other hand, if the sleeve valve 30 moves too far to the right in the figure than the target value, the actual value signal SF from the position detection circuit 44 becomes thicker than the target value signal SO (9, the output of the comparison circuit 48 becomes ′
Since it becomes H#, the selection circuit 49 outputs the 1 drive signal Ai to the output line C according to the deviation.

Therefore, the transistor Tr+ of the second drive circuit 51,
Tr4 is turned on, and excitation current is passed through the electromagnetic coils 33 and 34 in the directions shown by the broken line arrows in FIG.
As shown in b), N poles are generated in adjacent portions and S poles are generated at the outer ends.

As a result, the sleeve valve 30 receives a force so as to be displaced in the direction of the arrow B, and moves to the left in the axial direction of the plunger B.

In this way, by controlling the position of the sleeve valve 60 so that it is always at the target value, the fuel discharge amount can be adjusted to the optimal amount with respect to the operating parameters of the engine.

By the way, during such a discharge amount adjustment operation, for example, the fifth
If the first electromagnetic coil 66 has a failure such as disconnection while the electromagnetic coils 33 and 34 are being excited as shown in Figure (B), the second electromagnetic coil 64 will be activated as shown in Figure 6 (I). ), the sleeve valve 60 can be continuously displaced in the direction of arrow B.

Further, when the second electromagnetic coil 64 fails, the first electromagnetic coil 64
Since the electromagnetic coil 63 is excited with the polarity shown in FIG. 6(b), the sleeve valve 30 can still be displaced in the direction of arrow B.

As shown in FIG. 5(a), even if one of the electromagnetic coils 33, 34 is disconnected while the electromagnetic coils 33, 34 are energized, the sleeve valve 60 will continue to be operated by the remaining electromagnetic coil only. It can be displaced in the direction indicated by A.

In this way, when either one of the pair of electromagnetic coils 36, 34 fails, the sleeve valve 30 can be continuously displaced only by the other electromagnetic coil, so that excessive fuel continues to be discharged and the engine goes out of control. There is no fear that it will.

In addition, if one of the electromagnetic coils 33 or 34 has a failure such as a disconnection, it will be detected and the other electromagnetic coil will be energized as shown in Figure 6 (a) or (b) to remove the sleeve. The valve 30 may be displaced in the direction of opening the fuel relief passage 11 of the plunger B to stop the discharge of fuel.

FIG. 7 shows a sleeve valve according to another embodiment of the invention.

This sleeve valve 60 has a cylindrical non-magnetic material 67 in the part that directly comes into sliding contact with the plunger B, a cylindrical permanent magnet 61 is integrally fitted on its outer periphery, and ring-shaped pole pieces 32 a are attached to both end surfaces of the sleeve valve 60 . 32b is fixed.

In this way, even if the plunger 6 is made of a magnetic material, a closed magnetic path will not be formed between the two poles of the permanent magnet 610, so the thrust force for displacing the sleeve valve 30 can be increased, and responsiveness can be improved.

FIG. 8 shows still another embodiment of the present invention, in which a compression coil spring 52 is interposed between the right pole piece and the plunger storage member 17a in the sleeve valve 300 view.
The repulsive force biases the sleeve valve 60 in the direction of opening the fuel escape passage 11 provided in the plunger B (leftward in the figure).

In this way, even if both of the pair of electromagnetic coils 33 and 34 fail, the sleeve valve is displaced to the left by the biasing force of the spring 68, opening the fuel escape passage 11 and allowing fuel to escape into the pump space. Discharge can be stopped.

As explained above, the fuel injection pump discharge rate adjusting device according to the present invention has a simple structure and low cost because the valve member for adjusting the discharge rate is directly displaced by the electromagnetic force generated by the permanent magnet and the electromagnetic coil. You can measure the reduction and improve the adjustment accuracy.

Furthermore, even if one of the pair of electromagnetic coils fails, the excitation current can be passed through the other electromagnetic coil to control the valve member, which improves safety.

[Brief explanation of the drawing]

FIGS. 1A and 1B are a configuration diagram and a sectional view of a main part of a conventional fuel injection pump discharge amount adjusting device. FIG. 2 is a vertical cross-sectional view of the discharge amount adjusting device portion of a mode-specific injection pump showing an embodiment of the present invention, FIG. 6 is a block diagram showing the same drive control circuit, and FIG. 4 is the same (Circuit diagram showing a specific example of the main part, Part 5
6 are explanatory diagrams showing the relationship between the excitation polarity of the electromagnetic coils 33 and 34 and the displacement direction of the sleeve valve 60, also for explaining the operation thereof. FIG. 7 is a sectional view showing a sleeve valve according to another embodiment of the invention. FIG. 8 is a sectional view similar to FIG. 2 showing still another embodiment of the invention. 2...Cam disc 3...Plunger 11...Fuel relief passage 17...Curved outer housing portion 60...Sleeve valve (valve member) 61...
... Permanent magnet 33, 34 ... Electromagnetic coil 35 ... Field 37 ... Position sensor Fig. 4 - 413 - Fig. 5 Fig. 6 (a) (B)

Claims (1)

[Scope of Claims] 1. Timing of opening the fuel relief passage during the fuel discharge stroke of the plunger by displacing a cylindrical valve member provided in the plunger of the fuel injection pump in the axial direction of the plunger, which closes the fuel relief passage. In the discharge amount adjusting device that adjusts the discharge amount of fuel by changing the amount of fuel, the valve member is formed of a cylindrical permanent magnet or is formed integrally with a cylindrical permanent magnet, and the valve member is configured with a cylindrical permanent magnet that faces the outer periphery of the valve member at a distance. a pair of electromagnetic coils configured to directly displace the valve member by varying the excitation current of the pair of electromagnetic coils in relation to operating parameters of the internal combustion engine; 1. A discharge amount adjusting device for a fuel injection pump, characterized in that even when the valve member malfunctions, the other electromagnetic coil can be energized to displace the valve member. 2. The discharge amount adjusting device for a fuel injection pump according to claim 1, wherein the valve member is formed by integrally fitting a cylindrical permanent magnet to the outer periphery of a cylindrical non-magnetic material. 6. Claim 1, wherein a spring is interposed between the valve member and the plunger storage member to bias the valve member in a direction to open a fuel escape passage provided in the plunger.
The discharge amount adjusting device for a fuel injection pump according to item 1 or 2.